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86120B User Manual - Custom-Cal

1. CAUTION Getting Started Step 2 Connect the Line Power Cable Step 2 Connect the Line Power Cable This is a Safety Class 1 Product provided with protective earth The mains plug shall only be inserted in a socket outlet provided with a protective earth contact Any interruption of the protective conductor inside or outside of the instrument is likely to make the instrument dangerous Intentional interruption is prohibited Always use the three prong AC power cord supplied with this instrument Failure to ensure adequate earth grounding by not using this cord may cause instrument damage Do not connect ac power until you have verified the line voltage is correct as described in the following paragraphs Damage to the equipment could result This instrument has autoranging line voltage input Be sure the supply voltage is within the specified range Verify that the line power meets the requirements shown in the following table Line Power Requirements Voltage max 100 115 230 240 V Frequency 50 60 Hz Connect the line power cord to the instrument s rear panel connector Connect the other end of the line power cord to the power receptacle 14 Getting Started Step 3 Connect a Printer Various power cables are available to connect the Agilent 86120B to ac power outlets unique to specific geographic areas The cable appropri ate for the area to which the Agilent 86120B is originally shippe
2. Laser Line Selection Cursor Power Bars Position of 15H5 435nm 1H8 5dBm Selection 1548 084 9 46 SE Pub rem 1549 695 T 81 mmu t OF 1551 31M b 92 Perr Wa 1552 933 10 30 a m 77 Medium for Sottkeys L_2 _ Leek cee listwl Display after List by WL key pressed Also notice that power bars graphically show the relative power levels between laser lines To display multiple laser lines 1 Connect the fiber optic cable to the front panel OPTICALINPUT connector 2 Press the green Preset key 3 Press List by WL to display the laser lines from the shortest wavelength 40 Using the Multi Wavelength Meter Displaying Wavelength and Power to the longest wavelength Press List by Powerto display the laser lines in order of decreasing amplitudes Total power and average wavelength In the third available display mode the Agilent 86120B displays the average wavelength as shown in the following figure The displayed power level is the total input power to the instrument It is the sum of the powers of each laser line it is not a measure of the average power level of the laser lines 1549 6380n l 51las times The following equation shows how individual wavelengths of laser lines are summed together to obtain the average wavelength value where n is the number of laser lines included in the average P is the peak power of an indivi
3. Used With lt expected_value gt lt resolution gt SCALar optional ignored ARRay ignored ignored When used with a SCALar command a single value is returned The display is placed in the single wavelength mode and the marker is placed on the signal having a power level that is closest to the expected value parameter When used with an ARRay command an array of amplitudes is returned The display is placed in the list by power mode Returned values are in the current power units Wavelength units are not affected CONFigure command When this function is used with the CONFigure command the query question mark character must not be included in the string However the FETCh READ and MEASure command are queries and require the question mark Refer to the examples for this command MAXimum Displays the highest power signal MINimum Displays the lowest power signal DEFault Displays the signal at the current marker position 146 Examples Query Response Programming Commands Measurement Instructions CONFARR POW FETC ARR POW READ ARR POW MEAS ARR POW CONF SCAL POW 10 dBm FETC SCAL POW MAX READ SCAL POW MIN MEAS SCAL POW DEF The following line is an example of a returned string when MEAS SCAL POW MAX is sent 5 88346500 000 If six laser lines are located MEAS ARR POW is sent the follow ing string could be returned Notice that the first returned numbe
4. Query Error Not Used OPC Operation Complete 133 Example Syntax Description Query Response Example Syntax Description Programming Commands Common Commands OUTPUT 720 ESR ENTER 720 Event PRINT Event IDN The IDN identification number query returns a string value which identifies the instrument type and firmware version IDN An IDN query must be the last query in a program message Any queries after the IDN query in a program message are ignored The maximum length of the identification string is 50 bytes The following identification string is returned The third entry is the instrument s serial number The last entry in the string is the firmware version number this value may vary between instruments HEWLETT PACKARD 86120B USaaaabbbb 2 000 DIM 19 150 OUTPUT 720 IDN ENTER 720 1d PRINT 19 OPC The OPC operation complete command sets the operation complete bit in the event status register when all pending device operations have finished OPC OPC The OPC query places an ASCII 1 in the output queue when all pending device operations have finished 134 Query Response Example Syntax Description Programming Commands Common Commands This command is useful when the computer is sending commands to other instruments The computer can poll the event status register to check when the Agilent 86120B has completed the operati
5. 49 Peak threshold limit Using the Multi Wavelength Meter Defining Laser Line Peaks Defining Laser Line Peaks The Agilent 86120B uses two rules to identify valid laser line peaks Understanding these rules is essential to getting the most from your measurements For example these rules allow you to hide AM modu lation sidebands or locate laser lines with small amplitudes In order to identify a laser line the laser line must meet both of the following rules Power must be greater than the power established by the peak threshold limit Power must rise and then fall by at least the peak excursion value In addition the input wavelength range can be limited as described in this section The peak threshold limit is set by subtracting the peak threshold value from the power of the largest laser line So if the largest laser line is 2 dBm and the peak threshold value is 10 dB the peak threshold limit is 8 dBm 8dBm 2dBm 10dB You can set the peak threshold value between 0 to 40 dB The peak threshold s default value is 10 dB This ensures that any modulated signals being measured are not confused with their AM sidebands For unmodulated lasers or Fabry Perot lasers it may be desirable to increase this threshold to look for responses that are more than 10 dB from the peak Peak threshold can be used to suppress spurious signals For example a laser that is amplitude modulated in the audio frequency range can c
6. FNidentity ON TIMEOUT 7 5 CALL Err mngmt Cmd_opc RST Change to list by wavelength display Cmd_opc CONF ARR POW WAV Trigger and wait for one measurement Cmd_opc INIT Cmd_opc WAI Turn on delta mode Cmd opc CALC3 DELT WPOW STAT ON Set first wavelength as reference Cmd_opc CALC3 DELT REF WAV MIN Query number of data points OUTPUT Mwm CALC3 POIN ENTER Mwm USING K Nb_pt ALLOCATE Delta wl 1 Nb pt ALLOCATE Delta pwr 1 Nb pt Query wavelengths and powers OUTPUT Mwm CALC3 DATA WAV ENTER Mwm Delta wl OUTPUT Mwm CALC3 DATA POW ENTER Mwm Delta_pwr OFF TIMEOUT FOR 1 1 TO Nb_pt 1 PRINT USING 6A 2D 17A M4D 3D 31A S2D 2D 4A Line 1 wavelength is 115 Programming Example Programs Delta wl I NOT I 1 Delta_wl 1 1 0E 9 nm Absolute line level is Delta_pwr l NOT I 1 Delta_pwr 1 dBm PRINT USING 17A 2D 6A M4D 3D 23A 2D 6A S2D 2D 3A Delta WI to line I 1 is Delta wl I 1 NOT I21 Delta wl I 1 E 9 nm Delta Pwr to line I 1 is I 1 Delta_pwr I 1 NOT I 21 Delta pwr I 1 Delta pwr l dB NEXT I PRINT USING 6A 2D 17A M4D 3D 31A S2D 2D 4A Line l wavelength is Delta wlI 1 Delta wl Nb pt 1 0E 9 nm Absolute line level is Delta pwr 1 Delta pwr Nb pt D Error msg PRINT The program is aborted due to ERRMS END Err_mngmt SUB Err_mngmt OPTIONAL Cmd_msg COM Instrument Mwmt D
7. form is then curve fit into a decaying exponential Refer to To measure coherence length on page 76 When the SCALar command is used data for a single measurement value is returned When the ARRay command is used multiple data values are returned The MEASure measurement instruction always acquires new measure ment data In order to obtain both wavelength and power values from the same measurement data use two FETCh commands This is shown in the following program fragment OUTPUT 720 INIT CONT OFF OUTPUT 720 CONF ARR POW MAX OUTPUT 720 INIT IMM OUTPUT 720 FETC ARR POW ENTER 720 powers OUTPUT 720 FETC ARR POW WAV ENTER 720 wavelengths In the example above the data in the power and wavelength arrays are returned in the same order so that powers can be matched to wavelengths You can also send a MEASure command followed by a FETCh command 144 Programming Commands Measurement Instructions The commands in this subsystem have the following command hierar chy MEASure READ FETCh CONFigure ARRay SCALar POWer FREQuency WAVelength WNUMber SCALar LENGth COHerence ALPHa BETA CLENgth DELay 145 Syntax Description lt expected_value gt Constants Programming Commands Measurement Instructions MEASure ARRay SCALar POWer Returns amplitude values POWer lt expected_value gt lt resolution gt
8. mental because the amplitude correction at 775 nm is much greater by about 15 dB than that at 1550 nm the interferometer is less sensitive at 775 nm To avoid displaying this second harmonic line limit the input wavelength range from 1200 nm to 1650 nm Or reduce the peak threshold below its preset value Because the peak threshold level is used to determine which signals are to be displayed before amplitude cor rections are applied the harmonic will be eliminated To define laser line peaks 1 Press the Setup key 52 wo N Using the Multi Wavelength Meter Defining Laser Line Peaks Press the THRSHLD softkey Press PX EXC and enter the peak excursion value Use the softkey to select the digit that requires editing Use the and softkeys to change the value The peak excursion value can range from 1 to 30 dB The default value is 15 dB Press RETURN Press PK THLD and then enter the peak threshold value The peak threshold value can range from 0 to 40 dB Setting this value to 0 dB ensures that only the peak wavelength is identified The default value is 10 GB Pressing the green PRESET key changes the peak excursion and peak threshold values to their default settings It also turns wavelength range limiting on Turning the Agilent 86120B s power off and then on does not change these settings If too many lines are identified If the following message is displayed too many lase
9. 69 non sequential command 90 159 164 165 166 167 168 169 170 171 172 202 217 218 NORMAL softkey 48 87 204 notation definitions 130 Index 266 NTRansition programming command 208 NUM LINES lt NUM REFS 74 NUM LINES gt NUM REFS 74 numbers 103 0 Off key 56 menu map 249 On key 56 menu map 249 OPC 107 131 134 OPTICAL INPUT connector 6 17 49 output queue 99 105 packaging for shipment 33 PARALLEL PRINTER PORT connector 15 64 parameters adding 103 PEAK annotation 38 softkey 39 70 peak definition of 50 excursion 44 51 power 3 39 threshold limit 50 53 59 wavelength 3 39 Peak WL key 38 menu map 250 softkey 39 74 performance tests 220 PEXCursion programming command 163 PK EXC softkey 53 PK THLD softkey 53 POINts programming command 159 164 190 polarization dependence 234 236 power bar 4 38 46 maximum input 4 maximum measurable 36 measuring total 41 162 165 peak 39 separation 54 Index state when turned on 213 244 tuning laser 38 POWer programming command 146 179 218 POWER softkey 48 PRBS 59 69 Preset conditions set by 213 244 key 36 44 82 menu map 250 PRESet programming command 178 187 210 213 PREV PK softkey 39 PREV WL softkey 39 PREVious programming command 197 Print key 63 menu map 251 printer cable 15 connecting 15 output 63 programming 80 command notation convention 130
10. A fast update measurement mode is avail able for quicker measurement acquisition But because only 8 192 data values are collected in fast update measurement mode the ability to resolve closely spaced signals is reduced 83 Programming Making Measurements After collecting the uncorrected data the Agilent 86120B searches the data for the first 100 peak responses Searching starts at 1700 nm and progresses towards 700 nm for WLIMit OFF If WLIMit is on searching starts at WLIMit STARt to WLIMit STOP These peak values are then placed into the corrected data buffer Each peak value con sists of an amplitude and wavelength measurement Amplitude and wavelength correction factors are applied to this data CALCulate2 WLIMit SENSe CORRection ELEVation PTHreshold MEDium PEXCursion OFFSet MAGNitude Corrected data buffer 100 pairs of selection A and amplitude Display values DISPlay WINDow UNIT CALCulate2 DATA CONFigure POINts DISPlay MARKer PWAVerage CALCulate3 DELTa CALCulate3 DATA DRIFt FETCH SNR READ MEASure flow2 For a listing of the programming commands including a cross refer ence to front panel keys refer to the following tables Table 4 10 Programming Commands on page 121 Table 4 11 Keys Versus Commands on page 126 84 Programming Making Measurements Commands are grouped in subsystems The Agilent 86120B commands are grouped in
11. INTEGER Cme CLEAR Mwm REPEAT OUTPUT Mwm ESR ENTER Mwm Cme OUTPUT Mwm SYST ERR ENTER Mwm Err_msg IF NPAR gt 0 AND NOT POS Err_msgS 0 THEN PRINT This command Cmd msg makes the following error IF NOT POS Err_msg 0 THEN PRINT Err_msg UNTIL NOT BIT Cme 2 AND NOT BIT Cme 4 AND NOT BIT Cme 5 AND POS Err msg 0 Subend SUBEND Set_ese SUB Set ese COM Instrument Mwm OUTPUT Mwm ESE IVAL 00110100 2 SUBEND Identity DEF FNIdentity COM Instrument Mwm DIM IdentityS 50 IdentityS OUTPUT Mwm RST OUTPUT GMwm 0PC ENTER Mwm pc done OUTPUT GMwm IDN ENTER GMwm ldentity RETURN IdentityS FNEND Cmd opc SUB opc Set cmd COM Instrument Mwm OUTPUT Mwm Set_cmd OUTPUT GMwm OPC ENTER Mwm 0pc_done SUBEND Tempo SUB Tempo Temp FOR Iz Temp TO 0 STEP 1 DISP Waiting for VALS I sec WAIT 1 NEXT I DISP SUBEND 114 Programming Example Programs Example 4 Measure WDM channel separation This program measures the line separations on a WDM system It mea sures separation delta between power and wavelength of each line using commands from the CALCulate3 subsystem Refer to the introduction to this section for a description of each sub routine that is contained in this program COM Instrument Mwm ASSIGN Mwm TO 720 DIM Key 1 ON ERROR GOTO Error msg Set ese PRINT USING 37A 33A Multi Wavelength Meter Identity is
12. L LIST ORT a Contact us for your service needs Phone 888 530 9009 Email sales custom cal com Custom Calibration Solutions LLC Agilent HP 86120B User Manual Custom Cal has in depth experience having repaired over 1000 86120 s with a success rate of over 99 Our typical repair time is less than 5 business days as we have most replacement parts in stock We repair the E14 error using NEW original manufacturer parts which come with a one year manufacturer warranty which we will extend for three years We don t use refurbished or cheap generic parts Agilent 86120B Repair E14 E7 E4 E34 Agilent 86120B Multi Wavelength Meter User s Guide GE Agilent Technologies Notices This document contains propri etary information that is pro tected by copyright All rights are reserved No part of this document may reproduced in including elec tronic storage and retrieval or translation into a foreign lan guage without prior agreement and written consent from Agilent Technologies Deutschland GmbH as governed by United States and international copywright laws Copyright 2001 2003 by Agilent Technologies Deut schland GmbH Herrenberger Str 130 71034 Boblingen Germany Subject Matter The material in this document is subject to change without notice Agilent Technologies makes no warranty of any kind with regard to this printed material includ ing but not limited to the implied warranti
13. Turn Off Wavelength Limiting After the Preset key is pressed the input wavelength range is limited to measuring lasers between 1200 nm and 1650 nm You can easily expand the input range to the full 700 nm to 1650 nm range with the following steps Press the Preset key Press the Setup key Press the WL LIM softkey Press LIM OFFto remove the limits on wavelength range All responses in the full 700 nm to 1650 nm range are now displayed 20 Getting Started Cleaning Connections for Accurate Measurements Cleaning Connections for Accurate Measurements Today advances in measurement capabilities make connectors and connection techniques more important than ever Damage to the con nectors on calibration and verification devices test ports cables and other devices can degrade measurement accuracy and damage instru ments Replacing a damaged connector can cost thousands of dollars not to mention lost time This expense can be avoided by observing the simple precautions presented in this book This book also contains a brief list of tips for caring for electrical connectors Choosing the Right Connector A critical but often overlooked factor in making a good lightwave mea surement is the selection of the fiber optic connector The differences in connector types are mainly in the mechanical assembly that holds the ferrule in position against another identical ferrule Connectors also vary in the polish curve and conc
14. command sets the bits in the service request enable register SRE integer SRE lt integer gt is defined as an integer mask from 0 to 255 The service request enable register contains a mask value for the bits to be enabled in the status byte register A bit set to one in the service request enable register enables the corresponding bit in the status byte register to generate a service request A zero disables the bit The fol lowing table lists the bits in the service request enable register and what they mask 139 Query Response Example Programming Commands Common Commands The service request enable register is cleared when the instrument is turned on The RST and CLS commands do not change the register The SRE query returns the value of the service request enable regis ter Table 5 16 Service Request Enable Register Bit Bit Weight Enables 7 128 Not Used 6 64 Not Used 5 32 Event Status Bit ESB 4 16 Message Available MAV 3 8 Not Used 2 4 Error queue status 1 2 Not Used 0 1 Not Used a High enables the status byte register bit lt integer gt from 0 to 63 or from 128 to 191 OUTPUT 720 SRE 32 In this example the command enables ESB event summary bit 5 in the status byte register to generate a service request 140 Syntax Description Query Response Example Programming Commands Common Commands STB The STB status byte query returns the cur
15. equivalent softkeys 126 examples See example programs list of commands 121 measurement instructions 144 PTRansition programming command 209 PWR BAR softkey 46 PWR OFS annotation 60 softkey 60 A PWR softkey 57 0 queries 105 multiple 105 queues 99 radiation exposure 6 17 range wavelength 82 166 range wavelengths 42 READ measurement instruction 144 rear panel labels 242 regulatory duration 232 Index 267 Index Remote annotation 81 repetitive data formats 69 RESet programming command 187 RESET softkey 57 74 75 return loss 234 237 returning data 105 returning for service 32 RF modulation 59 RIGHT programming command 197 RST 82 107 136 S S N AUTO annotation 67 S N softkey 69 S N USER annotation 67 safety 6 7 17 laser classification 7 sales and service offices 261 SCALar programming command 144 SCPI standard commands for programmable in struments standard 80 syntax rules 101 second harmonic distortion 52 SELECT softkey 40 55 selectivity 234 237 semicolon 101 sending common commands 103 SENSe subsystem 200 sensitivity 234 236 serial number instrument 13 service 32 request enable register 98 139 returning for 32 sales and service offices 261 Set ese subroutine 106 settings conflict error 92 166 176 178 182 183 185 186 188 189 195 257 Setup key 20 43 46 81 menu map 252 shipping procedure 33 short form c
16. for up to 20 seconds This query will generate a Settings conflict error if the instrument is in either the coherence length or the signal to noise average applica tion 158 Syntax Attribute Summary Description Programming Commands CALCulate1 Subsystem TRANsform FREQuency POINts Sets the size of the fast Fourier transform FFT performed by the instrument CALCulate1 TRANsform FREQuency POINTs lt integer gt MINimum MAXimum lt integer gt Sets FFT size Must be either 34123 or 4268 Other values result in an error Constant Description MINimum 4 268 MAXimum 34 123 Non sequential command Preset State array size set to 34 123 RST State 34 123 SCPI Compliance instrument specific A NORMAL updated display corresponds to an FFT size of 34 123 A FAST updated display corresponds to an FFT size of 4 268 These val ues are a subset of the uncorrected data buffer shown in the figure that is located in Making Measurements on page 4 83 Changing the number of points causes the instrument to reprocess the current set of data The query form of the command returns the number of points in the data set This is the number of measurement points that will be returned by the CALC1 DATA query Non sequential command Always use an OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always f
17. there tends to be reduced vigilance in connec tor care and cleaning It takes only one missed cleaning for a piece of grit to permanently damage the glass and ruin the connector Measuring insertion loss and return loss Consistent measurements with your lightwave equipment are a good indication that you have good connections Since return loss and inser tion loss are key factors in determining optical connector performance they can be used to determine connector degradation A smooth pol ished fiber end should produce a good return loss measurement The quality of the polish establishes the difference between the PC phys ical contact and the Super PC connectors Most connectors today are physical contact which make glass to glass connections therefore it is critical that the area around the glass core be clean and free of scratches Although the major area of a connector excluding the glass may show scratches and wear if the glass has maintained its polished smoothness the connector can still provide a good low level return loss connection If you test your cables and accessories for insertion loss and return loss upon receipt and retain the measured data for comparison you will be able to tell in the future if any degradation has occurred Typ ical values are less than 0 5 dB of loss and sometimes as little as 0 1 dB of loss with high performance connectors Return loss is a measure of reflection the less reflection
18. 4 6 2001 3 V 0 15 80 MHz IEC 61000 4 8 2001 EN 61000 4 8 2001 30 A m IEC 61000 4 11 2001 EN 61000 4 11 2001 1 cycle 100 Canada ICES 001 1998 Australia New Zealand AS NZS 2064 1 Safety IEC 61010 1 2001 EN 61010 1 2001 Canada CSA C22 2 No 1010 1 1992 USA UL 3111 1 1994 FDA 21CFR1040 10 Laser Notice No 50 Supplemental Information The products were tested in a typical configuration with Agilent Technologies test systems 2004 March 11 Date ns Martin Fischer Name Product Regulations Representative Title For further information please contact your local Agilent Technologies sales office agent or distributor Authorized EU representative Agilent Technologies Deutschland GmbH Herrenberger Strasse 130 D 71034 Boeblingen Germany Revision C Issue Date 2004 March 11 241 Specifications and Regulatory Information Product Overview Product Overview lent 86120A 700 1650 nm v Ag MULTI WAVELENGTH METER Front view of instrument ise Lay DELTA ME ASUR EME NT e SERIAL LABEL ban ATTACH HERE NO USER SERVICEABLE PARTS INSIDE REFER SERVICING TO QUALIFIED PERSONNEL immunem TU CFR 1040 10 AND 4041 LINE 100 115 230 240 V 5060 Hz 80 VA FUSE F6 3A 250V PARALLEL PRINTER PORT Rear view of instrument frntview rearview 242 Instrument Preset Conditions 244 Menu Maps 246 Error Message
19. 44 classification laser 6 product 7 cleaning adapters 30 263 Index cabinet 7 fiber optic connections 21 29 non lensed connectors 29 CLEAR softkey 74 CLENgth programming command 154 CLS 99 131 CM 1 softkey 48 Cmd opc subroutine 107 COH LEN softkey 76 coherence length 3 76 237 colon 103 commands combining 102 common 101 measurement instructions 101 non sequential 90 159 164 165 166 167 168 169 170 171 172 202 217 218 standard SCPI 101 termination 105 common commands CLS clear status 131 ESE event status enable 106 131 ESR event status register 133 IDN identification number 107 134 OPC operation complete 107 134 RST reset 107 136 SRE service request enable 139 STB status byte 141 TRG trigger 142 TST test 142 WAI wait 143 definition 101 sending 103 compressed dust remover 29 computer control 83 CONFigure measurement instruction 144 connector care 21 Cont key 49 74 CONT softkey 64 CONTinuous programming command 217 cotton swabs 29 covers dust 260 cursor 40 D damaged shipment 13 data corrupt or stale 104 136 257 data questionable 257 DATA programming command 156 162 177 204 DBM softkey 48 default GPIB address 81 DELay programming command 154 Delta Off softkey See Off Delta On softkey See On DEVICES softkey 44 DFB lasers 44 dispersion See calibration measurements display an
20. 50 dB Measurement Cycle Time Normal update mode characteristic Fast update mode characteristic 1 0 s 1 measurement per second 0 33 s 3 measurements per second Measurement Applications Signal to Noise channel spacing 2200 GHz characteristic Signal to noise with Averaging modulated lasers 100 averages channel spacing 2200 GHz characteristic Coherence Length characteristic gt 35 dB 0 1 nm noise bandwidth lines above 25 dBm gt 35 dB 0 1 nm noise bandwidth lines above 25 dBm Fabry Perot lasers 1 to 200 mm coherence length accuracy 5 0 75s cycle time 237 Specifications and Regulatory Information Specifications Operating Specifications Use Power Voltage Frequency Altitude Operating temperature Maximum relative humidity Weight Dimensions H x W x D indoor 70 W max 100 115 230 240 V 50 60 Hz Up to 2000 m 6600 ft 0 C to 55 C 80 for temperatures up to 31 C decreasing linearly to 50 relative humidity at 40 C 8 5 kg 19 Ib 140 x 340 x 465 mm 5 5 x 13 4 x 18 3 in 238 Specifications and Regulatory Information Laser Safety Information Laser Safety Information The light sources specified by this user guide are classified according to IEC 60825 1 2001 The light sources comply with 21 CFR 1040 10 except for deviations pursuant to Laser Notice No 50 dated 2001
21. 86120B com mands they control GPIB control lines and do not send any characters to the Agilent 86120B Initialize the instrument at start of every program It is good practice to initialize the instrument at the start of every program This ensures that the bus and all appropriate interfaces are in a known state HP BASIC provides a CLEAR command which clears the interface buffer and also resets the instrument s parser The 81 Programming Addressing and Initializing the Instrument parser is the program that reads the instructions that you send Whenever the instrument is under remote programming control it should be in the single measurement acquisition mode This is auto matically accomplished when the RST common command is used The RST command initializes the instrument to a preset state CLEAR 720 OUTPUT 720 RST Notice in the example above that the commands are sent to an instru ment address of 720 This indicates address 20 on an interface with select code 7 Pressing the green Preset key does not change the GPIB address Set single acquisition mode An advantage of using the RST command is that it sets the Agilent 86120B into the single measurement acquisition mode Because the READ and MEASure data queries expect this mode their proper operation is ensured Establish the wavelength range At the start of each program be sure to establish the input wavelength range using the Agilent 86120B s CALCulat
22. Accuracy and Linearity 227 7 Specifications and Regulatory Information Definition of Terms 233 Specifications 235 Laser Safety Information 239 Declaration of Conformity 241 Product Overview 242 7 Reference Instrument Preset Conditions 244 Menu Maps 246 Error Messages 253 Front Panel Fiber Optic Adapters 258 Power Cords 260 Agilent Technologies Service Offices 261 Step Step Step Step Step Step Step 1 2 3 4 5 6 ds Inspect the Shipment 13 Connect the Line Power Cable 14 Connect a Printer 15 Turn on the Agilent 86120B 16 Enter Your Elevation 18 Select Medium for Wavelength Values 19 Turn Off Wavelength Limiting 20 Cleaning Connections for Accurate Measurements 21 Returning the Instrument for Service 32 Getting Started CAUTION CAUTION Getting Started Getting Started Getting Started The instructions in this chapter show you how to install your Agilent 86120B You should be able to finish these procedures in about ten to twenty minutes After you ve completed this chapter continue with Chapter 2 Using the Multi Wavelength Meter Refer to Chapter 7 Specifications and Regulatory Information for information on oper ating conditions such as temperature Install the instrument so that the ON OFF switch is readily identifiable and is easily reached by the operator The ON OFF switch or the detachable power cord is the instrument disconnecting device It disconne
23. Attribute Summary Description Syntax Attribute Summary Programming Commands SENSe Subsystem CORRection MEDium Sets the Agilent 86120B to return wavelength readings in a vacuum or standard air SENSe CORRection MEDium AIR VACuum Argument Description AIR Selects wavelength values in standard air VACuum Selects wavelength values in a vacuum Preset State VAC RST State VAC SCPI Compliance instrument specific Standard air is defined to have the following characteristics Barometric pressure 760 torr Temperature 15 C Relative humidity 0 CORRection OFFSet MAGNitude Enters an offset for amplitude values SENSe CORRection 0FFSet MAGNitude lt real gt MINimum MAXimum lt real gt is the logarithmic units in dB Constant Description MINimum 40 0 dB MAXimum 40 0 dB Preset State 0 0 RST State 0 0 SCPI Compliance standard 203 Query Response Syntax Attribute Summary Description Programming Commands SENSe Subsystem The query form returns the current offset setting as shown in the fol lowing example 5 00000000E 000 DATA Queries the time domain samples of the input laser line SENSe DATA Preset State none SCPI Compliance instrument specific Query Only Be prepared to process a large amount of data when this query is sent The amount of data returned depends on the measurement update state of the instrument which is set usin
24. Codes S indicates a standard SCPI command indicates an instrument specific command CALCulate1 Subsystem CALCulate1 DATA Queries the uncorrected frequency spectrum data of the S input signal CALCulate1 TRANsform FREQuency POINts Sets and queries the number of points in the data set S CALCulate2 Subsystem CALCulate2 DATA Queries the corrected frequency spectrum data ofthe input signal CALCulate2 PEXCursion Sets the peak excursion limit CALCulate2 POINts Queries the number of points in the data set CALCulate2 PTHReshold Sets the peak threshold limit CALCulate2 PWAVerage STATe Places the instrument in the average wavelength mode Data queries return the power weighted average frequency wavelength or wavenumber or total power CALCulate2 WLIMit STATe Limits input wavelength range of the Agilent 86120B CALCulate2 WLIMit STARt FREQuency Sets the starting frequency for the wavelength limit range CALCulate2 WLIMit STARt WAVelength Sets the starting wavelength for the wavelength limit range 1 CALCulate2 WLIMit STARt WNUMber Sets the starting wavenumber for the wavelength limit CALCulate2 WLIMit STOP FREQuency Sets the stopping frequency for the wavelength limit range 1 CALCulate2 WLIMit STOP WAVelength Sets the stopping wavelength for the wavelength limit CALCulate2 WLIMit STOP WNUMber Sets the stopping wavenumber for the wavelength limit CALCulate3
25. Data Desired Measurement Command to Configure Measurement partial listing Command to Query Data Wavelength nm CONFigure FETCh READ and MEASure MEASure ARRay POWer WAVelength Frequency THz CONFigure FETCh READ and MEASure MEASure ARRay POWer FREQuency Wavenumber CONFigure FETCh READ and MEASure MEASure ARRay POWer WNUMber Coherence Length m CONFigure FETCh READ and MEASure FETCh READ or MEASure Power W dBm CONFigure FETCh READ and MEASure MEASure ARRay POWer Average Wavelength Wavenumber or Frequency CALCulate2 PWAVerage STATe CALCulate2 DATA Total Power W dBm CALCulate2 PWAVerage STATe CALCulate2 DATA Laser Line Separation CALCulate3 DELTa REFerence CALCulate3 DATA Laser Line Drift CALCulate3 DRIFt STATe CALCulate3 DATA Signal to Noise Ratio CALCulate3 SNR STATe CALCulate3 DATA Signal to Noise Ratio Average CALCulate3 ASNR STATe CALCulate3 DATA Time Domain Data CALCulate1 TRANsform FREQuency POINt s SENSe DATA Corrected Frequency Domain Data CALCulate1 TRANsform FREQuency POINt s CALCulate2 DATA Uncorrected Frequency Domain Data CALCulate1 TRANsform FREQuency POINt s CALCulate1 DATA 86 Programming Making Measurements Measurement instructions give quick results The easiest way to measure wavelength frequency po
26. Return Loss Measurement Cycle Time Specifications and Regulatory Information Definition of Terms dards laboratory of the United States Flatness refers to the maximum amplitude error in a measurement between two lines that are separated in wavelength by no more than the specified amount Linearity indicates the maximum power error in measuring the change in power of one laser line Polarization Dependence indicates the maximum displayed power variation as the polarization of the input signal is varied Display Resolution indicates the minimum incremental change in displayed power Sensitivity is defined as the minimum power level of a single laser line input to measure wavelength and power accurately A laser line with less than the min imum power may be measured but with reduced wavelength and power accu racy For multiple laser lines input sensitivity may be limited by total input power Selectivity indicates the ability to measure the wavelength and power of a weak laser line in the proximity of a specified stronger laser line and separated by the specified amount Maximum displayed level indicates the maximum total input power total of all laser lines present to accurately measure wavelength and power Maximum safe input power indicates the maximum total input power total of all laser lines present to avoid permanent optical damage to the instrument Maximum number of lines input is the maximum number of displayed line
