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2. D12 c40 Fao 8 E 93 8 csi E ROA eE ve E Lm6142 1 R99 243211071 A 100 Me C24 Jess o 2 L o R44 jo o P 3 D2 oll 3 amp phi 50 R71 E g J ee o o E JJ M tu E 1 tes S U TE I o0P 07 R27 R20 DOLO peP Dm U SN Rad pl 3252 J Rei C53 25083 7 Figure 7 15 TCU main board current adjustment 2013 ALP S LAS RS SA 99 Chapter 7 Maintenance 11 Temperature limit testing a Decrease the temperature limit threshold from 0 7 V to 0 3 V For more details see Temperature limit threshold on page 97 b Increase the temperature reference to 35 C When the threshold is overpassed the red LED 1 in front panel should light up c Wait the real temperature drops 10 C below the threshold d Reset the instrument with the RESET button 2 gt The red LED 1 should turn off e Reset the temperature limit threshold to 0 7 V For more details see Tem perature limit threshold on page 97 12 Monitoring check the output voltage on the rear instrument BNC connector 5 For 35 C the voltage should be 350 mV 13 External reference a connect an external power supply to the External Reference BNC con nector 6 b Set the voltage to 3 5 V Set the switch External Internal 3 to External Set the selector 4 to mode Setting C gt The temperature displayed 2 should be 35 C Set the selector 4 t
3. 65 in ha Pii N i 1 i j l i 1 ae ley H 2 2 2x 4 E 1 9 m pam 5 y t ell ed CA e l e6 9 5 15 0 5x45 Lx les 19 M A 19 gt a 2 D Figure 6 7 NS left and ST right mounting support 2013 ALPES LAS RS SA 79 Chapter 6 Technical specifications 1 5 lt 2 5 front view 1 5 19 P top view p 7 Y values in mm ed emission 2 from front facet Figure 6 8 NS mounting 80 QCL user s manual v3 1 2 top view Cy 0 6mm pad front view copper submount 2mm 20mm 4mm A laser chip 7mm Y y 4mm emission from front facet Figure 6 9 ST mounting 6 0 2013 ALPES LAS RS SA 81 This page intentionally left blank 7 Maintenance In this chapter the maintenance procedures for the installation of a QCL in the HHL housing and Starter Kit components calibration are presented IMPORTANT The maintenance procedures included in this chapter have to be followed carefully by expert users only Delicate operations may result in permanent damage to the laser if not carried out properly Contents 7 1 Laser installation in LLH housing 84 11 Handig e e cesos be enh eee DA eee Roe eS 84 7 1 2 ContactSetl o e 0200208 a 85 113 PIO
4. 2013 ALP S LAS RS SA 65 Chapter 5 Starter Kit Operation 5 2 3 TCU interlock The built in TCU interlock is activated when a fault occurs on the TCU controller e g prompt temperature rise The interlock is by default an NC Normally Close relay contact and may be reset by pressing the reset button 3 shown in figure 5 3 Note it is also possible to set the Interlock as a NO Normally Open contact Figure 5 3 TCU interlock Recovery procedure This procedure must be followed in order to recover the temperature controller from an interlock event 1 Turn off the QCL following procedure 5 4 2 2 Identify the fault which activated the interlock and fix it 3 Wait until the temperature is lower than the maximum allowed 4 Press the RESET button 3 on the TCU rear panel see figure 5 3 The interlock is reset and the red LED alarm 2 should be off 66 QCL user s manual v3 1 2 5 3 TTL Pulse Generator TPG 5 3 TTL Pulse Generator TPG The front and rear panels of the TPG are shown in figure 1 12 a detailed view of the front panel is shown below in figure 5 4 Figure 5 4 TPG front panel Command description The pulse duration can be set from 0 to 200ns and the interval between pulses from 200ns to 105 us in 3 ranges using the 2 3 and 4 knobs shown in figure 5 4 Note the parameters should be adjusted using a scope following procedure 5 3 2
5. 60 5 1 1 Quick Start Procedure 0 e 60 5 2 Temperature Controller Unit TCU o o 63 52 CUSANU 2 ess bas Ac ie a ees Se 65 5 2 2 Internal external Mode o 65 5 2 3 TCU interlock wok a o a a dl 66 5 3 TTL Pulse Generator TPG o e 67 5 3 1 Internal and external modes 68 5 3 2 Setting the pulse parameterS 70 A AN oe Be ed 71 5 4 General procedures e 72 5 4 1 QCL SiaMUD 06500 eta aa a AA EA em 72 5 4 2 IL SNOWN e amp oe oem ee ease es A Ge a rd 74 6 Technical specifications 75 83 7 1 Laser installation in LLH housing o o 84 7 1 1 Handling 22 2a e pese e eo eR ade SS ROR w S 84 viii QCL user s manual v3 1 2 7 1 2 Contact set 7 1 3 Procedure 02 00 ee ee ee 7 1 4 UP and DN contact exchange 7 2 Calibration procedures 2 a 7 2 1 TCU interlock level setting procedure 7 2 2 TCU calibration 7 2 3 IPG calibration A QCL theory and application notes A 1 QCL wavelength range 0 ee ee ee A 2 QCL electrical response 0 B 1 Direct QCL voltage o o ee B 2 Soldering wire bonds from laser chip to submount B 3 Bias T circuit for pulsed lasers a ee nn O San Lee eo oe
6. 3 3 Connections 3 3 6 CTLm cable The CTLm cable connects the HHL on one side and splits into two connectors on the other side one for the TCU the other for the laser driver The TCU controls the temperature of the HHL with a Peltier junction and monitors the temperature with a PT100 temperature sensor The TCU side of the CTLm cable is the same as the CTL cable as described in section 3 3 5 The laser driver connector is compatible with the CIL cable for CW mode operation or the LBI cable for pulsed mode operation The HHL side of the CTLm cable contains the female connections described in table 3 5 pin nb purpose 1 power supply for Peltier element no corresponding pin not connected power supply for laser signal PT100 signal PT100 power supply for laser not connected not connected power supply for Peltier element CO JO 01 On o Table 3 5 CTLm cable HHL connector pinout The CTLm male connector for the laser driver has the same function as the LLH laser and base connector It consists of two rows of pins in one row all pins are connected and correspond to the aser connector negative polarity in the other row two pins are removed and correspond to the base connector positive polarity 2013 ALP S LAS RS SA 39 Chapter 3 Installation 3 3 7 TC LLH cable The TC 3 controls the te
7. permanently damaged CAUTION Avoid any dust to deposit on the laser chip or any laser submount item Malfunctioning or permanent damage to the laser may occur 7 1 2 Contact set The contact set shown in figures 7 2 connects the laser active pad to the low impedance line of the LLH through a copper contact as shown in figure 7 3 Figure 7 2 LLH contact set top left and bottom right The laser submount is screwed onto the LLH base copper plate on which the con tact set is screwed to insure electrical contact between the selected pad and the low impedance line as shown in figure 7 4 The low impedance line LBI connects the laser chip to the LDD in pulsed mode or external power supply in CW mode through the LLH laser and base connectors 2013 ALP S LAS RS SA 85 Chapter 7 Maintenance PET contact set E submount copper plate A base copper plate Peltier junction Figure 7 3 Schematic side view of the laser submount contact set and LLH Figure 7 4 Inside view of the LLH without left and with right contact set 86 QCL user s manual v3 1 2 7 1 Laser installation in LLH housing 7 1 3 Procedure This procedure allows the installation of a new laser into the LLH housing 1 disconnect the LLH and open its cover 2 as shown in figure 7 7 Figure 7 5 Exchanging the laser in the LLH housing 2 re
8. Chapter Content 1 Overview General overview of ALPES LASERS QCLs and Starter Kit components 2 Safety Information for ensuring safety during the installation op eration and maintenance of ALPES LASERS QCLs and electronic equipment 3 Installation Prerequisites guidelines and list of connections for the installation of ALPES LASERS equipment 4 QCL operation Principle of operation of QCLs ALPES LASERS datasheet and QCL parameters 5 Starter Kit Operation Procedures for setting up the Starter Kit and operating a QCL 6 Technical specifications Technical specifications and drawings of ALPES LASERS QCLs and electronic equipment 7 Maintenance Procedures for exchanging a laser in the LLH housing and calibrating ALPES LASERS electronic equipment Appendices Informations and procedures for advanced users Table 1 Structure of the QCL User s Manual Typesetting conventions e Table 2 gives a list of the acronyms used in this manual e A boxed item indicates a hardware setting on an electronic device Acronym Official name Other name AR _ Anti Reflection coating DFB Distributed FeedBack laser EPS External power supply laser driver FP Fabry Perot laser LDD Laser Diode Driver QCL pulser switching unit LLH Laboratory Laser Housing NDR Negative Differential Resistance NTC Negative Thermal Coefficient NS screwed laser submount
9. 1 Power ON OFF switch 2 Pulse period fine potentiometer 10 turns 4 Pulse duration potentiometer 10 turns 2 3 Pulse period range switch 3 positions 4 5 5 BNC 50Q TTL Output 6 BNC 502 TTL Trig OUT 7 BNC 502 TTL Trig IN 8 BNC 502 TTL Gate IN 9 CPL cable Lemo 00 12VDC output connector 2013 ALP S LAS RS SA 67 Chapter 5 Starter Kit Operation 5 3 1 Internal and external modes The TPG can be operated in internal or external mode the mode is selected with a switch on the rear panel of the TPG as shown in figure The input and output signals are provided or generated through the four BNC connectors shown in figure e in internal mode a periodic signal is generated through the Output BNC con nector The Trig OUT BNC connector provides a 200 ns pulse for monitoring purpose or lock in operation e in external mode a signal is provided to the TPG through the Gate IN or Trig IN BNC connectors in both cases the trigger precedes the output pulse y about 100ns the output generated with the Gate IN is a train of pulses corresponding to intANDext signals as shown in figure 5 5 the output generated with the Trig IN is a single pulse for a rising signal as shown in figure 5 6 TPG internal signal Gate In external signal Output signal Figur
10. Switzerland Telephone 41 32 729 9510 Fax 41 32 721 3619 Email info alpeslasers ch Web site http www alpeslasers ch 2013 ALP S LAS RS SA ili DOCUMENT VERSION This is Version 3 1 2 of the manual published on April 29th 2013 It supersedes version 3 1 1 published on March 7th 2013 The following modifications have been applied since the publication of version 3 0 Date of publication Version number Changes o 29 04 2013 3 1 2 Updated table 5 2 07 03 2013 3 1 1 Added C 1 was added and is depre cated 3 3 7 and 3 3 8 have been added 85 1 has been added Various references to temperature con trollers have been updated throughout the manual 28 01 2013 3 1 0 24 05 2012 3 0 1 8 the LDD voltage is typically be low the ratings not above iv QCL user s manual v3 1 2 Preface This manual is a reference tool for personnel using ALPES LASERS QCLs and elec tronic equipment Its purpose is to provide the customer with sufficient information to carry out normal installation and operational procedures It is not intended to replace or supersede any local directive Table 1 gives a summary of the content of each chapter CAUTION All personnel must read and understand this manual before attempting to operate ALPES LASERS QCLs or electronic device Failure to follow safety instructions could result in death or serious injury
11. as reducing the pulse period increases the average heat load e the exact percentage of maximum duty cycle depends on the laser 2013 ALP S LAS RS SA 71 Chapter 5 Starter Kit Operation 5 4 General procedures CAUTION The laser shall only be operated under conditions as specified in the datasheet or by ALPES LASERS directly all other operation may result in the destruction of the laser and loss of warranty 5 4 1 QCL startup In order to insure the laser s performance and enhance its lifetime the following steps must be followed thoroughly 1 make sure all devices are turned off 2 start cooling for LLH or HHL housing see section 8 1 for prerequisites CAUTION damage the laser and will result in the loss of warranty The laser must be used at the temperature specified in the datasheet Operating the laser below or above the given temperature is likely to Contact ALPES LASERS or a representant before using the laser at a tempera ture outside the range specified in the datasheet 3 startup the TCU following procedure 5 2 1 or the TC 3 following procedure 4 if the laser is operated in CW mode follow procedures included in the CW laser driver OEM manual Always keep the current 1mA above 0 to avoid reversing the polarity 5 if the laser is operated in pulsed mode a startup the external power supply i connect the external power supply to mains ii remove the red black ba
12. for which the emission wavelength is closely related to the band gap energy the QCL transition consists in the transition of an electron inside sub bands from one upper quantum well level to a lower quantum well level A series of potential wells and barriers for the electrons are built by using two dif ferent semiconductor materials InGaAs and AllnAs These wells and barriers are so thin that the electrons are allowed only a discrete set of energy levels similar to the orbitals of an atom The positions of the allowed energy levels are determined by the thicknesses of the wells and barriers making it possible to define a wide range of laser transitions by using only one material system InGaAs AllnAs grown on InP This range is limited by the intrinsic absorption of the material and the potential differ ence between the wells and barriers All QCLs are grown using the same materials but with layers of specific thicknesses and compositions to obtain a given emission wavelength which is determined by the geometry of the semiconductor layers that compose the laser crystal 105 Chapter A QCL theory and application notes A 2 QCL electrical response The QCL can be modeled with a combination of one resistor and two capacitors R1 increases from a higher resistance at low biases to 1 4 Ohms at the operating point The resistance at low bias varies from 10 20 Q to 10 kQ for 10 ym and 4 um wave length QCLs respectively C1 is a 100 pF ca
