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Matisse User's Guide 4

1. Matisse Installation 72 Alignment Procedure remove the lids on both ends of the reference cell using an Allen key size 3 connect the fiber to the reference cell by screwing the outcoupling end of the fiber into the 2 mm lens socket be careful that the bayonet on the fiber connector fits properly into the lens socket by placing a piece of paper in front of the photodiode look at the light coming out at the other end most likely you will see two bright spots which should be overlapped To do so adjust the knobs of the in coupling XY mount Matisse Installation 73 at this point you can connect the two cables from the Reference Cell Unit to the Temperature Stabilization Unit and to The Matisse Laser Head respectively the photodiode is now supplied with voltage launch the Matisse Commander program choose S Stabilization menu and open the Ref Cell Waveform window which must display the transmission spectra of the reference cavity optimize the fiber coupling unit in the Matisse Laser Head by tweaking the vertical and horizontal controls such that the transmission peaks show maximum intensity Optimize coupling into the cavity in the same way by using the controls on the XY mount in front of the reference cavity check if the photodiode is correctly aligned by loosening the lateral screws DV1 DV2 and gently move the diode up and down looking for a maximum signal Do the same on the horizontal axis by
2. Matisse Power Optimization Once your Matisse laser is emitting radiation you should follow the procedures given below for a fast and easy optimization of the laser ring cavity and the angular position of the thin etalon and the birefringent filter On a daily working routine this optimization should take only some minutes and allow you to fully optimize the laser power Before starting the optimization follow the start up procedure given above If not yet done boot the laser control computer and start the Matisse Commander Place a power meter in the Matisse beam and monitor the generated power Matisse Operation 92 Cavity Mirror Optimization Figure 35 Alignment screws of the Matisse three mirror set Screws S Iv and S Ih allow to adjust the reflection direction of Mirror M 1 in the vertical and horizontal direction respectively Screws S 3h and S 3v act similarly on mirror M3 The Matisse laser cavity is designed for excellent long term stability Therefore only minor adjustments are necessary to keep the power of your laser system at maximum level Once the laser is set up and fixed with respect to the pump laser only two screws will allow to compensate the small day to day shifts of the laser alignment The figure below shows the three off plane folding mirrors M1 M2 and M3 in the Matisse cavity As already mentioned in the Laser Description Chapter M1 is the Matisse outcoupling mirror whereas M3 is equippe
3. Input Impedance gt 1 MQ CHAPTER 11 186 Frequently Asked Questions and Troubleshooting I cannot get the expected or usual power output from the laser apply the procedures given in the Power Optimization see page 91 section check the laser optics for damages or dust particles Observe the information given in the Maintenance chapter see page 119 check if the clockwise running mode of the ring resonator is exited see question below check if the laser beam shows spatial instabilities see question below I experience strong power fluctuations a big drop in power output more than 30 and I can see a second laser spot in the laser on its housing about 4 cm right to the normal laser beam exit In this case the clockwise running mode of the ring resonator is exited This can happen if the two surfaces forming the Piezo Etalon are adjusted perpendicularly to the laser beam so that reflected parts of the beam fully interact with the laser gain medium This may lead to complex intensity and polarization dynamics of the laser making the optical diode inoperable Therefore the orientation of the Piezo Etalon relative to the laser beam can be adjusted For this purpose there are two screws with black knobs on the opposite side of the two silver colored micrometer screws of the Piezo Etalon Observe the wrong laser spot on the laser housing and turn the screws to get rid of it Instead of the laser spot you