27. SIGNALS FOUND 16 MOTOR INTERRUPT RECEIVED 253 Reference Error Messages Table 7 2 Instrument Specific Error Messages 2 of 3 Error Number Error Message 17 ROM BYTE UNERASED 18 ROM WRITE OPERATION FAILED 19 ROM DEFECTIVE 20 ROM DATA INVALID 21 ROM VERSION INCOMPATIBLE 22 ROM POLLING LIMITED OUT 23 INPUT OUT OF RANGE 24 BAD CAL ROM DATA 25 BAD CAL ROM DATA 26 BAD CAL ROM DATA 27 BAD CAL ROM DATA 28 BAD CAL ROM DATA 29 BAD CAL ROM DATA 30 NVSRAM WRITE OPERATION FAILED 31 SOFTWARE INITIALIZATION FAIL 32 HARDWARE INITIALIZATION FAIL 33 INITIALIZATION TIMEOUT 34 BATTERY FAILED 36 TOO MANY ERRORS 37 FUNCTION NOT YET IMPLEMENTED 38 PRINTER OFF LINE 39 PRINTER OUT OF PAPER 40 PRINTER ERROR DETECTED 41 PRINTER TIMED OUT 254 Reference Error Messages Table 7 2 Instrument Specific Error Messages 3 of 3 Error Number Error Message 42 43 44 45 46 47 48 49 50 51 PRINTOUT WAS ABORTED NOT ALLOWED IN COH LEN NOT ALLOWED IN S N UNKNOWN KEYPRESS NUM LINES lt NUM REFS NUM LINES gt NUM REFS NO REFERENCE SIGNAL GAIN RANGING ERROR INCOMPATIBLE HARDWARE UNKNOWN ERROR 255 Reference Error Messages Table 7 3 General SCPI Error Messages 1 of 3 Error Number Description 0 No errors 100 Command error unknown command 101 Invalid character 102 Syntax error 103 Invalid separator 104 Data type error 10
28. Specifying ARRay places the display in the List by Power or List by WL modes an array of data is returned to the computer A common programming error is to send the MEASure command when the instrument is in the continuous measurement acquisition mode Because MEASure contains an INIT IMM command which expects the single measurement acquisition mode an error is gener ated and the INIT command is ignored READ command The READ command works like the MEASure command except that it does not configure the instrument s settings You can use the CONFig ure command to configure the instrument for a particular measure ment without returning any data The MEASure and READ commands are identical to combining the fol lowing commands Command Equivalent Commands ABORt CONFigure READ READ ABORt INITiate IMMediate FETCh A common programming error is to send the READ command when the instrument is in the continuous measurement acquisition mode Because READ contains an INIT IMM command which expects the single measurement acquisition mode an error is generated and the INIT command is ignored FETCh command The FETCh command returns data from previously performed mea surements it does not initiate the collection of new data Because FETCh does not configure the instrument or acquire new input data you can use FETCh repeatedly on the same set of acquired data For example use two FETCh commands
29. Subsystem CALCulate3 ASNR CLEar Resets and restarts the signal to noise ratio averaging CALCulate3 ASNR COUNt Sets the number of measurements to average the signal to 1 noise ratio CALCulate3 ASNR STATe Turns signal to noise ratio averaging mode on and off CALCulate3 DATA Queries the data resulting from delta drift and signal to S noise measurements CALCulate3 D ELTa POWer STATe Turns the delta power measurement mode on and off CALCulate3 D ELTa REFerence FREQuency Selects the signal to be used as the reference for the DELTa calculations CALCulate3 D ELTa REFerence POWer Queries the power level of the reference signal CALCulate3 DELTa REFerence WAVelength Selects the signal to be used as the reference for the DELTa calculations 122 Programming Lists of Commands Table 4 10 Programming Commands 3 of 5 Command Description Code Codes S indicates a standard SCPI command indicates an instrument specific command CALCulate3 D ELTa REFerence WNU Mber Selects the signal to be used as the reference for the DELTa calculations CALCulate3 DELTa WAVelength STATe Turns the delta wavelength measurement mode on and off CALCulate3 D ELTa WPOWer STATe Turns the delta wavelength and power measurement mode on and off CALCulate3 DRIFt DIFFerence STATe Sets the drift calculation to subtract the minimum values measured from the maximu
30. bit in the status byte high Use the SRE common command to set or query the mask for the Sta tus Byte Register The masks for the OPERation Status and QUEStionable Status registers are set and queried using the STATus subsystem s ENABle commands Use the ESE common command to set or query the mask for the Standard Event Status Register 98 Programming Monitoring the Instrument The CLS common command clears all event registers and all queues except the output queue If CLS is sent immediately following a pro gram message terminator the output queue is also cleared In addition the request for the OPC bit is also cleared For example suppose your application requires an interrupt whenever any type of error occurs The error related bits in the Standard Event Status Register are bits 2 through 5 The sum of the decimal weights of these bits is 60 Therefore you can enable any of these bits to gener ate the summary bit by sending the ESE 60 command Whenever an error occurs it sets one of these bits in the Standard Event Status Register Because the bits are all enabled a summary bit is generated to set bit 5 in the Status Byte Register If bit 5 ESB in the Status Byte Register is enabled via the SRE command an SRQ service request interrupt is sent to the external computer Standard Event Status Register bits that are not enabled still respond to their corresponding conditions that is they are set if the c
31. by the fol lowing wavelength spacing spacing 6x10 FA where is the modulation frequency in Hz and X is the correct wave length in nm For example an amplitude modulation of 10 kHz on a 1550 nm laser will produce spurious wavelengths spaced by 15 nm from the correct wavelength and the spurious wavelengths will be at 1535 and 1565 nm Low frequency 10 kHz AM modulation graph showing rounded sideband spurs 58 Lasers modulated at high frequencies Directly modulated lasers Using the Multi Wavelength Meter Measuring Modulated Lasers The graphical display is useful for locating these spurious wavelengths Their amplitude will be below that of the correct wavelength and they will be broad rounded peaks compared to the sharp peak of the cor rect wavelength Use the Peak Threshold function to place the dotted line above the spurious peaks so they will not be displayed in the List by WL or List by Power table A laser modulated at high frequency in the RF or microwave range can also cause spurious wavelengths to be displayed especially when the modulation is of a repetitive nature such as that of PRBS or SONET digital formats In general no spurious wavelengths will be dis played using preset instrument conditions The preset condition includes peak excursion peak threshold and wavelength range limit ing However increasing peak threshold can cause spurious wave lengths to be displa
32. it to Agilent Technologies for repair Refer to Returning the Instrument for Service on page 32 Getting Started Step 4 Turn on the Agilent 86120B Instrument firmware version When the instrument is first turned on the display briefly shows the instrument s firmware version number In the unlikely event that you have a problem with the Agilent 86120B you may need to indicate this number when communicating with Agilent Technologies There is no output laser aperture The Agilent 86120B does not have an output laser aperture However light less than 1 nw escapes out of the front panel OPTICAL INPUT connector Operator maintenance or precautions are not necessary to maintain safety No controls adjustments or performance of procedures result in hazardous radiation expo sure Input Connector inptconr Measurement accuracy it s to you Fiber optic connectors are easily damaged when connected to dirty or damaged cables and accessories The Agilent 86120B s front panel INPUT connector is no exception When you use improper cleaning and handling techniques you risk expensive instrument repairs damaged cables and compromised measurements Before you connect any fiber optic cable to the Agilent 86120B refer to Cleaning Connections for Accurate Measurements on page 21 Getting Started Step 5 Enter Your Elevation Step 5 Enter Your Elevation In order for your Agilent 86
33. nm and 1200 nm 42 Limiting the wavelength range 43 Measuring broadband devices and chirped lasers 44 Graphical display of optical power spectrum 45 Instrument states 46 Power bar 46 37 Using the Multi Wavelength Meter Displaying Wavelength and Power Peak WL mode When Peak WL is pressed the display shows the largest amplitude line in the spectrum This is the peak wavelength mode The word PEAK is shown on the screen If multiple laser lines are present at the input the number of lines located will be shown along the right side of the screen Displayed Laser Line has the Measurement Greatest Power Wavelength Power Acquisition Power Bar MJ 7 PEAK x Laser Lines Ww Found 1551 314 3 6 ams 6 LINES i PWR A Power Offset EET 7 DP Applied evation Calibration Display after Peak WL key pressed In addition to the digital readouts there is a power bar It provides a convenient analog meter movement for tuning laser power Although the Peak WL mode shows one signal at a time softkeys are provided that allow you to scroll through and display all the measured laser lines You can scroll through the list according to the wavelengths or powers measured The signals are displayed in order from shortest to longest wavelengths The Agilent 86120B can measure up to 100 laser lines simultaneously 38 Using the Multi Wavelength Meter Displaying Wavelength and Power To dis
34. on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 92 for additional information on selecting measurements 184 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DRIFt MAXimum STATe Sets the drift calculation to return the maximum power and frequency values measured CALCulate3 DRIFt MAXimum STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific Use the CALC3 DRIF PRES command to turn off all the drift states before turning on this state The CALC3 DATA query returns the max imum power and frequency Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 92 for additional information on selecting measurements 185 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DRIFt MINimum STATe Sets the drift calculation to return the minimum power and frequency values measured CALCulate3 DRIF MINimum STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific Use the CALC3 DRIF PRES command to turn off all the drift states before turning on this state The CALC3 DATA query returns the m
35. string is a typical example of the first few returned val ues 4 02646500E 001 6 78125100E 001 6 17986600E 001 4 26768200E 001 4 80245300E 00 1 3 10491300E 001 1 13409400E 001 5 07832500E 001 2 77746200E 001 3 89150500E 0 01 3 50217600E 001 7 34649800E 001 5 64983800E 000 Notice that only measurement values are returned to the computer There is no first value that indicates the number of values contained in the string as there is for example with the FETCh READ and MEASure commands Use the CALCulatel TRANsform FRE Quency POINTs command to query the number of points the CALCI DATA returns 156 Programming Commands CALCulate1 Subsystem When NORMAL measurement mode is selected the uncorrected fre quency domain data consists of 64K 65 536 values Only the fre quency domain data corresponding to 700 1650 nm wavelength in vacuum is returned 34 123 values In FAST measurement mode the data consists of 8K 8 192 values of which 4 268 values are returned The frequency spacing between values is uniform and is equal to the reference laser frequency 473 6127 THz divided by 64K or 7 226756 GHz Note the spacing between values is not uniform in wavelength units The values returned are in ascending optical frequency The first value of the uncorrected frequency data corresponds to an optical frequency of 181 6879 THz 1650 041 nm The last value of the uncorrected frequency data corresponds to an optical f
36. the character is followed by one digit which indicates how many of the following digits convey the byte count The next digits give the actual byte count For example in the listing below 4387 bytes are indicated in the file Each command in the listing is separated by a linefeed character The following is an example of the first few lines and last few lines returned in the string The term nquery indicates that a command cannot be sent as a query The term qonly indicates that a command can only be sent as a query 44387 ABORt nquery CALCulate DATA gonly CALCulate TRANsform FREQuency POINts CALCulate1 DATA gonly CALCulate1 TRANsform FREQuency POINts CALCulate2 DATA gonly 212 Syntax Attribute Summary Description IDN gonly OPC RCL nquery RST nquery SAV nquery SRE STB qonly TRG nquery TST qonly WAl nquery Programming Commands SYSTem Subsystem PRESet Performs the equivalent of pressing the front panel PRESET key SYSTem PRESet Preset State none RST State none SCPI Compliance standard Command Only The instrument state is set according to the settings shown in the fol lowing table Table 5 19 Instrument Conditions 1 of 2 Settings after Preset Settings after Power om Key Pressed Turned On Display mode single wavelength last state Wavelength range limiting on last state Start wavelength 1200 nm last state Stop wavele
37. the following sub systems You ll find a description of each command in Chapter 5 Pro gramming Commands Subsystem Purpose of Commands Measurement Instruc tions Perform frequency wavelength wavenumber and coherence length measurements CALCulate1 Queries uncorrected frequency spectrum data CALCulate2 Queries corrected peak data and sets wavelength limits CALCulate3 Performs delta drift and signal to noise measurements DISPlay Applies markers and displays power bars HCOPy Prints measurement results SENSe Sets elevation correction values selects readings for air or vacuum and enters amplitude offsets Configures instrument for measuring broadband devices and chirped lasers Queries time domain values of the input data STATus Queries instrument status registers SYSTem Presets Agilent 86120B and queries error messages TRIGger Stops current measurement Acquires new measurement data Also used to select single or continuous acquisition of measurement data UNIT Sets the amplitude units to watts or dBm Table 2 4 on page 4 86 shows the kinds of measurements that the Agilent 86120B can perform and the associated programming com mands used to return that data In some cases there is more than one method that can be used to obtain the desired data Refer to Chapter 5 Programming Commands for the correct syntax for these com mands 85 Programming Making Measurements Table 2 4 Commands for Capturing
38. to query uncorrected frequency spec trum data In NORMAL measurement update mode 34 123 values are returned If the Agilent 86120B is set for FAST measurement update mode low resolution 4 268 values are returned The commands in this subsystem have the following command hierar chy CALCulatel DATA TRANsform FREQuency POINtS 155 Syntax Attribute Summary Description Programming Commands CALCulate1 Subsystem DATA Queries uncorrected frequency spectrum data of the input laser line CALCulate1 DATA Preset State not affected SCPI Compliance standard Query Only The returned values are in squared Watts linear units No amplitude or frequency correction is applied to the values To obtain the logarith mic dB result normalize the returned values by the largest value then take five times the logarithm of the returned values Be prepared to process a large amount of data when this query is sent The amount of data returned depends on the measurement update state of the instrument which can be set using the CALCulate1 TRANsform FREQuency POINts command or the resolution argument of an instrument function Refer to Measurement Instruc tions on page 144 When NORMAL measurement update is specified over 580 kilobytes of data 34 123 values can be returned to the computer When FAST mea surement update is specified over 72 kilobytes of data 4 268 values can be returned The following
39. to return wavelength and then power values for the same measurement This is shown in the follow ing program fragment OUTPUT 720 INIT CONT OFF OUTPUT 720 CONF ARR POW MAX OUTPUT 720 INIT IMM OUTPUT 720 FETC ARR POW ENTER 720 powers OUTPUT 720 FETC ARR POW WAV 88 Programming Making Measurements ENTER 720 wavelengths In the example above the data in the power and wavelength arrays are returned in the same order so that powers can be matched to wavelengths Also because new data is not collected FETCh is especially useful when characterizing transient data FETCh does not reconfigure the display For example if the display is in the Peak WL mode sending FETCh ARRay does not configure the display to the List by WL even though an array of data is returned to the computer A common programming error occurs when the FETCh command is used after an RST command This generates error number 230 Data corrupt or stale In this instance you must send INIT IMM after the RST command and before FETCh command to capture a new array of measurement data CONFigure command The CONFigure command changes measurement settings without taking a measurement The instrument is placed in the List by WL List by Ampl Peak WL display or in the coherence length application CONFigure can be queried The query returns the last configuration setup by the CONFigure command The instrument returns a string
40. used SETTIing RANGing not used MEASuring not used not used not used not used Processing Hardcopy Averaging not used not used not used not used MAV RQS Standard Event Status Register Operation Complete Request Control Query Error Device Dependent Error Execution Error Command Error User Request Power On y y Status Byte status 96 Programming Monitoring the Instrument Table 4 6 Bits in Operation Status Register Bit Definition 0 not used 1 SETTling indicating that the instrument is waiting for the motor to reach the proper position before beginning data acquisition 2 RANGing indicating the instrument is currently gain ranging 3 not used 4 MEASuring indicating that the instrument is making a measurement 5 through 8 not used 9 Processing indicating that the instrument is currently processing the data acquired 10 Hardcopy indicating that the instrument is currently printing the data to the parallel port 11 Averaging indicating that the instrument is in the process of averaging the noise for the signal to noise ratio calculation 12 through 16 not used Standard Event Status register The Standard Event Status Register monitors the following instrument status events OPC Operation Complete RQC Request Control QYE Query Error DDE Device Dependent Error EXE Execution Error CME Command Error URQ User Request PON Powe
41. walled corrugated cardboard carton of 159 kg 350 lb test strength The carton must be large enough to allow approximately 7 cm 3 inches on all sides of the instrument for packing material and strong enough to accommodate the weight of the instrument Surround the equipment with approximately 7 cm 3 inches of pack ing material to protect the instrument and prevent it from moving in the carton If packing foam is not available the best alternative is S D 240 Air Cap from Sealed Air Corporation Commerce Califor nia 90001 Air Cap looks like a plastic sheet filled with air bubbles Use the pink antistatic Air Cap to reduce static electricity Wrap ping the instrument several times in this material will protect the instrument and prevent it from moving in the carton 4 Seal the carton with strong nylon adhesive tape 5 Mark the carton FRAGILE HANDLE WITH CARE 6 Retain copies of all shipping papers 34 Displaying Wavelength and Power 37 Changing the Units and Measurement Rate 47 Defining Laser Line Peaks 50 Measuring Laser Separation 54 Measuring Modulated Lasers 58 Measuring Total Power Greater than 10 dBm 60 Calibrating Measurements 61 Printing Measurement Results 63 Using the Multi Wavelength Meter CAUTION Using the Multi Wavelength Meter Using the Multi Wavelength Meter Using the Multi Wavelength Meter In this chapter you ll learn how to make a variety of fast accurate measur
42. which is the last instrument function sent by a CONFigure command or MEASure query The returned string is in the short command form Use caution when using this query because if any instrument settings were changed since the last CONFigure command or MEASure query these changes may not be included in the returned string For example if the last CONFigure command was CONFigure SCALar POWer WAVelength 1300NM MAX a CONFigure query would return a string that is similar to the follow ing line POW WAV 1 300000 6 0 01 The 1300NM and resolution values track the actual instrument settings and input signals Notice that the quotation marks are part of the returned string 89 Programming Making Measurements Return single or multiple measurement values You can specify whether FETCh READ or MEASure returns a single value SCALar or multiple values ARRay The following example specifies SCALar data which returns a single value MEASure SCALar POWer WAVelength MAX ARRay and the SCPI standard According to the SCPI command reference ARRay command causes an instru ment to take multiple measurements A size parameter indicates the number of measurements to take However the Agilent 86120B s ARRay command refers to the measurements performed for one measurement sweep this results in an array of measured signals Because the size parameter does not apply any size parameter sent will be ignored by the instr
43. 120B to accurately measure wavelengths and meet its published specifications you must enter the elevation where you will be performing your measurements 1 Press the Setup key 2 Press the MORE softkey 3 Press the CAL softkey 4 Press ELEV 5 Use the and softkeys to enter the elevation in meters Entries jump in 500 meter steps from 0 m to 5000 m The elevation value selected with the softkeys must be within 250 meters of the actual elevation 6 Press RETURN to complete the entry Converting feet to meters If you know your elevation in feet you can convert this value to meters by using the following equation cree 3 281 18 Getting Started Step 6 Select Medium for Wavelength Values Step 6 Select Medium for Wavelength Values Because wavelength varies with the material that the light passes through the Agilent 86120B offers wavelength measurements in two mediums vacuum and standard air Press the Setup key Press the MORE softkey Press the CAL softkey Make the following selection Press VACUUM for wavelength readings in a vacuum e Press STD AIR for wavelength readings in standard air Press RETURN to complete the entry Definition of standard air Standard air is defined to have the following characteristics Barometric pressure 760 torr Temperature 15 C Relative humidity 096 A UU N Getting Started Step 7 Turn Off Wavelength Limiting Step 7
44. 2 SUBEND Identity DEF FNIdentity COM Instrument Mwm DIM IdentityS 50 IdentityS OUTPUT Mwm RST OUTPUT GMwm 0PC ENTER Mwm pc done OUTPUT GMwm IDN ENTER Mwm ldentity RETURN IdentityS FNEND 111 Programming Example Programs Example 3 Measure WDM channel drift This program measures the drift of channels in a WDM system It mea sures drift in both power and wavelength of each line First the pro gram sets the Agilent 86120B in the continuous acquisition measurement mode Then it measures drift using commands from the CALCulate3 subsystem Notice the use of the Tempo subroutine to pause the program for 10 seconds while the Agilent 86120B measures the drift on the laser The use of the Err_mngmt subroutine is optional Refer to the intro duction to this section for a description of each subroutine that is contained in this program COM Instrument Mwm ASSIGN Mwm 720 DIM Key 1 ON ERROR GOTO Error msg Set ese PRINT USING 37A 33A Multi Wavelength Meter Identity is FNIdentity ON TIMEOUT 7 5 CALL Err_mngmt Cmd_opc RST opc INIT I MM Cmd_opc OPC Cmd_opc CONF ARR POW WAV Turn on the drift calculation Cmd opc CALC3 DRIF STAT ON Err_mngmt CALC3 DRIF STAT ON Turn off all drift states Cmd opc CALC3 DRIF PRES Err_mngmt CALC3 DRIF PRES Turn on drift reference state Cmd_opc CALC3 DRIF REF STAT ON Err_mngmt C
45. 4 236 FNidentity function 107 foam swabs 29 FREQuency programming command 148 179 192 front panel adapters 258 labels 242 lockout 81 G GPIB address 81 address changing from front panel 81 address default 81 Index softkey 81 hardcopy See printer HCOPy subsystem 199 HELP HEADers programming command 212 HP BASIC 80 106 IDN 107 134 IEC Publication 1010 6 IEEE 488 2 standard 80 IMMediate programming command 199 217 init ignored 257 initializing the instrument 82 input connector 21 power definition of 234 INPUT connector 5 inspecting instrument 13 installing 12 instrument addressing over GPIB 81 default state 36 front view 242 preset conditions 213 244 rear view 242 returning for service 32 state when turned on 213 244 integration limits 44 L laser aperture 6 17 classification 6 drift 3 73 74 line separation 3 54 linewidth 36 modulated 58 tuning power 38 LEFT programming command 196 LIM OFF softkey 20 43 LIM ON softkey 20 43 LINE key 16 Index 265 Index linearity 234 236 line power cable 14 cables 260 initial state 213 244 requirements 14 specifications 238 linewidth 36 List by Power menu map 248 mode 88 softkey 41 74 List by WL key 40 menu map 248 mode 88 softkey 41 74 LOCAL softkey 81 long form commands 101 lowercase letters 102 low power laser lines 52 M M annotation 38 MAGNitude pro
46. 5 GET not allowed 108 Parameter not allowed 109 Missing parameter 112 Program mnemonic too long 113 Undefined header 120 Numeric data error 121 Invalid character in number 123 Exponent too large 124 Too many digits 128 Numeric data not allowed 131 Invalid suffix 134 Suffix too long 138 Suffix not allowed 141 Invalid character data 148 Character data not allowed 150 String data error 151 Invalid string data 256 Reference Error Messages Table 7 3 General SCPI Error Messages 2 of 3 Error Number Description 158 161 168 170 171 178 200 211 213 221 222 223 224 230 232 273 String data not allowed Invalid block data Block data not allowed Expression error Invalid expression Expression data not allowed Execution error Trigger ignored Caused by sending the TRG command when the instrument is already taking a measurement or when the instrument is in continuous measurement mode nit ignored Caused by sending an INIT IMM READ or MEASure command while a measurement is already in progress or while the instrument is in continuous measurement mode Settings conflict Caused by trying to set the instrument to a state that is not allowed For example turning on drift maximum and drift minimum state
47. 541 747 nm laser line is selected as the reference It is shown in absolute units The wavelengths and powers of the remaining responses are shown relative to this reference For example the first response is 2 596 nm below the reference 2 598 amp 6nm 4 41dE lt 1 388 ed AO me PEN ME 1541 747 S 46dEm mem OF 8 S OE 1 SS8dE m Wa EGE mem 8 M To determine channel spacing simply read the relative wavelength measurement of the laser lines immediately preceding and following the reference Use the and SELECT softkeys to change the refer ence laser line and read the channel spacing between each channel To measure channel separation 1 Press the front panel Preset key 55 Using the Multi Wavelength Meter Measuring Laser Separation Press List by WL Press the Delta On key Use the Off key to turn off the measurement Select the type of separation to observe A WL displays channel separation A WL A PWR displays both channel separation and differences in power Use the and softkeys to select the reference laser line Press SELECT Press SELECT at any time to select a new reference Press RESET at any time to turn off the delta calculation Measuring flatness You can use relative power measurements to measure flatness pre emphasis in a WDM system Simply select one carrier as the reference and measure the remaining carrie
48. 775 nm You can also avoid displaying this second harmonic line by reducing the peak threshold below its preset value Because the peak threshold level is used to determine which signals are to be displayed before amplitude corrections are applied the harmonic will be eliminated Refer to Defining Laser Line Peaks on page 50 To use the full wavelength range Press the Setup key Press the WLLIM softkey Press LIM OFF to remove the limits on wavelength range All responses in the full 700 nm to 1650 nm range are now displayed 42 Using the Multi Wavelength Meter Displaying Wavelength and Power Limiting the wavelength range The wavelength range of measurement can be limited with the wave length limit function Both start and stop wavelengths can be chosen The units of wavelength start and stop are the same as the currently selected wavelength units If wavelength units are later changed the start and stop wavelength units will change accordingly Note that a start wavelength limit in nm will become a stop wavelength limit if THz or cm is chosen See To change the units of measure on page 47 The wavelength limit can be useful when laser modulation causes spu rious wavelengths to be displayed Reducing the wavelength range to the region of interest minimizes the number of spurious wavelengths displayed Also the graphical display uses these start and stop wave length values to plot the power spectrum wheth
49. ALC3 DRIF REF STAT ON Query the number of data points OUTPUT Mwm CALC3 POIN ENTER Mwm USING K Nb_pt ALLOCATE Current_ref_wl 1 Nb_pt ALLOCATE Current_ref_pwr 1 Nb_pt 112 Programming Example Programs Query reference wavelengths and powers OUTPUT Mwm CALC3 DATA WAV ENTER Mwm USING K Current_ref_wi OUTPUT Mwm CALC3 DATA POW ENTER Mwm USING K Current_ref_pwr Turn off drift reference state Cmd_ope CALC3 DRIF REF STAT OFF Err_mngmt CALC3 DRIF REF STAT OFF Turn on drift max min calculation Cmd_opc CALC3 DRIF DIFF STAT ON Err_mngmt CALC3 DRIF DIFF STAT ON Tempo 10 ALLOCATE Current diff wl 1 Nb pt ALLOCATE Current diff pw 1 Nb pt Query drift wavelengths and powers OUTPUT Mwm CALC3 DATA WAV ENTER Mwm USING K Current_diff_wil OUTPUT Mwm CALC3 DATA POW ENTER Mwm USING K Current_diff_pw OFF TIMEOUT FOR 1 1 TO Nb pt PRINT USING 18A 2D 6A M4D 2DE 3A 21A MDD 3DE 3A Wavelength number is Current ref wl I m with a drift from Current diff wl l m PRINT USING 28A SDD 2DE 4A 20A MDD 3DE 3A it has a power level of Current ref pwr l dBm with a drift from Current diff pw l dB NEXT I STOP Error msg PRINT The program is aborted due to ERRMS END 113 Programming Example Programs Err_mngmt SUB Err_mngmt OPTIONAL Cmd_msg COM Instrument Mwmt DIM Err_msg 255
50. Agilent 86120B signal to noise application works best when the laser being tested is not modulated or modulated with non repetitive data formats With repetitive data formats such as PRBS data and SONET formats there is signifi cant low frequency amplitude modulation of the laser This modulation raises the noise floor of the Agilent 86120B significantly The signal to noise measured can be limited to about 15 dB while measuring lasers modulated by repetitive data for mats For improved performance when the laser is modulated with repetitive data formats use the Signal to Noise with Averaging application To measure signal to noise 1 Press the front panel Preset key 2 Press List by WL or List by Power 3 Press Appl s and then S N 69 Measurements Applications Measuring Signal to Noise Ratios To select the wavelength reference for measuring the noise do the following steps a Press WL REF and press AUTO to let the instrument interpolate the wavelength or press USER to select the last wavelength manually entered b If you chose USER you can specify the wavelength by pressing USER WL Use the softkey to select the digit that requires editing Use the i and softkeys to change the value c Press RETURN While the signal to noise measurements are displayed you can press PEAK anytime to select the signal with the highest power 70 Measurements Applications Measuring Signal to Noise Ratios with Averagin
51. BAR Press BAR ON to display the power bar and press BAR OFF to hide the power bar display 46 Using the Multi Wavelength Meter Changing the Units and Measurement Rate Changing the Units and Measurement Rate This section includes step by step instructions for changing the units and measurement rate This section includes Displayed units 47 Measurement rate 48 Continuous or single measurements 49 Displayed units As described below it s easy to change the wavelength and amplitude units You can choose between the following units Table 2 3 Available Units Wavelength Power nm dBm cm1 mW THz uw To change the units of measure 1 Press Setup 2 Press the MORE softkey 3 Press the UNITS softkey 47 U N m Using the Multi Wavelength Meter Changing the Units and Measurement Rate Press WL and select one of the following units Then press RETURN to complete your selection NM for nanometers THZ for terahertz CM 1 for wave number Press POWER and select one of the following units DBM for decibels relative to a milliwatt MW for milliwatts UW for microwatts Measurement rate Under normal operation the Agilent 86120B makes a measurement and displays the results about once every second It is in this normal update mode that maximum accuracy and wavelength resolution are achieved However should a faster update be desired for example when real time feedback is requir
52. C3 DRIF PRES command to turn off all the drift states before turning on the drift reference state Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 92 for additional information on selecting measurements 188 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DRIFt STATe Turns on and off the drift measurement calculation CALCulate3 DRIFt STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific When the drift mode is first turned on the current list of laser lines is placed into the reference All subsequent measurements take the new data subtract the reference data and display the differences in wave lengths and powers The CALC3 DATA query returns the power and frequency of the cur rent measurement minus the power and frequency of the reference Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 92 for additional information on selecting measurements 189 Syntax Attribute Summary Description Syntax Attribute Summary Description Programming