13. refer to figure 7 11 a Replace the cable connected to J8 4 with the 100 1 Q resistor Note the precision gold band on the resistor is important Connect one side of the resistor to pins 1 and 2 the other side to pins 3 and 4 b Measure the voltage on Zn3 R10 3 the value should be V 1 22 to 1 25V c Measure the voltage at the intersection of R19 R35 5 the value should be V 100mV adjustable with the P1 2 knob Note f the range is too small replace the resistor R1 1 1 3kQ with 1 4k0 d Set the selector 9 to display Real C e Adjust the trimmer P6 6 in order to obtain the value of 000 C on the screen 8 f Vary the Temperature Reference by using the Set Temperature 5 turns knob 7 located on the front panel The range displayed should be 074 to 074 a R 3 J D amp 3 Boa E RiOo J8 pa M385M3 1 2 Lye 3 0000 L J ra uu R38 c o s Jess nm E JE he e at o tn o 6095 JoL c46 C R37 jo pel y o lo N E ol cs C34 cis LI Rei C53 44 P6 l o C l i su_2 M o R105 REAN M L o o Le E R124 14 59 o 2057 ent g l p OU fl pooooppoooopit o 00000
14. 2 3 3 Connections Figure 3 11 CPL cable Figure 3 12 DE 9 connector pinout numbering pin nb purpose external power supply red banana cable center of LEMO connector 12 V not connected center of BNC connector yellow banana cable external power supply black banana cable associated with red banana cable LEMO ground chassis BNC ground chassis olo NI 01 BON black banana cable associated with yellow banana cable Table 3 7 CPL cable connector pinout 2013 ALP S LAS RS SA 41 Chapter 3 Installation 3 3 10 CIL cable The CIL cable connects the LLH housing to the ILX LDX 3232 CW laser driver On the LLH end the connector consists of two rows of pin slots All slots of one row are connected together resulting in two terminals In order to insure the correct po larity some slots are filled with solder which should match broken pins on the LLH connector The ILX side of the CIL cable consists of a D sub 9 connector shown in figure 3 12 and described in table 3 8 pin nb purpose shorted with pin 2 shorted with pin 1 not connected LLH connector negative polarity LLH connector negative polarity not connected not connected LLH connector positive polarity LLH connector positive polarity 00 NOIA AOIN Table 3 8 CIL cable connector pinout 42 QCL us
15. 9 TE Tre Y op 07 R24 R20 gt c y R32 DLS E o 0 o Rag Rei C53 9895 u4 4 LM6144 o P6 l o Ss eel R114 SH_2 Flo R105 rq4 o e m z A Lp m4 85 ra Figure 7 12 TCU main board view l 2013 ALP S LAS RS SA 95 Chapter 7 Maintenance 6 Oscillator check refer to figure 7 13 measure the frequency on the pin 7 of U13 1 the value must be 28KHz 3KHz 7 Current Voltage ratio adjustment refer to figure 7 13 a Adjust the trimmer P4 6 in order to read B4 0 6V 4 b Set the selector 5 to mode Setting l the LCD screen should display 1 00 A Note If it is not the case adjust it with P2 2 c Adjust the trimmer P4 in order to read B4 3 0 V the LCD screen should display 5 00 A Note If it is not the case adjust it with P2 2 Example 0 6 V gt 0 99 A and 3V gt 4 99 A d Set the switch on the front panel to mode Setting l e Repeat steps 2 and 4 for P5 7 and B5 3 o O o C59 o c57 e Jaja y le LO gt 5 o ooo TJ Aros S U16 2 a E y E LM6144 LIY 0000 o mM R109 Pp P2 tio G zZ o o O Beo cs C66 4 o o o b mes R126 O J3 O a e12 O 100E 5W
16. ALPES LASERS as it is a non standard measurement Figure 3 6 LLH IMPORTANT The low impedance line and laser chip are floating and connected to the laser connector and have negative polarity the base connector must have positive polarity 34 QCL user s manual v3 1 2 3 3 Connections 3 3 2 HHL The HHL housing and CTLm cable shown in figure 3 7 must be connected according to the numbering of the CTLm connector pins from 1 to 10 and the HHL connector pins description provided in section If you use a TC 3 temperature controller you should use the TC HHL cable instead with an identical connector on the HHL side Figure 3 7 HHL housing and CTLm cable 2013 ALP S LAS RS SA 35 Chapter 3 Installation 3 3 3 TO3 Figure 3 8 shows the TO3 housing connector the pinout is detailed in table 3 3 TO3 L and TO3 W housing have identical pinouts The polarity of the laser connection is specified on the laser datasheet bottom view oe a J Figure 3 8 TO3 housing connector Pin nb Purpose 1 TEC Thermistor Thermistor laser bondpad laser substrate Not connected Not connected TEC 00 NI o A A 0 N Table 3 3 TO3 housing pinout Note ALPES LASERS does not produce cables for TO3 housings 36 QCL user s manual v3 1 2 3 3 Connections 3 3 4 LDD Figure 3 9 show the L
17. Cable LEMO 6 poles female 6 bananas female LEMO connector LFGG 1B 306 CLAD72Z LEMO handler GMA 1B 065 DG DANGER Contact with AC line potential can cause death or serious injury If work on live electrical circuits is required use all appropriate precautions and hot work procedures required at your location Procedure 1 Power off the instrument 2 Open the TCU top cover to access the main board 92 QCL user s manual v3 1 2 7 2 Calibration procedures 3 5V 5V power supply check CAUTION Do not connect the signal IN 34 V DC connector J1 3 This may result in permanent damage to the Peltier junction a Check that the input impedance between 5V 5V and GND have the fol lowing values e TP1 4 GND 5 gt 2 5 KQ e TP2 6 GND 5 lt 4 kQ b Power on the instrument c Check that the 5V 5V power supply voltage have the following values e TP1 4 GND 5 4 95 to 5 2 V e TP2 6 GND 5 4 95 to 5 2 V REGI REG2 Lm7905cT EMeBoScr J9 NO NC 2 Interlock oo o0 1 u c45 0440 o Rizo REG3 LM 805CT ULL 47uF 16U 47uF716U SN74LS74A ooo Cl Figure 7 10 TCU main board zoom 2013 ALP S LAS RS SA 93 Chapter 7 Maintenance 4 Sensing level and range adjustement
18. Figure 7 8 TPG left and TCU right cover removal 3 Switch on the device DANGER Contact with AC line potential can cause death or serious injury If work on live electrical circuits is required use all appropriate precautions and hot work procedures required at your location 90 QCL user s manual v3 1 2 7 2 Calibration procedures 7 2 1 TCU interlock level setting procedure This procedure allows to set the TCU interlock level 1 switch off the TCU 2 unplug the power cable 3 remove the cover to access the main board following step 2 of the previous procedure 4 locate the J9 Interlock connector 5 position the associated jumper according the desired type of interlock e NC normally closed pins 4 and 5 e NO normally open pins 3 and 4 ag REG2 LMZ905CT raa o Zl Z D13 gt O Figure 7 9 TCU board J9 Interlock connector 2013 ALPES LAS RS SA 91 Chapter 7 Maintenance 7 2 2 TCU calibration This procedure must be followed for a general calibration of the TCU command knobs and selectors Refer to section 5 2 for TCU front panel commands description IMPORTANT The TCU is calibrated in factory This procedure is not a routine procedure and must be performed by experts only Material needed e Voltmeter HP3458A or equivalent e Voltage source Keithley SMU237 or equivalent e Precision resistor 100 Ohm 1 or better e
19. Installation Sole PreregUISIteS e sa a es E a a a a ae 3 1 1 Environmental conditions 3 1 2 COQINOL s lt e elisa ina ee AN O os es ee ne Be 3 3 Connections 0000 ee a es NOOR WNNDYDP lt 00 11 13 14 15 16 16 17 19 20 21 22 23 23 23 23 25 26 26 28 29 32 34 vii oe IE a a O Se ee a RN 35 SO TOS era ads dobla irae oe ae 36 Bat LOD ecos parda a 37 A DA ee ee ee 38 3 3 6 CTLm cable 4 2 a 24s 2 cae a See oe ba eae 39 A ah E A ee 40 338 GEHL CADIA ooo ei ok Rae in oa sa wok Kita br or Bo aS 40 aser din ee foe Pk ee a 40 Ce ee Se a ee ee ee ee ee ee 42 G Alea feud me ee eae ace A a 43 45 4 1 Principle of operation o e e eee 46 4 2 ALPES LASERS datasheet o 47 4 3 OGE Spectral s c 6 ate a ia eae oa p GE eo eee E 48 4 3 1 Temperature and current tuning 48 4 3 2 Linewidth of pulsed single mode DFB QCLs 51 4 3 3 Linewidth of CW single mode DFB QCLs 51 4 3 4 Bandwidth of multi mode FP QCLs 52 4 4 l V curve and emitted power o 52 4 4 1 Maximum operating current o 54 a da ds Os ee da 55 4 4 3 Other DFB QCL plotS o 56 4 5 Beam Properties lt lt e 2 o 57 59 5 1 Temperature Controller TC 3 0 0 o
20. O EEE 00000 R102 Ula c7 ENERO gs oad caog 7 im E E C13 c39 oN d oz LALLY LILI AFFICHAGE Lo 8 ul c40 04 03 02 c 2 8 7 r 194 f 7 ra rq C37 o o o o m mM n mq Figure 7 13 TCU main board oscillator check left current voltage ratio adjustment right 96 QCL user s manual v3 1 2 7 2 Calibration procedures IMPORTANT For the remainder of this procedure limit the positive current to 1 A and the negative current to 1 2 A using the 5 turns knob 8 Temperature limit threshold a Measure the voltage on pin 2 of U10 1 the value should be 0 7V 70 C If needed adjust it with the trimmer P9 2 b Power off the instrument 9 Starting the power section of the instrument a Remove the 100 E reference resistor from J8 4 and plug the output cable J8 b Plug the external cable into the LLH100 and verify that the Pt100 is pro prely mounted in the latter c Use an external power supply 0 30VDC 3A to simulate the internal power supply d Limit the current to 200 mA and connect it to main board J7 connector 3 e Power on the instrument and the external power supply 2013 ALP S LAS RS SA 97 Chapter 7 Maintenance a Oj go oog oog aog D11 07 a5 098 q MBR 1060 F25NOSL 6 o y 2 amp Ne o ZNZ o zmY12 A Decin _pectier
21. OEM Original Equipment Manufacturer QCL Quantum Cascade Laser ST clamped laser submount TCU Temperature Control Unit TEC ThermoElectric Cooler Peltier cooler TPG TTL Pulse Generator QCL pulser timing unit Table 2 Acronyms used in this manual vi QCL user s manual v3 1 2 Contents Preface 1 Overview 1 1 ALPES LASERS products 2 x2 xs 28d Coe we Be Se ee 1 1 1 QCL parameters and performance 1 1 2 QCL geometry o o 0200002 ee eee 1 1 3 GUE MOUNTING 04 60 ia a a eS 1 2 QCL housings and packageS o 1 2 1 Laboratory Laser Housing LLH 1 2 2 High Heat Load HHL Housing lt 1 28 TOS FOUSING 25 e seca a er E dee ges 1 3 Starter kit 1 3 1 Temperature Controller TCU 1 3 2 Temperature Controller TC 3 1 3 3 Laser Diode Driver LDD 1 3 4 TIL Pulse Generator TPG 1 4 Peripherals 1 5 Fields of applications 2000002 ee eee 1 5 1 IR 1 5 2 THz 2 Safety 2 1 General safety considerations 0 a 2 2 Notation 2 2 1 Symbols and labels 0 2 3 Health Marat 2 vic eR De a le a ES 2 3 1 LASER radiation hazard 2 3 2 Electricalhazard 0 000000 eee ee 2 3 3 Environmental hazard 00 3
22. Putting these constraints together leads to Lac lt Ug Zac For the capacitor C to let pass the AC current 27 R4cC gt 1 f must be true and with Xc Rac 100 or smaller to make sure that the impedance of the AC current source does not vary too much with frequency it follows that roughly C gt 8 Zac f For a 50 Q generator at 10kHz C should therefore be of the order of 16uF or larger Please keep in mind that such high capacity components may have a remarkably high inductivity so it may be useful to put a second capacitor of small value some nF Tantalum or similar non polarized type in parallel to the one calculated before 2013 ALP S LAS RS SA 113 This page intentionally left blank C Cryogenic operation of QCLs Some rare lasers necessitating cryogenic temperatures Alpes Lasers can offer to deliver lasers with a cooling solution C 1 LN2 Dewar The LN2 Dewar is a modified Kadel dewar that serves as housing for a QCL As it lacks a temperature control it is typically used for lasers which do not tune appreciably with temperature such as THz lasers or other Fabry Perot lasers Figure C 1 A LN2 dewar The light output is seen on the left the LBI connector on the right 115 Chapter C Cryogenic operation of QCLs The LN2 Dewar is only available with the laser pre assembled and no user ser vicing is available The laser is installed on a cold finger in an empty enclosure The laser output is through a t
23. QCL in a piece of equipment manufactured by the customer Note most lasers listed on ALPES LASERS website cannot be mounted in a TO3 housing address your inquiry directly to ALPES LASERS Bare Chips untested laser chips 4 QCL user s manual v3 1 2 1 2 QCL housings and packages 1 2 1 Laboratory Laser Housing LLH The LLH consists in a housing including a TEC and encapsulating the QCL chip it is designed to ease its installation and replacement Its internal temperature is controlled by a Peltier junction and a PT 100 temperature sensor and can go down to less than 30 C Heat should be dissipated using one of the setups described in section 3 1 2 The LLH temperature is controlled by the TC 3 see section 5 1 Figure 1 4 LLH housing connection panel and window 2013 ALPES LAS RS SA Chapter 1 Overview 1 2 2 High Heat Load HHL Housing The HHL housing is much smaller than the LLH and is completely sealed The HHL contains a Peltier junction and a PT 100 or NTC temperature sensor which can be controlled by the TC 3 see section 5 1 or a local temperature control system Heat dissipation is performed by thermal contact with its copper base the heat dissipation capacity depends on the operation mode and environmental conditions The IR beam is collimated through a chalcogenide glass lens and goes through an AR coated ZnSe window Figure 1 5 HHL housing 6 QCL user s manual v3 1 2 1 2 QC
24. Temperature Controller TCU CAUTION The TCU unit was sold from 1998 until 2012 It came under two different marks TCU151 and TCU200 with identical functionalities and controls It was superseded starting in 2013 with the TC 3 unit described in The TCU purpose is to control the laser temperature inside the LLH or HHL hous ing It powers the Peltier junction and reads the temperature from the PT100 sensor coupled to the laser chip see section 1 2 1 The TCU internal parameters are set in factory according to its use with a LLH or HHL housing It maintains a preset tem perature using the front panel knobs internal mode or from a user supplied voltage external mode It also provides an output for real temperature monitoring The TCU interlock system protects the laser from overheating see section 5 2 for TCU opera tion procedures TCU 200 Temperature Controller U Figure 1 9 TCU front panel 2013 ALP S LAS RS SA 11 Chapter 1 Overview 1 3 2 Temperature Controller TC 3 The TC 3 purpose is to control the laser temperature inside the LLH or HHL housing It powers the Peltier junction and reads the temperature from the PT100 sensor coupled to the laser chip see section 7 2 1 The TC 3 software is set at the factory to work with your instrument if it was bought as a Kit The parameters can easily be modified by the client to work with a different housing A Quick Start procedure for the TC 3