4. Figure 55 Device Configuration Administration dialog Matisse Commander 140 Device Configuration Administration Device Configuration Administration Active Configuration LISER ONE Default Configuration USER OMNE Device Configurations Factory Configurations Activate FACTORY THREE FACTORY TwO Make Default FACTORY ONE User Configurations Te USER OME EE LISER THREE USER Two Delete The Device Configurations control lists all available configurations differentiated by Factory and User configurations for a description what configuration means see Device Configurations see page 139 There is also the Active and the Default Configuration displayed With Activate or Make Default you can give any of the available configurations the corresponding status Only User Configurations can be saved deleted or newly created Active gt File will save the active configuration to a text file File gt Active will load a configuration from such a file Note Listing the various configurations saving or creating a configuration will interrupt the execution of the Thick Piezo Etalon control loop Matisse Commander 141 Advanced Options Tools Interactive Shell Matisse Command Command MOTBL POS Response SS lt IDA Matisse TS S N 05 25 20 D5 gt MOTBIIPOS lt MOTBIPOS 66664 Figure 56 Interactive Command Shell You can directly communica
5. Signal monitors the thin etalon error signal allowing for a rapid check of proper etalon operation by just a glimpse Matisse Commander 1 8 S N 99 99 99 Matisse Birefringent Filter Thin Etalon Piezo Etalon 5 Stabilization Scan Help Current Position 200 0 i Laser Locked Laser Power oo Pa I gt a un e cuj aa LI i 0 40 ui Es ID ci UT T c E P3 L9 o n m e 0 00 Clear Chart m Thin Etalon m Piezo Etalon J Scan T Direction m Stabilization Thin Etalon Signal Piezo Etalon Baseline Scan Piezo Voltage Slow Piezo Voltage A j IA PA UN ACA eat NO AI EN O O A O AN D D 25 05 c D 1 D D5 07 o 0 5 0 7 0 13398 0 00000 0 10000 0 35000 a a Figure 43 Main Window Your laser is now ready to work Matisse Operation 104 Aligning the Thin Etalon Monitor Diode to the intracavity beam reflection The Thin Etalon TE Unit consists of a thin quartz plate 400 um mounted on a solid metal frame which can be tilted with respect to the cavity laser beam by using a stepper motor The moveable plate is attached to a solid plate on which the stepper motor is positioned and which is mounted to the Matisse Base plate The reflection from the quartz plate is picked up by a aluminium mirror passed through a 35 mm converging lens and directed with a second aluminium mirror into a monitoring Photodiode Unit Before the photodiode unit there is an attenuation stage filter wheel plu
6. The Matisse dye circulator is equipped with a unidirectional check valve non return valve to prevent spraying of dye at start up due to air in the nozzle and in the dye supply hose This valve only allows the dye to flow in one direction to the nozzle and prevents air from entering through the nozzle when the circulator is not running The valve is pre adjusted and tested at the factory There are no user adjustable or serviceable parts on the valve Note Due to the valve s design the flow of the dye works against the pressure of a spring there is a little pressure drop of about 0 5 1 bar For starting up and shuting down the dye circulator it is strongly recommended to set the pressure control on the circulator bypass valve to 10 bar and not to the lowest pressure At very low pressures the dye may not flow perpendicularly down from the nozzle which increases the risk of missing the drain hole It may occasionally become necessary to disconnect the valve from the dye supply hose e g if the hose is to be completely drained during a dye change To disconnect the valve use a metric 14 mm wrench for the nut on the hose and counter on the valve housing with a 5 8 wrench Use adjustable wrenches if these sizes are not available Matisse Operation 91 When the valve and the hose are separated make sure that the ends are kept clean because any piece of dirt poses the danger of clogging the nozzle when the dye is running again
7. and 12 kHz Frequency Output Displays the calculated modulation frequency for the selected combination of Sample Rate and Oversampling Average This parameter determines how many cycles of the modulation are averaged before the controller action is calculated An increase in the number of averaged cycles lead to a betters signal to noise ratio of the control signal but makes the control loop less responsive Proportional Gain The Proportional Gain determines the magnitude of the controller action Low Proportional Gain will result in a slow reaction from the controller but overshoot will be avoided Phase Shift This parameters controls the phase shift that 1s applied to the modulation signal that is applied to the tweeter The modulation of the piezo etalon results in a small modulation of the cavity length and subsequently of the emission wavelength A direct feedback of the modulation to the tweeter removes some workload from the tweeter control loop For an optimal setting of the Phase Shift parameter you require an external optical spectrum analyser Amplitude Matisse Commander 157 This parameters controls the amplitude of the modulation signal that is applied to the tweeter The modulation of the piezo etalon results in a small modulation of the cavity length and subsequently of the emission wavelength A direct feedback of the modulation to the tweeter removes some workload from the tweeter control loop For an optim