53. Commands CALCulate3 Subsystem POINts Queries the number of points in the data set CALCulate3 POINts Preset State unaffected by RST State unaffected by SCPI Compliance instrument specific Query Only The value returned is the number of points returned by the CALC3 DATA query PRESet Turns off any CALCulate3 calculation that is on CALCulate3 PRESet Preset State unaffected by RST State unaffected by SCPI Compliance instrument specific Command Only This command turns off any CALCulate3 calculation delta drift sig nal to noise or coherence length that is on 190 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem SNR AUTO Selects the reference frequency value for measuring noise in the sig nal to noise calculation CALCulate3 SNR AUTO ON OFF 1 0 Constant Description ON Selects internally generated reference frequency OFF Selects user entered reference frequency Preset State on RST State on SCPI Compliance instrument specific The command argument allows you to select either an internally gen erated or a user entered frequency reference for measuring the noise To enter a value to use as the reference use the SNR REFerence FRE Quency SNR REFerence WAVelength and SNR REFerence WNUMber commands 191 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem SNR REFerence FR
54. Compliance instrument specific Command Only 178 Syntax Attribute Summary Description Syntax Attribute Summary Programming Commands CALCulate3 Subsystem DELTa REFerence FREQuency Selects the reference laser line for DELTa calculations CALCulate3 DELTa REFerence FREQuency lt real gt MINimum MAXimum real is a frequency value that is within the following limits Constant Description MINimum 181 6924 THz MAXimum 428 6 THz Preset State 428 6 THz 700 nm RST State 428 6 THz 700 nm SCPI Compliance instrument specific The reference will be the laser line at the frequency closest to the fre quency entered Subsequent measurements will use the frequency clos est to the reference frequency used for the previous measurement The query returns the reference laser line s frequency The default units for the real parameter are Hz DELTa REFerence POWer Queries the reference laser line s power level CALCulate3 DELTa REFerence POWer Preset State not affected RST State not affected SCPI Compliance instrument specific Query Only 179 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DELTa REFerence WAVelength Selects the reference laser line for DELTa calculations CALCulate3 DELTa REFerence WAVelength lt real gt MINimum MAXimum lt real gt is a wavelength value that is within the following lim
55. EQuency Enters a frequency that can be used for the noise measurement refer ence in signal to noise calculations CALCulate3 SNR REFerence FREQuency lt real gt MINimum MAXimum lt real gt is a frequency value that is within the following limits Constant Description MINimum 181 6924 THz MAXimum 428 2750 THz Preset State unaffected by RST State 193 4145 THz 1550 0 nm in a vacuum SCPI Compliance instrument specific After entering this value use the SNR AUTO command to configure the instrument to use this value in subsequent signal to noise calculations The default units for the lt real gt parameter are Hz 192 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem SNR REFerence WAVelength Sets the wavelength used for the noise measurement reference in the signal to noise calculation CALCulate3 SNR REFerence WAVelength lt real gt MINimum MAXimum lt real gt is a wavelength value that is within the following limits Constant Description MINimum 700 0 nm MAXimum 1650 0 nm Preset State unaffected by RST State 1550 0 nm in a vacuum SCPI Compliance instrument specific After entering this value use the SNR AUTO command to configure the instrument to use this value in subsequent signal to noise calculations The number entered is converted internally to the corresponding fre quency The default units for the lt real gt parame
56. FF CALCulate3 DELTa POWer STATe ON CALCulate3 DELTa POWer STATe PEAK DISPlay MARKer MAXimum Peak WL See NEXT PK NEXT WL PEAK PREV PK and PREV WL PK EXC CALCulate2 PEXCursion PK THLD CALCulate2 PTHReshold POWER UNIT POWer Preset SYSTem PRESet PREV PK DISPlay MARKer MAXimum PREVious PREV WL DISPlay MARKer MAXimum LEFT Print HCOPy IMMediate PWR BAR See BAR ON and BAR OFF PWR OFF SENSe CORRection 0FFSet MAGNitude RESET CALCulate3 DRIFt REFerence RESet S N CALCulate3 SNR STATe S N AVG CALCulate3 ASNR STATe SELECT CONFigure POWer 127 Table 4 11 Keys Versus Commands 3 of 3 Key Equivalent Command Setup See CAL UNITS and UPDATE Single INITiate CONTinuous OFF START WL CALCulate2 WLIMIt STARt STOP WL CALCulate2 WLIMItSTOP STD AIR SENSe CORRection MEDium AIR THRSHLD See PK EXC and PK THLD THZ MEASure ARRay POWer FREQuency UNITS UNIT POWer UPDATE Measurement Instructions and CALCulate1 TRANsform FREQuency POINts USER CALCulate3 SNR AUTO OFF USER WL CALCulate3 S NR REFerence WAVelength UW UNIT POWer VACUUM SENSe CORRection MEDium VACuum WL See CM NM and THZ WL LIM CALCulate2 WLIMit STATe WL REF See AUTO USER and USER WL Common Commands 131 Measurement Instructions 144 CALCulatel Subsystem 155 CALCulate2 Subsystem 161 CALCulate3 Subsystem 173 CONFigure Measurement Instruction 195 DISPlay Subsystem 195 FETCh Measurement Instruction 198 HCOPy Subsys
57. IM Err_msg 255 INTEGER Cme CLEAR Mwm REPEAT OUTPUT Mwm ESR ENTER Mwm Cme OUTPUT Mwm SYST ERR ENTER Mwm Err_msg IF NPAR gt 0 AND NOT POS Err_msgS 0 THEN PRINT This command Cmd msg makes the following error IF NOT POS Err_msg 0 THEN PRINT Err_msg UNTIL NOT BIT Cme 2 AND NOT BIT Cme 4 AND NOT BIT Cme 5 AND POS Err msg 0 Subend SUBEND Set_ese SUB Set ese COM Instrument Mwm OUTPUT Mwm ESE IVAL 00110100 2 SUBEND Identity DEF FNidentity COM Instrument Mwm DIM IdentityS 33 Identity z OUTPUT Mwm RST OUTPUT GMwm OPC ENTER Mwm pc done OUTPUT GMwm IDN ENTER Mwm ldentity RETURN IdentityS FNEND Cmd opc SUB opc Set cmd COM Instrument Mwm OUTPUT Mwm Set_cmd OUTPUT QGMwm OPC ENTER Mwm 0pc_done SUBEND 116 Programming Example Programs Example 5 Measure SN ratio of WDM channels This program measures signal to noise ratios on a WDM system It measures the ratio for each line using commands from the CALCulate3 subsystem Refer to the introduction to this section for a description of each sub routine that is contained in this program COM Instrument Mwm ASSIGN Mwm TO 720 DIM Key 1 ON ERROR GOTO Error msg Set ese PRINT USING 37A 33A Multi Wavelength Meter Identity is FNidentity ON TIMEOUT 7 5 CALL Err mngmt Cmd_opc RST OUTPUT Mwm MEAS ARR POW WAV ENTER Mwm USING K Nb_pt ALLOCATE C
58. If the MEAS SCAL POW WNUM 6451 command is sent and a 1550 nm laser line is present the following response would be returned to the computer 6 45286262E 005 Notice that the returned units are 1171 If six laser lines are measured and MEAS ARR POW WNUM is sent the following response is returned Notice that the first returned number indicates the number of laser line values returned in the query 6 6 47298400E 005 6 46627900E 005 6 45957000E 005 6 45286300E 005 6 44615600E 0 05 6 43945300E 005 MEASure SCALar LENGth COHerence ALPHa Queries the alpha constant LENGth COHerence ALPHa Query Only The alpha constant is a unitless ratio 153 Syntax Attribute Summary Description Syntax Attribute Summary Syntax Attribute Summary Description Programming Commands Measurement Instructions MEASure SCALar LENGth COHerence BETA Queries the beta constant LENGth COHerence BETA Query Only The beta constant is a unitless ratio MEASure SCALar LENGth COHerence CLENgth Queries the coherence length of the input signal in meters LENGth COHerence CLENgth Query Only MEASure SCALar LENGth COHerence DELay Queries the round trip path delay in the laser chip LENGth COHerence DELay Query Only The units of the returned value are in meters 154 Programming Commands CALCulate1 Subsystem CALCulatel Subsystem Use the CALCulatel commands
59. July 26 Laser type LED Wavelength 1200 1650 nm Max CW output power 1 nW Beam waist diameter 10 um Numerical aperture 0 1 Laser class according to 1 IEC 60825 1 2001 Max permissible 10 mW CW output power Max CW output power means the highest possible optical CW power that the laser source can produce at its output Max permissible CW output power is the highest optical power that is permitted within the appropriate IEC laser class WARNING Please pay attention to the following laser safety warnings 239 Specifications and Regulatory Information Laser Safety Information Under no circumstances look into the end of an optical cable attached to the optical output when the device is operational The laser radiation can seriously damage your eyesight Do not enable the laser when there is no fiber attached to the optical output connector Pressing the active button enables the laser The laser is on when the green LED is lit The use of optical instruments with this product will increase eye haz ard Refer servicing only to qualified and authorized personnel Compliance with This ISM device complies with Canadian ICES 001 Canadian EMC Cet appareil ISM est conforme la norme NMB 001 du Canada Requirements Notice for Noise Declaration of Conformity Germany Acoustic Noise Emission Ger uschemission LpA 70 dB LpA 70 dB Operator po
60. QUEStionable EVENt 0 to 32767 Preset State none RST State none SCPI Compliance standard Query Only The response will be a number from 0 to 32767 indicating which bits are set Reading the register clears the register OUTPUT 720 STATUS OPERATION EVENT OPERation QUEStionable NTRansition Selects bits in the event register which can be set by negative transi tions of the corresponding bits in the condition register STATus OPERation NTRansition lt integer gt integer an integer from to 65535 Preset State none RST State none SCPI Compliance standard 208 Description Example Syntax Attribute Summary Description Example Programming Commands STATus Subsystem Changes in the state of a condition register bit causes the associated OPERation Status or QUEStionable Status register bit to be set This command allows you to select a negative bit transition to trigger an event to be recognized A negative transition is defined to occur when ever the selected bit changes states from a 1 to a 0 You can enter any value from 0 to 65535 When queried the largest value that can be returned is 32767 This is because the most significant register bit cannot be set true OUTPUT 720 STATUS OPER NTRansition 16 OPERation QUEStionable PTRansition Selects bits in the event register which can be set by positive transi tions of the corresponding bits in the condition reg
61. ST State 6 060606E5 m SCPI Compliance instrument specific This command sets the starting range for the wavelength limit The default units for the real parameter value are nr The start wave number value must be less than or equal to the stop wavenumber value or the start wavenumber will be clipped to the stop wavenumber and a Data out of range error will be generated Non sequential command Always use an OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120B to wait for non sequential commands on page 90 for more information 169 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem WLIMit STOP FREQuency Sets the stopping frequency for the wavelength limit range CALCulate2 WLIMit STOP FREQuency lt real gt MINimum MAXimum lt real gt is a frequency value that is within the following limits Constant Description MINimum start wavelength limit MAXimum 428 2750 THz Non sequential command Preset State 249 8271 THz RST State 249 8271 THz SCPI Compliance instrument specific This command sets the stopping range for the wavelength limit The default units for the lt real gt parameter are Hz The stop frequency value must be greater than or equal to the start frequency value or the stop frequency will be clipped to the s
62. SouthAfrica India 100V 8120 4753 Straight MITI 90 230 Dark Gray Japan 8120 4754 90 90 230 Part number shown for plug is the industry identifier for the plug only Number shown for cable is the Agilent Technologies part number for the complete cable including the plug Agilent Technologies Service Offices Before returning an instrument for service call the Agilent Technologies Instrument Support Center at 800 403 0801 visit the Test and Measurement Web Sites by Coun try page at http www tm agilent com tmo country English index html or call one of the numbers listed below Agilent Technologies Service Numbers Austria 0 820 87 4411 Belgium 32 0 2 404 9340 Brazil 11 4197 3700 261 Reference Agilent Technologies Service Offices Agilent Technologies Service Numbers China 800 810 0508 Denmark 45 70 131515 Finland 358 0 10 855 2100 France 08 25 010 700 Germany 0180 524 6337 India 1600 112 626 Italy 39 02 9260 8484 Ireland 353 1890 924 204 Japan 0120 421 345 Korea 080 769 0800 Mexico 5 258 4826 Netherlands 020 547 2111 Norway 47 6710 1080 Russia 7 095 797 3930 Spain 34 91 631 3300 Sweden 0200 88 22 55 Switzerland 0800 80 5353 United Kingdom 44 0 7004 666666 United States 1 877 447 7278 262 Index Numerics 1 nm annotation 69 72 A ABORt programming command 216 ABORT softkey 64 ac power cables 15 adapters fiber optic 258 adding param
63. T ON Separate multiple parameters with a comma Spaces can be added around the commas to improve readability OUTPUT 720 MEAS SCAL POW FREQ 1300 MAX White space White space is defined to be one or more characters from the ASCII set of 0 through 32 decimal excluding 10 NL White space is usually optional and can be used to increase the readability of a program Numbers All numbers are expected to be strings of ASCII characters Thus when sending the number 9 you would send a byte representing the ASCII code for the character 9 which is 57 A three digit number like 102 would take up three bytes ASCII codes 49 48 and 50 This 103 Programming Reviewing SCPI Syntax Rules is taken care of automatically when you include the entire instruction in a string Several representations of a number are possible For example the following numbers are all equal 28 0 28E2 280E 1 28000m 0 028K 28E 3K If a measurement cannot be made no response is given and an error is placed into the error queue For example RST FETCh POW will timeout the controller and place a Data stale or corrupt error in the error queue Table 4 9 Suffix Multipliers Multiplier Mnemonic 1E18 EX 1E15 PE 1E12 T 1E9 G 1E6 MA 1E3 K 1E 3 M 1E 6 U 1E 9 N 1E 12 P 1E 15 F 1E 18 A 104 Programming Reviewing SCPI Syntax Rules Program message terminator The string of instructions sent to the instrument are exec
64. a tory Information as the performance standard All of the tests are done manually without the aid of a computer None of these tests require access to the interior of the instrument Test 1 Absolute Wavelength Accuracy Test 2 Sensitivity Test 3 Polarization Dependence Test 4 Optical Input Return Loss Test 5 Amplitude Accuracy and Linearity Allow the Agilent 86120B to warm up for 15 minutes before doing any of the performance tests Calibration Cycle This instrument requires periodic verification of performance The instrument should have a complete verification of specifications once every two years 220 Description CAUTION Procedure Performance Tests Test 1 Absolute Wavelength Accuracy Test 1 Absolute Wavelength Accuracy Wavelength accuracy is verified using traceable light sources such as the following devices Stable lasers Gas lamps HeNe gas lasers Do not exceed 18 dBm source power The Agilent 86120B s input circuitry can be damaged when total input power exceeds 18 dBm Use three or four light standards that cover the Agilent 86120B s wavelength range Connect the traceable sources to the Agilent 86120B and verify that the Agilent 86120B is reading the sources to within the absolute wavelength accuracy specification 221 Description CAUTION Procedure Performance Tests Test 2 Sensitivity Test 2 Sensitivity Sensitivity is verified using the follow
65. acteristics of the instrument The dis tinction between these terms is described as follows Specifications describe warranted performance over the temperature range 0 C to 55 C and relative humidity lt 95 unless otherwise noted All specifications apply after the instrument s temperature has been sta bilized after 15 minutes of continuous operation Characteristics provide useful information by giving functional but nonwarranted performance parameters Characteristics are printed in italics Calibration Cycle This instrument requires periodic verification of performance The instrument should have a complete verification of specifications once every two years 232 Wavelength Amplitude Specifications and Regulatory Information Definition of Terms Definition of Terms Range refers to the allowable wavelength range of the optical input signal Absolute accuracy indicates the maximum wavelength error over the allowed environmental conditions The wavelength accuracy is based on fundamental physical constants which are absolute standards not requiring traceability to artifacts kept at national standards laboratories Four He Ne gas lasers are used First there is an internal 632 991 nm vacuum 473 6127 THz reference laser To verify absolute wavelength accuracy three external lasers are mea sured during manufacturing with these wavelengths 730 685 nm or 410 2896 THz 1152 591 nm or 260 1032 THz 1523 488 n
66. ak search is completed If CALC2 PWAV STAT is on the power weighted average wave number is returned Preset State not affected SCPI Compliance standard Query Only Use the CALC2 POIN query to determine the number of points the CALC2 DATA query will return The following string is a typical example of the first few returned values returned when WAVelength is specified 1 54488600 006 1 54649100 006 1 54808300 006 1 54969600 006 1 55131200 006 1 55293000E 006 This next string resulted by specifying the WNUMber argument 6 47296600E 005 6 46625000E 005 6 45959900E 005 6 45287500E 005 6 44615500E 00 5 6 43943900 005 Notice that only measurement values are returned to the computer There is no first value that indicates the number of values contained in the string as there is for example with the FETCh READ and MEASure commands 162 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem When there is no input signal the POWer query returns 200 dBm the WAVelength query returns 100 nm 1 0E 7 PEXCursion Sets the peak excursion limit used by the Agilent 86120B to determine valid laser line peaks CALCulate2 PEXCursion lt integer gt MINimum MAXimum DEFault lt integer gt represents logarithmic units in dB Valid range is 1 to 30 dB Constant Description MINimum 1dB MAXimum 30 dB DEFault 15 dB Non sequential command Preset Stat
67. al of interest See points and P in the following figure If the closest signal is more than 200 GHz from the signal of interest or if there is no other signals present then the noise power is mea sured at 100 GHz on either side of the signal of interest The two mea sured noise power levels are then averaged to estimate the noise power level at the signal wavelength The noise power measurements use linear interpolation to estimate the noise power level at the signal of interest s wavelength Automatic interpolation 68 User entered wavelength Noise bandwidth Measurements Applications Measuring Signal to Noise Ratios When the signal to noise user function is selected the Agilent 86120B uses only one wavelength to measure the noise power for all signals This wavelength is set by the user and all signals are compared to the noise level at this wavelength to determine their cor responding signal to noise ratios When measuring noise power the Agilent 86120B must account for the noise bandwidth used during the measurement Because noise band width varies with measurement bandwidth a wide bandwidth allows more noise to the Agilent 86120B s detector than a narrow bandwidth the Agilent 86120B normalizes all noise power measurements to a bandwidth of 0 1 nm The annotation 0 1 nm is displayed to show that the noise bandwidth is being normalized to a 0 1 nm bandwidth Repetitive data formats The
68. and off the display of the power bars DISPlay WINDow GRAPhics STATe ON OFF 1 0 Preset State on RST State on SCPI Compliance standard Specifying on displays the power bars in all modes except the drift and signal to noise modes Specifying off prevents the display of power bars for all instrument modes FETCh Measurement Instruction For information on the FETCh measurement instruction refer to Mea surement Instructions on page 144 198 Syntax Attribute Summary Description Programming Commands HCOPy Subsystem HCOPy Subsystem Use the command in this subsystem to print the displayed measure ment results to a printer This subsystem has the following command hierarchy HCOPy IMMediate IMMediate Prints measurement results on a printer HCOPy IMMediate Preset State none RST State none SCPI Compliance standard Command Only Connect the printer to the Agilent 86120B s rear panel PARALLEL PRINTER PORT connector The output to the printer is ASCII text MEASure Measurement Instruction For information on the MEASure measurement instruction refer to Measurement Instructions on page 144 199 Programming Commands READ Measurement Instruction READ Measurement Instruction For information on the READ measurement instruction refer to Mea surement Instructions on page 144 SENSe Subsystem Use the SENSe commands to correct m
69. ar display on last state a The term last state refers to the last setting that this parameter was in before the instrument power was turned off 245 Reference Menu Maps Menu Maps This section provides menu maps for the Agilent 86120B softkeys The maps show which softkeys are displayed after pressing a front panel key they show the relation ship between softkeys The softkeys in these maps are aligned vertically instead of horizontally as on the actual display This was done to conserve space and to make the maps easier to interpret 246 Reference Menu Maps Appl s Menu 4 AUTO Y USER PEAK USER WL Appl s WL REF CANCEL EXIT RETURN RETURN S N S N AVG DRIFT 4 COH LEN Y RETURN PEAK NUM AVG EXIT MAX MIN RESET EXIT mappls Display Avg WL Menu There is no menu associated with this key Measurement Cont Menu There is no menu associated with this key 247 Reference Menu Maps Display List by Power Menu List by Power PEAK GRAPH SELECT mlistpwr Display List by WL Menu List by WL Y PEAK GRAPH SELECT mlistwl 248 Reference Menu Maps Delta On Menu AWL 4 APWR AWL PWR SELECT RESET RETURN EXIT Delta Off Menu Off EAK SELECT 249 Reference Menu Maps Display Peak WL and System Preset Menus Peak WL PREV WL NEXT WL PEAK PREV PK NEXT PK mpreset Measurement Single Menu Th
70. are displayed in the List by Wavelength and List by Power modes All peaks below this line are not displayed Adjust the Peak Threshold value with the Setup key and the THRSHLD softkey The wavelength limit start and stop wavelength values are used for the graphical display even if the wavelength limit function is off The graphical display cannot be printed To see the graphical display 1 Press the List by WL or List by Power key 2 Press the GRAPH softkey 3 To exit the graphical display press any softkey 45 U N m Using the Multi Wavelength Meter Displaying Wavelength and Power Instrument states Four different instrument states can be saved and recalled at a later time The actual instrument conditions that are saved are identical to those saved from the previous state after power is turned on These conditions are shown in Table 7 1 on page 244 If drift measurements or an application such as signal to noise is on when an instrument state is saved it is off when that state is recalled To save an instrument state Press the Setup key Press the SAV RCL softkey Press the SAVE softkey Press one of the four SAVE softkeys to save the instrument state To recall a state Press the Setup key Press the SAV RCL softkey Press the RECALL softkey Press one of the four RCL softkeys to recall an instrument state Power bar To control the power bar Press the Setup key Press MORE twice and then PWR
71. ast update list by WL list by Pwr peak or avg display mode frequency units power units elevation peak excursion peak threshold power 136 Programming Commands Common Commands offset signal to noise auto mode on off wavelength limit on off wave length limit start wavelength limit stop and signal to noise average 137 Programming Commands Common Commands Table 5 15 Conditions Set by RST Reset Item Setting Display mode Wavelength range limiting Start wavelength Stop wavelength Graphical display Measurement acquisition Wavelength calibration Elevation correction value Wavelength units Amplitude units Power offset Peak threshold Peak excursion Measurement speed Number of uncorrected data points Delta Measurements A power A wavelength A wavelength and power reference signal position Drift measurements Coherence length measurements single wavelength on 1200 nm 1650 nm off single vacuum 0 meters nm dBm 0 dB 10 dB 15 dB normal 34123 off off off 700 nm off off 138 Syntax Description Programming Commands Common Commands Table 5 15 Conditions Set by RST Reset Continued Item Setting Signal to Noise Measurements measurement off wavelength reference auto reference user wavelength 1550 nm in vacuum number of averages count 100 GPIB address not affected Power bar display on count SRE The SRE service request enable
72. ause spurious wavelengths to be displayed below and above the cor rect wavelength The power of these spurious wavelengths is below that of the correct wavelength These spurious signals can be elimi nated by decreasing Peak threshold from its Preset value 50 Peak excursion Examples of valid and invalid signals Using the Multi Wavelength Meter Defining Laser Line Peaks The peak excursion defines the rise and fall in amplitude that must take place in order for a laser line to be recognized The rise and fall can be out of the noise or in the case of two closely spaced signals out of the filter skirts of the adjacent signal The peak excursion s default value is 15 dB Any laser line that rises by 15 dB and then falls by 15 dB passes the rule You can set the peak excursion value from 1 to 30 dB In the following figure three laser lines are identified responses 1 3 and 4 Response j is not identified because it is below the peak thresh old The portion of each signal that is within the peak excursion limits is shown in bold lines Because of the peak excursion rule responses 4 and 5 are identified as one laser line the minimum point between 4 and 5 does not drop to the peak excursion limit This response has the highest power shown which is peak 4 Whenever the peak threshold limit or peak excursion value is changed the new limits are applied to the current displayed measurements even if the instrument is in the Sin
73. ber optic cable to the front panel OPTICAL INPUT con nector on page 2 39 Characterize laser lines easily With the Agilent 86120B you can quickly and easily measure any of the following parameters Wavelengths and powers Average wavelength Total optical power Laser line separation Laser drift wavelength and power Signal to noise ratios Coherence length The Agilent 86120B At a Glance In addition to these measurements a power bar is displayed that shows power changes like a traditional analog meter You can see the power bar shown in the following figure of the Agilent 86120B s dis play 1551 314 6 92 apm 5 PREY WL NEXT mExr PEK CAUTION peakwl The input circuitry of the Agilent 86120B can be damaged when total input power levels exceed 18 dBm To prevent input damage this specified level must not be exceeded Print measurement results You can get hardcopy results of your measurements by connecting a printer to the rear panel PARALLEL PRINTER PORT connector Program the instrument for automatic measurements The Agilent 86120B offers an extensive set of GPIB programming com mands These commands allow you to perform automated measure ments on manufacturing production lines and remote sites Chapter 4 Programming and Chapter 5 Common Commands provide all the information you ll need to know in order to program the Agilent 86120B Di
74. c and Medi cal Group 1 Class A product ISMI A Typographical Conventions The following conventions are used in this book Key type for keys or text located on the keyboard or instrument Softkey type for key names that are displayed on the instrument s screen Display type for words or charac ters displayed on the computer s screen or instrument s display User type for words or characters that you type or enter Emphasis type for words or char acters that emphasize some point orthat are used as place holders for text that you type Second Edition 86120 90B03 July 2004 First Edition 86120 90033 February 2000 The Agilent 86120B At a Glance The Agilent 86120B At a Glance The Agilent 86120B Multi Wavelength Meter measures the wavelength and optical power of laser light in the 700 1650 nm wavelength range Because the Agilent 86120B simultaneously measures multiple laser lines you can characterize wavelength division multiplexed WDM systems and the multiple lines of Fabry Perot lasers NOTE The front panel OPTICAL INPUT connector uses a single mode input fiber What s new with the Agilent 86120B This book directly applies to Agilent 86120B instruments with firm ware version number 2 0 When first turned on the instrument briefly displays the firmware version These instruments have the added capa bility of measuring broadband devices and chirped lasers Refer to Connect the fi
75. ce length Lc Round trip optical length of diode laser cavity 2nLd Alpha factor Beta factor Coherence length in the region of 1 mm to 200 mm can be measured The following figure shows a coherence length measurement COHERENCE LENGTH UNCAL Le 3 6 mm EY WL znLp 1 491 mm OF E alpha 6 984 MAC beta Hbl B oH L 1L IL IL To measure coherence length Press the front panel Preset key Press Appl s and then COH LEN 76 Coherence length L Round trip optical length of diode Measurements Applications Measuring Coherence Length The interferogram of the laser being tested is sampled and the enve lope of the interferogram is found This envelope has peaks regions of high fringe visibility at zero optical path delay and at delays equal to multiples of the laser cavity round trip optical length This is shown in the following figure of the interferogram envelope Interferogram Envelope 0 nlp Optical Path Delay OPD The amplitudes of the peaks decreases exponentially from the largest peak at zero path delay The exponential decay constant is defined as the coherence length Lc The curve that connects the tops of the enve lope peaks is given by the following equation decay curve e OPD is the optical path delay and Lc is the coherence length Thus at an optical path delay equal to the coherence length the envelope peaks are down to e of their value at zero pa
76. connector 1005 0595 ST connector 1005 0596 SC connector 1005 0597 Power Cords Plug Type is Plug Description roo Color Country 250V 8120 1351 Straight BS1363A 90 228 Gray United Kingdom 8120 1703 90 90 228 Mint Gray Cyprus Nigeria Zimbabwe Singapore 250V 8120 1369 Straight NZSS198 ASC 79 200 Gray Australia New 90 Zealand prey 0698 87 221 Mint Gray 8120 1689 Straight 7 11 79 200 Mint Gray East and West Europe Saudi 8120 1692 90 79 200 Mint Gray Arabia So 8120 2857p Straight Shielded 79 200 Coco Brown Africa India unpolarized in many nations 125V 8120 1378 Straight NEMA5 15P 90 228 Jade Gray United States 8120 1521 90 90 228 Jade Gray 791808 Mexico Philippines 8120 1992 Straight Medical 96 244 Black Taiwan UL544 Part number shown for plug is the industry identifier for the plug only Number shown for cable is the Agilent Technologies part number for the complete cable including the plug 260 Reference Agilent Technologies Service Offices Cable Part ae Length Plug Type No Plug Description Color Country 250V 8120 2104 Straight SEV1011 79 200 Mint Gray Switzerland 8120 2296 1959 24507 79 200 O L gt RA T o Sx 12 90 220V 8120 2956 Straight DHCK107 79 200 Mint Gray Denmark TE 8120 2957 90 79 200 Mint Gray 250V 8120 4211 Straight SABS164 79 200 Jade Gray Republic of 8120 4600 90 79 200
77. cts the mains circuits from the mains supply before other parts of the instrument Alternately an externally installed switch or circuit breaker which is really identifiable and is easily reached by the operator may be used as a disconnecting device Install the instrument according to the enclosure protection provided This instrument does not protect against the ingress of water This instrument protects against finger access to hazardous parts within the enclosure 12 Getting Started Step 1 Inspect the Shipment Step 1 Inspect the Shipment 1 Verify that all system components ordered have arrived by comparing the shipping forms to the original purchase order Inspect all shipping containers If your shipment is damaged or incomplete save the packing materials and notify both the shipping carrier and the nearest Agilent Technologies sales and service office Agilent Technologies will arrange for repair or replacement of damaged or incomplete shipments without waiting for a settlement from the transportation company Notify the Agilent Technologies customer engineer of any problems 2 Make sure that the serial number and options listed on the instrument s rear panel label match the serial number and options listed on the shipping document The following figure is an example of the rear panel serial number label ui Agi ilent MADE IN GERMANY 86120B ATO 1234 DE44101234 WARNING CAUTION CAUTION
78. d is included with the unit The cable shipped with the instrument also has a right angle connector so that the Agilent 86120B can be used while sitting on its rear feet You can order additional ac power cables for use in different geographic areas Refer to Front Panel Fiber Optic Adapters on page 258 Step 3 Connect a Printer The Agilent 86120B can print hardcopies of measurement results on a printer The output is ASCII text If you don t have a printer continue with Using a standard parallel printer cable connect the printer to the Agilent 86120B s rear panel PARALLEL PRINTER PORT connector CAUTION N Getting Started Step 4 Turn on the Agilent 86120B Step 4 Turn on the Agilent 86120B The front panel LINE switch disconnects the mains circuits from the mains supply after the EMC filters and before other parts of the instrument Press the front panel LINE key After approximately 20 seconds the display should look similar to the following figure The front panel LINE switch disconnects the mains circuits from the mains supply after the EMC filters and before other parts of the instru ment HO SIGNAL CE m Wal LD eee JD If the Agilent 86120B fails to turn on properly consider the following possibilities Is the line fuse good Does the line socket have power Is it plugged into the proper ac power source If the instrument still fails return