25. X 6 8cm Power and timing input provided by CTL cable and Input associated equipment see manual Power Input Mains power 120 240V 50 60Hz Output High current pulses through low impedance cable Power Output 12V on Lemo connector Peak Current output 0 15 A Timing input Optional TTL Gate in Trig in Voltage compliance 50V Timing Output TTL signal on BNC connector Rise fall time 10 ns Max Current 150 mA Pulse duration gt 10ns with attenuation flat from 20ns to DC Pulse duration 22 ns 200 ns Fr Interval between Repetition Rate Up to 4 MHz pulses 100 ns 105 us Duty Cycle lt 90 Duty Cycle up to 50 Operation 7 3 Operation lans Temperature lcd Temperature ea Temperature Control Unit TCU CW current driver Size 11 5cm x 22cm x 27 5cm Manufacturer j ILX Lightwave Power Input Mains power 120 240V 50 60Hz Size 31 5 cm X 21 5 cm X 8 5 cm Input Output Through supplied CTL cable Power Input Mains power 120 240V 50 60Hz Internal Control Front panel buttons Power Output D Sub 9 connector and CIL cable External Control Temperature setpoint can be controlled by voltage on a BNC connector 10 C V from 6 5V to 6 5V Max Current 40A Compliance Max Current 5 0A Voltage 15V a 65 C 65 C ets DC 250 kHz through 400mAVV input Temperature sensor pt100 Duty Cycle up to 50 Figure 6 3 Technical specifications of ALPES LASERS electronic equipment f
26. a base copper plate Peltier junction Figure 1 2 ALPES LASERS QCL NS submount mounted in a HHL or LLH housing 2013 ALP S LAS RS SA 3 Chapter 1 Overview 1 2 QCL housings and packages ALPES LASERS QCLs can be delivered in 5 kinds of packages Chip on Carrier CoC A laser chip available on stock is mounted on either a NS or ST submount see section 1 1 3 These submounts can be integrated into a LLH or HHL housing or can be sold as an such to be integrated in a piece of equipment manufactured by the customer Laboratory Laser Housing LLH The LLH is designed for research applications and can be cooled down to 30 C with water cooling With easy laser exchange and compatibility with the Starter Kit it is the most versatile housing available All ALPES LASERS available on stock can be used in a LLH housing See sec tion 1 2 1 for details High Heat Load HHL The HHL housing is a sealed collimated housing with TEC for CW or pulsed lasers The optional collimating lens is protected by a plane window making it ideal for operation in aggressive environments See section 1 2 2 for details TO3 Pulsed lasers are available in TO3 cans which are smaller and less power intensive than the HHL packages TO3 housings are sealed include a TEC and are available with AR coated lenses for beam collimation or flat windows Their small size and low dissipation less than 4W in pulsed mode make them ideal for integrating the
27. and instructions for use with the ALPES LASERS housings The more complete manual is available on the ALPES LASERS website http www alpeslasers ch a 1 42 144 5 1 1 Quick Start Procedure After unpacking the unit ensure that the voltage selection on the Input Power Con nector IPC on the back of the unit is set to the correct voltage This is critical as incorrect voltages can damage the unit The TC 3 is typically shipped in the 120V con figuration from the factory but may be set to your local voltage Make no assumptions and change the voltage as needed Once the voltage selection has been completed plug the AC cord into the unit and into the wall outlet Turn on the power switch located on the IPC and the unit will power up displaying the model information and firmware version number The front panel is shown in figure 5 1 a ALP S LAS RS hy Error Remote Output Menu TEC Controller Power Figure 5 1 TC 3 front panel Press the MENU button to enter the menu and using the knob turn to the right until the Lim setting is displayed Press the knob to edit the setting and adjust the limit as appropriate to your Peltier refer to Table B 1 Press the knob again to save the value Make the same adjustments to the high and low temperature limits T High Lim and T Low Lim as appropriate for your application These values should not exceed those stated in the datasheets of the laser used Navigate to the Senso
28. change rate HHL 0 2 C s TO 3 0 2 C s LLH 1 0 C s Table 5 3 Recommended temperature change rates 62 QCL user s manual v3 1 2 5 2 Temperature Controller Unit TCU 5 2 Temperature Controller Unit TCU The TCU front and rear panels are shown in figure 5 2 and described below Figure 5 2 TCU front left and rear right panels 2013 ALP S LAS RS SA 63 Chapter 5 Starter Kit Operation Command description 1 Set Temperature 5 turns knob Allows to set the internal temperature refer ence 2 LCD 3 digits display Used to display either the actual sensor or reference temperature current 3 Switch to select which temperature or current signals to display 4 Alarm display LED 5 Alarm reset switch 6 Toggle switch to select a function Set C targeted temperature setting Real C actual temperature measurement in C Real actual current in TEC given in A Set I highest current allowed Set 1 lowest current allowed 7 Setting Current adjustment knobs allow to modify the highest and lowest allowed currents which are set in factory to 5A for the LLH and 2A for the HHL 8 Power ON OFF fuse combined main switch 9 To LLH AMPHENOL connector for LLH or LLH temperature control 10 Interlock BNC connector see section 5 2 3 11 External reference BNC connector 12 Monitoring BNC connector se
29. control drive electronics gas cell s and photodetector e User has and understands ALPES LASERS datasheets for the device to be used 110 QCL user s manual v3 1 2 B 3 Bias T circuit for pulsed lasers Procedure 1 set the temperature to 15 C so that any moisture inside the package does not condense on the laser chip 2 Use current settings as indicated in the ALPES LASERS datasheet 3 start the laser the powermeter if installed should indicate some power dissi pation 4 set the temperature to allow the highest frequency shortest wavelength of in terest to be emitted 5 Reset the current to settings appropriate for that temperature and wavelength then reduce it a little bit further but not below threshold so you still see energy on the detector 6 put a gas cell between laser and detector and verify that you can still see the laser energy on the detector take note of the amplitude of the detector signal 7 Turn on the bias T current to a low value typically 0 001A and record the de tector signal 8 repeat at 0 001A increments of bias T current recording values for each incre ment until 0 060 A is reached or some other value that has been discussed agreed with ALPES LASERS If the temperature and pulse current starting points were right the line of interest should be visible in the data when plotted If not per form the same procedure with new temperature and pulse current settings 9 Continue to op
30. datasheet provided with each ALPES LASERS QCL upon delivery Contents 4 1 Principle of operation 46 4 2 ALPES LASERS datasheet 47 4 3 QCL spectra ad Gao 6 S we oe Roos eS Soe Re eS 48 4 3 1 Temperature and current tuning 48 4 3 2 Linewidth of pulsed single mode DFB QCLs 51 4 3 3 Linewidth of CW single mode DFB QCLs 51 4 3 4 Bandwidth of multi mode FP QCLs 52 4 4 l V curve and emitted power o 52 4 4 1 Maximum operating current aoaaa aa 54 A e a ae a a eee 55 4 4 3 Other DFB QCL plots 0 56 4 5 Beam Properties oaoa a a 57 45 Chapter 4 QCL Operation 4 1 Principle of operation Quantum Cascade Lasers QCLs are unipolar lasers emitting in the mid infrared from 4 to 20 microns The laser is a ridge of InGaAs and AllnAs grown on InP providing gain and a Fabry P rot cavity in order to build up the laser oscillations ALPES LASERS produces QCLs of two types e Distributed Feedback DFB QCL a grating is etched over the active region to force the operation of the laser at very specific wavelength given by the grating periodicity e Fabry P rot FP QCLs are capable of producing higher powers but are typ ically multi mode They emit in a broad range of wavelengths and can cover more than 10 of the central emitting wavelength FP QCLs are well suited for app
31. eo E o e sar o lo zL ele je gt 19 CAN 90 o Ra yee o epics ME NE O nF eco SHer Gey awe O E b Sa rg AD VEIS amp ele NU 150pF o oo eo 6 5 90 gt pa 900 2 eo o ec C c elle EA E o E ws a A LS lels 0 0 o gt f Y x NO 00 ole h Np o S 500 ss QQ o9 y Figure 7 16 TPG main board view l 102 QCL user s manual v3 1 2 7 2 Calibration procedures 5 Select the range 5 us to 105 us on the period selection knob Turn the 10 turns adjustment knob to its last position Adjust the adjustable capacitor max 105 us adj 4 in order to obtain a 105 us long period 6 Turn the 10 turns adjustment knob to its first position Ajust the pot Period min adj 1 in order to have a period of 5 ys 7 Repeat steps 5 and 6 in order to obtain 105 1 us and 5 0 1 us for the two settings of the Period knob 8 Choose the range 0 2 ys to 2 2 us Turn the 10 turns adjustment knob to its last position Adjust the max 2 2 us adj capacitor 2 in order to obtain a period of 2 2 us 9 Turn the 10 turns adjustment knob to its first position Check that the period is 200 ns If this is not the case re adjust the pot 50 ns adj 5 in order to obtain 200 20 ns In general it is not possible to go below 210 ns 10 Choose the range 0 5 us to 10 5 ys Pot 10 turn Period on 10 Adjust capacitor max 10 5 us adj 3 in order to have a period of 10 5 us 11 Turn the 10 turns adjus
32. is shown in 5 1 and a complete manual dedi cated to the TC 3 is available separately Figure 1 10 TC 3 controller 12 QCL user s manual v3 1 2 1 3 Starter kit 1 3 3 Laser Diode Driver LDD The Laser Diode Driver shown in figure 1 11 is a switching unit which creates cur rent pulses to drive the laser The LDD is controlled by a TPG see section 1 3 4 and powered by an external power supply It is equipped with a Bias T for electrical wavelength tuning see section B 3 for details WARNING DO NOT GROUND Pulse on top Bottom connected to high voltage pa aa o Monitor 20 A V i Z 50 Ohms INPUT Power supply 12V gt Current control max 60V x a LDD 400 Figure 1 11 Laser Diode Driver LDD Voltage rating and operating temperature The LDD is based on dedicated power MOSFETS with compliance with up to 30A and 60V During operation the temperature of the case should not exceed 60 C The LDD electronic card lies on a copper plate and no other means of active cooling is provided In normal conditions those temperatures are not reached as the laser operating current and voltage are of typically less than 2 A and 15 V well below the LDD ratings Laser pulse parameters measurement Estimated values of the laser pulse parameters peak voltage supply voltage duty cycle frequency can be measured through the BNC monitor connector with 20A V shown in figure 1 11 The data provided by t
33. 0000000 win C ILS P7 P2_ R110 8 Jee o oesO Figure 7 11 TCU main board zoom Il 94 QCL user s manual v3 1 2 7 2 Calibration procedures 5 Temperature Reference offset adjustment refer to figure 7 12 a Adjust B13 3 to 0 000 with P3 4 b Set the temperature with the Set Temperature knob Fig 40 7 to 5 C gt The temperature reference signal B13 should be gt 4 3V c Set the temperature with the Set Temperature knob Fig 40 7 to 5 C gt The temperature reference signal B3 should be lt 4 3V d Check the switch range by setting the Temperature Reference at 2 C and 2 C B7 5V and 5V B6 5V and 5V e Check the output voltage of the transistors gt The signals on R78 and R81 should toggle simultaneously with the inversal signals on R79 and R80 CAUTION The signals B6 and B7 2 must never be at OV simultaneously This may result in a short circuit
34. 009 O mamout 00 1 5K 330E o IN_ 34U 4 e ery cso m ll g Q 3 o R126 o o o 3 e cuts X 2 Sa ad Y db if Lmzgosct eof 7 c3 ANA ul m2 1 LS a7uF ABU 47uFl6U GULL oo gt R133 Sege J E AS r IE EE 182 5 0 ne o o o o c36 o c81 a mn C35 d o el tps e 100UF AD E R84 nea hee R101 5USH R86 R43 A A gt u R121 C47 R93 NVA 2 oo Mo uu u cla ogg gg 8 07 IPT m c85 R25 2M ez 38_ R30 R120 Ee E TE gt u ze CJ na C J Cos n OC ae o RISA gt al E Jri Anne o ul u ess J IML a Lee en inal SE a go ase T a ill et ES lol C64 Panto Lol A 8 Ro PS 84 6077 R52 R58 z iz n ue ora A Sr LI R100 2 TS E Juego pat Lama aut be c22 Li R92 C73 nits os 7T c67 aa D us E Jew Llus 013 0070 B 6 1 o 5 gt oly LM3110 ae M l4 ne q USTNI a E 0 35 om M R y e OU 7 tramo Sy m cesi o c a a o o o lel 2 tel e R51 R68 R46 03 1 2 3 8 R37LM385M3 Jcss J GOECKELEC Neuc SGo 3 11 2Q00 a cane a 1 SO a Fans Fxterme 7 Figure 7 14 TCU main board zoom Ill and IV 98 QCL user s manual v3 1 2 7 2 Calibration procedures 10 Current adjustment a Set the selector 3 to
35. 1 2 2 1 Symbols and labelS o 22 2 3 Health hazard ee ee 23 2 3 1 LASER radiation Nazard o 23 2 3 2 Electrical hazard o o 23 2 3 3 Environmental hazard 23 19 Chapter 2 Safety 2 1 General safety considerations If any of the following conditions exist or are even suspected do not use the instru ment until safe operation can be verified by trained service personnel e Visible damage e Severe transport stress e Prolonged storage under adverse conditions e Failure to perform intended measurements or functions If necessary return the instrument to ALPES LASERS for service or repair to ensure that safety features are maintained 20 QCL user s manual v3 1 2 2 2 Notation 2 2 Notation The use of DANGER WARNING and CAUTION notation in this manual is conform to the SEMI standard S 13 0298 their definition is given below They may also be used to alert against unsafe practices DANGER Indicates an immediate hazardous situation which if not avoided may result in death or serious injury WARNING Indicates a potentially hazardous situation which if not avoided may result in death or serious injury CAUTION Indicates a potentially hazardous situation which if not avoided may result in minor or moderat
36. ALP S LAS RS QUANTUM CASCADE LASER USER S MANUAL Version number 3 1 2 2013 ALPES LASERS SA This page intentionally left blank COPYRIGHT INFORMATION This manual can be copied and distributed under the following conditions the work must be attributed in the manner specified by the author or licensor and cannot be altered or transformed WARRANTY 1 The customer must control the incoming deliveries and inform ALPES LASERS about incomplete shipments or defective goods within 30 days after delivery ALPES LASERS warrants that the products respect the performance set forth in the quotation provided that the product is used according to ALPES LASERS recommendations described in the datasheet included in the shipment 2 Defective products will be replaced during the 2 years following delivery 3 All other claims such as purchase refund product reconditioning or damage of any nature be it direct indirect or consequential are expressly ousted 4 The customer is aware of laser products being devices with a statistical rate of failure Depending on the use made of this product it is the customer s respon sibility to use caution redundancy and appropriate technical measurement to ensure the final product s proper operation 5 In case of discrepancy between the manual and terms written in the order con firmation the order confirmation prevails CONTACT INFORMATION Max Meuron 1 3 C P 1766 CH 2001 Neuchatel