8. base you can identify a repeating pattern where the strongest peaks are separated by one free spectral range Note that the peak structure does not exactly overlap with the input signal because there is an additional electronic filter on the way to the piezo The peaks due to higher order modes can be suppressed by walking the beam going into the cavity by tweaking mirrors 6 and 7 Do this in an iterative manner start with the horizontal control of 6 then switch to the horizontal control of 7 then do the same with the vertical controls For an optimal mode matching the image on the oscilloscope screen will look like this Tek JL Tria d M Pos 10 00ms MESSUNG E CHI Max 1 02 CHI Liss 1 00 CH2 Aus Max CH Aus Liss CH Aus Max 1 CH1 200m M 5 00ms Ext 0 00 o 0kt 07 15 33 lt 10Hz Matisse Installation 79 Even at optimum alignment the smaller peaks in between will however not disappear completely Due to the principle of the Matisse stabilization scheme it is also not necessary to remove them completely if the value for the Fast Piezo Lock Point is set correctly they will be ignored On the other hand the peaks should be kept as small as possible to obtain a good finesse A ratio of 1 10 or better should be achieved between the strong and weak peaks In case you cannot achieve the 1 10 suppression ratio by walking the beam you have to alter the position of the two mode matching lenses 3 4 F
9. compensate the changes of the beam path in the resonator by using mirror TM Observe the mode pattern on the laser housing to see if it is improves Do not make more than 4 to 6 steps When you find a good position you can use FM 1 and FM 2 in parallel decrease FM 1 and increase FM 2 by the same amount to shift the position of the beam waist in the crystal to further improve the mode quality Changes of the beam path introduced by a position change of FM 1 are compensated with mirror M1 Dye Matisse Changing the pump focus position can mitigate saturation effects in the dye jet Increase the distance between PM and dye jet by turning the translation stage knob of the pump mirror in steps of 1 8 turns Compensate for pump beam path changes with two adjustements screws of the pump mirror Observe the mode pattern on the laser housing to see if it is improves With increasing distance you will probably experience decreasing power If the pump mirror position change does not porduces the desired results start changing mirrors FM 1 and FM 2 as described for the Matisse Ti Sa case Instead of changing the position of one full turn per step use one half turn per step CHAPTER 12 189 Customer Service Warranty Sirah lasers are thoroughly designed and assembled and we take great pride in the reliability of our instruments Nevertheless each precision instrument will need occasional service Therefore our aim is not only to pro
10. loosening the screws DH1 and DH2 by choosing an appropriate neutral density filter and attenuator wheel position make sure you have a good signal to noise ratio a signal above 0 3 is recommended To proceed with locking the laser now refer to the Chapter Matisse Commander Section S Stabilization Matisse Installation 74 Optical Alignment Procedure for the Matisse X Reference Cell Figure 28 Topview of the Matisse X Reference Cell Unit The constitutive parts are numbered and explained below the picture If you consider installing the Reference Cell for the Matisse X version here is a step by step procedure which describes the setup and the optical alignment For the principles and the description of the Pound Drever Hall stabilization scheme please look into the Frequency Stabilization Chapter 1 glass substrate beam splitter picking off a small fraction from hereon named low intensity beam of the Matisse output beam 2 6 7 aluminium mirrors steering off the low intensity beam 3 4 telescope positive convergent and negative divergent lens for mode matching of the Matisse beam to the high finesse cavity 5 resonant EOM generation of the 20 MHz side bands 8 polarizing beam splitter PBS cube directs the back reflection from the high finesse cavity into the Fast Diode 9 quarter wave plate together with the PBS forms an optical diode 10 high finesse cavity a Fabry Perot