79. d laser line peaks CALCulate2 PTHReshold lt integer gt MINimum MAXimum DEFault integer represents logarithmic units in dB Valid range is O to 40 Constant Value MINimum 0 dB 164 Attribute Summary Description Syntax Attribute Summary Programming Commands CALCulate2 Subsystem MAXimum 40 dB DEFault 10 dB Non sequential command Preset State 10 dB RST State 10 dB SCPI Compliance instrument specific A laser line is identified as a valid peak if its amplitude is above the maximum amplitude minus the peak threshold value The subtraction is done in dB units This setting works in conjunction with the peak excursion setting to determine which responses are located Refer to PEXCursion on page 163 Changing the peak threshold limit causes the instrument to reprocess the current set of data Refer also to To define laser line peaks on page 2 52 The query response is the current value For example if the current value is set to 15 dB the following value is returned 15 Non sequential command Always use OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120B to wait for non sequential commands on page 90 for more information PWAVerage STATe Places the instrument in the power weighted average mode CALCulate2 PWAVerage STAT
80. ds on page 90 for more information 166 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem WLIMit STARt FREQuency Sets the starting frequency for the wavelength limit range CALCulate2 WLIMit STARtFREQuency real MINimum MAXimum lt real gt is a frequency value that is within the following limits Constant Description MINimum 181 6924 THz MAXimum wavelength limit stop value Non sequential command Preset State 181 6924 THz RST State 181 6924 THz SCPI Compliance instrument specific This command sets the starting range for the wavelength limit in Hertz The start frequency value must be less than or equal to the stop frequency value or the start frequency will be clipped to the stop fre quency and a Data out of range error will be generated The default units for the lt real gt parameter are hertz Non sequential command Always use OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120B to wait for non sequential commands on page 90 for more information 167 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem WLIMitSTARt WAVelength CALCulate2 WLIMit STARt WAVelength lt real gt MINimum MAXimum lt real gt is a wavenumber value t
81. dual laser line Power units are in Watts linear The following equation shows how individual powers of laser lines are summed together to obtain the total power value n i 41 Using the Multi Wavelength Meter Displaying Wavelength and Power where nis the number of laser lines included in the measurement is the peak power of an individual laser line Power units are in Watts linear To display average wavelength and total power Press the Avg WL key Measuring lasers between 700 nm and 1200 nm After the Preset key is pressed the input wavelength range is limited to measuring lasers between 1200 nm and 1650 nm This prevents the accidental display of spurious signals that may not exist You can eas ily expand the input range to the full 700 nm to 1650 nm range how ever you should learn how to identify spurious signals Spurious signals below 1200 nm may be displayed whenever low power laser lines power levels near the Agilent 86120B s specified sensitiv ity are present at the input For example a low power laser line at 1550 nm has a second harmonic line at 775 nm If this second har monic is above the peak threshold level relative to the fundamental line it is considered a peak Its displayed power level may be greater than that of the fundamental because the amplitude correction at 775 nm is much greater by about 15 dB than that at 1550 nm the inter ferometer is less sensitive at
82. e ON OFF 1 0 Preset State off RST State off 165 Description Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem When the state is on the CALC2 DATA POW query returns the total power and the CALC2 DATA WAV FREQ or WNUM query returns the power weighted average wavelength frequency or wave number val ues Turning power weighted average mode on while making delta coher ence length or signal to noise measurements results in a 221 Set tings conflict error WLIMit STATe Limits input wavelength range of the Agilent 86120B CALCulate2 WLIMit STATe ON OFF 1 0 Non sequential command Preset State on RST State on SCPI Compliance instrument specific When this function is on the Agilent 86120B has an input range from the WLIMit STARt to the WLIMit STOP When this function is off the instrument displays peaks over the full wavelength range If you want to measure signals over a narrower wavelength range set this function on to avoid identifying spurious second harmonic peaks Whenever the Agilent 86120B receives this command it reprocesses the data and performs a new peak search Non sequential command Always use OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120B to wait for non sequential comman
83. e 15 dB RST State 15 dB SCPI Compliance instrument specific A laser line is identified as a valid peak if its amplitude is greater than the peak excursion plus the amplitudes of the closest local min ima on either side of the peak This command works in conjunction with the peak threshold setting Refer to PTHReshold on page 164 Changing the peak excursion limit causes the instrument to reprocess the current set of data Refer also to Defining Laser Line Peaks on page 2 50 The query response is the current value For example if the current value is set to 15 dB the following value is returned 15 163 Syntax Attribute Summary Description Query Response Syntax Programming Commands CALCulate2 Subsystem Non sequential command Always use an OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120B to wait for non sequential commands on page 90 for more information POINts Queries the number of points in the data set CALCulate2 POINts Preset State unaffected RST State unaffected SCPI Compliance instrument specific Query Only This is the number of points that will be returned by the CALC2 DATA query For example if six laser lines are located 6 PTHReshold Sets the peak threshold limit used by the instrument to determine vali
84. e Summary Programming Commands DISPlay Subsystem DISPlay MARKer MAXimum NEXT Preset State marker set to maximum power laser line RST State marker set to maximum power laser line SCPI Compliance instrument specific Command Only If the display is in the Listby WL mode it will be changed to List by Ampl before the marker is moved MARKer MAXimum PREVious Moves the marker to the laser line that has the next higher power level DISPlay MARKer MAXimum PREVious Preset State marker set to maximum power laser line RST State marker set to maximum power laser line SCPI Compliance instrument specific Command Only If the display is in the List by WL mode it will be changed to List by Ampl before the marker is moved MARKer MAXimum RIGHt Moves the marker right to the next laser line DISPlay MARKer MAXimum RIGHt Preset State marker set to maximum power laser line RST State marker set to maximum power laser line SCPI Compliance instrument specific Command Only 197 Description Syntax Attribute Summary Description Programming Commands FETCh Measurement Instruction Moves the marker from the current marker position to the next laser line having the following characteristic longer wavelength higher frequency higher wave number If the display is in the List by Ampl mode it will be changed to List by WL before the marker is moved WINDow GRAPhics STATe Turns on
85. e measurements are shown on the display Additional amplification can also be accounted for To measure total power exceeding 10 dBm The maximum total input power that can be applied to the Agilent 86120B before damage occurs is 18 dBm The maximum total input power that can be measured is 10 dBm Connect an optical attenuator between the front panel OPTICAL INPUT connector and the fiber optic cable The attenuator must reduce the total input power to the Agilent 86120B so that it is below 10 dBm Press Setup MORE CAL and then PWR OFS Notice that the PWR OFS annotation appears on the screen to indicate an offset is applied Use the softkey to select the digit that requires editing Use the and softkeys to change the value Power offset values are added to the display power readings For example if you placed a 10 dB attenuator on the front panel connec tor enter a power offset value of 10 dB Negative values can also be entered if you connect an amplifier instead of an attenuator 60 Using the Multi Wavelength Meter Calibrating Measurements Calibrating Measurements The wavelength of light changes depending on the material that the light is passing through To display meaningful wavelength measure ments the Agilent 86120B performs two steps Measures the wavelength in air Converts the wavelength to show values in either a vacuum or standard a For example a laser line with a wav
86. e string does not contain a first value which specifies the string length This is shown in the following example OUTPUT 720 CALCulate1 POINts ENTER 720 Length OUTPUT 720 CALCulate1 DATA ENTER 720 Result Data can be corrected for elevation and vacuum Normally the Agilent 86120B provides measurement values calculated for conditions in air at sea level Use the SENSe CORRection ELEVa tion command to compensate for air dispersion Altitudes up to 5000 meters can be entered Use the SENSe CORRection MEDium command to switch to readings in a vacuum Amplitude units The default amplitude units are dBm If you need measurements in watts use the UNIT POWer command When the Agilent 86120B is turned on the amplitude units are automatically set to the units used before the instrument was last turned off 93 Programming Monitoring the Instrument Monitoring the Instrument Almost every program that you write will need to monitor the Agilent 86120B for its operating status This includes querying execu tion or command errors and determining whether or not measure ments have been completed Several status registers and queues are provided to accomplish these tasks In this section you ll learn how to enable and read these registers In addition to the information in this section you should review the com mands documented in Common Commands on page 131 and STA Tus Subsystem on page 206 S
87. e to be lost This also generates an error in the error queue The output of the instrument may be numeric or character data depending on what is queried Refer to the specific commands for the formats and types of data returned from queries You can send multiple queries to the instrument within a single pro gram message but you must also read them back within a single pro gram message This can be accomplished by either reading them back into a string variable or into multiple numeric variables When you read the result of multiple queries into string variables each response is separated by a semicolon 105 Programming Example Programs Example Programs The following example programs are provided in this section Example 1 Measure a DFB laser 108 Example 2 Measure WDM channels 110 Example 3 Measure WDM channel drift 112 Example 4 Measure WDM channel separation 115 Example 5 Measure SN ratio of WDM channels 117 Example 6 Increase a source s wavelength accuracy 119 These programs are provided to give you examples of using Agilent 86120B remote programming commands in typical applications They are not meant to teach general programming techniques or pro vide ready to use solutions They should allow you to see how mea surements are performed and how to return data to the computer All of the examples are written in the HP BASIC programming lan guage Many subroutines are repeated in the examples The f
88. e commands from the same subsystem provided that they are both on the same level in the subsystem s hierarchy Simply separate the commands with a semi colon For example the follow ing two lines OUTPUT 720 CALC2 PEXC 12 OUTPUT 720 CALC2 PTHR 20 can be combined into one line OUTPUT 720 CALC2 PEXC 12 PTHR 20 102 Programming Reviewing SCPI Syntax Rules The semicolon separates the two functions Combine commands from different subsystems You can send commands and program queries from different sub systems on the same line Simply precede the new subsystem by a semicolon followed by a colon In the following example the colon and semicolon pair before DISP allows you to send a command from another subsystem OUTPUT 720 CALC2 PEXC 12 DISP WIND GRAP STAT OFF Sending common commands If a subsystem has been selected and a common command is received by the instrument the instrument remains in the selected subsystem For example if the program message DISPLAY MARK MAX LEFT CLS DISP MARK MAX RIGH is received by the instrument the Display subsystem remains selected If some other type of command is received within a program message you must reenter the original subsystem after the command Adding parameters to a command Many commands have parameters that specify an option Use a space character to separate the parameter from the command as shown in the following line OUTPUT 720 INIT CON
89. e inside sleeve of connectors made with ceramic material When inserting a fiber optic connector into a connector make sure that the fiber end does not touch the outside of the mating connector or adapter Avoid over tightening connections Unlike common electrical connections tighter is not better The pur pose of the connector is to bring two fiber ends together Once they touch tightening only causes a greater force to be applied to the deli cate fibers With connectors that have a convex fiber end the end can be pushed off axis resulting in misalignment and excessive return loss Many measurements are actually improved by backing off the connec 26 Getting Started Cleaning Connections for Accurate Measurements tor pressure Also if a piece of grit does happen to get by the cleaning procedure the tighter connection is more likely to damage the glass Tighten the connectors just until the two fibers touch Keep connectors covered when not in use Use fusion splices on the more permanent critical nodes Choose the best connector possible Replace connecting cables regularly Frequently measure the return loss of the connector to check for degradation and clean every connector every time All connectors should be treated like the high quality lens of a good camera The weak link in instrument and system reliability is often the inappropriate use and care of the connector Because current connec tors are so easy to use
90. e2 WLIMit command Set ting this command to off enables the full wavelength range of the instrument If you are measuring signals over a narrow wavelength range use this command to ensure that spurious second harmonic peaks are not identified Refer to WLIMit STATe on page 166 WLIMit STARt WAVelength on page 168 and WLIMit STOP WAVe length on page 171 Refer also to To limit the wavelength range on page 43 82 Programming Making Measurements Making Measurements Making measurements remotely involves changing the Agilent 86120B s settings performing a measurement and then returning the data to the computer The simplified block diagram of the Agilent 86120B shown here lists some of the available programming commands Each com mand is placed next to the instrument section it configures or queries data from Uncorrected data buffer frequency domain data 64K 8K Michelson Interferometer Resolution argument of CALCulatel DATA FETCh READ or INITiate MEASure continuous time domain or single data HeNE measurement 128K Reference acquisition Laser SENSe DATA flow Notice that there are two buffers from which data can be queried an uncorrected data buffer and a corrected data buffer With each scan of the input wavelength range the analog to digital converter loads 65 536 data values into the uncorrected data buffer This is considered to be one measurement
91. eak OUTPUT 720 MEAS SCAL POW MAX Use either short or long forms Commands and queries may be sent in either long form complete spelling or short form abbreviated spelling The description of each command in this manual shows both versions the extra characters for the long form are shown in lowercase The following is a long form of a command OUTPUT 720 MEASure SCALar POWer MAXimum 101 Programming Reviewing SCPI Syntax Rules And this is the short form of the same command OUTPUT 720 MEAS SCAL POW MAX Programs written in long form are easily read and are almost self doc umenting Using short form commands conserves the amount of con troller memory needed for program storage and reduces the amount of I O activity The rules for creating short forms from the long form is as follows The mnemonic is the first four characters of the keyword unless the fourth character is a vowel in which case the mnemonic is the first three characters of the keyword This rule is not used if the length of the keyword is exactly four char acters Table 4 8 Examples of Short Forms Long Form Equivalent Short Form ROUTE ROUT LAYER LAY SYSTEM SYST ERROR ERR You can use upper or lowercase letters Program headers can be sent using any combination of uppercase or lowercase ASCII characters Instrument responses however are always returned in uppercase Combine commands in the same subsystem You can combin
92. easure WDM channels 110 Example 3 Measure WDM channel drift 112 Example 4 Measure WDM channel separation 115 Example 5 Measure SN ratio of WDM channels 117 Example 6 Increase a source s wavelength accuracy 119 Lists of Commands 121 Programming Programming Programming Programming This chapter explains how to program the Agilent 86120B The pro gramming syntax conforms to the IEEE 488 2 Standard Digital Inter face for Programmable Instrumentation and to the Standard Commands for Programmable Instruments SCPI Where to begin The programming examples for individual commands in this manual are written in BASIC 6 0 for an HP 9000 Series 200 300 Control ler For more detailed information regarding the GPIB the IEEE 488 2 standard or the SCPI standard refer to the following books Hewlett Packard Company Tutorial Description of Hewlett Packard Interface Bus 1987 Hewlett Packard Company SCPI Standard Commands for Program mable Instruments 1995 International Institute of Electrical and Electronics Engineers IEEE Standard 488 1 1987 IEEE Standard Digital Interface for Program mable Instrumentation New York NY 1987 International Institute of Electrical and Electronics Engineers IEEE Standard 488 2 1987 IEEE Standard Codes Formats Protocols and Common commands For Use with ANSI IEEE Std 488 1 1987 New York NY 1987 Types of commands The Agilent 86120B responds to three types of co
93. easurement results for elevation above sea level and to select between measurements in air or vacuum You can also enter an amplitude offset The commands in this sub system have the following command hierarchy SENSe CORRection DEVice ELEVations MEDium OFFSet MAGNitude DATA 200 Syntax Attribute Summary Description Query Response Programming Commands SENSe Subsystem CORRection DEVice Selects the wavelength measurement algorithm This command applies to Agilent 86120B instruments with firmware version number 2 0 When first turned on the instrument briefly displays the firmware version Instruments with a firmware ver sion number less than 2 0 do not have this feature SENSe CORRection DEVice NARRow BROad Constant Description NARRow Selects wavelength measurements for narrowband devices such as DFB lasers and modes of FP lasers BROad Selects wavelength measurements for broadband devices such as optical filters and LEDs Non sequential command Preset State NARRow RST sets this value to NARRow SCPI Compliance instrument specific The narrow bandwidth algorithm used for measuring lasers deter mines the wavelength based upon the peak The broad bandwidth algorithm used for LEDs filters and chirped lasers determines the wavelength based upon the center of mass of the power spectrum The peak excursion function is used to determine the value of the integration l
94. ed to tune a laser to its designated channel the Agilent 86120B can be set to update approximately three times per second This reduces both wavelength resolution and accu racy but can be beneficial in some applications When FAST update is selected one less digit of resolution is displayed Also if multiple wavelengths are present these individual responses with the reduced resolution may no longer be recognized To change the measurement speed Press the Setup key Press the MORE softkey Press the UPDATE softkey Select either NORMAL or FAST 48 Using the Multi Wavelength Meter Changing the Units and Measurement Rate Continuous or single measurements The Agilent 86120B continuously measures the input spectrum at the front panel OPTICALINPUT connector Whenever measurements are being acquired an asterisk is displayed in the display s upper right cor ner When you switch between normal and fast update modes the rate that the asterisk blinks changes You can specify that the instrument perform a measurement only when the front panel Single key is pressed This is the single acquisition measurement mode and it is useful for capturing and preserving data After capturing the data you can display it using many of the proce dures included in this chapter You can return to continuous measure ment mode at any time by pressing the Cont key To select single measurement acquisition Press the Single key
95. elength of 1550 000 nm in a vac uum would have a wavelength in standard air of 1549 577 nm Because all measurements made inside the Agilent 86120B are per formed in air the density of air due to elevation affects the wave length results You must calibrate the Agilent 86120B by entering the elevation Elevations from 0 to 5000 meters can be entered The eleva tion correction is immediately applied to the current measurement even if the instrument is in the single measurement acquisition mode Annotation on the display shows the current calibration elevation in meters and whether the wavelength measurements are shown for a vacuum VAC or standard air STD AIR If you select frequency instead of wavelength measurements switching between vacuum and standard air will not affect the measurement results This is because the frequency of an optical signal does not change in different mediums only the wavelength changes Definition of standard air Standard air is defined to have the following characteristics Barometric pressure 760 torr Temperature 15 C Relative humidity 096 61 amp WO N m Using the Multi Wavelength Meter Calibrating Measurements To enter the elevation Press the Setup key Press the MORE softkey Press the CAL softkey Press ELEV Use the and softkeys to enter the elevation in meters Entries jump in 500 meter steps from 0 m to 5000 m In order for the Agilent 86120B to meet
96. em DELTa WAVelength STATe Turns the delta wavelength measurement mode on and off CALCulate3 DELTa WAVelength STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific When on the wavelength of the reference laser line is subtracted from the wavelength values of all laser lines except the reference For the CALC3 DATA query the power data returned is the array of absolute powers measured for each laser line The frequency data is the array of frequency values normalized to the frequency of the refer ence laser line The frequency of the reference laser line is returned as an absolute frequency unnormalized Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 92 for additional information on selecting measurements 182 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DELTa WPOWer STATe Turns the delta wavelength and power measurement mode on and off CALCulate3 DELTa WPOWer STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific When on the wavelength of the reference laser line is subtracted from the wavelength values of all laser lines except the reference The power value of the reference
97. ements As you perform these measurements keep in mind the following points 700 nm to 1650 nm maximum input wavelength range The range is normally limited from 1200 nm to 1650 nm To use the full range refer to Measuring lasers between 700 nm and 1200 nm on page 42 10 dBm maximum total displayed input power Laser linewidths assumed to be less than 10 GHz If you change the elevation where you will be using your Agilent 86120B refer to Calibrating Measurements on page 61 Press the green Preset key to return the Agilent 86120B to its default state Do not exceed 18 dBm source power The Agilent 86120B s input circuitry can be damaged when total input power exceeds 18 dBm You can measure power levels that are greater by adding attenuation and entering a power offset as described in To measure total power exceeding 10 dBm on page 60 36 Using the Multi Wavelength Meter Displaying Wavelength and Power Displaying Wavelength and Power This section gives you step by step instructions for measuring peak wavelength average wavelength peak power and total input power There are three display modes Peak wavelength List by wavelength or power Average wavelength and total power If the measured amplitudes are low clean the front panel OPTICAL INPUT connector This section includes Peak WL mode 38 List by WL or power modes 40 Total power and average wavelength 41 Measuring lasers between 700
98. ength CALC3 DELT WPOW STAT delta power and wavelength CALC3 DRIF STAT drift CALC3 SNR STAT signal to noise ratios CALC3 ASNR STAT signal to noise ratio averaging If you select a drift measurement you can additionally select one of the following additional states CALC3 DRIF DIFF STAT difference CALC3 DRIF MAX STAT maximum drift CALC3 DRIF MIN STAT minimum drift CALC3 DRIF REF STAT drift reference values The CALCulate3 DRIFt PRESet command turns off the minimum max imum difference and reference states but leaves the drift state on Attempting to turn more than one state on at a time results in a 221 Settings Conflict error The RST and SYSTem PRESet commands turn all calculations off CALCulate3 PRESet turns off any CALCulate3 calculations 92 Programming Making Measurements The format of returned data Measurements are returned as strings All measurement values are returned from the Agilent 86120B as ASCII strings When an array is returned the individual values are separated by the comma character Determine the number of data points When a FETCh READ or MEASure command is used with ARRay specified the first returned value indicates the total number of mea surement values returned in the query If you use the CALCulate1 DATA CALCulate2 DATA or CALCulate3 DATA queries to query data send the POINts query first to determine the number of values returned in the string Th
99. entricity of the core within the cladding Mating one style of cable to another requires an adapter Agilent Technologies offers adapters for most instruments to allow testing with many different cables Figure 1 1 on page 22 shows the basic components of a typical connectors The system tolerance for reflection and insertion loss must be known when selecting a connector from the wide variety of currently available connectors Some items to consider when selecting a connector are How much insertion loss can be allowed Will the connector need to make multiple connections Some connectors are better than others and some are very poor for making repeated connections 21 Getting Started Cleaning Connections for Accurate Measurements What is the reflection tolerance Can the system take reflection degra dation Is an instrument grade connector with a precision core alignment re quired Is repeatability tolerance for reflection and loss important Do your specifications take repeatability uncertainty into account Will a connector degrade the return loss too much or will a fusion splice be required For example many DFB lasers cannot operate with reflections from connectors Often as much as 90 dB isolation is needed Connecting Body and Ferrule 2 5 mm Mechanical Retainer Fiber 125 um actual fiber s diameter is smaller than a human hair Alignment Key Figure 1 1 Basic components of a connector Over the las
100. ependence Polarization Dependence is verified using the following devices 1310 nm and 1550 nm DFB lasers Optical attenuator Agilent 11896A Polarization Controller Do not exceed 18 dBm source power The Agilent 86120B s input circuitry can be damaged when total input power exceeds 18 dBm Perform the following procedure first using the 1310 nm laser and then repeat the steps using the 1550 nm laser Turn on the lasers and allow them to warm up Set the polarization controller to a scan rate of 5 On the Agilent 86120B press the Preset key Connect the laser s optical output to the polarization controller s optical input Connect the polarization controller s optical output to the Agilent 86120B being tested Set the polarization controller to autoscan On the Agilent 86120B press Peak WL Appl s and then DRIFT Press MAX MIN so that both MAX and MIN in the softkey label are highlighted The display shows the total drift since the drift measurement was started Wait five minutes read the peak amplitude drift from the Agilent 86120B and compare with the specification listed in Chapter 7 Specifications and Regulatory Information 223 Description Procedure 10 11 Performance Tests Test 4 Optical Input Return Loss Test 4 Optical Input Return Loss Input return loss is verified using the following devices Agilent 8153A Lightwave Multimeter Agilent 81553SM 1550 nm Fabry Perot laser SM 9 125 um S
101. er Sets the instrument for single or continuous measurement S Sets the power units to watts linear or dBm logarithmic S 125 Programming Lists of Commands Table 4 11 Keys Versus Commands 1 of 3 Key Equivalent Command A PWR CALCulate3 DELTa POWer STATe AWL CALCulate3 DELTa WAVelength STATe A WL PWR CALCulate3 DELTa WPOWer STATe Appl s See COH LEN DRIFT and S N AUTO CALCulate3 SNR AUTO ON Avg WL CALCulate2 PWAVerage STATe BAR OFF DISPlay WINDow GRAPhics STATe BAR ON DISPlay WINDow GRAPhics STATe BROAD SENSe CORRection DEVice BROad CAL See ELEV PWR OFS STD AIR and VACUUM CM 1 MEASure ARRay POWer WNUMber COH LEN MEASure LENGth COHerence CLENgth Cont INITiate CONTinuous ON DBM UNIT POWer DEVICE SENSe CORRection DEVice DRIFT CALCulate3 DRIFt STATe ELEV SENSe CORRection ELEVation EXIT none FAST See UPDATE GPIB none LIM OFF CALCulate2 WLIMit STATe OFF LIM ON CALCulate2 WLIMit STATe ON List by Power CONFigure ARRay POWer List by WL MEASure ARRay POWer WAVelength 126 Programming Lists of Commands Table 4 11 Keys Versus Commands 2 of 3 Key Equivalent Command MAX MIN CALCulate3 DRIFt MINimum STATe and CALCulate3 DRIFt MAXimum STATe MW UNIT POWer NARROW SENSe CORRection DEVice NARRow NEXT PK DISPlay MARKer MAXimum NEXT NEXT WL DISPlay MARKer MAXimum RIGHt NM MEASure ARRay POWer WAVelength NORMAL See UPDATE O
102. er the wavelength limit function is on or off Preset will turn the wavelength limit on and will set the start wave length to 1200 nm and the stop wavelength to 1650 nm To limit the wavelength range 1 Press the Setup key 2 Press the WL LIM softkey 3 Press the LIM ON softkey if it is not already highlighted 4 Press the STARTWL softkey to adjust the start wavelength value 5 Press the STOPWL softkey to adjust the stop wavelength value 43 Using the Multi Wavelength Meter Displaying Wavelength and Power Measuring broadband devices and chirped lasers When first turned on or the green Preset key is pressed the Agilent 86120B is configured to measure narrowband devices such as DFB lasers and modes of FP lasers If you plan to measure broadband devices such as LEDs optical filters and chirped lasers use the Setup menu first to reconfigure the instrument When broadband devices are selected the display shows the BROAD annotation on the screen The measurement algorithm for broadband devices determines the wavelength based upon the center of mass of the power spectrum The peak excursion function is used to determine the value of the integra tion limits Care must be taken to ensure that the integration limits are above any noise This is especially true when measuring devices with sloping noise floors like an EDFA amplifier For more informa tion on peak excursion refer to Defining Laser Line Peaks on page 50 In
103. ere is no menu associated with this key 250 Reference Menu Maps System Print Menu CONT ABORT mprint 251 Reference Menu Maps System Setup Menu LIM ON LIM OFF START WL STOP WL RETURN WL LIM THRSHLD SAV RCL MORE RETURN SAVE RECALL NORMAL FAST UPDATE a el n CM MORE THZ RETURN RETURN RETURN VACUUM STD AIR ELEV PWR OFS RETURN MW UW RETURN HP IB PWR BAR DEVICE BAR ON NARROW BAR OFF RETURN BROAR RETURN RETURN SAVE 1 SAVE 2 SAVE 3 SAVE 4 RETURN RCL 1 RCL2 RCL 3 RCL 4 RETURN CANCEL RETURN msetup 252 Reference Error Messages Error Messages In this section you ll find all the error messages that the Agilent 86120B can display on its screen Table 7 2 on page 7 253 lists all instrument specific errors Table 7 3 on page 7 256 lists general SCPI errors Table 7 2 Instrument Specific Error Messages 1 of 3 Error Number Error Message 1 BAD CHECKSUM FROM MOTOR 2 MOTOR COMMUNICATION PROBLEM 3 MOTOR NOT MOVING 4 MOTOR INDEX PULSE NOT FOUND 5 MOTOR CHIP SET INIT FAILED 6 MOTOR COMMUTATION FAILURE 7 MOTOR NOT SETTLED 8 MOTOR DID NOT STOP 9 MOTOR MOTION ERROR 10 MOTOR POSITION LIMIT FAILED 11 MOTOR POSITION WRAP FAILED 12 POWER LEVEL TOO HIGH 13 DATA DOWNLOAD PROBLEM 14 DATA ACQUISITION PROBLEM 15 MAX NUMBER OF
104. es of merchantability and fitness for a particular purpose Agilent Technologies shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing performance or use of this material Warranty This Agilent Technologies instru ment product is warranted against defects in material and workmanship for a period of one year from date of shipment Dur ing the warranty period Agilent will at its option either repair or replace products that prove to be defective For warranty service or repair this product must be returned to a service facility designated by Agi lent Buyer shall prepay shipping charges to Agilent and Agilent shall pay shipping charges to return the product to Buyer How ever Buyer shall pay all shipping charges duties and taxes for products returned to Agilent from another country Agilent warrants that its software and firmware designated by Agilent for use with an instrument will execute its programming instructions when properly installed on that instrument Agilent does not war rant that the operation of the instrument software or firm ware will be uninterrupted or error free limitation of Warranty The foregoing warranty shall not apply to defects resulting from improper or inadequate mainte nance by Buyer Buyer supplied software or interfacing unautho rized modification or misuse operation outside of the environ mental s