37. B 3 2 Connection B 3 4 Gas concentration measurement B 4 CW modulation 0 000 ee ee ee B 4 1 External power supply protection C Cryogenic operation of QCLs GA UN2 Dewan 3 486 oe be A oe OR EE A AE eS eee Ss Ge SAGE s oe ee See we ee he bh aoe ow bw ees C 2 Others 2013 ALP S LAS RS SA This page intentionally left blank 1 Overview In this chapter a general overview of ALPES LASERS lasers and equipment is given as well as a brief introduction to the detection principle and fields of application of quantum cascade lasers QCLs Contents 1 1 ALPES LASERS Products us secs 24 25 is 24 2 1 1 1 QCL parameters and performance 2 1 1 2 QCL geometry o o e e 2 1 1 3 QCL mounting o o e e 0008 3 1 2 QCL housings and packagesS 0 4 1 2 1 Laboratory Laser Housing LLH 5 1 2 2 High Heat Load HHL Housing 6 1 2 3 TO3 Ho sing se sc sard o e 7 LE SIBERIA E A 8 1 3 1 Temperature Controller TCU 11 1 3 2 Temperature Controller TC 3 12 1 3 3 Laser Diode Driver LDD 13 1 3 4 TTL Pulse Generator TPG 14 1 4 Peripherals 20 EE A oO a eS 15 a ei Meee la eee At A 16 DRA A ad dida aid hoa A 16 lara mesada Oe is e a 17 Chapter 1 Overview 1 1 ALPES LASERS products ALPES LASERS
38. COQUIS 2 ss ae kk ee map RR adop RA A 87 iin ase ye ann eves ad 89 7 2 Calibration procedures o o 90 Se ee ee ee a 91 7 2 2 TCU calibration o o 92 7 2 3 TPG calibration o e e 101 83 Chapter 7 Maintenance 7 1 Laser installation in LLH housing In this sections are presented guidelines for manipulating the laser safely and the procedure for exchanging the laser in a LLH housing 7 1 1 Handling The laser should always lay flat with its vertical axis upwards on a flat and stable surfaces without touching anything around its circumference When mounted in an appropriate and stable holder it can be operated in any orientation CAUTION Do not position the laser upside down This may damage the bonding wires and possibly the laser itself The most delicate parts of a QCL are the laser chip itself and the bonds connecting it to the ceramic pads see section 1 1 2 for details Therefore the QCL should be manipulated using tweezers touching the submount as shown in figure 7 1 When ever possible carry the QCL laying flat on a stable surface Avoid contact of the front facet of the QCL with any object like the walls of its storage box Figure 7 1 Handling of QCL 84 QCL user s manual v3 1 2 7 1 Laser installation in LLH housing CAUTION Do not touch the bonds nor the laser chip itself as the QCL may be
39. DD connectors The low impedance line LBI has a locating pin to avoid false connection on the LLH laser housing and on LDD The LBI has to be connected with NEG up unless specifically told to connect with POS up Figure 3 9 LDD low impedance connector for LBI cable 1 drive cable connector for CPL cable 2 and monitoring BNC connector 3 IMPORTANT The connection between the LDD and LLH or HHL must be floating and should not be grounded Do not twist the LBI cable 2013 ALP S LAS RS SA 37 Chapter 3 Installation 3 3 5 CTL cable The TCU controls the temperature of the LLH with a Peltier junction and monitors the temperature with a PT100 through the CTL cable The Peltier connector shown in figure 3 10 carries 6 pins described in table 3 4 Pin 1 is circled and a half moon engraving runs from pin 1 to pin 6 A fixed current is supplied to pin 3 and 6 The resistance of the PT100 varies as a function of temperature and the temperature measurement is given by the voltage between pin 4 and 5 Figure 3 10 Peltier junction and PT100 cable connectors on LLH left and TCU right pin nb name purpose 1 1 power supply for Peltier element 2 2 power supply for Peltier element 3 3 IPT100 4 4 _ signal PT100 5 5 signal PT100 6 6 1PT100 7 GND ground Table 3 4 CTL cable connector pinout 38 QCL user s manual v3 1 2
40. DFB and FP lasers operated in CW at different temperatures On the same graph the emitted power is plotted as a function of op eration current showing the current threshold for each temperature For example the DFB laser operated in CW mode figure 4 4 has a threshold of 0 6 A at 20 C It can be seen that cooling the QCL during operation enhances its performance as the threshold current decreases and output power increases CAUTION Do not operate the laser with a temperature and current above the values specified in the ALPES LASERS datasheet Permanent damage may result Figure 4 5 can be used to illustrate the temperature and current tuning of a DFB QCL operated in pulsed mode e the power increases from 3 to 6 mW using a peak current of 4 A and varying the temperature from 30 to 30 C e for a temperature of 0 C the power increases from 0 to 5 5 mW by increasing the peak current from 2 to 5A 52 QCL user s manual v3 1 2 4 4 V curve and emitted power sbcw3383 DN 8 power 30C voltage 30C power 20C voltage 20C power 10C voltage 10C power 0C voltage 0C power oc 8 r 80 voltage 10C power 15C Max single mode p i A 60 Voltage V 40 20 Light mW avg on power mete 0 01 02 03 04 05 06 07 08 09 Current A sbcw2970 DN 14 power 06 voltage 30C power 20C voltage 20C 12 Dower 106 v
41. L housings and packages 1 2 3 TO3 Housing The TO3 housing is a hermetically sealed small footprint housing designed for inte gration into commercial devices It is available in two versions the TO3 W has a divergent output through an AR coated window and the TO3 L shown in figure 1 6 has a collimated output The TO3 contains a TEC and a NTC temperature sensor The TEC power is limited compared to the TEC included in the HHL or LLH housing therefore only pulsed lasers can be encapsulated in TO3 housings Figure 1 6 TO3 L housing Note QCLs mounted on an NS submount and controllers of the Starter Kit see section are not compatible with the TO3 housing therefore encapsulation of a QCL in a TO3 housing is performed upon specific request only 2013 ALP S LAS RS SA 7 Chapter 1 Overview 1 3 Starter kit The purpose of the Starter Kit is to readily operate an ALPES LASERS QCL The user must provide an external power supply see section 8 1 for prerequisites and section 1 4 for recommended peripherals The kit is delivered with all cables needed to connect the LLH or HHL housing electronic devices TCU or TC 3 LDD and TPG for pulsed operation power cables and connections for optional water cooling The installation and connections of the Starter Kit components are described in chapter B The photos in this chapter show the TCU temperature controller but the Starter Kit is delivered with the fully compatible TC 3 co
42. QCL operated in pulsed mode at different temperatures 54 QCL user s manual v3 1 2 4 4 V curve and emitted power 4 4 2 Maximum LDD voltage Figure 4 6 shows the pulse peak current and emitted power as a function of the volt age fed to the LDD In pulsed mode the QCL operating current is controlled by the LDD which is itself controlled by changing its operating voltage The maximum LDD voltage is indicated by green squares on the emitted power curves in this particular case the voltage must not exceed 15 VDC CAUTION The maximum operating LDD voltage is indicated in the ALPES LASERS datasheet Do not operate the LDD with a voltage above those values permanent damage may result 5 power 30C current 30C 6 4 5 power 15C current toc e power 0C 4 current 0C al power 15C current 15C power 30C current 30C Max single mode power m o al S se Light mW avg on power meter wo Peak Current A N al 2 1 5 z 1 1 0 5 0 0 2 4 6 8 10 12 14 16 DC Voltage fed to LDD V Figure 4 6 Peak voltage and averaged emitted power as a function of LDD voltage of a DFB QCL operated in pulsed mode at different temperatures 2013 ALP S LAS RS SA 55 Chapter 4 QCL Operation 4 4 3 Other DFB QCL plots The plots displayed in figure 4 7 show the emitted power and LDD voltage as a
43. S LAS RS SA 49 Chapter 4 QCL Operation sbcw2970 DN Spectral density normalized to 1 0 8020 2040 2060 2080 2100 2120 Wavenumber cm 1 Figure 4 2 Spectra of a FP laser operated in CW mode at fixed temperature and different currents Wavelength um 13121110 9 8 7 6 10 dB Spectral density normalized to 1 800 900 1000 1100 1200 1300 1400 1500 1600 1700 Wavenumbers cm 1 Figure 4 3 Spectra of four different broadgain lasers 50 QCL user s manual v3 1 2 4 3 QCL spectra 4 3 2 Linewidth of pulsed single mode DFB QCLs The linewidth of DFB QCLs operated in pulsed mode depends on the pulse length and is affected by chirping which occurs because of thermal variations of the laser e Fine linewidth is obtained with short pulses 25 to 50 ns ALPES LASERS QCLs are tested using pulse length of 25 to 50 ns showing a linewidth lt 0 2 cm e Very fine linewidth lt 0 1 cm is obtained with pulses of 10 ns which can be produced by dedicated equipment only e Longer pulses gt 50 ns induce chirping producing a broader linewidth when detected with a slow detector ALPES LASERS standard tests verify that DFB QCLs are singlemode i e have a linewidth not exceeding 0 2 cm with pulses of 50 ns Note ALPES LASERS QCLs are characterized with a pulse length of 50 ns but some QCLs may withstand pulse lengths up to 400 ns IMPORTANT The maximum pulse length an ALPES LASERS DFB QCL op
44. a 2 ee Ci wha ak ead an 26 3 1 1 Environmental conditions 26 31 2 COOUNG a a a A A a ees 28 3 2 Receiving procedure 00 005 ee eae 29 3 3 Connections a2 dn Seve eee de Bee A 32 tae gos Grae boar eis Grated Gree ides Gee Bare aoe eee a 34 30 2 HAR os 2 e g oS ee Ae ee ROR RR OR Bd Bae eo 35 833 A A te es Sas ee ae Sas A ee 36 834 LOD e s Se ai cate aoe ek Be a Ad ee D gul Soale g Ge g 37 3 3 0 CIL cablej o sa 6 200 aard BE AA E 38 3 3 6 CTLMcCablel o e 02200000048 39 SA 40 E ree er a ee 40 Lale dite oh ak adh bee tet de we ee a Oe ete a a 40 De Rew eee bes 2 Ou bed bod bad 42 3 3 11 Connection procedure 00 000 2 eee 43 25 Chapter 3 Installation 3 1 Prerequisites In this section are described the environmental conditions in which ALPES LASERS QCLs and electronic equipment should be stored and manipulated and prerequisites for its operation The items listed in table 3 1 must be provided by the customer for ALPES LASERS QCLs and electronic equipment to be operated It is highly advisable to have the recommended equipment available external power supply for LDD optional LDD when not provided by AL maximum rise fall time of 10ns to prevent detrimental heating e id equipment Table 3 1 Prerequisites for the operation of the ALPES LASERS QCLs and Starter Kit 3 1 1 Environmental conditions The following guidelines are standa
45. an be performed at ALPES LASERS on demand IMPORTANT The operating parameters are specified in the datasheet provided with each laser upon delivery any operation outside the specified range must be agreed with ALPES LASERS or may result in the loss of warranty In the following sections examples of plots shown in the datasheets are presented in order to help the user in operating ALPES LASERS QCLs in a safe and efficient manner 2013 ALP S LAS RS SA 47 Chapter 4 QCL Operation 4 3 QCL spectra A QCL is characterized by its emission frequency spectral domain wavelength or wavenumber spatial domain all three are equivalent The following table gives typi cal values for ALPES LASERS QCLs wavelength A frequency f wavenumber v 4 20 um 15 75 THz 500 2500 cm 4000 20 000 nm 4 3 1 Temperature and current tuning QCL emission can be precisely tuned with temperature slow tuning or current quick tuning but the later is in fact just apparent as it results from the increase of temper ature of the active region DFB QCL Figure 4 1 shows the temperature and current tuning on a DFB laser operated in CW and pulsed modes The wavelength increases or the wavenumber decreases by a factor varying between 7 107 and 9 10 for a temperature increase of 1 degree For example the total tuning for a 2000 cm QCL operating over a range of 30 to 30 C will vary betw
46. anual v3 1 2 5 3 TTL Pulse Generator TPG 5 3 3 Maximum duty cycle The TPG is capable of operating with pulses as long as 200 ns however for short periods high duty cycle the following limitations apply TE400N S a tarecceweecdiet wide placa t max 200ns TiS OOS AP O t max 200ns TELS tere eee reese tee eee a teen etnies cee t max 150ns o O ashes onesdauctecoanenserce t max 100ns where T is the period and tmaz is maximum pulse length CAUTION The laser shall only be operated under conditions as specified in the datasheet or by ALPES LASERS directly all other operation may result in the destruction of the laser and loss of warranty While the TPG alone is capable of exceeding a duty cycle of 50 in some con ditions the maximum duty cycle of the pulser system is of 50 a fuse protects the TPG from operating at larger cycles when under load If larger cycles are needed the LDD must be powered by an external 12V power supply To operate a laser with a duty cycle higher than specified it is mandatory to monitor its average output power and comply to the following guidelines e do not increase the duty cycle further when the power saturates but rather reduce it e it is advisable to increase the duty cycle by reducing the pulse period rather than increasing the pulse length since the latter is more likely to damage the laser increasing the pulse length increases the short time heat load on the laser
47. attering from dust and rain drops dramatically allowing applica tions such as radars ranging anti collision systems covert telecommunications etc As an example Rayleigh scattering decreases by a factor 10 for wavelengths ranging from 1um to 10um Examples of applications are e Industrial process monitoring contamination in semiconductor fabrication lines food processing brewering combustion diagnostics Life sciences and medical applications e Medical diagnostics biological contaminants e Law enforcement Drug or explosive detection e Military chemical biological agents detection counter measures covert telecom munications 16 QCL user s manual v3 1 2 1 5 Fields of applications 1 5 2 THz Terahertz radiation is safe and non ionizing It bridges the gap between the mid infrared and microwaves It can penetrate most non conductive materials and can be used in a wide range of applications e Water content mapping e Tissue density mapping e Metals detection e Spectral identification Terahertz QCLs operate in the range from 1 to 6 THz Coherent polarized THz radiation is generated by means of direct stimulated optical transitions of electrons within the conduction band of a semiconductor heterostructure THz lasers need cryogenic cooling but at temperatures higher than 77K boiling point of liquid nitrogen making their operation non prohibitive in terms of cooling equipment ALPES LASERS THz QCLs are a