11. screws iteratively one should be able to overlap all the spots forming the tail such that you obtain a single spot of maximum brightness Matisse Operation 99 Placing the etalon back into the cavity Now 1f you want to place the etalon back in the cavity there are a couple of hints that might make achieving laser activity easier re insert the etalon in the cavity in its original place without tightening the screws on the ground plate and rotate it gently to the left and to the right 10 15 deg until lasing occurs if you have difficulties in getting the laser to work again make sure that the back reflection will not overlap with the incoming beam for a Ti Sapphire laser this can be easily checked by looking at the reflection of the green pump beam on the tuning mirror whereas for a dye laser one can trace back the reflection of the fluorescence spot do not make a direct attempt to tweak the etalon knobs first after fixing the etalon to the ground plate try pulling the M1 OC and TM mirror control knobs looking for laser flashes if you get the laser to work try and rotate the etalon to the left and right as described above trying to maximize the output power in searching of maximum output one should look at the back reflections of the Piezo Etalon which are visible on inner side of the lateral housing close to the Brewster window see photo below they should be brought together by alternatively turning the plastic knob
12. together with the mirrors from the mounts without the risk of mirrors dropping on the floor as shown on the Figure below Figure 49 Matisse mirror and mirror mount ring with the two o rings in place Figure 50 Use mirror mount ring to press the mirror in the metal ring Matisse Maintenance 122 To remove the mirror from the mount just gently pull the mirror with your fingers Two o rings are used in the mirror mounts When mounting the new mirror in the ring make sure that both of these o rings are present as shown on the figure below One thick o ring covers the bottom of the mirrors metal ring Another thinner o ring is used for squeezing This one needs to be wrapped around the mirror as shown in the figure Then place the mirror on the ring and squeezed it in the ring by using tool 6 see figure below Apply pressure on mirror mount ring 123 Dye Exchange Procedure This section describes the exchange of dye solution for the D version of the Matisse laser An exchange of the dye might be necessary if one wishes to use a different dye for accessing a different wavelength range see also the part about Exchanging the Matisse Optics Sets Also a fresh dye solution might be needed if the Matisse laser presents a decreased output power and instabilities flickering unstable locking etc A Drain the old dye from the circulator To drain the circulator it is convenient to place the circ
13. 1 Switch on your pump laser and allow for sufficient warm up time Please check your pump laser manual for details about the exact procedure and the necessary warm up time During this time take care that the pump beam is blocked before entering the Matisse laser If present use the internal shutter of your pump laser or any other suitable external beam dump 2 In the case of a Matisse TX first switch on the XBox Controller Switch on the Matisse electronics box and start up the Matisse Commander program 3 Place a power meter or any other suitable beam dump at the Matisse output port 4 Open the pump laser shutter or remove the external beam dump and apply pump power to the Matisse 5 Increase the pump power until the Matisse laser threshold is reached The energy level necessary for first laser operation depends on the mirror set and the current wavelength As a rough indication if pumped with a 532 nm beam and used at around 780 nm the Matisse should start lasing at about 2 5 3 W input power 6 Slowly increase the pump power up to 5 W At this pump energy most Matisse laser configurations should start lasing However for wavelengths at the edge of the tuning range of the used mirror set or at the limit wavelengths of the Ti Sa crystal itself even higher pump power might be necessary Your Matisse laser should now operate In this case please refer to the next Sections for a quick optimization of the Matisse output power I