105. eter measures a power level of 0 dBm Enter the attenuator setting and the measured power level in the first row of Table 6 21 on page 6 229 Be sure to enter these values into the Attenuator Settings and Power Meter Readings columns Enter the measured power on the following line Pwr Change the attenuator in 1 dB steps as shown in Table 6 21 and enter the attenuator settings and power measurements 227 Performance Tests Test 5 Amplitude Accuracy and Linearity After completing this step the first two columns of the table should be completely filled in 10 Disconnect the fiber optic cable from the optical power meter and connect it to the Agilent 86120B s OPTICAL INPUT connector 11 Set the optical attenuator for the value that you recorded in Step 8 12 Place the polarization controller in the auto scan mode 13 Press the Agilent 86120B s front panel Preset key 14 Press List by Power Appl s and then DRIFT 15 After two minutes stop the polarization controller s auto scan function 16 Press the MAX MIN softkey so that MAX is highlighted Enter the maximum drift reading on the following line maximum drift 17 Press the MAX MIN softkey so that MIN is highlighted Enter the minimum drift reading on the following line minimum drift 18 Use the values recorded in Step 8 Step 16 and Step 17 to calculate the power correction offset value as shown in the following equation minimum drift max
106. eters 103 address See GPIB address Agilent offices 261 air measurements in 61 alpha factor 76 78 ALPHa programming command 153 AM modulation 50 58 amplitude offset 60 specifications 236 annotation asterisk 38 40 49 1 nm 69 72 AVERAGE 41 BROAD 44 BY PWR 40 BY WL 40 DRIFT 73 M 38 PEAK 38 PWR OFS 60 Remote 81 S N AUTO 67 S N USER 67 STD AIR 61 VAC 61 Appl s key 69 74 76 menu map 247 ARRay programming command 144 ASNR CLEar programming command 174 COUNt programming command 174 STATe programming command 176 asterisk 38 40 49 attenuation See external attenuation audio modulation effects of 50 58 AUTO programming command 191 softkey 70 AVERAGE annotation 41 average wavelength 3 41 Avg WL key 41 42 B BAR OFF softkey 46 BAR ON softkey 46 beta factor 76 78 BETA programming command 154 bit error rate 67 block diagram 83 BROAD annotation 44 BROAD softkey 44 broadband devices measuring 44 programming command 201 broadband mode 44 235 BY PWR annotation 40 BY WL annotation 40 C cabinet cleaning 7 CAL softkey 18 CALCulate1 subsystem 155 CALCulate2 subsystem 161 CALCulate3 subsystem 92 112 115 117 173 calibration accuracy 234 cycle 220 232 elevation 18 measurements 61 medium for light 19 care of cabinet 7 of fiber optics 5 case sensitivity 102 channel spacing 55 characteristics 235 chirped lasers
107. g Measuring Signal to Noise Ratios with Averaging When the lasers being measured are modulated especially with repeti tive data formats such as SONET or PRBS the noise floor is raised Averaging reduces the noise floor and allows an improvement of greater than 10 dB in a signal to noise measurement In general aver aging will decrease the noise floor caused by modulation until the true optical noise level is reached The displayed signal to noise will improve with each average until the true optical noise level is reached and then the displayed signal to noise will remain approximately con stant If however the true signal to noise is below the instrument sensitivity of approximately 40 dB Gin a 0 1 nm noise bandwidth it will not be measured Averaging can also improve the accuracy of measuring signal to noise of unmodulated lasers 1546 454nm 18 81dBm 31 746 1548 868 6 06 S6 TaiHM EY WL 1549 663 e 4 25 37 8 s 1551 281 4 34 37 8 T 1552 894 11 22 33 4 8 M Signal to noise with averaging display Averaging is performed on the noise not on the wavelength or power of the laser signals The signal to noise with averaging measurement uses the automatic interpolation method to determine the wavelengths where the noise is measured Refer to Measuring Signal to Noise Ratios on page 3 67 for a description of automatic interpolation There is no user entered wavelength selection in signal to noise w
108. g a wave number that is closest to the expected value parameter Default units for expected value parameter in m When used with an ARRay command an array of wave number is returned The display is placed in the list by wavelength mode The resolution parameter sets the resolution of the measurement It is a unitless number whose value will be limited to either 0 01 or 0 001 whichever is closer Returned values are in inverse meters Displayed units are inverse centimeters Power units are not affected CONFigure command When this function is used with the CONFigure command the query question mark character must not be included in the string However the FETCh READ and MEASure command are queries and require the question mark Refer to the examples for this command MAXimum The laser line having the largest wave number MINimum The laser line having the smallest wave number DEFault The current marker position 152 lt resolution gt Constants Examples Query Response Syntax Attribute Summary Description Programming Commands Measurement Instructions MAXimum 0 01 resolution fast update MINimum 0 001 resolution normal DEFault Current resolution CONF ARR POW WNUM DEF MAX FETC ARR POW WNUM DEF MIN READ ARR POW WNUM MEAS ARR POW WNUM CONF SCAL POW WNUM 6451 MAX FETC SCAL POW WNUM 6451 MIN READ SCAL POW WNUM 6451 MEAS SCAL POW WNUM 6451
109. g the resolution argu ment of an instrument function Refer to Measurement Instructions on page 144 When NORMAL measurement update is specified over 2 200 kilobytes of data 128K values can be returned to the computer When FAST mea surement update is specified over 250 kilobytes of data 16K values can be returned The floating point values are scaled from 1 000 to 1 999 1 1023 1024 Amplitude values are not calibrated The input laser line s generate an interference pattern on the photo detector as a function of the Michelson interferometer optical path delay The time domain data is sampled at uniform optical path delay increments of half the reference laser wavelength or 0 316495 microns When NORMAL measurement update is selected the first data value is sampled at 20 74 mm optical path delay and the last value is sam pled at 20 74 mm optical path delay When FAST measurement update is selected the first data value is sampled at 2 59 mm optical path delay and the last value is sampled at 2 59 mm optical path delay The data value that corresponds to zero optical path delay is approxi mately but not exactly located in the center of the time domain data 204 Programming Commands SENSe Subsystem If your program is aborted or interrupted after sending this query the Agilent 86120B continues to process the data but does not place it in the output buffer Because of the amount of data processed the instrume
110. gle measurement mode 15 dB peak excursion 10 20 10 dB peak threshold Power dBm 30 40 50 Wavelength wavlth15 The following figure shows the same laser lines as the previous figure but the peak excursion value has been changed from 15 to dB Four laser lines are now identified with responses D and f identified as two distinct laser lines 51 Using the Multi Wavelength Meter Defining Laser Line Peaks 3 dB peak excursion 10 20 10 dB peak threshold Power dBm 30 40 50 Wavelength wavith3 Limiting the input The Agilent 86120B s preset condition limits the wavelength measure wavelength range ment range from 1200 nm to 1650 nm You can expand the wavelength range to cover the entire 700 nm to 1650 nm range Although wave length range limiting reduces the number of laser lines found its main purpose is to eliminate the identification of second harmonic distor tion products as described in the following sidebar Distortion caused by low power laser lines Low power laser lines power level near the Agilent 86120B s specified sensitivity may be accompanied by second harmonic or other distortion For example a low power laser line at 1550 nm has a second harmonic line at 775 nm If this second harmonic is above the peak threshold level relative to the fundamental line it is considered a peak Its displayed power level may be greater than that of the funda
111. gramming command 203 MAX NUMBER OF SIGNALS FOUND 53 maximum power input 4 MAXimum programming command 196 MAX MIN softkey 74 MEASure measurement instruction 108 110 144 measurement accuracy 17 air in 61 AM modulation 50 58 audio modulation effects of 50 58 average wavelength 41 calibration 61 channel separation 56 channel spacing 55 coherence length 76 continuous acquisition 49 cycle time 234 237 definition of peaks 50 elevation effects of 61 flatness 57 via GPIB 83 instructions 101 144 laser drift 73 laser line separation 54 low power laser lines effects of 52 modulated lasers effects of 58 monitoring performance over time 73 multiple laser lines 40 47 of broadband devices 44 PRBS format present 59 69 relative power 54 relative wavelength 54 repetitive data formats 69 signal to noise 67 69 single acquisition 49 SONET format present 59 69 speed 48 87 159 204 total power 41 units 47 update rate 87 159 204 in vacuum 61 measuring chirped lasers 44 EDFA amplifiers 44 menu maps 246 messages error 253 microwatts 48 milliwatts 48 modulated lasers 58 monitoring the instrument 94 MW softkey 48 nanometers 48 NARROW softkey 44 narrowband mode 44 new line character 105 NEXT PK softkey 39 NEXT programming command 196 NEXT WL softkey 39 NM softkey 48 noise power automatic interpolation 68 bandwidth 69 72 user entered wavelength
112. hat is within the following limits Constant Description MINimum 700 0 nm MAXimum wavelength limit stop value Non sequential command Preset State 700 nm RST State 700 nm SCPI Compliance instrument specific This command sets the starting range for the wavelength limit The start wavelength value must be less than or equal to the stop wavelength value or the start wavelength will be clipped to the stop wavelength and a Data out of range error will be generated Setting the start wavelength is equivalent to setting the stop frequency wavenumber because of the inverse relationship of frequency to wavelength The default units for the lt real gt parameter are meters Non sequential command Always use an OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120B to wait for non sequential commands on page 90 for more information 168 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem WLIMit STARt WNUMber Sets the starting wavenumber for the wavelength limit range CALCulate2 WLIMit STAREWNUMber lt real gt MINimum MAXimum lt real gt is a wavenumber value that is within the following limits Constant Description MINimum 6060 cm MAXimum wavelength limit stop value Non sequential command Preset State 6 060606E5 m R
113. he CALC3 DATA query returns In the SNR or ASNR calculation only the POWer argument is valid The other arguments will generate a Settings conflict error Use the CALC2 DATA query to retrieve the signal wavelengths and powers 177 Syntax Attribute Summary Description Syntax Attribute Summary Programming Commands CALCulate3 Subsystem DELTa POWer STATe Turns the delta power measurement mode on and off CALCulate3 DELTa POWer STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific When this state is on the power of the reference laser line is sub tracted from the power values of all laser lines except the reference The power data returned by the CALC3 DATA query is the array of laser line power levels normalized to the power level of the reference laser line The power of the reference laser line is returned as an absolute power unnormalized The frequency data returned is the array of absolute frequency values Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 92 for additional information on selecting measurements DELTa PRESet Turns off all delta measurement states CALCulate3 DELTa PRESet Preset State not affected RST State not affected SCPI
114. his subsystem have the following command hierar chy SYSTem ERRor HELP HEADers PRESet VERSion ERRor Queries an error from the error queue Syntax SYSTem ERRor Attribute Preset State none Summary RST State none SCPI Compliance standard Query Only Description The Agilent 86120B has a 30 entry error queue The queue is a first in first out buffer Repeatedly sending the query SYSTEM ERROR returns the error numbers and descriptions in the order in which they occur until the queue is empty Any further queries returns 0 No errors until another error occurs For a complete list of error messages refer to Error Messages on page 253 Query Response value string 211 Example Syntax Attribute Summary Description Programming Commands SYSTem Subsystem lt value gt is an integer lt string gt is the text of the error message The following is an example of a response 113 Undefined header DIM Error 250 OUTPUT 720 SYSTEM ERROR ENTER 720 Error PRINT Error HELP HEADers Queries a listing of all the remote programming commands available for the Agilent 86120B SYSTem HELP HEADers Preset State none RST State none SCPI Compliance instrument specific Query Only The returned ASCII string of commands is in the IEEE 488 2 arbitrary block data format The first line indicates the total number of bytes returned to the computer That is
115. hreshold 10 dB Device Narrow nput Wavelength Power 1280 384nm 16 97dBm 1281 473 13 14 1282 569 13 92 1283 651 13 34 1284 752 11 69 1285 840 8 11 1286 944 10 38 1288 034 14 65 To create a hardcopy 1 Connect the printer to the Agilent 86120B s rear panel PARALLEL PRINTER 1 Hewlett Packard and LaserJet are registered trademarks of Hewlett Packard Company 63 PORT connector 2 Press Print You can use the ABORT and CONT softkey to stop and restart a print job that is in progress Measuring Signal to Noise Ratios 67 Measuring Signal to Noise Ratios with Averaging 71 Measuring Laser Drift 73 Measuring Coherence Length 76 Measurements Applications Measurements Applications Measurements Applications Measurements Applications In this chapter you ll learn how to make a variety of fast accurate measurements using the measurement tools accessed by pressing the Appl s key 66 Measurements Applications Measuring Signal to Noise Ratios Measuring Signal to Noise Ratios Signal to noise measurements provide a direct indication of system performance Signal to noise measurements are especially important in WDM systems because there is a direct relation between signal to noise and bit error rate The Agilent 86120B displays signal to noise measurements in the third column For example the selected signal in the following figure has a signal to noise ratio of 30 0 dB Signal
116. if no errors have occurred Notice that the logic test in the subroutine tests for the same event status register bits enabled by the Set_ese subroutine BIT Cme 5 BIT Cme 4 BIT Cme 2 This subroutine is called in examples 1 through 5 However it is mod ified in examples 3 4 and 5 to allow it to indicate the last program ming command that was sent to the instrument before an error occurred This is accomplished by adding an optional argument string Cmd_opc subroutine The Cmd_opc subroutine found in examples 3 4 and 5 pauses the program until a non sequential command has finished executing on the Agilent 86120B It uses the OPC query For more information on non sequential commands refer to Always force the Agilent 86120B to wait for non sequential commands on page 90 Tempo subroutine This subroutine which is only found in example 3 pauses the program for a few seconds while the Agilent 86120B measures the drift on a laser The argument in the example sets the pause for 10 seconds 107 Programming Example Programs Example 1 Measure a DFB laser This program measures the power and wavelength of a DFB laser It first sets the Agilent 86120B in the single acquisition measurement mode Then it triggers the Agilent 86120B with the MEASure com mand to capture measurement data of the input spectrum Because the data is stored in the instrument s memory it can be queried as needed Refer to the int
117. imits Care must be taken to ensure that the integration limits are above any noise This is especially true when measuring devices with sloping noise floors like an EDFA amplifier For more information on peak excursion refer to PEXCursion on page 163 Instrument specifications apply when the device is set to NARRow Specifications do not apply in BROad mode The query form returns the previously selected device NARRow 201 Syntax Attribute Summary Description Query Response Programming Commands SENSe Subsystem CORRection ELEVation Sets the elevation value used by the instrument to compensate for air dispersion SENSe CORRection ELEVation lt integer gt MINimum MAXimum lt integer gt is the altitude in meters Constant Description MINimum 5000 Non sequential command Preset State unaffected by RST sets this value to the minimum SCPI Compliance instrument specific Changing the elevation value causes the current data to be repro cessed The query form returns the current elevation setting as shown in the following example 1500 Non sequential command Always use OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120B to wait for non sequential commands on page 90 for more information 202 Syntax
118. improved process control Safety Notices CAUTION Caution denotes a hazard It calls attention to a procedure which if not correctly performed or adhered to could result in dam age to or destruction of the prod uct Do not proceed beyond a caution sign until the indicated conditions are fully understood and met WARNING Warning denotes a hazard It calls attention to a procedure which if not correctly performed or adhered to could result in injury or loss of life Do not proceed beyond a warning sign until the indicated conditions are fully understood and met The instruction manual A symbol The product is marked with this warning symbol when it is neces sary for the user to refer to the instructions in the manual The laser radiation sym bol This warning symbol is marked on products which have a laser out put The AC symbol is used to Ny indicate the required nature of the line module input power nm The ON symbols are used to mark the posi tions of the instrument power line switch m The OFF symbols used to mark the posi tions of the instrument power line switch The CE mark is a regis tered trademark of the European Community The CSA mark is a regis tered trademark of the Canadian Standards Association The C Tick mark is a reg istered trademark of the Australian Spectrum Management Agency This text denotes the instrument is an Indus trial Scientifi
119. imum drift offset mmm ori Pwr Enter the calculate value on the following line power correction offset 19 Change the attenuator to the settings shown in Table 6 21 For each setting record the power measured on the Agilent 86120B After completing this step the table s column titled Agilent 86120B Power Reading should be completely filled in 20 Calculate the Linearity value for each row in the table using the following equation Linearity Power Meter Reading HP 86120B Power Reading offset 21 Compare the linearity values with the specification listed in Chapter 7 Specifications and Regulatory Information The data may show 228 Performance Tests Test 5 Amplitude Accuracy and Linearity multiple amplitude plateaus separated by small amplitude steps This is not a problem as long as the amplitude steps are within the linearity specification Table 6 21 Linearity Data Values Desired Power Power Meter Agilent 86120B dBm Attenuator Setting Reading Power Reading Linearity 229 Definition of Terms 233 Specifications 235 Laser Safety Information 239 Specifications and Regulatory Information Specifications and Regulatory Information Specifications and Regulatory Information Specifications and Regulatory Information This chapter lists specification and char
120. in imum power or frequency Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 92 for additional information on selecting measurements 186 Syntax Attribute Summary Description Syntax Attribute Summary Programming Commands CALCulate3 Subsystem DRIFt PRESet Turns off all the drift states for DIFFerence MAXimum MINimum and REFerence CALCulate3 DRIFt PRESet Preset State unaffected by RST State unaffected by SCPI Compliance instrument specific Command Only This command allows the CALC3 DATA query to return the difference between the current measurement and the reference DRIFt REFerence RESet Places the current list of laser lines into the reference list CALCulate3 DRIFt REFerence RESet Preset State unaffected by RST State unaffected by SCPI Compliance instrument specific Command Only 187 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DRIFt REFerence STATe Turns on and off the drift reference state CALCulate3 DRIFt REFerence STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific When this command is set to on the CALC3 DATA command returns the reference laser lines Use the CAL
121. in the Agilent 86120B is 1995 0 Table 5 20 SCPI Version Numbers SCPI Version Instrument Serial Prefix 1995 0 US3545 and above 215 Syntax Attribute Summary Description Programming Commands TRIGger Subsystem TRIGger Subsystem The SCPI definition defines the TRIGger subsystem to include ABORt ARM INITiate and TRIGger commands The Agilent 86120B has no ARM or TRIGger commands The commands in this subsystem have the following command hierar chy ABORt INITiate CONTinuous IMMediate ABORt Halts the current measurement sequence and places the instrument in the idle state ABORt Preset State not affected SCPI Compliance standard Command Only If the instrument is configured for continuous measurements a new measurement sequence will begin Otherwise the instrument stays in the idle state until a new measurement is initiated 216 Syntax Attribute Summary Description Syntax Attribute Summary Programming Commands TRIGger Subsystem INITiate CONTinuous Selects single or continuous measurement acquisition INITiate CONTinuous ON OFF 1 0 Non sequential command Preset State on RST State off SCPI Compliance standard When on is specified the instrument continuously measures the input spectrum Non sequential command Always use an OPC query or a WAI command to ensure that this command has the time to complete before sending a
122. ing devices Optical power meter Optical attenuator 1310 nm and 1550 nm lasers gt 0 dBm output power Do not exceed 18 dBm source power The Agilent 86120B s input circuitry can be damaged when total input power exceeds 18 dBm Perform the following procedure first using the 1310 nm laser and then repeat the steps using the 1550 nm laser Connect the laser s output to the optical attenuator s input Connect the optical attenuator s output to the optical power meter Adjust the attenuator for a reading of 0 dBm on the power meter Record the attenuator s setting Attenuation at 0 dBm Adjust the attenuator for a reading of 35 dBm on the power meter Record the attenuator s setting Attenuation at 35 dBm Disconnect the fiber optic cable at the power meter s input and connect the cable to the Agilent 86120B being tested Reset the optical attenuator to the setting recorded in Step 3 Read the power and wavelength measured on the Agilent 86120B and compared them to the specifications listed in Chapter 7 Specifications and Regulatory Information Reset the optical attenuator to the setting recorded in Step 4 Read the power and wavelength measured on the Agilent 86120B and compared them to the specifications listed in Chapter 7 Specifications and Regulatory Information 222 Description CAUTION Procedure A U N me Performance Tests Test 3 Polarization Dependence Test 3 Polarization D
123. irst five example programs contain several common subroutines These routines along with one function are described in the rest of this introduction The descriptions are listed in the general order that the subroutines are called in the programs Error msg subroutine This function is found in examples 2 3 4 and 5 It displays an error message on the computer s screen explaining the reason that the pro gram s execution stopped Set ese subroutine The subroutine sets the enable mask for the event status register to a value of 52 This allows bits 2 4 and 5 to be set whenever a query error QYE execution error EXE or command error CME respec tively occurs All this is accomplished using the ESE common com mand 106 Programming Example Programs The Err_mngmt subroutine is used to actually read the value of the event status register Examples 1 through 5 call this subroutine FNIdentity function When this function is called it resets the instrument and queries the instrument s identification string which is displayed on the computer s screen by the calling function To accomplish this task the FNIdentity function uses the RST OPC and IDN common commands This function is called from examples 1 through 5 Err_mngmt subroutine This subroutine checks to make sure that no errors have set bits in the event status register and that there are no errors in the queue Exiting this subroutine is only possible
124. is subtracted from the power values of all laser lines except the reference For the CALC3 DATA query the power data returned is the array of powers normalized to the power of the reference laser line The power of the reference laser line is returned as an absolute power unnor malized The frequency data is the array of frequency values normalized to the frequency of the reference laser line The frequency of the reference laser line is returned as an absolute frequency unnormalized Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 92 for additional information on selecting measurements 183 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DRIFt DIFFerence STATe Sets the drift calculation to subtract the minimum values measured from the maximum values measured CALCulate3 DRIFt DIFFerence STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific Use the CALC3 DRIF PRES command to turn off all the drift states before turning on this state The CALC3 DATA query returns the max imum power and frequency minus the minimum power and frequency Note Only one STATe command can be turned on at any one time Attempting to turn more than one state
125. ister STATus OPERation PTRansition lt nteger gt integer an integer from 0 to 65535 Preset State none RST State none SCPI Compliance standard Changes in the state of a condition register bit causes the associated OPERation Status or QUEStionable Status event register bit to be set This command allows you to select a positive bit transition to trigger an event to be recognized A positive transition is defined to occur whenever the selected bit changes states from a 0 to 1 You can enter any value from 0 to 65535 When queried the largest value that can be returned is 32767 This is because the most significant register bit cannot be set true OUTPUT 720 STATUS OPER PTRansition 16 209 Syntax Attribute Summary Description Example Programming Commands STATus Subsystem PRESet Presets the enable registers and the PTRansition and NTRansition fil ters STATus PRESet Preset State none RST State none SCPI Compliance standard Command Only The PRESet command is defined by SCPI to affect the enable register If you want to clear all event registers and queues use the CLS com mand Table 5 18 Preset Values Status Node Preset Value Operation enable register 0 Questionable enable register 0 PTRansition filters 32767 NTRansition filters 0 OUTPUT 720 STATUS PRESET 210 Programming Commands SYSTem Subsystem SYSTem Subsystem The commands in t
126. ith averaging During a signal to noise with averaging measurement the display indi cates S N A xx where A indicates averaging and xx is the number of averages taken so far The maximum number of averages is 900 the 71 Noise bandwidth affects measurement A U N me Measurements Applications Measuring Signal to Noise Ratios with Averaging minimum number of averages is 10 and the default Preset value is 100 averages A measurement with 100 averages takes about 2 minutes to complete When the measurement is complete the instrument switches to single measurement mode Then pressing the Cont key will start a completely new measurement During a measurement and before the number of averages has been reached pressing the Single key will stop the measurement Then pressing the Cont key will continue with the current measurement While making a signal to noise with averaging measurement the num ber of averages can be changed As long as the new number of aver ages is greater than the number of averages taken so far the measurement continues If the new number of averages selected is less than the number of averages taken so far the measurement stops and the instrument switches to single measurement mode Then pressing the Cont key will start a completely new measurement When measuring noise power the Agilent 86120B must account for the noise bandwidth used during the measurement Because noise band width varies with meas
127. itions for the error messages and 1 position for the Queue overflow message The error queue is read with the SYSTEM ERROR query Executing this query reads and removes the oldest error from the head of the queue which opens a position at the tail of the queue for a new error When all the errors have been read from the queue subsequent error queries return 0 No error For more information on reading the error queue refer to ERRor on page 211 For a list of errors messages refer to Error Messages on page 253 100 Programming Reviewing SCPI Syntax Rules Reviewing SCPI Syntax Rules SCPI command are grouped in subsystems In accordance with IEEE 488 2 the instrument s commands are grouped into subsystems Commands in each subsystem perform sim ilar tasks The following subsystems are provided Measurement Instructions Calculatel Subsystem Calculate2 Subsystem Calculate3 Subsystem Display Subsystem Hcopy Subsystem Sense Subsystem Status Subsystem System Subsystem Trigger Subsystem Unit Subsystem Sending a command It s easy to send a command to the instrument Simply create a com mand string from the commands listed in this book and place the string in your program language s output statement For commands other than common commands include a colon before the subsystem name For example the following string places the cursor on the peak laser line and returns the power level of this p
128. its Constant Description MINimum 700 0 nm MAXimum 1650 0 nm Preset State 700 nm 428 6 THz RST State 700 nm 428 6 THz laser line SCPI Compliance instrument specific The reference will be the laser line at the wavelength closest to the wavelength entered Subsequent measurements will use the wavelength closest to the reference wavelength used for the previous measurement The query returns the current wavelength of the reference laser line The default units for the lt real gt parameter are meters 180 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DELTa REFerence WNUMber Selects the reference laser line for delta calculations CALCulate3 DELTa REFerence WNUMber lt real gt MINimum MAXimum lt real gt is a wave number value that is within the following limits Constant Description MINimum 6 061 cm MAXimum 14 286 cm Preset State 14 286 cm 1 700 nm RST State 14 286 cm 1 700 nm SCPI Compliance instrument specific The reference will be the laser line at the wave number closest to the wave number entered Subsequent measurements will use the wave number closest to the reference wave number used for the previous measurement The query returns the current wave number of the reference laser line The default units for the real parameter are m7 181 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsyst
129. its published specifications the elevation value selected with the softkeys must be within 250 meters of the actual elevation Press RETURN to complete the entry Converting feet to meters If you know your elevation in feet you can convert this value to meters by using the following equation To select the medium for light Press the Setup key Press the MORE softkey Press the CAL softkey and make the following selection Press VACUUM for wavelengths in a vacuum e Press STD AIR for wavelengths in standard air Press RETURN to complete the entry 62 Using the Multi Wavelength Meter Printing Measurement Results Printing Measurement Results Measurement results can be sent directly to a printer Simply connect a compatible printer to the rear panel PARALLEL PRINTER PORT connec tor The output is ASCII text An example of a compatible printer is Hewlett Packard s LaserJet series printer Be sure to use a parallel printer cable to connect the printer The printer output is not a copy of the display Rather it is a listing of all signals present at the input up to 100 The measurement values printed depend on the settings of the instrument when the Print key is pressed The following is an example of a typical printout Agilent 86120B SER US36151025 Firmware Ver 2 000 List By Wavelength 8 Lines Power Offset 0 0 dB Vacuum Elevation 0 Meters Update Normal Peak Excursion 15 dB Peak T
130. l poll command Both commands return the decimal weighted sum of all set bits in the register The difference between the two methods is that the serial poll command reads bit 6 as the Request Service RQS bit and clears the bit which clears the SRQ interrupt The STB command reads bit 6 as the Master Sum mary Status MSS and does not clear the bit or have any effect on the SRQ interrupt The value returned is the total bit weights of all of the bits that are set at the present time OPERation Status and QUEStionable Status registers You can query the value of the OPERation Status and QUEStionable Status registers using commands in the STATus subsystem The STATus subsystem also has transition filter software which give you the ability to select the logic transitions which set bits in the OPERation Status and QUEStionable Status registers For example you can define the POWer bit of the QUEStionable Status register to report an event when the condition transitions from false to true This is a positive transition You can also specify a negative transition where the bit is set when the condition transitions from true to false 95 Programming Monitoring the Instrument QUEStionable Status Error Event not used Queue not used not used POWer not used not used not used not used not used Maximum Signals Drift Reference Delta Reference not used not used Command Warning not used 0 1 2 3 4 5 6 7 8 9 not