48. ctronic equipment in table 6 3 e Broadgain Lasers bandwidth in table 6 5 Some technicals drawings are provided in figures 6 6 6 7 6 8 and 6 9 Distributed Feedback Fabry Perot Type Single mode lasers Multi mode lasers Wavelength 4 2 14 microns 4 2 14 microns Navelength range 2 7 cm 1 50 300 cm 1 Power 0 5 300 milliwatt 0 5 300 milliwatt Pulse length 25 ns to continuous 25 ns to continuous Temperature of 77K to 323 K 77K to 323 K operation Mounts NS or ST or special NS or ST or special Figure 6 1 Technical specifications of ALPES LASERS QCLs 75 92 Z EA enueu sasn 190 Laser Laboratory Housing LLH High Heat Load HHL TO3 TO3W Main purpose Easy laser exchange Sealed with lens with window Size 100 mm X 50 mm X 50 mm 70 mm X 54 mm X 25 5 mm 38 8 mm X 25 4 mm X 20 5 mm 38 8 mm X 25 4 mm X 20 5 mm Input LBI connector CTL connector water connectors Ten Pin connector 8 pins connector 8 pins connector Output port Anti reflection coated ZnSe protective window Anti reflection coated ZnSe protective window Anti reflection coated ZnSe collimating lens Anti reflection coated ZnSe window Output beam Divergent beam Collimated divergence lt 6 mrad 4 mm beam diameter Collimated beam divergence lt 10 mrad 4 mm beam diameter Divergent beam 40 X 60 FWHM Thermoelectric Peltier c
49. d on a submount right The laser chip is soldered to a copper base and is bonded with gold bonds to two AIN ceramic pads which are themselves mounted on the same copper base as 2 QCL user s manual v3 1 2 1 1 ALPES LASERS products shown in figure 1 2 The ceramic pads surface is covered with a gold layer and their sides have a whitish ceramic color the golden surface must be positioned upwards When looking into the LLH from the top the pad left of the direction of emission is called DN for down and the right pad UP for up Only one pad is characterized as specified in the datasheet If only one pad is present it is in the DN position by default Polarity By default the laser has negative polarity the cathode is connected to the ceramic pads and the anode is connected to the submount copper plate see figure 1 2 The laser may be mounted junction down this is clearly indicated on the laser box In this case the laser has positive polarity the cathode is connected to the submount copper plate and the anode to the ceramic pads 1 1 3 QCL mounting ALPES LASERS QCLs can be mounted on two types of submounts e ST clamped mounting e NS screwed mounting The QCL submount can be integrated in a LLH HHL or in any package designed by the customer The QCL submount is itself mounted on a copper plate which lies on a Peltier junction for heat dissipation as shown in figure 1 2 gold wire bonds a submount copper plate
50. dicates a shortcut infinite resistance indicates a misconnectiorl In those two cases perform step 7 until a good contact is obtained 9 close the LLH cover The laser s resistance is measured between the submount copper base and the ceramic pad The resistance between the base and the laser connectors on the LLH should be the same as the laser s resistance 29 88 QCL user s manual v3 1 2 7 1 Laser installation in LLH housing 7 1 4 UP and DN contact exchange Follow procedure adding those additional steps to step 7 1 remove the screw 5 located at the back of the contact set as shown in figure 7 7 2 remove the copper contact 6 3 replace it with the copper contact supplied by ALPES LASERS with the new laser 4 tighten back the screw 5 Figure 7 7 Exchanging the laser submount UP and DN contact right 2013 ALP S LAS RS SA 89 Chapter 7 Maintenance 7 2 Calibration procedures In this section the calibration procedures for the TPG and TCU are detailed In both cases a few preliminary steps must be followed 1 Switch off the device 2 remove the TPG or TCU cover refer to figure 7 8 a Pull off the light gray plastic pieces of the side of the front and back plates b Lift off the light gray plastic shades form the side of the box which gives access to the screws holding the top and bottom covers
51. e use fref measurement measurement standard power cable 240 VAC power suppl lol standard power cable 240 VAC power supply measurement temperature control and standard power cable 240 VAC power suppl pulsed mode suppl cables external control CPL yellow black l TPG LDD 12 VDC on center wire OPL LOMO Pp power supply for LDD BNC L N s laser current control LBI via CTLm or TC low impedance line for HHL 2 laser current control CW mode CI MEA ILX driver i current for laser control ILX driver power supply and low oF O o Ta impedance line for laser current control ILX driver mains standard power cable 240 VAC power suppl LDD LLH HHL LLH HHL Table 3 2 Starter Kit connections The ref column refers to cable numbering in figure 3 5 32 QCL user s manual v3 1 2 3 3 Connections Figure 3 5 Starter Kit cables 2013 ALP S LAS RS SA 33 Chapter 3 Installation 3 3 1 LLH The LLH front and rear panels shown in figure 3 6 consist of the following items anti reflective 3 5 to 12 ym ZnSe coated laser beam window 1 CTL cable connector 2 for Peltier junction and PT 100 sensor connector for LBI or CIL cable 3 cooling water flow fittings 4 for 4 mm flexible cables monitoring base connector 5 and laser connector 6 for direct voltage mea surement on the laser The cables are not supplied by
52. e 5 5 TPG Gate IN external mode signal 68 QCL user s manual v3 1 2 5 3 TTL Pulse Generator TPG TPG internal signal Trig In external signal Output signal Figure 5 6 TPG Trig IN external mode signal 2013 ALP S LAS RS SA 69 Chapter 5 Starter Kit Operation 5 3 2 Setting the pulse parameters 1 2 3 remove the TPG from the Starter Kit and connect it to the mains independently set the TPG mode to internal connect the TPG to a scope using the Output BNC cable a 5V TTL signal should be displayed set the pulse parameters as specified in the datasheet see section 4 2 a set the pulse duration to 50 ns using the 0 200 ns knob 4 b set the pulse period to 2 5 us using the period knob 2 and toggle switch 3 once the testing conditions are retrieved set the pulse parameters as desired but within a reasonable range of the parameters specified in the datasheet Note the pulse duration should be kept long enough to not distort the TTL signal lock the knobs 2 and 4 turn off the TPG and disconnect it from the mains IMPORTANT The operating parameters are specified in the datasheet provided with each laser any operation outside the specified range must be agreed with ALPES LASERS or may result in the loss of warranty 70 QCL user s m
53. e described in section 3 2 e if a current above 100 mA is read a ground loop might be the cause review all connections according to section 3 3 7 monitor the laser power using a powermeter a make sure that the range suits the power range of the laser see datasheet b reset it to 0 c align the laser beam with the powermeter The power should start rising around the threshold of the ALPES LASERS datasheet IV curve see section 4 4 Note exact power measurement of an IR beam is very difficult as it depends on ambient temperature and powermeter characteristics Therefore the exact values shown in the datasheet might not be reproduced in a different setup as the one used by ALPES LASERS for routine tests 2013 ALP S LAS RS SA 73 Chapter 5 Starter Kit Operation 5 4 2 QCL shutdown 1 reduce the external power supply voltage slowly do not reach 0 as the polarity might reverse CAUTION Make sure the polarity of the laser is correct Permanent damage may occur if the QCL is operated in pulsed mode turn off the TPG set the temperature controller to a temperature close to ambient temperature wait until the temperature setting is reached 2 3 4 5 turn off the temperature controller 74 QCL user s manual v3 1 2 6 Technical specifications The technical specifications of ALPES LASERS products are given in the following tables e QCLs in table 6 1 e housings in table 6 2 e ele
54. e injury or property damage The use of IMPORTANT and Note notations is defined below IMPORTANT Contains instructions or practices associated with maintenance and operation of the Starter Kit Highlights specific actions or steps to be followed in order to avoid defeating equipment functionality or cause product damage Note contains instructions or practices associated with maintaining the Starter Kit Clarifies issues needing the reader s attention SEMI S13 0298 Safety Guidelines for Operation and Maintenance Manuals Used with Semicon ductor Manufacturing Equipment Semiconductor Equipment and Materials International Moun tainview CA 1998 2013 ALP S LAS RS SA 21 Chapter 2 Safety 2 2 1 Symbols and labels The danger and warning symbols used in this manual are shown in table 2 1 electrical hazard es safety eyewear mandatory Table 2 1 Safety symbols most commonly used in the ALPES LASERS user s manual general danger LASER radiation hazard 22 QCL user s manual v3 1 2 2 3 Health hazard 2 3 Health hazard There are three main sources of hazard associated with the Starter Kit e LASER radiation detailed in section 2 3 1 e electrical detailed in section 2 3 2 e environmental detailed in section 2 3 3 2 3 1 LASER radiation hazard The eye and skin are the body parts the most likely to be injured Warnings for tasks that may lead to health hazard w
55. e section for details Note the temperature setting and reading may have an offset of typically 0 1 C 64 QCL user s manual v3 1 2 5 2 Temperature Controller Unit TCU 5 2 1 TCU startup 1 make sure the laser power supply is disconnected see section 3 3 for connec tions 2 turn on the TCU 3 set the desired temperature a select Setting oC using the switch 3 shown in figure 5 2 to display the desired temperature b turn the knob 5 to set the temperature to the desired value c select Real oC using the switch 3 to display the actual temperature 4 allow the laser temperature to reach the temperature setting CAUTION Do not operate the laser at a temperature above the values specified in the ALPES LASERS datasheet Permanent damage may result 5 connect back the laser power supply 5 2 2 Internal external mode In internal mode the temperature setting is performed using the temperature knob of the TCU front panel In external mode the temperature setting monitoring and interlock are performed by an external control system using the BNC connections of the rear panel In that case 1 set the switch 5 to external 2 provide a 6 5V power supply to the External Ref BNC connector using 100 mV C 3 read out the temperature through the Monitoring BNC connector providing 10 mV C
56. een 8 4 and 10 8 cm depending on the laser FP QCL The spectrum of a FP laser of figure 4 2 shows an interference structure caused by the Fabry Perot effect of the reflections at both ends of the laser chip superimposed on a wide gain envelope A temperature change will modify both these structures the FP spectrum evolution is driven by the length of the laser cavity which can vary and the gain envelope evolves in unpredictable ways due to mode competition The ALPES LASERS datasheet provides spectra taken at regular temperature intervals additional requests on the spectral shape should be discussed with ALPES LASERS Figure 4 3 shows the spectrum of broadgain lasers The temperature changes the apparent optical length of the grating tuning the waveguide refraction index 48 QCL user s manual v3 1 2 4 3 QCL spectra 10C 0 854 OC 0 804 20C 0 804 20C 0 70A 30C 0 754 lt E o S 20C 0 60A 30C 0 65A OC 0 85A Spectral density normalized to 1 DT 987 988 989 990 991 992 993 994 995 Wavenumber cm 1 12 04 30C 13 0V 15 188 13 0V 15C 14 0V OPV 8 12 0V 30C 9 0V 30C 11 0V 0 30C 14 0V 30C 15 0V 0 8 0 6 0 4 Spectral density normalized to 1 0 2 Mt 10340 1 wy ml i JN J 0420 10440 10460 Wavelength nm 0 Figure 4 1 Spectra of a DFB laser operated in CW mode top and pulsed mode bottom with different currents and temperatures 2013 ALP
57. er s manual v3 1 2 3 3 Connections 3 3 11 Connection procedure The procedure to connect the Starter Kit components depends on the laser housing and operation mode Refer to figure 3 5 for cable identification In all cases To prevent any damage to the Starter Kit components make sure the TPG TCU TC 3 and the external power supply are all turned off CAUTION Make sure that the connectors polarity is correct the laser s ground must be floating for both its anode and cathode Inverting the connector s polarity may result in permanent damage to the laser CW mode operation e LLH housing in CW mode 1 connect the LLH to the TC 3 using the TC LLH cable or TCU and CTL respectively 2 connect the ILX to the LLH using the CIL cable 3 if available connect the cooling water tubing to the corresponding connec tors of the LLH Note if no water cooling is being used carefully monitor the LLH module case temperature Air cooling and heat dissipation must be provided CAUTION If the LLH module case exceeds a temperature of 60 C permanent damage to the laser chip may occur e HHL housing in CW mode 1 connect the HHL to the TC 3 using the TC HHL cable or TCU and CTLm respectively 2 connect the ILX to the HHL using the CIL cable through the previous cable 2013 ALPES LAS RS SA 43 Chapter 3 Installation Pulsed mode operation 1 connect the CPL cable to the LDD 2 connec
58. erated in pulsed mode can withstand is of typically 200 ns Requirements for operation with pulses longer than 50 ns must be specified before purchasing a laser IMPORTANT The operating parameters are specified in the datasheet provided with each laser upon delivery any operation outside the specified range must be agreed with ALPES LASERS or may result in the loss of warranty 4 3 3 Linewidth of CW single mode DFB QCLs DFB QCLs operated in CW mode reach thermal equilibrium with pulse length of 10 ms and longer In this case transient behavior affects only the beginning of the pulse and can be neglected The linewidth is therefore limited by thermal noise and electronic noise produced by the driver Very long pulses gt 100 ms will behave in a CW manner and shorter pulses will exhibit chirping as pulsed lasers do and may induce multi mode behavior IMPORTANT ALPES LASERS QCLs operated in CW mode are guaranteed to be single mode if operated with long pulses gt 10 ms only 2013 ALP S LAS RS SA 51 Chapter 4 QCL Operation 4 3 4 Bandwidth of multi mode FP QCLs In the case of FP QCLs the bandwidth is defined as the wavelength range in which 99 of the power is emitted It depends on the driving current and is not affected by the operating temperature ALPES LASERS QCLs operated in CW mode can withstand any pulse length 4 4 l V curve and emitted power Figures 4 4 show the IV curves of