14. 3 are sufficient to cover the entire wavelength spectrum see the Laser Description chapter Some effort has been undertaken so that the complete mirror change is possible in less than 30 minutes The focusing mirrors FM 1 and FM 2 are supplied with broadband coatings covering the entire tuning range of either the dye or the Titanium Sapphire laser Therefore changing the focusing mirrors is only necessary when changing from dye to Ti Sa set up or from T1 Sa to dye When changing from one mirror set to another the most simple procedure is to set the laser to a wavelength where the two mirror sets overlap Then operate the Matisse laser with medium pump power in order to have a stable output beam One by one unscrew all four mirrors to be changed and replace the removed mirror with the respective new one from the new mirror set After each replaced mirror the Matisse should restart lasing immediately and you should do a rapid optimization by tuning the exchanged mirror in order to come back or close to the initial power ATTENTION You are working and operation inside a laser Take great care to use the correct laser safety goggles and make sure that your work does not represent any danger for anyone else present in the laboratory The mirrors TM M 1 M 2 and M 3 are squeezed in metals rings which are then screwed in the massive body of the mirror mount Squeezing the mirrors in the rings by using o rings allows to unscrew the rings
15. Attenuator which has a range of 0 to 63 Smaller or bigger values will be coerced to the corresponding limit value Figure SI Drever Hall Setup parameters Matisse Commander 171 PDH Multiplexer Input shows which signal is currently as output from the multiplexer Modulation On indicates sets the status of the 20 MHz sideband generation and EOM active shows sets the control status of the intra cavity EOM C Pound Drever Hall Control E Basic Advanced EOM Slow Offset 127 a EOM Fast Offset 129 d Pound Control advanced Advanced Parameters With Fast and Slow Offset offsets in the fast and slow control signal branch for the intra cavity EOM can be compensated TX light remark Fast and Slow Offset and Attenuator are disabled Matisse Commander 172 Pound Drever Hall Waveforms Figure 82 Waveforms dialog PDH only available for Matisse TX DX and TX DX light E Pound Drever Hall Waveforms 3 i X Scan Upper Limit FAO 127639 scan Lower Limit 0 125598 sA Sampling Points 123 m Amplitude Sampling Mode D Average Modulation On EOM active Autoscale Y Axis PDH Multiplexer Input J Mixer Output Basic Advanced DSP Offset 103 m Phaseshift 150 The graph shows the various signals Photo Diode signal Phase Mixer output Slow Side EOM signal Transmission Diode signal that play a role for the PDH stabilization scheme b
16. Device 48 P Photodiode Attenuator Stages 32 Piezo Amplifier Board Input Characteristics 184 Piezo Etalon 154 Piezo Etalon Control Setup 154 Piezo Etalon Description 45 Piezo Etalon Dither 47 Piezo Etalon Optimization 93 Piezo Etalon Waveform 157 Pound Drever Hall Control Setup 170 Pound Drever Hall Error Signal Measurement e 175 Pound Drever Hall Frequency Noise 174 Pound Drever Hall frequency stabilization 52 Pound Drever Hall Waveforms 172 Powermeter 145 Precautions for the Safe Operation of Class IV High Power Lasers 13 Problems and Solutions 193 Index 195 R RefCell Frequency Noise 164 RefCell Properties Measurement 165 RefCell Spectrum Analysis 166 RefCell Waveform 163 Remove Wavemeter 142 Required Dye Solvents 30 Return of the Instrument for Repair 190 S S Stabilization 158 Safety Precautions 13 Scan 176 Scan Device Calibration with Wavemeter 182 Scan Device Configuration 178 Scan Setup 176 Service Box 9 Service Centres 191 Shipping Locks 58 Shut Down Matisse D 118 Shut Down Matisse T 118 Side of Fringe frequency stabilization 50 S Single Frequency Tunable Laser Physics 34 Slow Piezo Control Setup 162 Standard Units 8 Start Up 135 Start Up Matisse D 86 Start Up Matisse Ti Sa 85 System Components 9 T The unidirectional dye check valve 90 Thin Etalon 44 151 Thin Eta
17. For the BiFi used in this example we consider the following parameters n 1 55 aarctan n 57 17 B arcsin sin 1 55 32 83 60290 By choosing the above angles the optical axis c will always be in a plan parallel to the plate s surface In order to calculate the phase difference between the o and e ray one can use the dispersion equation ze n n 8 5 0 65 A4 1 5 x10 3 which is a good approximation to experimental data for the wavelength range 0 6 2 4 um The phase difference Ad between the ordinary and extraordinary ray will lead to a change in the polarization of the beam emerging from the quartz plate There will always be a wavelength for which the phase difference satisfies the condition Ad 27m and thus for this specific wavelength the phase will be retarded by exactly one wavelength leaving the polarization state unchanged All the other wavelengths will suffer a slight phase retardation coming out of the quartz plate with an elliptical polarization The thickness of the quartz plates should be designed in such a way that the resonance condition A 27m does not occur for plate orientation angles where the polarization of the incoming beam is exactly parallel or perpendicular to the optical axis since in this particular case there will be no reflection losses at the Brewster s angle In the following we calculated the spectral range for each of the three BiFis used with the Matisse laser Assuming a t