131. l this number regardless of where you are located Refer to Agilent Technologies Service Offices on page 261 for a list of service offices If the instrument is still under warranty or is covered by an Agilent Technologies maintenance contract it will be repaired under the terms of the warranty or contract the warranty is at the front of this man ual If the instrument is no longer under warranty or is not covered by an Agilent Technologies maintenance plan Agilent Technologies will notify you of the cost of the repair after examining the unit When an instrument is returned to a Agilent Technologies service office for servicing it must be adequately packaged and have a com plete description of the failure symptoms attached When describing the failure please be as specific as possible about the nature of the problem Include copies of additional failure information such as the instrument failure settings data related to instrument failure and error messages along with the instrument being returned Preparing the instrument for shipping Write a complete description of the failure and attach it to the 32 CAUTION CAUTION Getting Started Returning the Instrument for Service instrument Include any specific performance details related to the problem The following information should be returned with the instrument Type of service required Date instrument was returned for repair Descripti
132. l to noise on page 92 for additional information on selecting measurements 176 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DATA Queries the data resulting from delta drift and signal to noise mea surements CALCulate3 DATA POWer FREQuency WAVelength WNUMber Argument Description POWer Queries the array of laser line powers after the calculation is completed FREQuency Queries the array of laser line frequencies after the calculation is completed WAVelength Queries the array of laser line wavelengths after the calculation is completed WNUMber Queries the array of laser line wave numbers after the calculation is completed Preset State not affected SCPI Compliance standard Query Only The data returned by the query depends upon which calculation state is on If no calculation state is on an error is generated The returned data is comma delimited The following string is a typical example of six values returned when POWer is specified from a delta power mea surement 7 42833100E 000 1 00087200E 000 2 52121400E 000 3 41918900E 000 3 80437200E 000 6 36282900E 000 Notice that only measurement values are returned to the computer There is no first value that indicates the number of values contained in the string as there is for example with the FETCh READ and MEASure commands Use the CALC3 POIN query to determine the number of points t
133. length is stable 119 Programming Example Programs COM Current_wl Diff_wl Target_wl Previous_diff Diff_diff Current_wl 0 Diff wl 0 Target wl 0 Previous diffzO Diff_diff 0 ASSIGN Tls TO 724 ASSIGN Mwm T0 720 Initialize instrument DIM Identity 50 Identity OUTPUT Tls CLS OUTPUT Tls IDN ENTER TLS identity PRINT TLS IS A sidentity OUTPUT Mwm RST OUTPUT Mwm CLS OUTPUT Mwm IDN ENTER Mwm ldentity PRINT MWM IS A identity Ask user for desired wavelength INPUT What wavelength nm do you wish to have Target_wl Target_wl Target_wl 1 0E 9 PRINT the target wavelength is Target_wl Set wavelength of tunable laser source OUTPUT GTls WAVE VAL Target wl OUTPUT GTls OUTP ON Enter realignment loop REPEAT OUTPUT Mwm MEAS SCAL POW WAV ENTER Mwm Current_wl PRINT The current wavelength is VALS Current wl Diff wIZPROUND ABS Target wl Current wl 16 PRINT Diff between target amp Current is or VALS Diff wl OUTPUT Tls WAVEACT VALS Current wl Diff diffZPROUND ABS Diff wl Previous diff 16 PRINT differential difference between two turn VALS Diff_diff Previous diff Diff wl UNTIL Diff wl 1 5 1 0E 12 OR Diff diffz0 END 120 Programming Lists of Commands Lists of Commands Table 4 10 Programming Commands 1 of 5 Command Description Code Codes S indicates a standard SCPI command indicates a
134. m Use the CALCulate3 commands to perform delta drift and signal to noise measurements The commands in this subsystem have the follow ing command hierarchy CALCulate3 ASNR CLEar COUNIt STATe DATA DELTa POWer STATe PRESet REFerence FREQuency POWer WAVelength WNUMber WAVelength STATe WPOWer STATe DRIFt DIFFerence STATe MAXimum STATe MINimum STATe PRESet REFerence RESet STATe STATe POINts PRESet SNR AUTO 173 Programming Commands CALCulate3 Subsystem REFerence FREQuency WAVelength WNUMber STATe ASNR CLEar Clears the number of measurements used in the average signal to noise calculation Syntax CALCulate3 ASNR CLEar Attribute Preset State not affected Summary RST State not affected SCPI Compliance instrument specific Description This command clears the number of measurements used in the average signal to noise calculation The current measurement is used as the new reference for the average signal to noise calculation ASNR COUNt Sets the number of measurements to be used for the average signal to noise calculation Syntax CALCulate3 ASNR COUNt lt integer gt MINimum MAXimum integer is a value that is within the following limits Constant Description MINimum 10 MAXimum 900 Attribute Preset State 100 Summary RST State 100 SCPI Compliance instrument specific 174 Description P
135. m OUTPUT Mwm ESE IVAL 00110100 2 SUBEND Identity DEF FNIdentity COM Instrument Mwm DIM IdentityS 50 IdentityS OUTPUT Mwm RST OUTPUT GMwm OPC ENTER Mwm pc done OUTPUT GMwm IDN ENTER GQMwm ldentity RETURN IdentityS FNEND Cmd opc SUB opc Set cmd COM Instrument Mwmd OUTPUT Mwm Set_cmd OUTPUT GMwm OPC ENTER Mwm 0pc_done SUBEND 118 Programming Example Programs Example 6 Increase a source s wavelength accuracy This example program uses the Agilent 86120B to increase the abso lute wavelength accuracy of Agilent 8167A 8168B and 8168C Tunable Laser Sources Essentially the Agilent 86120B s accuracy is transferred to the tunable laser source The absolute accuracy of the tunable laser source is increased from lt 0 1 nm to lt 0 005 nm which is the Agilent 86120B s absolute accuracy at 1550 nm In order to run this program the tunable laser source s firmware must support the automatic alignment command WAVEACT The program uses the following measurement algorithm Identify and initialize the Agilent 86120B and tunable laser source Ask user for desired wavelength Set wavelength of tunable laser source Turn tunable laser source s output on Enter loop Measure wavelength Compare wavelength to desired wavelength Realign tunable laser source s wavelength Check if wavelength changed from last pass Repeat until delta wavelength lt 0 0015 nm or wave
136. m or 196 7804 THz Differential Accuracy indicates the maximum wavelength error in measuring the wavelength difference between two signals that are simultaneously present Minimum Resolvable Separation indicates the minimum wavelength separa tion of two laser lines required to measure each wavelength simultaneously Two laser lines closer in wavelength than the minimum resolvable separation are not resolved and one average wavelength is displayed Display Resolution indicates the minimum incremental change in displayed wavelength Calibration Accuracy indicates the maximum power calibration error at the specified wavelengths over the allowed environmental conditions The ampli tude calibration accuracy is traceable to a National Institute of Standards and Technology NIST calibrated optical power meter NIST is the national stan Obarski G E 1990 Wavelength Measurement System for Optical Fiber Communications NIST Tech nical Note 1336 February 18 Take the average of the two frequencies straddling gain center Moore C E 1971 Atomic Energy Levels as Derived from the Analysis of Optical Spectra Vol 1 NSRDS NBS 35 Vol 1 COM 72 51282 December 77 D A Jennings F R Peterson and K M Evenson 1979 Frequency measurement of the 260 THz 1 15 micron He Ne laser Optics Letters Vol 4 No 5 May 129 130 233 Sensitivity Selectivity Input Power Maximum Number of Lines Input Input
137. m values measured CALCulate3 DRIFt MAXimum STATe Sets the drift calculation to return the maximum power frequency values measured CALCulate3 DRIFt MINimum STATe Sets the drift calculation to return the minimum power frequency values measured CALCulate3 DRIFt PRESet Turns off all the drift states for DIFFerence MAXimum MINimum and REFerence CALCulate3 D RIFt REFerence RESet Places the current list of signals into the reference list CALCulate3 D RIFt REFerence STATe Turns the drift state on and off so that CALC3 DATA will return the reference signal list CALCulate3 DRIFt STATe Turns the drift measurement calculation on and off CALCulate3 POINts Queries the number of points in the data set CALCulate3 PRESet Turns off any CALCulate3 calculation that is on CALCulate3 SNR AUTO Selects the internal or externally entered frequency value for the noise measurement reference in the SNR calculation CALCulate3 SNR REFerence FREQuency Sets the frequency used for the noise measurement reference in the SNR calculation CALCulate3 SNR REFerence WAVelength Sets the wavelength used for the noise measurement reference in the SNR calculation CALCulate3 SNR REFerence WNUMber Sets the wave number used for the noise measurement reference in the SNR calculation CALCulate3 SNR STATe Turns the SNR calculation on and off DISPla
138. m when the parameter is on Parameters are VAC AIR SENSe DATA Queries the time domain samples of the input signal STATus Subsystem STATus OPERation QUEStionable CONDitio Returns the value for the condition register for the node S n STATus OPERation QUEStionable EVENt Returns the value of the event register for the node STATus OPERation QUEStionable ENABle Sets the enable register STATus OPERation QUEStionable PTRansit Sets the positive transition filter register ion STATus OPERation QUEStionable NTRansit Sets the negative transition filter register S ion STATus PRESet Presets the enable registers for all status nodes S SYSTem Subsystem SYSTem ERRor Queries an error from the error queue S SYSTem HELP HEADers Queries an ASCII listing of all Agilent 86120B remote commands SYSTem PRESet Performs the equivalent of a front panel PRESET key press SYSTem VERSion Queries the version of SCPI with which this instrument is S compliant TRIGger Subsystem 124 Programming Lists of Commands Table 4 10 Programming Commands 5 of 5 Command Description Code Codes S indicates a standard SCPI command indicates an instrument specific command ABORt INITiate IMMediate Stops the current measurement sequence S Places the instrument into the initiated state and initiatesa new measurement sequence INITiate CONTinuous UNIT Subsystem UNIT POW
139. ments Use the following guidelines to achieve the best possible performance when making measurements on a fiber optic system Never use metal or sharp objects to clean a connector and never scrape the connector Avoid matching gel and oils Zz o Figure 1 4 Clean problem free fiber end and ferrule Sa mS Rs 3 Figure 1 5 Dirty fiber end and ferrule from poor cleaning 25 Getting Started Cleaning Connections for Accurate Measurements LEUR 2 h EE ewe Figure 1 6 Damage from improper cleaning While these often work well on first insertion they are great dirt mag nets The oil or gel grabs and holds grit that is then ground into the end of the fiber Also some early gels were designed for use with the FC non contacting connectors using small glass spheres When used with contacting connectors these glass balls can scratch and pit the fiber If an index matching gel or oil must be used apply it to a freshly cleaned connector make the measurement and then immedi ately clean it off Never use a gel for longer term connections and never use it to improve a damaged connector The gel can mask the extent of damage and continued use of a damaged fiber can transfer damage to the instrument When inserting a fiber optic cable into a connector gently insert it in as straight a line as possible Tipping and inserting at an angle can scrape material off the inside of the connector or even break th
140. mmands Common commands Measurement instructions Subsystem commands All of these commands are documented in Chapter 5 Programming Commands HP is a registered trademark of Hewlett Packard Company 80 A UU N Programming Addressing and Initializing the Instrument Addressing and Initializing the Instrument The Agilent 86120B s GPIB address is configured at the factory to a value of 20 You must set the output and input functions of your pro gramming language to send the commands to this address To change the GPIB address Press the Setup key Press MORE twice then GPIB Use the i and softkeys to change the GPIB address Press RETURN Remote mode and front panel lockout Whenever the instrument is controlled by a computer the Remote message is displayed on the instrument s screen and the softkey menu is blanked except for the LOCAL softkey This softkey can be pressed by the user to restore front panel control of the instrument You can specify a local lockout mode that prevents the LOCAL softkey from being displayed If the instrument is in local lockout mode all the softkeys may be blanked For example if the instrument is first placed in local lockout mode and then placed in remote mode no soft keys are displayed Consult the documentation for your programming environment to determine which commands are used to put an instrument in the remote and local lockout modes These are not Agilent
141. n instrument specific command Common Commands CLS Clears all event registers and the error queue ESE Sets the bits in the standard event status enable register ESR Queries value standard event status register IDN Queries instrument model number and firmware version OPC Sets operation complete bit of the standard event status register RCL Recalls a saved instrument state RST Resets instrument SAV Saves an instrument state SRE Sets bits in service request enable register STB Queries value of status byte TRG Triggers acquisition of measurement data TST Performs an instrument self test WAI Causes instrument to finish processing current command before continuing Measurement Instructions CONFigure Configures instrument for wavelength wavenumber frequency power and coherence length measurements FETCh Queries wavelength wavenumber frequency power and coherence length measurements that have already been captured MEASure Configures measures and queries wavelength wavenumber frequency power and coherence length measurements READ Measures and queries wavelength wavenumber frequency power and coherence length measurements 121 Programming Lists of Commands Table 4 10 Programming Commands 2 of 5 Command Description Code
142. n measurement mode Then it triggers the Agilent 86120B with the MEASure com mand to capture measurement data of the input spectrum Because the data is stored in the instrument s memory it can be queried as needed Refer to the introduction to this section for a description of each sub routine that is contained in this program COM Instrument Mwm ASSIGN Mwm TO 720 ON ERROR GOTO Error msg Set ese PRINT USING 37A 33A Multi Wavelength Meter Identity is FNidentity OUTPUT GMwm INIT CONT OFF ON TIMEOUT 7 5 CALL Err_mngmt OUTPUT Mwm MEAS ARR POW WAV ENTER Mwm USING K Nb_wl ALLOCATE Current wl 1 Nb wl ENTER Mwm USING K Current wl OUTPUT Mwm FETC ARR POW ENTER Mwm USING K Nb_wl ALLOCATE Current pwr 1 Nb wl ENTER Mwm USING K Current_pwr FOR 1 1 TO wl PRINT USING 22A 2D 6A 4D 2DE 4A S2D 2D 3A The wavelength number Current wl I at Current pwr l dBm NEXT I OFF TIMEOUT STOP Error msg PRINT the prgm is aborted due to ERRMS END 110 Programming Example Programs Err_mngmt SUB Err_mngmt COM Instrument Mwm DIM Err_msg 255 INTEGER Cme CLEAR 7 REPEAT OUTPUT Mwnm ESR ENTER Mwm Cme OUTPUT Mwm SYST ERR ENTER Mwm Err_msg PRINT Err_msg UNTIL NOT BIT Cme 2 AND NOT BIT Cme 4 AND NOT BIT Cme 5 AND ErrS 0 Subend SUBEND Set_ese SUB Set_ese COM Instrument Mwm OUTPUT Mwm ESE IVAL 00110100
143. ngth 1650 nm last state Graphical display off off Measurement acquisition continuous last state 213 Programming Commands SYSTem Subsystem Table 5 19 Instrument Conditions 2 of 2 Settings after Preset Settings after Power Item Key Pressed Turned On Wavelength calibration vacuum last state Elevation correction value not affected last state Wavelength units nm last state Amplitude units dBm last state Power offset 0 dB last state Peak threshold 10 dB last state Peak excursion 15 dB last state Measurement speed normal last state Device bandwidth narrowband last state Drift measurements off off Coherence length measurements off off Delta Measurements A power off off A wavelength off off A wavelength and power off off reference signal position 700 nm 700 nm Signal to Noise Measurements measurement off off wavelength reference auto last state user wavelength not affected last state number of averages 100 last state GPIB address not affected last state Power bar display on last state a The term last state refers to the last setting that this parameter was in before the instrument power was turned off 214 Syntax Attribute Summary Description Programming Commands SYSTem Subsystem VERSion Queries the version of SCPI that the Agilent 86120B complies with SYSTem VERSion Preset State none RST State none SCPI Compliance standard Query Only The SCPI version used
144. notation See annotation cursor 40 modes 37 resolution 234 236 scrolling through 40 setting update rate 48 softkeys blanked 81 update rate 48 DISPlay subsystem 195 distortion 42 52 down arrow softkey 40 DRANge programming command 164 DRIFT annotation 73 softkey 74 drift laser See laser drift dust caps 29 dust covers 260 E E15 MAX NUMBER OF SIGNALS FOUND message 53 E46 NUM LINES NUM REFS message 74 E47 NUM LINES NUM REFS message 74 EDFA amplifier 44 ELEV softkey 18 62 elevation changing feet to meters 18 62 effects of 61 entering 18 62 ELEVation programming command 201 202 ENABle programming command 207 EOI signal 105 Err mngmt subroutine 107 error Index 264 messages 253 queue 100 ERRor programming command 211 Error_msg subroutine 106 ESE 106 131 ESR 133 EVENT programming command 207 208 event status enable register 106 132 example programs 106 increase source accuracy 119 measure DFB laser 108 measure SN ratio 117 measure WDM channel drift 112 measure WDM channel separation 115 measure WDM channels 110 external attenuation 60 F Fabry Perot lasers 44 coherence length 76 measuring 50 fast fourier transform 159 FAST softkey 48 87 204 FETCh measurement instruction 144 fiber optics adapters 258 care of 5 cleaning connections 21 connectors covering 33 firmware version 3 44 201 displayed 17 over GPIB 134 flatness 23
145. nt will not respond to any new commands in its input buffer for 30 or 40 seconds 205 Programming Commands STATus Subsystem Query Response The following string shows an example of the first few measurements returned by this query 1 51367200E 000 1 51855500E 000 1 49902300E 000 1 47949200E 000 1 50488300E 00 0 1 53320300E 000 1 50097700E 000 1 47265600E 000 1 50293000E 000 1 50781300E 0 00 1 51171900 000 1 48242200 000 1 50097700 000 1 51855500 000 1 50683600 000 1 48632800E 000 1 50488300E 000 Notice that only values are returned to the computer There is no first value that indicates the number of values contained in the string as there is for example with the FETCh READ and MEASure com mands STATus Subsystem Use the commands in this subsystem to control the Agilent 86120B s status reporting structures These structures provide registers that you can use to determine if certain events have occurred The commands in this subsystem have the following command hierar chy STATus OPERation CONDition ENABle EVENt PTRansition NTRansition PRESet QUEStionable CONDition ENABle EVENt PTRansition NTRansition 206 Syntax Query Response Attribute Summary Description Example Syntax Attribute Summary Description Programming Commands STATus Subsystem OPERation QUEStionable CONDition Queries the value of the questionable
146. ny more commands to the instrument Refer to Always force the Agilent 86120B to wait for non sequential commands on page 90 for more information INITiate IMMediate Initiates a new measurement sequence INITiate MMediate Non sequential command Preset State none SCPI Compliance standard Command Only 217 Programming Commands UNIT Subsystem Non sequential command Always use an query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120B to wait for non sequential commands on page 90 for more information UNIT Subsystem The only command provided in this subsystem is the POWer command as shown in the following command hierarchy UNIT POWer POWer Sets the power units to watts linear or dBm logarithmic Syntax UNIT POWer W DBM Attribute Preset State dBm Summary RST State dBm SCPI Compliance standard 218 Test 1 Absolute Wavelength Accuracy 221 Test 2 Sensitivity 222 Test 3 Polarization Dependence 223 Test 4 Optical Input Return Loss 224 Test 5 Amplitude Accuracy and Linearity 227 Performance Tests Performance Tests Performance Tests Performance Tests The procedures in this chapter test the Agilent 86120B s performance using the specifications listed in Chapter 7 Specifications and Regul
147. odule s output off Connect a single mode patchcord between the source module s optical output and the return loss module s INPUT SOURCE connector Set the return loss module s wavelength to 1550 nm and select an average time of 1 second Locate an HMS 10 HRL to FC APC angled FC patchcord Connect the HMS 10 HRL end of the patchcord to the return loss module s OUTPUT connector Terminate the FC APC end of the cable Zero the return loss module Turn on the source module Remove the termination from the cable and connect the FC APC end of an FC APC to FC PC cable to the free end of this cable Leave the cable s free end uncovered The return loss module measures the reflection reference 14 6 dB return loss of the patchcord s FC PC connector in air Disconnect the FC APC to FC PC cable Make a low reflection termination in the HMS 10 HRL to FC APC patchcord Do this by wrapping the cable 6 times around a 5 mm diameter mandrel The return loss module measures the termination parameter Connect the HMS 10 HRL to FC APC patchcord to the Agilent 86120B s front panel OPTICAL INPUT connector The lightwave multimeter measures the return loss Compare this measurement with the specification listed in Chapter 7 Specifications and Regulatory Information 225 Performance Tests Test 4 Optical Input Return Loss FC APC patchcord loss The effect of having loss in the FC APC patchcord 1 to 2 connector pair i
148. of the Diamond HMS 10 connector The nickel silver allows an active centering process that permits the glass fiber to be moved to the desired position This process first stakes the soft nickel silver to fix the fiber in a near center location then uses a post active staking to shift the fiber into the desired posi tion within 0 2 um This process plus the keyed axis allows very pre 23 Getting Started Cleaning Connections for Accurate Measurements cise core to core alignments This connector is found on most Agilent Technologies lightwave instruments The soft core while allowing pre cise centering is also the chief liability of the connector The soft material is easily damaged Care must be taken to minimize excessive scratching and wear While minor wear is not a problem if the glass face is not affected scratches or grit can cause the glass fiber to move out of alignment Also if unkeyed connectors are used the nickel sil ver can be pushed onto the glass surface Scratches fiber movement or glass contamination will cause loss of signal and increased reflec tions resulting in poor return loss Inspecting Connectors Because fiber optic connectors are susceptible to damage that is not immediately obvious to the naked eye poor measurements result with out the user being aware Microscopic examination and return loss measurements are the best way to ensure good measurements Good cleaning practices can help ensure tha
149. ommands 101 signal to noise measurements 67 noise calculation 67 191 ratios 3 specification 237 Single key 49 51 softkey equivalent commands 126 menus 246 SONET 59 69 specifications 232 235 and wideband mode 44 definition of terms 232 operating 238 spurious signals 42 suppressing 50 SRE 139 standard air 19 61 event status register 133 SCPI commands 101 STATe programming command 165 178 182 183 184 185 186 188 189 194 198 status byte register 141 reporting 94 STATus subsystem 206 STB 141 STD AIR annotation 61 softkey 19 62 subsystems 101 swabs 29 syntax rules 101 105 SYSTem subsystem 211 T Tempo subroutine 107 terahertz 48 THRSHLD softkey 53 THZ softkey 48 total power 3 41 maximum measurable 60 measuring 41 transient data 89 TRG 142 trigger ignore 257 TRIGger subsystem 216 Index 268 TST 142 U UNIT subsystem 218 units of measure 47 UNITS softkey 47 up arrow softkey 40 UPDATE softkey 48 uppercase letters 102 USER softkey 70 USER WL softkey 70 UW softkey 48 VAC annotation 61 VACuum programming command 203 VACUUM softkey 19 62 vacuum measurements in 61 VERSion programming command 215 WAI 143 wave number 48 wavelength definition of 233 input range 36 peak 39 range 42 82 166 separation 54 specifications 235 WAVelength programming command 150 180 193 WDM flatness 57 sys
150. on Use the OPC query to ensure all operations have completed before continuing the program By following a command with an OPC query and an ENTER statement the program will pause until the response ASCII 1 is returned by the instrument Be sure the computer s timeout limit is at least two seconds since some of the Agilent 86120B commands take approximately one second to complete OUTPUT 720 OPC ENTER 720 0p RCL This command recalls a saved instrument state RCL lt integer gt lt integer gt range is 1 to 4 For a description of an instrument state see SAV command 135 Syntax Description Syntax Description Programming Commands Common Commands RST The RST reset command returns the Agilent 86120B to a known condition RST For a listing of reset conditions refer to the following table This com mand cannot be issued as a query Since this command places the instrument in single measurement acquisition mode any current data is marked as invalid and a measurement query such as FETCh results in error number 230 Data corrupt or stale You must ini tiate a new sweep with INIT IMM before you can use the FETCh com mand SAV This command saves an instrument state SAV lt integer gt lt integer gt range is 1 to 4 The following constitutes an instrument state single continuous mea surement mode power bar on off vacuum STD air mode normal f
151. on of the problem Whether problem is constant or intermittent Whether instrument is temperature sensitive Whether instrument is vibration sensitive Instrument settings required to reproduce the problem Performance data Company name and return address Name and phone number of technical contact person Model number of returned instrument Full serial number of returned instrument List of any accessories returned with instrument Cover all front or rear panel connectors that were originally covered when you first received the instrument Cover electrical connectors to protect sensitive components from electrostatic damage Cover optical connectors to protect them from damage due to physical contact or dust Instrument damage can result from using packaging materials other than the original materials Never use styrene pellets as packaging material They do not adequately cushion the instrument or prevent it from shifting in the carton They may also cause instrument damage by generating static electricity Pack the instrument in the original shipping containers Original materials are available through any Agilent Technologies office Or use the following guidelines Wrap the instrument in antistatic plastic to reduce the possibility of damage caused by electrostatic discharge e For instruments weighing less than 54 kg 120 lb use a double 33 Getting Started Returning the Instrument for Service
152. or operation condition register STATus OPERation QUEStionable CONDition 0 to 32767 Preset State none RST State none SCPI Compliance standard Query Only Use this command to read the value of the OPERation Status or QUEStionable Status registers Refer to Monitoring the Instrument on page 94 OUTPUT 720 STATUS OPERATION CONDITION OPERation QUEStionable ENABle Sets the enable mask for the questionable or operation event register STATus OPERation QUEStionable ENABle lt value gt lt integer gt an integer from to 65535 Preset State none RST State none SCPI Compliance standard The enable mask selects which conditions in the event register cause the summary bit in the status byte to be set If a bit in the enable mask is set true and the corresponding event occurs the summary bit bit 3 for the questionable status or bit 7 for the operation status in the status byte will be set 207 Example Query Response Syntax Query Response Attribute Summary Description Example Syntax Attribute Summary Programming Commands STATus Subsystem OUTPUT 720 STATUS QUESTIONABLE ENABLE 1024 When queried the largest value that can be returned is 65535 This is because the most significant register bit cannot be set true OPERation QUEStionable EVENt Queries the contents of the questionable or operation event registers STATus OPERation
153. orce the Agilent 86120B to wait for non sequential commands on page 90 for more information 159 Query Response Programming Commands CALCulate1 Subsystem For normal update 34123 For fast update 4268 160 Programming Commands CALCulate2 Subsystem CALCulate2 Subsystem Use the CALCulate2 commands to query corrected values frequency spectrum data The commands in this subsystem have the following command hierar chy CALCulate2 DATA PEXCursion POINts PTHReshold PWAVerage STATe WLIMit STATe STARt FREQuency WAVelength WNUMber STOP FREQuency WAVelength WNUMber 161 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem DATA Queries the corrected peak data of the input laser line CALCulate2 DATA FREQuency POWer WAVelength WNUMber Constant Description FREQuency Queries the array of laser line frequencies after the peak search is completed If CALC2 PWAV STAT is on the power weighted average frequency is returned POWer Queries the array of laser line powers after the peak search is completed If CALC2 PWAV STAT is on the total input power is returned WAVelength Queries the array of laser line wavelengths after the peak search is completed If CALC2 PWAV STAT is on the power weighted average wavelength is returned WNUMber Queries the array of laser line wave numbers after the pe
154. orre sponding event occurs However because they are not enabled they do not generate a summary bit to the Status Byte Register Queues There are two queues in the instrument the output queue and the error queue The values in the output queue and the error queue can be queried Output queue The output queue stores the instrument responses that are generated by certain commands and queries that you send to the instrument The output queue generates the Message Available summary bit when the output queue contains one or more bytes This summary bit sets the MAV bit bit 4 in the Status Byte Register The method used to read the Output Queue depends upon the programming language and envi ronment For example with HP BASIC the output queue may be read using the ENTER statement 99 Programming Monitoring the Instrument Error queue As errors are detected they are placed in an error queue Instrument specific errors are indicated by positive values General errors have negative values You can clear the error queue by reading its contents sending the CLS command or by cycling the instrument s power The error queue is first in first out If the error queue overflows the last error in the queue is replaced with error 350 Queue overflow Any time the queue overflows the least recent errors remain in the queue and the most recent error is discarded The length of the instrument s error queue is 30 29 pos
155. ource Module Agilent 81534A Return Loss Model Standard instruments flat contacting connectors Turn the source module s output off Connect a single mode patchcord between the source module s optical output and the return loss module s INPUT SOURCE connector Set the return loss module s wavelength to 1550 nm and select an average time of 1 second Locate an HMS 10 HRL to FC PC patchcord Connect HMS 10 HRL end of the patchcord to the return loss module s OUTPUT connector Terminate the other end of the cable Zero the return loss module Turn on the source module Remove the termination from the cable and leave the cable s free end uncovered The return loss module measures the reflection reference 14 6 dB return loss of the patchcord s FC PC connector in air Make a low reflection termination in the HMS 10 HRL to FC PC patchcord Do this by wrapping the cable 6 times around a 5 mm diameter mandrel The return loss module measures the termination parameter Connect the HMS 10 HRL to FC PC patchcord to the Agilent 86120B s front panel OPTICAL INPUT connector 224 Procedure 12 10 11 12 13 Performance Tests Test 4 Optical Input Return Loss The lightwave multimeter measures the return loss Compare this measurement with the specification listed in Chapter 7 Specifications and Regulatory Information Option 022 instruments angled contacting connectors Turn the source m
156. parated by less than 30 GHz wavelength accuracy is reduced 235 Specifications and Regulatory Information Specifications Amplitude Calibration accuracy at calibration wavelengths 30 nm 1310 and 1550 nm 0 5 dB 780 characteristic 0 5 dB Flatness 30 nm from any wavelength 1200 1600 nm characteristic 0 2 dB 700 1650 nm characteristic 0 5 dB Linearity 1200 nm to 1600 nm lines above 30 dBm 0 3 dB Polarization dependence 1200 1600 nm 0 5 dB 700 1650 nm characteristic 1 0 dB Display resolution 0 01 dB Sensitivity 700 900 nm single line input 20 dBm 900 1200 nm single line input 25 dBm 1200 1600 nm single line input 40 dBm 1600 1650 nm single line input 30 dBm 700 1650 nm multiple lines input characteristic 30 dB below total input power but not less than single line input sensitivity a Spurious free under Preset conditions 236 Selectivity Specifications and Regulatory Information Specifications Two lines input separated by 2100 GHz characteristic Two lines input separated by 230 GHz characteristic Input Power Maximum displayed level sum of all lines Maximum safe input level sum of all lines Maximum Number of Laser Lines Input 25 dB characteristic 10 dB characteristic 10 dBm 18 dBm 100 Input Return Loss With flat contacting connectors With angled contacting connectors Option 022 35 dB