59. esigned to have a single spatial mode typically the Gaus sian TEMOO mode A mode measurement can be performed by ALPES LASERS on demand for a specific application 2013 ALP S LAS RS SA 57 This page intentionally left blank 5 Starter Kit Operation In this chapter are presented the operation instructions for the different components of the Starter Kit and the procedures to be followed for starting up and operating an ALPES LASERS laser IMPORTANT The operating parameters are listed in the datasheet provided with each laser any operation outside the specified range must be agreed with ALPES LASERS or may result in the loss of warranty Contents 5 1 Temperature Controller TC 3 0 60 pdas ed eae ees riores 60 5 2 Temperature Controller Unit TCU 63 5 2 1 TCU Startup o o e e e 65 AO a e ig O 65 5 2 3 TCU interlOCk o o e 66 5 3 TTL Pulse Generator TPG 67 5 3 1 Internal and external MOdes 68 5 3 2 Setting the pulse parameterS 70 AE e o d 71 5 4 General procedures eee eae 72 5 4 1 QCL startup o o e e ae 72 5 4 2 QCL ShuldOWN o o 74 59 Chapter 5 Starter Kit Operation 5 1 Temperature Controller TC 3 The TC 3 has its own complete manual This section outlines a quick start up
60. following setups can be used e for LLH only closed loop cooling system with chiller e for LLH only tap water Swagelok fitting to the tap 4 mm tubing e good mechanical contact between the LLH or HHL housing or QCL submount and the heat sink such as an optical table e heat sink and fan CAUTION Overheating the laser chip may result in permanent damage 28 QCL user s manual v3 1 2 3 2 Receiving procedure 3 2 Receiving procedure Upon delivery of the Starter Kit the following procedure must be performed 1 jpulsed CW _ pulsed CW LDD x x A TPG x Ilx Ct yx x J Ciim x x CC lx loo xp ato too fx x Figure 3 2 Packing lists with TCU IMPORTANT The customer must control the incoming deliveries and inform ALPES LASERS about incomplete shipments or defective goods within 30 days after delivery check that all components are included in the shipment By default the QCL is included in its housing the remainder consists of different sets of components depending on the housing and operation mode of the laser The default packing lists are given in tables 3 2 and 2 before unpacking the Starter Kit components make sure that all environmental conditions and prerequisites are fulfilled see sections and 3 1 Replacement lasers are delivered in their storage box for LLH only mount the laser submount into the LLH housing foll
61. func tion of frequency temperature and operating current These curves help when setting up the operation parameters of a DFB QCL 895 960 960 5 961 961 5 962 962 5 963 963 5 964 964 5 Frequency cm 1 sb56 Uldd V 959 5 960 960 5 961 961 5 962 962 5 963 963 5 964 964 5 Frequency cm 1 Figure 4 7 Emitted power top and LDD voltage bottom as a function of frequency for a DFB laser operated in pulsed mode at different temperatures 56 QCL user s manual v3 1 2 4 5 Beam Properties 4 5 Beam Properties Divergence Figure 4 8 shows a typical ALPES LASERS QCL beam profile Unipolar lasers consist in tightly confined waveguides for this reason the beam diffracts strongly at the output facet and has a full divergence angle of about 60 degrees perpendicular to the layer vertical angle and 40 degrees parallel to the layers horizontal angle A f 1 optics will typically collect about 70 of the emitted output power Note that the collected output power will decrease with the square of the f number of the collection optics Vertical angle 50 40 30 20 10 0 10 20 30 40 50 60 Horizontal angle Figure 4 8 QCL beam profile Polarization Because the intersubband transition exhibits a quantum mechanical selection rule the emission from a unipolar laser is always polarized linearly with the electric field perpendicular to the layers and the copper submount Mode ALPES LASERS QCLs are d
62. he bonds and the chip using only very thin and flexible wires 108 QCL user s manual v3 1 2 B 3 Bias T circuit for pulsed lasers B 3 Bias T circuit for pulsed lasers Since tuning of a QC laser is done by changing the temperature of the active zone the DC bias current can be used to control the emission wavelength of the laser via its heating effect The bias T therefore allows for electrically controlled rapid scanning of the emission wavelength B 3 1 Principle Since tuning of a QC laser is done by changing the temperature of the active zone a DC bias current can be used to control the emission wavelength of the laser via its heating effect Tuning can also be achieved by changing the temperature of the whole laser but at a much lower speed due to the high thermal capacity of the laser submount and base A bias T circuit allows for a quick scan of the emission wave length because the laser emission response is much faster as only the active zone is heated The DC current is drawn from the external power supply and applied to the laser in addition to the pulsed current It is recommended to apply currents of up to 0 1kHz but several customers have used the bias T at frequencies of up to several kHz Laser lifetime Heating of the active zone will increase thermal stress of the laser therefore the ex pected lifetime will decrease more rapidly compared to increasing the temperature of the laser submount and base If opera
63. he measuring unit is useful for monitoring and surveillance and to give a rough estimate of current parameters Note the exact measurement of short strong pulses with diodes and averaging circuitry is non trivial therefore accurate time and voltage measurements should be performed directly on the LLH or HHL housing through the aser and base connec tors 2013 ALP S LAS RS SA 13 Chapter 1 Overview 1 3 4 TTL Pulse Generator TPG The TPG shown in figure 1 12 is designed to power and control the LDD see section by generating TTL pulses on 500 The pulse duration can be set from 0 to 200 ns and the interval between pulses from 200 ns to 105 ys See section 5 3 for operation instructions Figure 1 12 TTL Pulse Generator TPG 14 QCL user s manual v3 1 2 1 4 Peripherals 1 4 Peripherals The following devices are recommended as peripherals for operating ALPES LASERS lasers CW laser driver precision laser diode current source such as e ILX LIGHTWAVE LDX 3232 High Compliance Quantum Cascade Laser Diode Driver http www ilxlightwave com propgs laser diode driver 3232 htm1 Note cables compatible with the LLH or HHL housing can be provided by ALPES LASERS e KEITHLEY Model 2420 High Current SourceMeter w Measurements up to 60V and 3A 60W Power Output http www keithley com products dcac currentvoltage highcurrent mn 2420 Powermeter To measure the la
64. he user It is center positive shield negative and can directly be connected to a stabilized DC supply make sure the polarity is correct and limits as specified in the datasheet are set B 4 1 External power supply protection To prevent current modulation to go back to the external power supply an RLC circuit needs to be added see figure B 3 The values of Rac L C depend on the modula tion frequency the AC source and to some extent on the QCL Rule of thumb for L As the impedance X 27 f L of the inductivity should be much higher than the dy namic resistance Xy of the laser to block the AC component from the DC supply applying Xz gt 100XqQ leads to roughly L gt 16XQ f 112 QCL user s manual v3 1 2 B 4 CW modulation QCL Ra 1 2 Ohm Figure B 3 RLC circuit for external power supply protection In general XQ is of the order of 1 2 Q For a modulation frequency of 10kHz L should therefore be of the order of 3mH or larger rules of thumb for R and C To prevent the AC source from dominating or reverse biasing the current through the QCL U1c lt Ug must always be given in absolute values Furthermore as the AC voltage source together with Rac C is forming a current source to prevent variations of QCL dynamic resistance Xy to influence the AC current RAC Xc gt gt Xq must be guaranteed As the generator for Uac will have an impedance Zac impedance matching demands for Rac Xc Xo Zac
65. hen operating a QCL are shown below WARNING Never insert shiny objects in the LASER beam path stray reflections can be extremely hazardous to eyes and skin 2 3 2 Electrical hazard Work on live electrical circuits must be performed using all appropriate precautions and site specific procedures Those tasks must be performed by qualified service personnel familiar with the wiring schematics of ALPES LASERS electronic equipment only electrical cabinets shall not be accessed during normal operation nor during maintenance tasks DANGER Contact with the AC line can cause death or serious injury ramp down power from all the equipment before attempting any maintenance procedure 2 3 0 Environmental hazard Always consult the material manufacturer s Material Safety Data Sheets MSDS pay ing close attention to dust and combustion by products 2013 ALP S LAS RS SA 23 This page intentionally left blank 3 Installation This chapter presents the general workflow between delivery and operation of ALPES LASERS QCLs and electronic equipment IMPORTANT The facility must fulfill all prerequisites listed in section 3 1 all utilities must be duly prepared in a suitable location The location of ALPES LASERS QCLs and electronic equipment must comply to the environmental conditions listed in section 3 1 1 Contents 3 1 Prerequisites 2 2 0 dime et
66. lications such as liquid spectroscopy and high power emitting sources for which broadband emission is acceptable and when no signal purity is required Broadgain QCLs consist in FP lasers designed for maximum width of the gain profile They can be used as broad spectrum illuminators for spec troscopy or imaging Combined with an anti reflection coating they are suitable for use in an external cavity to obtain a tunable laser with a wide tuning range THz FP QCLs can reach wavelengths of 70 to 200 ym but must be oper ated under cryogenic conditions contact ALPES LASERS for more details 46 QCL user s manual v3 1 2 4 2 ALPES LASERS datasheet 4 2 ALPES LASERS datasheet The datasheet provided with each ALPES LASERS QCL upon delivery contains the data obtained from standardized quality control tests performed at ALPES LASERS production site The tests are performed on the QCL installed in a test bench LLH housing operated at a temperature ranging from 30 C up to their maximal operating temperature up to 50 C If the QCL is then encapsulated in a different type of hous ing the tests are repeated and a new datasheet is provided to the user The mea sured parameters are used for controlling and comparing laser chips performance evaluation and as starting points for operation parameters they are readily available on ALPES LASERS website Those parameters can be extrapolated for a specific ap plication or broader tests c
67. manufactures Quantum Cascade Lasers QCLs of two types sin glemode Distributed Feedback DFB or multimode Fabry Perot FP which can be operated in two modes continuous wave CW or pulsed ALPES LASERS lasers are available in different types of packaging presented in section ALPES LASERS developed dedicated electronics to control the temperature and current drive of its QCLs see section 1 3 for details ALPES LASERS constantly develops new QCLs and electronics to satisfy inquiries from its customers Contact ALPES LASERS to find the best solution for your application 1 1 1 QCL parameters and performance All ALPES LASERS lasers are thoroughly tested and characterized The results are reported in datasheets which are readily available on ALPES LASERS website Each QCL is delivered with its datasheet containing data on singlemode and multimode emission IV curves emitted power maximum operating current and operation tem perature See section 4 2 for details 1 1 2 QCL geometry Figure 1 1 shows an ALPES LASERS QCL growth and a laser chip mounted on an NS submount see section 1 1 3 By convention the vertical axis of the laser is parallel to the growth direction as well as the beam polarization i e electric field and the NS submount screw holes axis The emission axis is perpendicular to the growth direction and to the edges of the NS submount Figure 1 1 ALPES LASERS QCL growth left and laser chip mounte
68. mode Setting C and adjust the temperature value to 25 C by means of the Set Temperature 5 tuns potentiometer P8 2 b On the external power supply rise slowly the voltage to 30 V and the cur rent to 1 5 A the tension should stabilize at 30 V Note If the current is too high stop the test and verify the transistors Q1 to Q4 1 and their associated resistors There might be a soldering problem In this case fix it and repeat the procedure from step 5 c Set the selector 3 to mode Real I the displayed value should be lt 1A d Set the selector 3 to mode Real C the value displayed should tend to the defined value If not adjust P3 e Wait for a certain time and check the Peltier temperature with a thermome ter f Set the selector 3 to mode Setting l g Increase the limit of positive current to 3 5A by means of the I trimmer 4 located on the front panel h Increase the limit of negative current to 5A by means of the trimmer 5 located on the front panel i Change the temperature reference to 25 C and check the displayed cur
69. move the two screws 3 holding the contact set 4 using a 2mm hex key 3 remove the contact set using the central PET knob as show in figure 7 6 Note this PET screw is used as a knob do not remove it 4 remove the two screws holding the laser submount using a 1 5 mm hex key as show in figure 7 6 5 remove the laser submount from its storage box using tweezers IMPORTANT The guidelines presented in section 7 1 1 must be followed carefully PET refers to polyethylene teraphtalate a common plastic 2013 ALP S LAS RS SA 87 Chapter 7 Maintenance Figure 7 6 Laser exchange procedure removing the contact set left securing the laser submount right CAUTION Do not drop the screws onto the submount This may result in permanent damage to the laser 6 secure the laser submount into the LLH with the two dedicated screws use tweezers to hold the screw in place while screwing with an allen key 7 put the contact set on top of the laser submount into the LLH housing a use the middle knob to hold the contact set b d press slightly for good electrical contact 8 use a multimeter to measure the resistance between the c tighten the two dedicated screws through the front holes base position the two rear holes above the pins for proper alignment and the laser connectors It should lie between 30 Q and 300 kQ no resistance in
70. mperature of the LLH with a Peltier junction and monitors the temperature with a PT100 through the TC LLH cable The Peltier connector is identical to the connector shown in the left side of Fig 8 10 The controller connector is a DB 15 connector described in Table 3 6 The Fans ID and Remote Sensor pins are not used by the ALPES LASERS products Pin number Description 1 2 amp 9 TE 3 48 10 TE 5 amp 6 Ground 7 Sensor 8 Sensor 11 Fan 12 Fan 13 ID 14 Remote Sensor 15 Remote Sensor Table 3 6 TC LLH cable connector pinout 3 3 8 TC HHL cable The TC 3 controls the temperature of the HHL with a Peltier junction and monitors the temperature with a PT100 or NTC sensor through the TC HHL cable The Peltier con nector is identical to the connector shown in the left side of Fig The controller connector is a DB 15 connector described in Table 3 6 The Fans ID and Remote Sensor pins are not used by the ALPES LASERS products 3 3 9 CPL cable The CPL cable shown in figure 3 11 connects the LDD to the TPG and external power supply using a DE 9 connector on the LDD side yellow black banana connectors for Bias T operation Lemo 00 for LDD power supply BNC for LDD timing signal and red black banana connectors for TPG power supply The LDD side consists of a D sub 9 connector composed of 9 pins as shown in figure 3 12 and described in table 40 QCL user s manual v3 1
71. nana cables iii turn on the external power supply iv set the voltage and current to 0 but keep the voltage 100 mV above 0 to avoid accidental polarity reversal v turn off the external power supply 72 QCL user s manual v3 1 2 5 4 General procedures vi connect the red black banana cables vii switch on the external power supply b setup the TPG pulse parameters following the guidelines of section 5 3 c connect the TPG back to the Starter Kit and turn it on CAUTION Make sure the laser temperature is below specifications before turning on the external power supply Overheating the laser chip may result in permanent damage 6 increase the voltage slowly and monitor the current according to the QCL IV curve included in the ALPES LASERS datasheet see section 4 4 e the current should start increasing at the threshold voltage at a value close to the one indicated in the ALPES LASERS datasheet e for pulsed mode at maximum voltage the current supplied by the exter nal power supply eps should correspond to the maximum peak current see section 4 4 1 of the datasheet multiplied by the duty cycle with some overhead leps Ipeak x duty cycle overhead CAUTION Do not exceed maximum voltage or current specified in ALPES LASERS datasheet Permanent damage to the laser chip may occur e if no current is flowing a misconnection might be the cause repeat step g of the installation procedur
72. ntroller starting in 2013 CW mode The Starter Kit shown in figure 1 7 is meant to operate QCLs in CW mode It consists of the following elements which are described in dedicated subsections e Temperature Controller Unit TCU section 1 3 1 or TC 3 Temperature Con troller section 1 3 2 e CIL and appropriate cable for laser driver and temperature controller section Figure 1 7 Starter Kit for CW mode operation shown with laser driver not included in the Starter Kit Note a CW QCL is very sensitive to electrical surges and instabilities as any con ventional bipolar laser diode telecom NIR laser It is necessary to use a good quality power supply see section 1 4 for recommended peripherals 8 QCL user s manual v3 1 2 1 3 Starter kit Pulsed mode The Starter Kit shown in figure is meant to operate QCLs in pulsed mode It consists of the following elements which are described in dedicated subsections e Temperature Controller Unit TCU section or TC 3 Temperature Con troller section e Laser Diode Driver LDD section 1 3 3 e TTL pulse generator TPG section 1 3 4 e CPL and appropriate cables for laser driver and temperature controller section 2013 ALP S LAS RS SA 9 Chapter 1 Overview TCU 200 Temperature Controller Unit Figure 1 8 Starter Kit TCU 2 LDD 3 and TPG 4 for operation in pulsed mode 10 QCL user s manual v3 1 2 1 3 Starter kit 1 3 1
73. o mode Real C gt The temperature displayed 2 should follow the reference temperature 100 QCL user s manual v3 1 2 7 2 Calibration procedures 7 2 3 TPG calibration This procedure describes the steps to be followed to calibrate the TPG front panel knobs settings Refer to figure 5 3 for the TPG commands description IMPORTANT The TPG is calibrated in factory This procedure is not a routine procedure and must be performed by experts only DANGER Contact with AC line potential can cause death or serious injury If work on live electrical circuits is required use all appropriate precautions and hot work procedures required at your location 1 Verify the 5 V power supply 2 During the first test set all knobs and adjustable capacitors to their medium values 3 Adjust to the knob 50 ns adj 3 in order to obtain a 500 ns long pulse on TP2 2 4 Measure the pulse period through the boxTrigOut output connector using a scope 2013 ALP S LAS RS SA 101 Chapter 7 Maintenance 02 07 99 3 TTL Puls Generator TPG 128 Y Ss E oo P 9 p 12pF e AE SCEE o O CIS1OnF 5k_R3 pcs 5m fg R10 O eooo An loo gt A 00 gt 5 E198 i BOF 108nF a 0 150pr 0 o Hie me cs CAL flete ou Vie yi LE Seles cee el ZO e o 00 0 e Came ole Ee Se AN i A 0
74. ollowed in figure 16 4 0 9 Chapter 6 Technical specifications Temperature Controller TC 3 Size 9cm x 21 5cm x 28cm Power Input Mains power 120 240V 50 60Hz Input Output Through supplied TC LLH HHL cable Internal Control Front panel buttons External Control USB connectors Max Current 5 0A Temperature setpoint 99 C 250 C limited range with allowed for QCL range use Temperature sensor pt100 NTC user defined Figure 6 4 Technical specifications of ALPES LASERS electronic equipment contin ued from 6 3 Type FP min FP max PEC min PEC max CWEC min CWEC max BG 10 12 780 1030 787 1042 BG 8 10 995 1260 976 1283 1020 1235 BG 7 8 1190 1425 1096 1473 1150 1420 BG 6 7 1345 1660 1325 1680 1370 1635 Figure 6 5 Examples of broadgain laser parameters where FP min and max are the limits of the multimode emission PEC min and max are the observed limits of single mode pulsed emission in an external cavity and CWEC min and max the observed limits of continuous emission in an external cavity Parameters were measured without AR coatings Note that performance may vary depending on the external cavity 78 QCL user s manual v3 1 2 6 0 8 CLEAR APERTURE m REFERENCE REFERENCE PLANE 2XM Sent ic iJ ql 1 TEC LEAD 1 0DIA 20 LON Figure 6 6 HHL housing
75. oltage 10C power 0C voltage OC 10 power 106 ee voltage 10C wer 20C valiage ITA power tper vlt AE 400 Voltage V O itage 506 power 50C voltage 50C 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 Figure 4 4 IV curves of DFB laser top and FP laser bottom operated in CW mode at different temperatures 2013 ALP S LAS RS SA 53 Chapter 4 QCL Operation 4 4 1 Maximum operating current All QCLs have a maximum operating current above which a Negative Differential Re sistance NDR appears and may destroy the laser As an example figure 4 5 shows the IV curve and emitted power of a DFB QCL operated in pulsed mode the green squares indicate the maximum current for monomode operation 4 7 A from 30 to 30 C in the present case Peak Voltage V CAUTION The maximum operating current of each ALPES LASERS QCL is indicated in the IV and emitted power plots caption of the datasheet Do not operate the laser with a current above those values permanent damage may result 10 Sado 1300 9 power 15C 6 voltage 15C power OC k 8 voltage 0c 2 anehe gt age 7 po 536 E voltage 30C Max single mode power 42 6 O a 5 o 32 3 2E 2 i 1 0 0 0 05 1 15 2 25 3 35 4 45 5 Peak Current A Figure 4 5 IV curves of a DFB
76. ooled laser stage inside Peltier cooled laser stage inside Peltier cooled laser stage inside Peltier cooled laser stage inside cooler minimal temperature 30 C minimal temperature 20 C max dissipation 4W max dissipation 4W Temperature Pt100 PAVO orNTC temperature NTC thermistor NTC thermistor monitoring measurement Max TEC cent 5 0A 3 0 A 2 5A on some items 3 0A 3 0A Max TEC A voltage 17V 11 6 V 11 0 V on some items 2 85V 2 85V Laser Capacity Supports all NS mounted CW and pulsed lasers from Alpes Lasers Supports CW or pulsed lasers with dissipation lt 6 W on NS mount Supports pulsed lasers with lt 4W average dissipation Supports pulsed lasers with lt 4W average dissipation Cooling needs The backplate is equipped with a water cooling circuit and connections suitable for 4mm flexible pipes Water cooling is only necessary for operation temperatures lt 0 C The backplate must be kept at room temperature up to 35W of heat dissipation needed The backplate must be kept at room temperature up to 10W of heat dissipation needed The backplate must be kept at room temperature up to 10W of heat dissipation needed Figure 6 2 Technical specifications of ALPES LASERS QCL housings suoleoyioeds jeo1uyoa 9 Jajdeyo Sv S dqw 10z2 VS SAZ ZL Laser Diode Driver LDD TTL Pulse Generator TPG Size 15cm X 6cm X 9 cm Size 23cm X 13 7cm
77. owing the procedure presented in section 7 1 3 check that the temperature controller voltage setting is appropriate For the TC 3 the procedure to change the fuse is outlined in the TC 3 manual For the TCU follow the following procedure the fuse holder 6 on the rear panel shown in figure 3 4 should be set to 100 120V and 60 Hz for North America 220 240 2013 ALP S LAS RS SA 29 Chapter 3 Installation MEA A O E ER tes x x PTC LLH 1 x x meria x x DEA PO E A E a Za a E ae a Figure 3 3 Packing lists with TC 3 V and 50 Hz in Europe If not set the appropriate AC voltage by setting the fuse holder in the proper position a Pull out the fuse holder 3 from the socket 2 b check that the fuse holder is in the proper position to get the appropriate voltage The arrow on the fuse holder 3 should correspond to the mark on the socket 2 c Insert the fuse holder 3 into the socket 2 30 QCL user s manual v3 1 2 3 2 Receiving procedure Figure 3 4 TCU installation rear panel left fuse holder right 2013 ALP S LAS RS SA 31 Chapter 3 Installation 3 3 Connections Table 3 2 lists the cables and use of all connections for the Starter Kit including the LLH or HHL housing operated in pulsed or CW mode Refer to figure 3 5 for cable identification from to cabl
78. pacitor essentially bias independent between the cathode and the anode coming from the bonding pads C2 depends on the laser mounting typically C1 lt 100 pF in the LLH As an example the values given below apply for a 10m laser wavelength Note Voltage and resistor values may vary according to the type of laser Odisea 10 to 200 when a voltage of less than 4 to 6 Volts is applied Pa terre eres eer ee ee ee eer 1 to 4Q up to 10 12 Volts Als 10 to 200 over 12 Volts after which the laser no longer operates lados 100pF capacitor between the anode and the cathode A Apidae es lt 100pF depending on your mounting of the laser R1 Z gt L c2 C1 Figure A 1 Electrical model for QCL 106 QCL user s manual v3 1 2 B Operations for advanced users In this section tips for advanced users are provided for specific application It is not recommended to perform those procedures in normal operation conditions IMPORTANT The operation instructions contained in this section must be performed by expert users only as permanent damage to the laser may occur if not manipulated correctly B 1 Direct QCL voltage These connections give direct access to the voltage of the laser IMPORTANT Direct voltage measurement of the QCL must be performed by experts only and agreed upon with ALPES LASERS The L connection is connected AC coupled
79. periment with several gain settings to find the ideal value and for even finer control you can set the Gain to PID and directly set the PID control values Finally adjust the set point downwards or upwards to the desired set point It is good practice to adjust the set point in steps of 5 C and wait for the actual tempera ture to stabilize before changing the set point again as the HHL and TO3 housing age prematurely with large temperature swings The LLH is less sensitive and can with stand large temperature swings The recommended temperature change rates are given in table 5 3 Using the settings of table ensures these rates are respected CAUTION AutoTune risks damaging or reducing the lifetime of the Peltier elements The TC 3 contains a feature known as AutoTune Usage of this feature is NOT RECOMMENDED with the housings of Alpes Lasers Using Housing lim HHL single stage 3 0 A HHL double stage 2 5 A LLH 5 0 A Table 5 1 Current limits settings 2013 ALP S LAS RS SA 61 Chapter 5 Starter Kit Operation Housing Sensor Type Coefficients HHL NTC NTC 10K4CG Adjust manually the PID values to P 0 01 0 0001 D 0 HHL pt100 pt100 Adjust manually the PID values to P 0 01 0 001 D 0 LLH pt100 Set the Gain Setting to 300 Table 5 2 Sensor characteristics Housing Maximum temperature
80. r Coeffs sub menu pressing the knob to enter the sub menu Adjust the constants to reflect the values for your temperature sensor as shown in table 5 2 These values ensure protection of the Peltier 60 QCL user s manual v3 1 2 5 1 Temperature Controller TC 3 Once you have made all your adjustments press the MENU button to exit the menu in the future if you are only changing one value you do not need to press the knob pressing the MENU button while changing a value will save the value and exit Next connect the cable between your housing and the Output connector of the TC 3 We recommend using our cables as they have been designed to work well with the TC 3 If using your own cables ensure they have been properly wired according to the pin out of the TECSource and your fixture Set the set point to a temperature close to room temperature typically 15 C and press the Output button The output will turn on and you will see the voltage and current begin driving the fixture to the set point you have chosen Depending on the thermal size of your fixture it may take seconds or several minutes to reach the set point If you notice the temperature is oscillating around the set point and not stabilizing you may need to adjust the Gain setting in the menu If the temperature is quickly jumping up and down the Gain will typically need to be reduced If the temperature is slowly moving up and down try a higher Gain You may need to ex