157. pecifications for the product or improper site prepara tion or maintenance No other warranty is expressed or implied Agilent Technologies specifically disclaims the implied warranties of Merchantability and Fitness for a Particular Purpose Exclusive Remedies The remedies provided herein are Buyer s sole and exclusive reme dies Agilent Technologies shall not be liable for any direct indi rect special incidental or conse quential damages whether based on contract tort or any other legal theory Assistance Product maintenance agreements and other customer assistance agreements are available for Agi lent Technologies products For any assistance contact your near est Agilent Technologies Sales and Service Office Certification Agilent Technologies Inc certifies that this product met its pub lished specifications at the time of shipment from the factory Agi lent Technologies further certi fies that its calibration measurements are traceable to the United States National Insti tute of Standards and Technology NIST formerly the United States National Bureau of Standards NBS to the extent allowed by the Institutes s calibration facility and to the calibration facilities of other International Standards Organization members ISO 9001 Certification Produced to ISO 9001 interna tional quality system standard as part of our objective of continu ally increasing customer satisfac tion through
158. play peak wavelength and power 1 Connect the fiber optic cable to the front panel OPTICALINPUT connector 2 To display the peak wavelength and power do one of the following Press the green Preset key Press Peak WL 3 To move the cursor to view other signals press PREVWL to select next previous shorter wavelength NEXT WL to select next longer wavelength PEAK to signal with greatest power e PREV PK to select next lower power signal NEXT PK to select next higher power signal 39 Using the Multi Wavelength Meter Displaying Wavelength and Power List by WL or power modes In the list by wavelength or list by power modes the measurements of five laser lines can be displayed at any one time In list by wavelength mode the signals are displayed in order from shortest to longest wave lengths The Agilent 86120B can measure up to 100 laser lines simul taneously Use the and softkeys to move the cursor through the list of signals the list can contain up to 100 entries Press the SELECT key and the display changes to peak wavelength mode with the signal at the cursor displayed Annotation in the upper right corner of the display indicates whether the signals are ordered according to wavelength BY WL or power BY PWR The cursor shows the currently selected laser line As you scroll through the responses the current position of the selection cursor is shown along the screen s right side
159. ple you can set the peak excursion peak threshold and elevation and use a WAI command at the end to save time However non sequential commands can also be a source of annoying errors Always use the OPC query or WAI command with the non sequential commands to ensure that your programs execute properly For example suppose that you wanted to set the elevation correction value and then send an INIT IMM command The following program ming fragment results in an error 213 Init ignored This occurs because the ELEVation command causes the recalculation of the data which is like sending the INIT IMM command When the actual INIT IMM is sent the error occurs because the command is already in progress OUTPUT 720 INIT IMM OUTPUT 720 SENSe CORRection ELEVation 1000 OUTPUT 720 INIT IMM Use an OPC query to ensure that the ELEVation command has com pleted as shown in the following lines OUTPUT 720 INIT IMM OUTPUT 720 SENSe CORRection ELEVation 1000 OUTPUT 720 OPC ENTER 720 Response OUTPUT 720 INIT IMM the WAI command could be used OUTPUT 720 INIT IMM OUTPUT 720 SENSe CORRection ELEVation 1000 OUTPUT 720 WAI OUTPUT 720 INIT IMM 91 Programming Making Measurements Measure delta drift and signal to noise To select a measurement use one of the following STATe commands CALC3 DELT POW STAT delta power CALC3 DELT WAV STAT delta wavel
160. posited on the end of the fiber during insertion of the cable a second cleaning should be performed It is not uncommon for a cable or connector to require more than one cleaning 28 Getting Started Cleaning Connections for Accurate Measurements CAUTION Agilent Technologies strongly recommends that index matching compounds not be applied to their instruments and accessories Some compounds such as gels may be difficult to remove and can contain damaging particulates If you think the use of such compounds is necessary refer to the compound manufacturer for information on application and cleaning procedures Table 1 1 Cleaning Accessories Item Agilent Technologies Part Number Pure isopropyl alcohol Cotton swabs 8520 0023 Small foam swabs 9300 1223 Compressed dust remover non residue 8500 5262 Table 1 2 Dust Caps Provided with Lightwave Instruments Item Agilent Technologies Part Number Laser shutter cap 08145 64521 FC PC dust cap 08154 44102 Biconic dust cap 08154 44105 DIN dust cap 5040 9364 HMS10 dust cap 5040 9361 ST dust cap 5040 9366 To clean a non lensed connector CAUTION Do not use any type of foam swab to clean optical fiber ends Foam swabs can leave filmy deposits on fiber ends that can degrade performance 29 CAUTION Getting Started Cleaning Connections for Accurate Measurements Apply pure isopropyl alcohol to a clean lint free cotton swab or lens pape
161. r Cotton swabs can be used as long as no cotton fibers remain on the fiber end after cleaning Clean the ferrules and other parts of the connector while avoiding the end of the fiber Apply isopropyl alcohol to a new clean lint free cotton swab or lens paper Clean the fiber end with the swab or lens paper Do not scrub during this initial cleaning because grit can be caught in the swab and become a gouging element Immediately dry the fiber end with a clean dry lint free cotton swab or lens paper Blow across the connector end face from a distance of 6 to 8 inches using filtered dry compressed air Aim the compressed air at a shallow angle to the fiber end face Nitrogen gas or compressed dust remover can also be used Do not shake tip or invert compressed air canisters because this releases particles in the can into the air Refer to instructions provided on the compressed air canister As soon as the connector is dry connect or cover it for later use If the performance after the initial cleaning seems poor try cleaning the connector again Often a second cleaning will restore proper per formance The second cleaning should be more arduous with a scrub bing action To clean an adapter The fiber optic input and output connectors on many Agilent Technol ogies instruments employ a universal adapter such as those shown in the following picture These adapters allow you to connect the instru ment to different type
162. r indicates the number of laser line values returned in the query The measurement units are in dBm 6 1 37444400E 001 1 10996100E 001 9 62396600E 000 7 94024500E 000 7 01303200E 000 1 04536200E 001 147 Syntax Description lt expected_value gt Constants Programming Commands Measurement Instructions MEASure ARRay SCALar POWer FREQuen cy Returns frequency values POWer FREQuency lt expected_value gt lt resolution gt Used With lt expected_value gt lt resolution gt SCALar optional optional ARRay ignored optional a Although ignored this argument must be present if the resolution argument is specified When used with a SCALar command a single value is returned The display is placed in the single wavelength mode and the marker is placed on the signal having a frequency that is closest to the lt expected_value gt parameter Default units for lt expected_value gt parameter are in Hz When used with an ARRay command an array of frequencies is returned The display is placed in the list by wave length mode The lt resolution gt parameter sets the resolution of the measurement It is a unitless number whose value will be limited to either 0 01 or 0 001 whichever is closer MAXimum resolution is equivalent to the FAST measurement update mode MINimum resolution is equivalent to the NORMAL measurement update mode Returned values are in Hz display is in THz Powe
163. r On When one of these events occur the event sets the corresponding bit in the register If the bits are enabled in the Standard Event Status Enable Register the bits set in this register generate a summary bit to set bit 5 ESB in the Status Byte Register 97 Programming Monitoring the Instrument Table 4 7 Bits in Questionable Status Register Bit Definition 0 1 and 2 not used 3 POWer indicating that the instrument is measuring too high of a power 4 through 8 not used 9 Maximum signals indicating that the instrument has found the maximum number of signals 10 Drift Reference indicating that the number of reference signals is different from the current number of input signals 11 Delta Reference indicating that there is no delta reference signal 12 through 13 not used 14 Command Warning indicating that the instrument has received some extra unexpected parameters for one of the measurement functions 15 not used The contents of the Standard Event Status Register can be read and the register cleared by sending the ESR query The value returned is the total bit weights of all of the bits that are set at the present time Enabling register bits with masks Several masks are available which you can use to enable or disable individual bits in each register For example you can disable the Hardcopy bit in the OPERation Status Register so that even though it goes high it can never set the summary
164. r lines have been identified E15 MAX NUMBER OF SIGNALS FOUND The maximum number of laser lines that the instrument can measure is 100 If this message appears decrease the peak threshold value increase the peak excursion value or decrease the wavelength range of operation with the WL LIM START WL and STOP WL functions 53 Using the Multi Wavelength Meter Measuring Laser Separation Measuring Laser Separation It is often important to measure the wavelength and power separation between multiple laser lines This is especially true in wavelength divi sion multiplexed WDM systems where channel spacing must be adhered to The Agilent 86120B can display the wavelength and ampli tude of any laser line relative to another In fact the following types of relative measurements can be made compared to the reference Relative wavelength absolute power Relative power absolute wavelength Relative wavelength and power This section includes Channel separation 55 Measuring flatness 56 54 Using the Multi Wavelength Meter Measuring Laser Separation Channel separation Suppose that you want to measure separation on a system having the spectrum shown in the following figure Reference 1541 747 nm 5 46 dBm 2 606 nm 1 302 nm 7 26 dB 1 98 dB 1 300 nm 2 596 nm 2 42 dB 4 41 dB peaks The Agilent 86120B displays separation on this spectrum as shown in the following figure Notice that the 1
165. r status command clears all the event status registers summarized in the status byte register CLS With the exception of the output queue all queues that are summa rized in the status byte register are emptied The error queue is also emptied Neither the event status enable register nor the service request enable register are affected by this command After the CLS command the instrument is left in the idle state The command does not alter the instrument setting OPC and OPC actions are cancelled This command cannot be issued as a query ESE The ESE event status enable command sets the bits in the event sta tus enable register and enables the corresponding bits in the event sta tus register ESE integer ESE 131 Description Query Response Example Programming Commands Common Commands lt integer gt is a mask from 0 to 255 The event status enable register contains a mask value for the bits to be enabled in the event status register A bit set to one 1 in the event status enable register enables the corresponding bit in the event status register to set the event summary bit in the status byte register A zero 0 disables the bit Refer to the following table for information about the event status enable register bits bit weights and what each bit masks The event status enable register is cleared at power on The RST and CLS commands do not change the register The ESE query ret
166. r units are not affected CONFigure command When this function is used with the CONFigure command the query question mark character must not be included in the string However the FETCh READ and MEASure command are queries and require the question mark Refer to the examples for this command MAXimum The highest frequency signal MINimum The lowest frequency signal 148 Programming Commands Measurement Instructions DEFault The current marker position lt resolution gt MAXimum 0 01 resolution fast update Constants MINimum 0 001 resolution normal DEFault Current resolution Examples CONF ARR POW FREQ DEF MIN FETCCARR POW FREQ DEF MAX READ ARR POW FREO MEAS ARR POW FREQ CONF SCAL POW FREO 230 8THZ MAX FETC SCAL POW FREQ 230 8THZ MIN READ SCAL POW FREO 230 8THZ MEAS SCAL POW FREQ 230 8THZ Query Response The following line is an example of a returned string when MEAS SCAL POW FREQ MAX is sent 1 940551 76E 014 If six laser lines are located and MEAS ARR POW FREQ is sent the following string is an example of the returned data Notice that the first returned number indicates the number of laser line values returned in the query 6 1 94055100 014 1 93854100 014 1 93653000 014 1 93452000 014 1 93250900 0 14 1 93050000 014 149 Syntax Description lt expected_value gt Constants Programming Commands Measurement Instructions MEASu
167. re ARRay SCALar POWer WAVe length Returns wavelength values POWer WAVelength lt expected_value gt lt resolution gt Used With lt expected_value gt lt resolution gt SCALar optional optional ARRay ignored optional a Although ignored this argument must be present if the resolution argument is specified When used with a SCALar command a single value is returned The display is placed in the single wavelength mode and the marker is placed on the signal having a wavelength that is closest to the expected value parameter Default units for expected value parameter are in meters When used with an ARRay command an array of wavelengths is returned The display is placed in the list by wavelength mode The resolution parameter sets the resolution of the measurement It is a unitless number whose value will be limited to either 0 01 or 0 001 whichever is closer Returned values are in meters Displayed units are nanometers Power units are not affected CONFigure command When this function is used with the CONFigure command the query question mark character must not be included in the string However the FETCh READ and MEASure command are queries and require the question mark Refer to the examples for this command MAXimum The highest wavelength signal MINimum The lowest wavelength signal DEFault The current marker position 150 lt resolution gt Cons
168. re that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120B to wait for non sequential commands on page 90 for more information 171 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem WLIMit STOP WNUMber Sets the stopping wavenumber for the wavelength limit range CALCulate2 WLIMit STOP WNUMber lt real gt MINimum MAXimum real is a wavenumber value that is within the following limits Constant Description MINimum start wavelength limit MAXimum 14286 cm 700 nm Non sequential command Preset State 8 333335 5 RST State 8 333335 5 m SCPI Compliance instrument specific This command sets the stopping range for the wavelength limit The default units for the real parameter are inverse meters The stop wavenumber value must be less than or equal to the start wavenumber value or the stop wavenumber will be clipped to the start wavenumber and a Data out of range error will be generated Non sequential command Always use OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120B to wait for non sequential commands on page 90 for more information 172 Programming Commands CALCulate3 Subsystem CALCulate3 Subsyste
169. rent value of the instru ment s status byte STB The master summary status MSS bit 6 indicates whether or not the device has at least one reason for requesting service When you read the status byte register the value returned is the total of the bit weights of all of the bits set to one at the time you read the byte The following table shows each bit in the status byte register and its bit weight The STB query does not affect the contents of the status byte register Table 5 17 Status Byte Register Bit Bit Weight Condition 7 128 Not Used 6 64 Master Summary Status MSS 5 32 Event Status Bit ESB 4 16 Message Available MAV 3 8 Not Used 2 4 Error queue status 1 2 Not Used 0 1 Not Used integer from 0 to 255 OUTPUT 720 STB ENTER 720 Value PRINT Value 141 Syntax Description Example Syntax Description Query Response Example Programming Commands Common Commands TRG The TRG trigger command is identical to the group execute trigger GET message or RUN command TRG This command acquires data according to the current settings This command cannot be issued as a query If a measurement is already in progress a trigger is ignored and an error is generated The following example starts the data acquisition according to the cur rent settings OUTPUT 720 TRG TST The TST test query starts a self test on the instrument IST The res
170. requency of 428 2793 THz 699 993 nm For example a laser line peak located at the 1 500th returned value has an optical frequency of frequency 181 6879 THz 1 499 7 226756 GHz 192 5208 THz or 1557 195 nm in vacuum When FAST measurement mode is selected the uncorrected frequency domain data consists of 8K 8 192 values The frequency spacing between elements is uniform and is equal to the reference laser fre quency 473 6127 THz divided by 8K or 57 81405 GHz Note the spac ing between values is not uniform in wavelength units The values returned are in ascending optical frequency Only the frequency domain data corresponding to 700 1650 nm wavelength in vacuum is returned 4 268 values The first value of the uncorrected frequency data corresponds to an optical frequency of 181 652 THz 1650 37 nm The last value of the uncorrected frequency data corresponds to an optical frequency of 428 344 THz 699 89 nm For example a laser line peak located at the 200th returned value has an optical frequency of frequency 181 652 THz 199 57 81405 GHz 193 157 THz or 1551 07 nm in vacuum 157 Programming Commands CALCulate1 Subsystem If your program is aborted or interrupted after sending this query the Agilent 86120B continues to process the data but does not place it in the output buffer Because of the amount of data processed the instrument will not respond to any new commands in its input buffer
171. roduction to this section for a description of each sub routine that is contained in this program COM Instrument Mwm ASSIGN Mwm TO 720 Set_ese PRINT USING 37A 33A Multi Wavelength Meter Identity is FNidentity OUTPUT Mwm INIT CONT OFF ON TIMEOUT 7 5 CALL Err_mngmt OUTPUT Mwm MEAS SCAL POW WAV ENTER Mwm Current_wl OUTPUT Mwm FETC SCAL POW ENTER Mwm Current_pwr OFF TIMEOUT PRINT USING 20A 4D 3D 3A 19A M2D 2D 4A The wavelength is Current_wl 1 0E 9 nm with a power of Current pwr dBm END Err mngmt SUB Err_mngmt COM Instrument Mwm DIM Err_msg 255 INTEGER Cme CLEAR 7 REPEAT OUTPUT Mwm ESR ENTER Mwm Cme OUTPUT Mwm SYST ERR ENTER Mwm Err_msg PRINT Err msg UNTIL NOT BIT Cme 2 AND NOT BIT Cme 4 AND NOT BIT Cme 5 AND POS Err msg 0 Subend SUBEND Set_ese SUB Set ese COM Instrument Mwm OUTPUT GMwm ESE IVAL 00110100 2 SUBEND 108 Programming Example Programs Identity DEF FNidentity COM Instrument MwmV DIM IdentityS 50 IdentityS OUTPUT Mwm RST OUTPUT GMwm OPC ENTER Mwm pc done OUTPUT GMwm IDN ENTER Mwm ldentity RETURN IdentityS FNEND 109 Programming Example Programs Example 2 Measure WDM channels This program measures the multiple laser lines of a WDM system It measures both the power and wavelengths of each line First the pro gram sets the Agilent 86120B in the single acquisitio
172. rogramming Commands CALCulate3 Subsystem This command sets the number of measurements to be used for the average signal to noise calculation If this count is changed while the average signal calculation is on and the new count is less than the number of measurements already taken the instrument will go into single measurement mode 175 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem ASNR STATe Turns the average signal to noise ratio on or off CALCulate3 ASNRI STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific This command turns the average signal to noise calculation on or off Only one of the CALCulate3 calculations ASNR DELTa DRIFt or SNR can be turned on at a time Turning on the ASNR calculation while another calculation is on will generate a Settings conflict error When the calculation is first turned on the lines measured in the cur rent measurement will be used as the reference values for the signal to noise ratio Subsequent measurements will average the noise values The signal values are not updated until the number of measurements used to average the noise is greater than or equal to the COUNt value Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signa
173. rs relative to the reference level The 56 Un Q Using the Multi Wavelength Meter Measuring Laser Separation power differences represent the system flatness Press RESET to turn off the delta calculations so that all responses are shown in absolute wavelength and powers To measure flatness Press the front panel Preset key Press List by Power This lists the input signals by power with the largest response listed first Press the Delta On key Select A PWR Use the and softkeys to select the first laser line Press SELECT Since the largest power signal is the reference the relative power measurements for the other responses shows system flatness 57 Lasers modulated at low frequencies Using the Multi Wavelength Meter Measuring Modulated Lasers Measuring Modulated Lasers A laser that is amplitude modulated at low frequencies for example modulated in the audio frequency range can cause spurious wave lengths to be displayed below and above the correct wavelength The power of these spurious wavelengths is below that of the correct wave length These spurious signals can be eliminated by decreasing the peak threshold Refer to Defining Laser Line Peaks on page 50 Even when the laser is amplitude modulated the correct wavelength and power is displayed The spurious wavelengths caused by low frequency amplitude modula tion will be located above and below the correct wavelength
174. s If more than 100 lines are input only the 100 longest wavelength lines are dis played Input Return Loss indicates the optical power reflected back to the user s fiber cable relative to the input power It is limited by the return loss of the front panel connector and assumes the user s connector is good Measurement cycle time refers to the cycle time when measuring wavelength and power of laser lines Specific advanced applications may require longer cycle times 234 Specifications and Regulatory Information Specifications Specifications Each laser line is assumed to have a linewidth including modulation side bands of less than 10 GHz All specifications apply when the instrument is in the following modes NORMAL update mode unless noted Refer to Measurement rate on page 48 Configured to measure narrowband devices Specifications do not apply when the instrument is configured to measure broadband devices Refer to Measuring broadband devices and chirped lasers on page 44 Wavelength Range 700 1650 nm 182 428 THz Absolute accuracy lines separated by gt 30 GHz 3 ppm 0 005 nm at 1550 nm 0 004 nm at 1310 Differential accuracy characteristic 2 ppm Minimum resolvable separation characteristic 20 GHz 0 16 nm at 1550 nm 0 11 nm at 1300 nm Display resolution 0 001 nm normal update mode 0 01 nm fast update mode a Signals of equal amplitude For lines that are se
175. s 253 Front Panel Fiber Optic Adapters 258 Power Cords 260 Agilent Technologies Service Offices 261 Reference Reference Reference Reference Instrument Preset Conditions Table 7 1 Instrument Preset Conditions 1 of 2 Settings after Preset Settings after Power Item Key Pressed Turned On Display mode single wavelength last state Wavelength range limiting on last state Start wavelength 1200 nm last state Stop wavelength 1650 nm last state Graphical display off off Measurement acquisition continuous last state Wavelength calibration vacuum last state Elevation correction value not affected last state Wavelength units nm last state Amplitude units dBm last state Power offset 0dB last state Peak threshold 10 dB last state 244 Reference Instrument Preset Conditions Table 7 1 Instrument Preset Conditions 2 of 2 Settings after Preset Settings after Power Hom Key Pressed Turned On Peak excursion 15 dB last state Measurement speed normal last state Device bandwidth narrowband last state Drift measurements off off Coherence length measurements off off Delta Measurements A power off off A wavelength off off A wavelength and power off off reference signal position 700 nm 700 nm Signal to Noise Measurements measurement off off wavelength reference auto last state user wavelength not affected last state number of averages 100 last state GPIB address not affected last state Power b
176. s of fiber optic cables 30 Getting Started Cleaning Connections for Accurate Measurements Figure 1 7 Universal adapters Apply isopropyl alcohol to a clean foam swab Cotton swabs can be used as long as no cotton fibers remain after clean ing The foam swabs listed in this section s introduction are small enough to fit into adapters Although foam swabs can leave filmy deposits these deposits are very thin and the risk of other contamination buildup on the inside of adapt ers greatly outweighs the risk of contamination by foam swabs Clean the adapter with the foam swab Dry the inside of the adapter with a clean dry foam swab Blow through the adapter using filtered dry compressed air Nitrogen gas or compressed dust remover can also be used Do not shake tip or invert compressed air canisters because this releases par ticles in the can into the air Refer to instructions provided on the com pressed air canister 31 Getting Started Returning the Instrument for Service Returning the Instrument for Service The instructions in this section show you how to properly return the instrument for repair or calibration Always call the Agilent Technolo gies Instrument Support Center first to initiate service before returning your instrument to a service office This ensures that the repair or calibration can be properly tracked and that your instrument will be returned to you as quickly as possible Cal
177. s to under measure the return loss by twice the FC APC patchcord 1 to 2 loss For example if this connector pair loss is 0 5 dB then the actual return loss caused by the 14 6 dB Fresnel reflection is 15 6 dB but we enter 14 6 dB as an R value Then if the DUT return loss is exactly 40 dB below that of the 14 6 Fresnel reflection the optical return loss module will display 53 6 dB because the 0 5 dB connector pair loss seen twice is removed In reality the return loss is 54 6 dB exactly 40 dB below 14 6 dB better than that displayed 226 Equipment Procedure Performance Tests Test 5 Amplitude Accuracy and Linearity Test 5 Amplitude Accuracy and Linearity Amplitude linearity is performed using the following devices 1550 nm DFB lasers Optical attenuator Agilent 11896A Polarization Controller Optical power meter Polarization sensitivity To ensure measurement accuracy minimize the movement of any fiber optic cables during this procedure Moving cables causes polarization changes which affect amplitude measurements Turn on the laser and allow it to warm up Connect the laser s output to the optical attenuator s input Connect the optical attenuator s output to the polarization controller s optical input Connect the polarization controller s optical output to the optical power meter Configure the optical power meter for 1550 nm Adjust the optical attenuator so that the power m
178. same type and ratings Fuse type F 6 3 A 250V IEC 60127 type 5x20mm The use of other fuses or materials is prohibited This product complies with Overvoltage Category Il and Pollution Degree 2 CAUTION CAUTION CAUTION CAUTION General Safety Considerations VENTILATION REQUIREMENTS When installing the product in a cabinet the convection into and out of the product must not be restricted The ambient temperature outside the cabinet must be less than the maximum operating temperature of the product by 4 C for every 100 watts dissipated in the cabinet If the total power dissipated in the cabinet is greater than 800 watts then forced convection must be used Always use the three prong ac power cord supplied with this instrument Failure to ensure adequate earth grounding by not using this cord may cause instrument damage Do not connect ac power until you have verified the line voltage is correct as described in Line Power Requirements on page 1 14 Damage to the equipment could result This instrument has autoranging line voltage input Be sure the supply voltage is within the specified range Contents The Agilent 86120B Ata Glance 3 General Safety Considerations 6 Getting Started Step 1 Inspect the Shipment 13 Step 2 Connect the Line Power Cable 14 Step 3 Connect a Printer 15 Step 4 Turn on the Agilent 86120B 16 Step 5 Enter Your Elevation 18 Step 6 Select Medi
179. simultaneously or turning on SNR state while drift or delta state is on Data out of range Too much data Illegal parameter value Data corrupt or stale Caused by trying to query measurement data immediately after a RST command For example sending RST FETCh or sending RST CALC2 DATA pow Data questionable Caused by sending a resolution value in one of the measurement functions that is outside the instrument s range Illegal macro label 257 Reference Front Panel Fiber Optic Adapters Table 7 3 General SCPI Error Messages 3 of 3 Error Number Description 310 System error 321 Out of memory 350 Too many errors 400 Query error 410 Query INTERRUPTED 420 Query UNTERMINATED 430 Query DEADLOCKED 440 Query UNTERMINATED after indef resp Query was unterminated after an indefinite response Front Panel Fiber Optic Adapters Front Panel Fiber Optic Adapter Description Agilent Part Number Diamond HMS 10 81000AI D4 8100001 S FC PC 81000FI 258 Reference Front Panel Fiber Optic Adapters ee Adapter Description Agilent Part Number SC 81000KI DIN 8100051 r E3 ST 81000VI Biconic 81000WI a The FC PC is the default front panel optical connector 259 Reference Power Cords Dust Covers Agilent Part Number FC connector 1005 0594 Diamond HMS 10 connector 1005 0593 DIN
180. sition am Arbeitsplatz Normal operation normaler Betrieb per ISO 7779 nach DIN 45635 1 240 Specifications and Regulatory Information Declaration of Conformity Declaration of Conformity DECLARATION OF CONFORMITY C Agilent Technologies According to ISO IEC Guide 22 and CEN CENELEC EN 45014 Manufacturer s Name Agilent Technologies Manufacturing GmbH amp Co KG Manufacturer s Address Photonic Measurement Division PMD Herrenberger Str 130 D 71034 Boeblingen Declares under sole responsibility that the product as originally delivered Product Name Multi Wavelength Meter Product Numbers 86120B 86120C Product Options This declaration covers all options of the above products complies with the essential requirements of the following applicable European Directives and carries the CE marking accordingly The Low Voltage Directive 73 23 EEC amended by 93 68 EEC e The EMC Directive 89 336 EEC amended by 93 68 EEC and conforms with the following product standards Standard Limit EMC IEC 61326 1997 A1 1998 A2 2000 EN 61326 1997 A1 1998 A2 2001 CISPR 11 1997 EN 55011 1998 Group 1 Class IEC 61000 4 2 2001 EN 61000 4 2 2001 4 kV CD 8kV AD IEC 61000 4 3 2001 EN 61000 4 3 2001 3 V m 80 1000 MHz IEC 61000 4 4 1995 A 1 2000 A2 2001 EN 61000 4 4 2002 0 5 kV signal lines 1 kV power lines IEC 61000 4 5 2001 EN 61000 4 5 2001 0 5 kV line line 1 kV line ground IEC 61000 4 6 2001 EN 61000
181. splay wavelengths as if measured in vacuum or standard air Although all measurements are made in air displayed results are cor rected for air dispersion to accurately show wavelength values in vac uum or in standard air To ensure accurate wavelength measurements make sure that you enter the elevation from which you will be making measurements as described in Chapter 1 Getting Started The Agilent 86120B At a Glance Measurement accuracy it s to you Fiber optic connectors are easily damaged when connected to dirty or damaged cables and accessories The Agilent 86120B s front panel INPUT connector is no exception When you use improper cleaning and handling techniques you risk expensive instrument repairs damaged cables and compromised measurements Before you connect any fiber optic cable to the Agilent 86120B refer to Cleaning Connections for Accurate Measurements on page 21 General Safety Considerations General Safety Considerations This product has been designed and tested in accordance with IEC 61010 1 and has been supplied in a safe condition The instruction documentation contains information and warnings which must be fol lowed by the user to ensure safe operation and to maintain the prod uct in a safe condition Laser Classification This product is classified to 60825 1 There is no output laser aperture The Agilent 86120B does not have an output laser aper
182. strument specifications apply when the Agilent 86120B is configured to measure narrowband devices Specifications do not apply when the instrument is configured to measure broadband devices This feature applies to Agilent 86120B instruments with firmware version number 2 0 When first turned on the instrument briefly displays the firmware version Instruments with a firmware version number less than 2 0 do not have this feature To measure broadband devices Press the Setup key Press MORE twice and then the DEVICE softkey Press the BROAD softkey To return to measuring narrowband devices press NARROW 44 Using the Multi Wavelength Meter Displaying Wavelength and Power Graphical display of optical power spectrum A graphical display of optical power versus wavelength is shown from the start wavelength value to the stop wavelength value The start wavelength value is shown in the upper left corner of the graphical display and the stop wavelength value is shown in the upper right corner of the graphical display The power scale is a fixed dB scale with 10 dBm at the display top and 53 dBm at the display bottom The power scale is not affected by the Power Offset value In most cases the noise floor will be visible if the total input power is greater than about 5 dBm 1545 8 1565 6 The Agilent 86120B graphical display The Peak Threshold value is displayed as a dotted line All peaks above this dotted line
183. t few years the FC PC style connector has emerged as the most popular connector for fiber optic applications While not the highest performing connector it represents a good compromise between performance reliability and cost If properly maintained and cleaned this connector can withstand many repeated connections However many instrument specifications require tighter tolerances than most connectors including the FC PC style can deliver These instruments cannot tolerate connectors with the large non concentrici ties of the fiber common with ceramic style ferrules When tighter alignment is required Agilent Technologies instruments typically use a 22 Getting Started Cleaning Connections for Accurate Measurements connector such as the Diamond HMS 10 which has concentric toler ances within a few tenths of a micron Agilent Technologies then uses a special universal adapter which allows other cable types to mate with this precision connector See Figure 1 2 Figure 1 2 Universal adapters to Diamond HMS 10 The HMS 10 encases the fiber within a soft nickel silver Cu Ni Zn center which is surrounded by a tough tungsten carbide casing as shown in Figure 1 3 Staking Groove Fixing oper Secondary Staking Active Centering Tungsten Carbide Hard Case 4 Nickel Silver Soft center 126 um Fiber Centered to about 0 2 microns Figure 1 3 Cross section
184. t optimum connector perfor mance is maintained With glass to glass interfaces any degradation of a ferrule or the end of the fiber any stray particles or finger oil can have a significant effect on connector performance Where many repeat connections are required use of a connector saver or patch cable is recommended Figure 1 4 shows the end of a clean fiber optic cable The dark circle in the center of the micrograph is the fiber s 125 um core and cladding which carries the light The surrounding area is the soft nickel silver ferrule Figure 1 5 shows a dirty fiber end from neglect or perhaps improper cleaning Material is smeared and ground into the end of the fiber causing light scattering and poor reflection Not only is the preci sion polish lost but this action can grind off the glass face and destroy the connector Figure 1 6 shows physical damage to the glass fiber end caused by either repeated connections made without removing loose particles or using improper cleaning tools When severe the damage of one con nector end can be transferred to another good connector endface that comes in contact with the damaged one Periodic checks of fiber ends and replacing connecting cables after many connections is a wise prac tice The cure for these problems is disciplined connector care as described in the following list and in Cleaning Connectors on page 28 24 Getting Started Cleaning Connections for Accurate Measure
185. ta measured before the conditions changed press CLEAR and then MAX MIN Notice that the measurement acquisition is changed from continuous to single To restart testing press CLEAR the CONT key and then RESET to use the new number of lines as the reference Pressing CONT restarts continuous measure ment acquisition Or you can restore the original number of lines on the input so that the drift measurement can continue To measure drift Press the front panel Preset key Press Peak WL List by WL or List by Power to select the display style for observing drift Press Appl s and then DRIFT Pressing DRIFT sets the current laser line values as the reference from which to compare all drift Press MAX MIN for the desired type of drift measurement as described in the following paragraphs Display shows the current values of laser lines relative to the wavelength and power values measured when the test was begun or the RESET softkey was pressed Display shows absolute maximum values since the drift measurement was started This measurement gives the longest wavelength and greatest power measured The laser line of interest may have since drifted to a lesser value Note that the Measurements Applications Measuring Laser Drift maximum wavelength and maximum power may not have occurred simultaneously Display shows absolute minimum values since the drift measurement was started This measurement gives the shortest wa
186. tants Examples Query Response Programming Commands Measurement Instructions MAXimum 0 01 resolution fast update MINimum 0 001 resolution normal DEFault Current resolution CONF ARR POW WAV DEF MAX FETC ARR POW WAV DEF MIN READ ARR POW WAV MEAS ARR POW WAV CONF SCAL POW WAV 1300NM MAX FETC SCAL POW WAV 1300NM MIN READ SCAL POW WAV 1300NM MEAS SCAL POW WAV 1300NM The following line is an example of a returned string when MEAS SCAL POW WAV MAX is sent 1 5529258E 006 If six laser lines are located and MEAS ARR POW WAV is sent the following string could be returned Notice that the first returned num ber indicates the number of laser line values returned in the query 6 1 54488100 006 1 54648400 006 1 54809000 006 1 54969900 006 1 55131100 006 1 55292600E 006 151 Syntax Description lt expected_value gt Constants Programming Commands Measurement Instructions MEASure ARRay SCALar POWer WNUMber Returns a wave number value POWerWNUMber lt expected_value gt lt resolution gt Used With lt expected_value gt lt resolution gt SCALar optional optional ARRay ignored optional a Although ignored this argument must be present if the resolution argument is specified When used with a SCALar command a single value is returned The display is placed in the single wavelength mode and the marker is placed on the signal havin
187. tart frequency and a Data out of range error will be generated Non sequential command Always use an query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120B to wait for non sequential commands on page 90 for more information 170 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem WLIMit STOP WAVelength Sets the stopping wavelength for the wavelength limit range CALCulate2 WLIMit STOP WAVelength lt real gt MINimum MAXimum lt real gt is a wavelength value that is within the following limits Constant Description MINimum start wavelength limit MAXimum 1650 0 nm Non sequential command Preset State 1650 nm RST State 1650 nm SCPI Compliance instrument specific This command sets the stopping range for the wavelength limit The default units for the lt real gt parameter are meters The stop wavelength value must be greater than or equal to the start wavelength value or the stop wavelength will be clipped to the start wavelength and a Data out of range error will be generated Setting the start wave length is equivalent to setting the start frequency wavenumber because of the inverse relationship of frequency to wavelength Non sequential command Always use OPC query or a WAI command to ensu
188. tatus registers The Agilent 86120B provides four registers which you can query to monitor the instrument s condition These registers allow you to deter mine the following items Status of an operation Availability of the measured data Reliability of the measured data All three registers are shown in the figure on the following page and have the following uses Register Definition Status Byte Monitors the status of the other three registers Standard Event Status This is the standard IEEE 488 2 register Contains bits which indicate the status of the other two registers OPERation Status Contains bits that report on the instrument s normal operation QUEStionable Status Contains bits that report on the condition of the signal 94 Programming Monitoring the Instrument Status Byte register The Status Byte Register contains summary bits that monitor activity in the other status registers and queues The Status Byte Register s bits are set and cleared by the presence and absence of a summary bit from other registers or queues Notice in the following figure that the bits in the Standard Event Status OPERation status and QUEStionable status registers are or d to control a bit in the Status Byte Register If a bit in the Status Byte Register goes high you can query the value of the source register to determine the cause The Status Byte Register can be read using either the STB common command or the GPIB seria
189. tem 54 white space characters 103 WL LIM softkey 20 43 WL REF softkey 70 A WL softkey 56 WL softkey 48 A WL PWR softkey 56 WLIMit programming command 166 167 169 170 171 172 WNUMber programming command 152 181 194 Index Index 269 www agilent com Agilent Technologies GmbH 2004 Printed in Germany July 2004 Second edition July 2004 86120 90B03 72 Agilent Technologies
190. tem 199 MEASure Measurement Instruction 199 READ Measurement Instruction 200 SENSe Subsystem 200 STATus Subsystem 206 SYSTem Subsystem 211 TRIGger Subsystem 216 UNIT Subsystem 218 Programming Commands Programming Commands Programming Commands Programming Commands This chapter is the reference for all Agilent 86120B programming com mands Commands are organized by subsystem Table 5 12 Notation Conventions and Definitions Convention Description lt gt Angle brackets indicate values entered by the programmer Or indicates a choice of one element from a list Square brackets indicate that the enclosed items are optional When several items are enclosed by braces one and only one of these elements must be selected lt integer gt An ASCII string representing an integer This is defined by the IEEE 488 2 lt NR1 gt format lt real gt An ASCII string representing a real number This is defined by the IEEE 488 2 lt NR2 gt or lt NRf gt formats 130 Syntax Description Syntax Programming Commands Common Commands Common Commands Common commands are defined by the IEEE 488 2 standard They control generic device functions which could be common among many different types of instruments Common commands can be received and processed by the instrument whether they are sent over the GPIB as separate program messages or within other program messages CLS The CLS clea
191. ter are meters 193 Syntax Attribute Summary Description Syntax Attribute Summary Programming Commands CALCulate3 Subsystem SNR REFerence WNUMber Sets the wave number used for the noise measurement reference in the signal to noise calculation CALCulate3 SNR REFerence WNUMber lt real gt MINimum MAXimum real is a wave number value that is within the following limits Constant Description MINimum 6060 cm 1650 nm MAXimum 14286 cm 700 nm Preset State unaffected by RST State 6451 614 cm SCPI Compliance instrument specific After entering this value use the SNR AUTO command to configure the instrument to use this value in subsequent signal to noise calculations The wave number entered is converted internally to the corresponding frequency The default units for the real parameter are SNR STATe Turns the signal to noise calculation on and off CALCulate3 SNR STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific 194 Programming Commands CONFigure Measurement Instruction Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 92 for additional information on selecting measurements CONF igure Measurement Instr
192. th delay peak All envelope peaks found are used to determine the exponential decay constant coherence length using a least squares fit The average optical path delay spacing of the envelope peaks is mea sured This is equal to the diode laser cavity round trip optical length laser cavity 2nLd 2nLd 71 Alpha factor Beta factor Measurements Applications Measuring Coherence Length The alpha factor is defined as the height of the first envelope peak away from zero path delay relative to the height of the envelope peak at zero path delay The alpha factor is always between and 1 The smaller the alpha factor the shorter the coherence length Alpha factor v The beta factor is defined as the height of the fringe visibility envelope midway between the zero optical path delay peak and the next peak relative to the height of the envelope peak at zero path delay The beta factor is always between 0 and 1 The smaller the beta factor the more longitudinal modes wavelengths the laser has B Vs eta factor f V5 78 Addressing and Initializing the Instrument 81 To change the GPIB address 81 Making Measurements 83 Commands are grouped in subsystems 85 Measurement instructions give quick results 87 The format of returned data 93 Monitoring the Instrument 94 Status registers 94 Queues 99 Reviewing SCPI Syntax Rules 101 Example Programs 106 Example 1 Measure a DFB laser 108 Example 2 M
193. the better the larger the return loss the smaller the reflection The best physically contacting connectors have return losses better than 50 dB although 30 to 40 dB is more common 27 WARNING Getting Started Cleaning Connections for Accurate Measurements Visual inspection of fiber ends Visual inspection of fiber ends can be helpful Contamination or imperfections on the cable end face can be detected as well as cracks or chips in the fiber itself Use a microscope 100X to 200X magnifica tion to inspect the entire end face for contamination raised metal or dents in the metal as well as any other imperfections Inspect the fiber for cracks and chips Visible imperfections not touching the fiber core may not affect performance unless the imperfections keep the fibers from contacting Always remove both ends of fiber optic cables from any instrument system or device before visually inspecting the fiber ends Disable all optical sources before disconnecting fiber optic cables Failure to do so may result in permanent injury to your eyes Cleaning Connectors The procedures in this section provide the proper steps for cleaning fiber optic cables and Agilent Technologies universal adapters The ini tial cleaning using the alcohol as a solvent gently removes any grit and oil If a caked on layer of material is still present this can hap pen if the beryllium copper sides of the ferrule retainer get scraped and de
194. to Noise Noise Bandwidth Auto Measurements Indicator Mode 13546 453nm 18 79dBm 21 6dB 1548 066 6 06 25 BY UL 1549 668 H z2Y 38 8 s OF 1531 279 4 92 29 8 WAC 13552 894 11 33 23 1 a M ser Signal to noise display During a signal to noise measurement the absolute power of the car rier in dBm is compared to the absolute power of the noise at the carrier wavelength See the following figure The noise power at the carrier must be determined by interpolation because the carrier in most cases can not or should not be turned off You can select one of two methods used to determine the wavelength where the noise is measured automatic interpolation or a user entered wavelength In the figure above notice that S N AUTO is displayed to indicate that automatic interpolation is selected 67 Automatic interpolation Measurements Applications Measuring Signal to Noise Ratios Plaser line Interpolated Noise value at noise value user entered using automatic wavelength mode peak Location of noise measurements When the signal to noise auto function is selected the Agilent 86120B first determines the proximity of any adjacent signal If the next closest signal is lt 200 GHz approximately 1 6 nm at 1550 nm away from the signal of interest then the noise power is measured half way between the two channels and an equal distance to the other side of the sign
195. ture However light less than 1 nW escapes out of the front panel OPTICAL INPUT connector Operator maintenance or precautions are not necessary to maintain safety No controls adjustments or performance of procedures result in hazardous radiation expo sure 85120 1270 1650 nm Agilent MOLTIWAVELENGTH METER Input Connector inptconr WARNING WARNING WARNING WARNING WARNING CAUTION General Safety Considerations If this instrument is not used as specified the protection provided by the equipment could be impaired This instrument must be used in a normal condition in which all means for protection are intact only No operator serviceable parts inside Refer servicing to qualified personnel To prevent electrical shock do not remove covers To prevent electrical shock disconnect the Agilent 86120B from mains before cleaning Use a dry cloth or one slightly dampened with water to clean the external case parts Do not attempt to clean internally This is a Safety Class 1 product provided with protective earth The mains plug shall only be inserted in a socket outlet provided with a protective earth contact Any interruption of the protective conductor inside or outside of the product is likely to make the product dangerous Intentional interruption is prohibited For continued protection againstfire hazard replace line fuse only with
196. uation burn in or development In addition you can monitor system performance over time temperature or other condition The following display shows power and wavelength drift measured on five laser lines The DRIFT annotation item tells you that drift mea surements are being performed The current relative drift values for wavelength and power are shown in items and respectively Item D indicates the absolute reference values for the laser line indicated by the cursor The reference values are measured before the measure ment starts 4 DRIFT m nad 4 16 EY WL 4 868 H 11 wesa zi4u OF E 8 888 Bn 83 E 37 NE m anad B 11 B M drift 73 Measurements Applications Measuring Laser Drift You can restart the drift measurement at any time by pressing the RESET softkey All minimum and maximum values are reset to the ref erence values and the Agilent 86120B begins to monitor drift from the current laser line values Move the cursor up and down the listing to see the reference wavelength and power of each laser line If measurement updating stops or the values become blanked If in the middle of a measurement the number of laser lines present changes the measurement stops until the original number of lines returns You ll notice that a CLEAR softkey appears and one of the following message is displayed E46 NUM LINES NUM REFS E47 NUM LINES NUM REFS To view the da
197. uction For information on the CONFigure measurement instruction refer to Measurement Instructions on page 144 DISPlay Subsystem The commands in this subsystem have the following command hierar chy DISPlay MARKer MAXimum LEFT NEXT PREVious RIGHt WINDow GRAPhics STATe 195 Syntax Attribute Summary Syntax Attribute Summary Description Programming Commands DISPlay Subsystem MARKer MAXimum Sets the marker to the laser line that has the maximum power DISPlay MARKer MAXimum Preset State marker set to maximum power laser line RST State marker set to maximum power laser line SCPI Compliance instrument specific Command Only MARKer MAXimum LEFT Moves the marker left to the next laser line DISPlay MARKer MAXimum LEFT Preset State marker set to maximum power laser line RST State marker set to maximum power laser line SCPI Compliance instrument specific Command Only Moves the marker from the current marker position to the next laser line having the following characteristic shorter wavelength lower frequency lower wave number If the display is in the List by Ampl mode it will be changed to List by WL before the marker is moved MARKer MAXimum NEXT Moves the marker to the laser line with the next lower power level 196 Syntax Attribute Summary Description Syntax Attribute Summary Description Syntax Attribut
198. ult of the test is placed in the output queue A zero indicates the test passed and a non zero value indicates the test failed The instrument will initiate a measurement and check for any hardware errors after the measurement is complete integer OUTPUT 720 TST ENTER 720 Result PRINT Result 142 Programming Commands Common Commands WAI The WAI command prevents the instrument from executing any fur ther commands until the current command has finished executing Syntax WAI Description All pending operations are completed during the wait period This command cannot be issued as a query 143 Programming Commands Measurement Instructions Measurement Instructions Use the measurement instructions documented in this section to per form measurements and return the desired results to the computer Four basic measurement instructions are used CONFigure FETCh READ and MEASure Because the command trees for each of these four basic measurement instructions are identical only the MEASure tree is documented To perform a measurement append to the measurement instruction a POWer or LENGth function The POWer functions select power fre quency wavelength or wave number measurements Use the LENGth functions to configure the instrument to measure coherence length The instrument measures the coherence length in the time domain by rec tifying and low pass filtering the interferogram The resulting wave
199. um for Wavelength Values 19 Step 7 Turn Off Wavelength Limiting 20 Cleaning Connections for Accurate Measurements 21 Returning the Instrument for Service 32 Using the Multi Wavelength Meter Displaying Wavelength and Power 37 Changing the Units and Measurement Rate 47 Defining Laser Line Peaks 50 Measuring Laser Separation 54 Measuring Modulated Lasers 58 Measuring Total Power Greater than 10 dBm 60 Calibrating Measurements 61 Printing Measurement Results 63 Measurements Applications Measuring Signal to Noise Ratios 67 Measuring Signal to Noise Ratios with Averaging 71 Measuring Laser Drift 73 Measuring Coherence Length 76 Programming Addressing and Initializing the Instrument 81 Making Measurements 83 Monitoring the Instrument 94 Reviewing SCPI Syntax Rules 101 Example Programs 106 Lists of Commands 121 5 Programming Commands Common Commands 131 Measurement Instructions 144 CALCulate1 Subsystem 155 CALCulate2 Subsystem 161 CALCulate3 Subsystem 173 CONFigure Measurement Instruction 195 DISPlay Subsystem 195 FETCh Measurement Instruction 198 HCOPy Subsystem 199 MEASure Measurement Instruction 199 READ Measurement Instruction 200 SENSe Subsystem 200 STATus Subsystem 206 SYSTem Subsystem 211 TRIGger Subsystem 216 UNIT Subsystem 218 6 Performance Tests Test 1 Absolute Wavelength Accuracy 221 Test 2 Sensitivity 222 Test 3 Polarization Dependence 223 Test 4 Optical Input Return Loss 224 Test 5 Amplitude
200. ument No syntax error will be generated if a size parameter is sent Always force the Agilent 86120B to wait for non sequential com mands The Agilent 86120B normally processes its remote programming com mands sequentially The instrument waits until the actions specified by a particular command are completely finished before reading and exe cuting the next command However there are a few non sequential commands where this is not true Non sequential commands do not finish executing before the next command is interpreted The following is a list of the Agilent 86120B s non sequential com mands CALCulate1 TRANsform FREQuency POINTs CALCulate2 PEXCursion CALCulate2 PTHReshold CALCulate2 WLIMItSTATe CALCulate2 WLIMit S TARtFREQuency CALCulate2 WLIMit STARtWAVelength CALCulate2 WLIMit SSTAREWNUMber CALCulate2 WLIMit STOP FREQuency CALCulate2 WLIMit STOP WAVelength CALCulate2 WLIMit STOP WNUMber CALCulate3 SNR AUTO SENSe CORRection ELEVation INITiate CONTinuous INITiate IM Mediate CD QD CD CD CD The following additional commands are also non sequential commands if CALCulate3 SNR AUTO is set to OFF CALCulate3 REFerence FREQuency CALCulate3 REFerence WAVelength 90 Programming Making Measurements CALCulate3 REFerence WNUMber The benefit of non sequential commands is that in some situations they can reduce the overall execution times of programs For exam
201. urement bandwidth a wide bandwidth allows more noise to the Agilent 86120B s detector than a narrow bandwidth the Agilent 86120B normalizes all noise power measurements to a bandwidth of 0 1 nm The annotation 0 1 nm is displayed to show that the noise bandwidth is being normalized to a 0 1 nm bandwidth To measure signal to noise with averaging Press the front panel Preset key Press List by WL or List by Power Press Appl s and then S N AVG To change the number of averages press NUM AVG The default Preset value is 100 To stop the measurement at the current number of averages shown press the Single key Then press the Cont key to continue the present measurement When the measurement is complete the instrument will switch to the single measurement mode and stop To make a new measurement press the Cont key To exit press the EXIT softkey then press the Cont key for continuous measurement 72 Measurements Applications Measuring Laser Drift Measuring Laser Drift In this section you ll learn how the Agilent 86120B can be used to monitor drift changes to a laser s wavelength and amplitude over time Drift is measured simultaneously for every laser line that is identified at the input The Agilent 86120B keeps track of each laser line s initial current minimum and maximum values and displays their differences relative to itself This allows the Agilent 86120B to be used for laser transmitter eval
202. urns the value of the event status enable register Table 5 13 Event Status Enable Register Bit Bit Weight Enables 7 128 PON Power On 6 64 Not Used 5 32 CME Command Error 4 16 EXE Execution Error 3 8 DDE Device Dependent Error 2 4 QYE Query Error 1 2 Not Used 0 1 OPC Operation Complete a A high enables the event status register bit lt integer gt is a mask from 0 to 255 OUTPUT 720 ESE 32 In this example the ESE 32 command enables CME event summary bit bit 5 of the event status enable register Therefore when an incor rect programming command is received the CME command error bit in the status byte register is set 132 Programming Commands Common Commands ESR The ESR event status register query returns the value of the event status register Syntax ESR Description When you read the standard event status register the value returned is the total of the bit weights of all of the bits that are set to one at the time you read the byte The following table shows each bit in the event status register and its bit weight The register is cleared when it is read Table 5 14 Standard Event Status Register Condition Bit Bit Weight 7 128 6 64 5 32 4 16 3 8 2 4 1 2 0 1 Query Response lt integer gt ranges from 0 to 255 PON Power Not Used CME Command Error EXE Execution Error DDE Device Dependent Error QYE
203. urrent wl 1 Nb pt ENTER Mwm USING K Current_wi OUTPUT Mwm FETC ARR POW ENTER Mwm USING pt ALLOCATE Current pwr 1 Nb pt ENTER Mwm USING K Current_pwr Turn signal to noise ratio on Cmd_opc CALC3 SNR STAT ON Err_mngmt CALC3 SNR STAT ON Set first wavelength as noise reference Cmd opc CALC3 SNR REF WAV MIN Err_mngmt CALC3 SNR REF WAV MIN Query number of data points OUTPUT Mwm CALC3 POIN ENTER Mwm USING K Nb_pt ALLOCATE Snr_pwr 1 Nb_pt Query signal to noise values OUTPUT Mwm CALC3 DATA POW ENTER Mwm Snr pwr OFF TIMEOUT 117 Programming Example Programs FOR 1 1 TO Nb pt PRINT USING 7A 2D 17A M4D 3D 25A S2D 2D 22A 2D 2D 3A Line 1 wavelength is Current wl I 1 0E 9 nm absolute level is Current pwr l dBm with a SNR of Snr pwr l dB NEXT I STOP Error msg PRINT The program is aborted due to ERRMS END Err_mngmt SUB mngmt OPTIONAL Cmd_msg COM Instrument Mwmt DIM Err_msg 255 INTEGER Cme CLEAR Mwm REPEAT OUTPUT Mwm ESR ENTER Mwm Cme OUTPUT Mwm SYST ERR ENTER QMwm Err msg IF NPAR gt 0 AND NOT POS Err_msgS 0 THEN PRINT This command Cmd msg makes the following error IF NOT POS Err_msg 0 THEN PRINT Err_msg UNTIL NOT BIT Cme 2 AND NOT BIT Cme 4 AND NOT BIT Cme 5 AND POS Err msg 0 Subend SUBEND Set_ese SUB Set ese COM Instrument Mw
204. uted after the instruction terminator is received The terminator may be either a new line NL character the End Or Identify EOI line asserted or a combination of the two All three ways are equivalent Asserting the EOI sets the EOI control line low on the last byte of the data message The NL character is an ASCII linefeed decimal 10 The NL terminator has the same function as an EOS End Of String and EOT End Of Text terminator Querying data Data is requested from the instrument using a query Queries can be used to find out how the instrument is currently configured They are also used to get results of measurements made by the instrument with the query actually activating the measurement String responses are returned as upper case letters Queries usually take the form of a command followed by a question mark After receiving a query the instrument places the answer in its output queue The answer remains in the output queue until it is read or another command is issued For example the query OUTPUT 720 CALCULATE2 POINTS places the number of points in the data set in the output queue In HP BASIC the controller input statement ENTER 720 Range passes the value across the bus to the controller and places it in the variable Range A newline character is appended to the response Sending another command or query before reading the result of a query causes the output queue to be cleared and the current respons
205. velength and smallest power measured The laser line of interest may have since drifted to a greater value Note that the minimum wavelength and minimum power may not have occurred simultaneously Display shows the total drift from the reference since the drift measurement was started Values represent the minimum wavelength and power drift values subtracted from the maximum drift values 5 In the List by WL and List by Power displays use the and softkeys to view the reference values wavelength and power values of each laser line before the test was started During the measurement you can change the display mode to Peak WL List by WL List by Power or Avg WL When List by WL or List by Power is se lected the signal list is sorted by reference values and not by the cur rent maximum or minimum values To restart the drift measurements press RESET This resets the reference values 75 N Measurements Applications Measuring Coherence Length Measuring Coherence Length Coherence length is a measure of the distance over which a laser s light retains the phase relationships of its spectrum The Agilent 86120B measures coherence length of Fabry Perot semiconduc tor diode lasers The Agilent 86120B cannot measure coherence length of light emitting diodes LEDs or distributed feedback DFB lasers When you select coherence length measurements the Agilent 86120B displays the following four values Coheren
206. wer or coher ence length is to use the MEASure command The MEASure command is one of four measurement instructions MEASure READ FETCh and CONFigure The syntax for measurement instructions is documented in Measurement Instructions on page 144 Each measurement instruction has an argument that controls the mea surement update rate This is equivalent to using the NORMAL and FAST softkeys MEASure command MEASure configures the Agilent 86120B captures new data and que ries the data all in one step For example to measure the longest wavelength send the following command MEASure SCALar POWer WAVelength MAX Table 2 5 The Different Forms of MEASure Desired Measurement Data Use this MEASure Query Display Format Power W dBm Frequency Hz Wavelength m Wavenumber Coherence Length m MEASure ARRay POWer MEASure SCALar POWer MEASure ARRay POWer FREQuency MEASure SCALar POWer FREQuency MEASure ARRay POWer WAVelength MEASure SCALar POWer WAVelength MEASure ARRay POWer WNUMber MEASure SCALar POWer WNUMber MEASure LENGth COHerence List by Power single wavelength mode List by WL frequency single wavelength mode List by WL single wavelength mode List by WL single wavelength mode coherence length 87 Programming Making Measurements Specifying SCALar places the display in the single wavelength format and returns a single value to the computer
207. y Subsystem DISPlay MARKer MAXimum Sets the marker to the signal with the largest power DISPlay MARKer MAXimum LEFT Moves marker to signal with the next lower wavelength or frequency DISPlay MARKer MAXimum NEXT Moves the marker to the signal with the closest power level just below the power level of the signal at the current marker position 123 Programming Lists of Commands Table 4 10 Programming Commands 4 of 5 Command Description Code Codes S indicates a standard SCPI command indicates an instrument specific command DISPlay MARKer MAXimum PREVious Moves the marker to the signal with the closest power level just above the power level of the signal at the current marker position DISPlay MARKer MAXimum RIGHt Moves marker to the next higher wavelength or frequency DISPlay WINDow GRAPhics STATe Turns the instrument display of the power bars on and off S HCOPy Subsystem HCOPy IMMediate Starts a printout S SENSe Subsystem SENSe CORRection DEVice Configures wavelength measurements for narrowband or broadband devices SENSe CORRection ELEVation Sets the elevation value used by the instrument to compensate for air dispersion SENSe CORRection OFFSet MAGNitude Sets the power offset value used by the instrument S SENSe CORRection MEDium Sets the instrument to return the wavelength reading in a vacuu
208. yed To control the wavelength range refer to on page 42 Even when the laser being tested is modulated with repetitive formats the carrier s correct wavelength and power is displayed the wavelength and power of the spurious sidebands are incorrect The graphical display is useful to see the effects of high frequency modulation Without modulation the noise floor is typically 45 dB below the laser power In general high frequency modulation will raise the noise floor to about 25 dB below the laser power The noise floor is typically flat or white The actual level of the noise floor depends on the type of data format and the data rate PRBS modulation graph showing raised noise floor Directly modulated lasers exhibit a linewidth that is broadband To measure directly modulated lasers refer to Measuring broadband devices and chirped lasers on page 44 59 CAUTION Using the Multi Wavelength Meter Measuring Total Power Greater than 10 dBm Measuring Total Power Greater than 10 dBm The maximum total power that can be measured by the Agilent 86120B is 10 dBm However with the addition of an external attenuator more power can be applied This may be necessary at the transmit end of a wavelength division multiplexed system where large signal levels are present By entering an amplitude offset equal to the amount of attenuation at the instrument s input accurate amplitud

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