81. ransparent window which can be of ZnSe or TPX depending on the wavelength The light is uncollimated The laser is connected to a series of pins which is identical to the pins found on a LLH see 3 3 1 C 1 1 Usage To cool down the dewar simply fill it with liquid nitrogen from its top A filled dewar should last for up to 6 hours when not in use and typically 3 4 hours when in use the actual cold time will depend highly on the energy dissipation of the laser Connect the pulser or CW driver to the pins as if it was a LLH housing C 1 2 Maintenance The laser sits in a vacuum In the course of normal operation the housing is air tight In case of a leak the dewar can be sent back to Alpes Lasers to be re evacuated C 2 Others Two other cryostats are offered by Alpes Lasers a LN2 liquid helium cryostat and a Stirling cooler The manuals for these devices is not yet available 116 QCL user s manual v3 1 2
82. rd across all ALPES LASERS products e Indoor use only Ordinary Protection This product is NOT protected against the harmful ingress of moisture Maximum Relative Humidity lt 80 RH non condensing Operating temperature range of 0 C to 40 C Storage and transportation temperature of 40 C to 70 C 26 QCL user s manual v3 1 2 3 1 Prerequisites Storage All ALPES LASERS lasers are delivered in a hermetic waterproof storage box shown in figure in which the laser chip is held with pins This box should always be used when storing the laser out of its housing The laser chip is soldered to the pads using In soldering which melts at 120 C therefore the storage temperature should not exceed 80 C Figure 3 1 ALPES LASERS QCL storage box QCLs can be stored at ambient temperature 10 to 30 C in normal atmosphere Humidity should not exceed 80 and condensation is to be avoided The laser must be operated in a dry atmosphere below 50 relative humidity If possible it should be completely dried using a desiccant material or by flushing with No CAUTION Even when packed ALPES LASERS equipment should not be exposed to rain snow or direct sunlight Extreme temperature changes must be avoided 2013 ALP S LAS RS SA 27 Chapter 3 Installation 3 1 2 Cooling The laser performance is highly dependent on its operating temperature it is therefore necessary to cool down the laser accordingly The
83. ser ouptput power semiconductor powermeters such as those from OPHIR can be used www ophiropt com Spectrometer Low resolution measurements measurements can be done with monochro mators such as a TRIAX320 from JOBIN YVON http www jobinyvon com special measurements high resolution and CW with a spectrometer such as the NICOLET 800 and 860 FTIR www nicolet com or BRUKER INSTRUMENTS www bruker com Fast detectors For time critical measurements detectors from VIGO SYSTEM SA www vigo com pl Monitoring For monitoring laser emission simple pyroelectric detectors can be used such as the LGTP101 by MEMTEK memtek Igcit com Beam collimation Due to the large divergence of the beam it is recommended to use fast optics f 1 f 0 8 to collect most of the emitted light like lens sys tem aspheres from JANOS http www janostech com or Optical solutions http www opticalsolutionsinc com 2013 ALP S LAS RS SA 15 Chapter 1 Overview 1 5 Fields of applications 1 5 1 IR The ALPES LASERS QCLs address the need for gas sensing and spectroscopy appli cations in the wavelength region from 3 to 15m as most chemical compounds have their fundamental vibrational modes in the mid infrared More specifically the high transparency of the atmosphere in two so called atmospheric windows at approxi mately 3 5 4m and 8 12ym allows remote sensing and detection The long wavelength reduces Rayleigh sc
84. t the LDD to the TPG a using the CPL Lemo 00 12VDC cable for power supply of the LDD b using the CPL BNC cable into the Out1 and Out2 output IMPORTANT The LDD ground must be floating 3 connect the LDD to the external power supply using the CPL red and black banana cables 4 if no bias T external circuit is to be used shortcut the signal yellow and ground black banana cables by connecting them together See section B 3 for details on bias T control e LLH housing in pulsed mode 1 connect the LLH to the TC 3 using the TC LLH cable or TCU and CTL respectively 2 connect the LLH to the LDD using the low impedance line LBI 3 if available connect the cooling water tubing to the corresponding connec tors of the LLH Note if no water cooling is being used carefully monitor the LLH module case temperature Air cooling and heat dissipation must be provided CAUTION If the LLH module case exceeds a temperature of 60 C permanent damage to the laser chip may occur e HHL housing in pulsed mode 1 onnect the HHL to the TC 3 using the TC HHL cable or TCU and CTLm respectively 2 connect the HHL to the LDD using the low impedance line LBI via the previous cable 44 QCL user s manual v3 1 2 4 QCL Operation In this chapter the general operation principle of a QCL is presented and its main characteristics are illustrated using actual plots included in the
85. timize the temperature and drive parameters a Adjust the pulse length lower and higher and repeat the scan thus learn about the effect of these parameters on power and laser linewidth b If possible repeat the measurement with a gas cell with the target gas at low pressure 1 Torr This will narrow the line greatly and allow to consider the apparent spectral resolution of the laser itself under the drive conditions and to learn whether the driver has any ringing or double pulsing which will make the line width seem higher 2013 ALP S LAS RS SA 111 Chapter B Operations for advanced users B 4 CW modulation To operate a laser in CW mode an AC signal is added to the DC current It is recom mended to modulate the external power supply directly within the parameter range specified in the ALPES LASERS datasheet If this is not possible an additional modu lated source must be used like a waveform ramp generator for example Interface circuit To reduce cross talk with other system components and to improve mechanical sta bility this interface circuit should be installed into a small metal box with only the connectors accessible as shown in figure B 2 loc C TA H connector BNC low impedance line Figure B 2 Interface circuit for CW laser modulation Connectors for the LLH with a BNC plug are available for CW laser operation ALPES LASERS provides the CIL cable pinout the adaptor must be made by t
86. tion at only a fixed wavelength is needed this should be adjusted with the overall temperature control B 3 2 Connection The bias T circuit can be integrated in the TPG The circuit included in the LDD pulser unit is controlled by the twisted black and yellow wires of the control cable with the CPL cable B 3 3 Procedure e Since the input stage of the bias T is a bipolar transistor applied voltage must be higher than about 0 6V to start bias current The input stage has a voltage limit of 2 6V but the laser itself may be destroyed at lower bias T control voltage therefore the maximum rating has to be agreed with Alpes Lasers SA e the laser should be operated initially at lowest possible temperature Since a bias T only allows to heat the laser the emission wavelength can only be in creased or emission wavenumber decreased and output power will decrease 2013 ALPES LAS RS SA 109 Chapter B Operations for advanced users with increased bias current due to the additional heating This reduces the number of lasers available for reaching a given emission wavelength CAUTION Applying a high bias current may destroy the laser due to thermal roll over Bias T setup must be performed by instructed personnel and approved by ALPES LASERS e The optical output power must be monitored when setting up the bias T to make sure the thermal roll over is not reached Temporary increase of the pulse cur rent must always res
87. tment knob to its first position Check the that period is of 0 6 0 0 1 ys AN 7 AN O e a Pa 4 43 0 AE a bA ua AE ihh A GND N ya S fe 2 eZ fe De ee z J9 f J10 lt a Tella 0 o 3 6 ZAR Ee ue B 17 2 PA O 2 E J12 311 y 7 TR6 15uF 4BV LE ws po eN Z aos S y Or XIXILI 9 HST lle 5 7 IA 9 x A lt D E meoeeceooe e eS R2 OPTIONAL O e 5 2pr Om els e f llel 6 e lo rE 5 DA E 7 TP 20 5k TP3 TP4 y E E y lt o 95 TP5 PA Sy eS e ZA A Ze ec v o io 10 07 ELA Se o mamo ERES ld gt ma 011 D 218 1000000 Booo ooo N E ae a 4 TA moro Or our 7 v2 N Gate IN gt a O 7 Qe 5 e se Figure 7 17 TPG main board view ll clearpage 2013 ALPES LAS RS SA 103 Chapter 12 Connect oscilloscope on the Output connector Load with a 502 Choose Maintenance a repetition period of about 5 ps 13 Turn the boxduration adjustment knob to its last position Adjust the Max duration capacitor 2 to have an output pulse of 200 ns 5 ns 14 Turn the boxduration adjustment knob to its first position Adjust the pot Out Ons adj 1 in order that the output pulse is Ons The pulse is 0 ns long when its shape is triangular with an amplitude of 1 1 V half of the maximum val
88. to the cathode of the laser through a divider by ten The end of cable must be 502 terminated for accurate measurement The B is connected the same to the anode of the laser Base Receptacle By using the math trace of an oscilloscope showing the L channel minus the B one can get the voltage on the laser This measurement is more accurate than the information obtained from the LDD Note the cables are not included in the Starter Kit but can be supplied by ALPES LASERS 107 Chapter B Operations for advanced users B 2 Soldering wire bonds from laser chip to submount IMPORTANT Soldering bonds to the carrier is a delicate operation Contact ALPES LASERS before attempting this operation As the QCL chip itself is soldered and the contact pads on the ceramics are made out of gold it is not possible to use a normal Lead Tin solder the temperature is too high the solder will destroy the gold contacts by forming an alloy ALPES LASERS recommends the use of pure Indium for soldering in the form of paste of microscopic beads in flux Acc V 5pot Magn Det WD 20 0 kya 200x SE 15 0 Alpe sers Figure B 1 Laser chip wire bonds It is of highest importance to never touch any part of the laser chip itself especially not the facets nor the bonds as this may result in fatal damage to the QCL Solder with a very fine tip solder iron at about 170 C only at the corner of the contact pad which is most distant from t
89. ue 15 Repeat points 13 and 14 until the values are OK 16 Check the operation of the boxGate in external mode A signal is present on the Output output connector if the input Gate in open high TTL level gate open no signal is measured on the Output output connector indicates a short circuit on on input Gate in low TTL level 17 Check that the 12 V is present on the Lemo 00 connector 12 V on the gate closed centre connector 2 1 cs how 23 4 8893 3 c7 228F 5Y GND c 3 BO we N LO fe on ac a relists lt 0 ES P 0 y HA E Da E O MU a a o Ed Ps Pe eae A O Ot Ss L J12 911 gt ae TRE 15uF Esa o TE e 00 9 y e ADO DO ATT 3 O M1 fe E Seas e z ce We ASIA ne PI ZE A E D n LEIA n E RATT e 4 G R2 OPTIONAL O ED R5 2 2pF 0 ED ets o e0 dee ls E TOOK ee IA Tok o amp S a TP P2 E TP3 TP4 4 7 y 5k E E pa Sos PO A 0 7 oS eo A 20 o0 00000000 _ 1207 6 e ere E A ry i far E D mecececece TIY N lt ri 9 x 4 T JB O rior JOURN ROUE ER 7 Q gt JO sw 0 Figure 7 18 TPG main board 104 QCL user s manual v3 1 2 A QCL theory and application notes A 1 QCL wavelength range Unlike standard bipolar semiconductor lasers e g 1 55um telecom devices
90. ult in increased optical power output otherwise the DC bias current is already too high e As a rule of thumb the overall dissipated power sum of DC bias current dis sipation and pulse current dissipation must never be higher than the average dissipated power given by the highest current voltage temperature combina tion specified in the datasheet e The average dissipated power for a given pulse current I pulse voltage U and duty cycle d is given by d x J x U whereas the dissipated power due to a bias current IB is given by JB x U U is the voltage on the laser but it is safe for this calculation of bias current dissipation to use the voltage on the LDD pulser input B 3 4 Gas concentration measurement The goal of this procedure is to calibrate and optimize the laser spectrum as a function of temperature and current A spectral scan of the laser is generated over a wave length region defined by the scan rate of the laser versus current cm 1 A a basic property of the laser A 60 mA range might be equivalent to 1 2 cm 1 of wavelength change in the laser The ALPES LASERS datasheets provide a few discrete settings that were measured with a different equipment which can be used as starting points but the curves obtained with the following procedure are to be used to acquire the real gas data Prerequisites e Using short pulses and bias T to scan wavelengths e User has appropriate short pulse generation electronics cooler
91. vailable as CoC or readily mounted in a variable temperature cryostat ALPES LASERS offers three types of cryogenic system solu tions e LN dewar e cryostat e standalone Contact ALPES LASERS for more details Note THz QCLs are not pre tested contact ALPES LASERS to discuss the require ments for a specific application 2013 ALP S LAS RS SA 17 This page intentionally left blank 2 Safety ALPES LASERS electronic equipment operates with high voltage and includes a LASER that may cause serious injury if not handled properly The guidelines in this document follow as closely as possible the IEC 60825 1 International Standard for safety of laser products IMPORTANT This document provides general safety instructions Site specific safety regulations on electricity and lasers must be followed if they supersede the recommendations in this manual Potential sources of hazard when working with the Starter Kit are environmental electrical or due to LASER radiation they are explained in more detail in sections 2 3 1 2 3 2Jand 2 3 3 The access to potentially dangerous operations is not controlled and is left to the supervision of the owner IMPORTANT Any personnel working directly or in the surroundings of ALPES LASERS equipment must read carefully and understand the safety issues discussed in this chapter Contents 2 1 General safety considerations 20 ee ee ee ee ee ee ee 2

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