18. MOS2 750 880 Ti Sa MOS3 850 1020 Ti Sa MOS4 550 670 Dye MOSS 650 780 Dye has the same high reflective mirrors as MOS but a different output coupler Single Frequency Tunable Laser Physics 37 Frequency Selective Elements This section gives a description of the frequency selective optical elements used in the Matisse One important parameters of these elements except for the Birefringent filter 1s the Free Spectral Range FSR as described above The FSR of the Matisse ring resonator is about 160 MHz The following figure illustrates the effect on the laser mode spectrum of the Matisse Ti Sa laser by the various frequency selective elements in the case of the MOS2 optics set Intrinsic emission spectrum of titanium sapphire 900 950 1000 MOS 2 750 870 nm 60 THz 375 000 Modes 80Q 850 Fu A Birefringent Filter Thin Etalon FSR 250 GHz UT Mode spacing 160 MHz Thick Etalon FSR 20 GHz Figure 8 Laser mode spectrum in the case of the MOS2 optics set The schematic setup of the Matisse TR is shown in the figure below to illustrate the geometric arrangement of the various frequency selective elements Tuning Titanium Sapphire Thick Etalon Unidirectional iU Mirror Crystal Piezo Driven Device TID t 7 la O Pump Laser M Thin Etalon Birefringent Filter Output Input Motor Driven 3 Plates Motor Driven Coupler Figure 9 Matisse TR Setup Birefringent Fi
19. aligning the pencil mark with the upper allen screw Note that the birefringent filter for MOS 1 and MOS 3 has two marks if the two optics sets were shipped with the laser see next picture Take care not to wipe off the marks accidentally Make sure the birefringent filter is mounted parallel to the mount then carefully tighten the two allen screws of the mount Load the respective DSP factory setting for the new optical set The configuration administration is accessed via Matisse gt Configuration gt Configuration Administration in the Matisse Commander software Note that the wavelength which is displayed in the upper left side of the Matisse Commander changes upon loading the new configuration To make this configuration the one used at the start up of the Matisse control box press Make Default Use the Birefringent gt Goto menu to set the birefringent filter motor to a wavelength which yields the maximum output power for the respective optics set e g 750 790 nm for MOS 1 MOS 2 and 870 880 nm for MOS 3 A change of the birefringent filter causes a different beam displacement within the ring cavity To compensate for this use the horizontal adjustment screw of TM and of M3 after adjustment with TM has maximized the output power 133 CHAPTER 9 Matisse Commander Installation The Matisse Commander program runs on Windows 2000 Windows XP and Windows Vista 32 and 64 bit versions Installing the
20. alternately block one of the beams while watching the overlap tool After some iterations a precise overlap of the two spots at both positions can be achieved Do a check by putting the beam overlap tool between the beam displacement rhombus PS and FM1 If the adjustment is good the two spots will also be superimposed here Remove the two pin holes Make sure that there is no obvious dust on PM If there is any dust refer to the chapter Handling of Optical Components for cleaning Then increase the pump power to at least 5 W 12 If the laser is not already lasing observe the fluorescence shapes in the laser output Carefully pull at the mirror knobs at the laser output side M1 and M3 to see if there is a short laser flash and adjust the respective mirrors to reach lasing Matisse Installation 69 13 If you have trouble getting lasing action it might be necessary to remove the Piezo Etalon and to replace it with the Dummy Etalon a block of glass of a cuboid shape placed on a metal block which was provided to you with the blue Service Box Please note that the Dummy Etalon should be placed in the beam path at a Brewster angle A good guidance for the eye is that the longer edge should be positioned parallel to the Birefringent Filter see photo below Figure 27 The Dummy 14 Repeat the procedure described at step 10 Etalon Matisse Installation 70 Optical Alignment Guidelines for the Fiber Coupled Matisse S Referenc
21. applied to the piezo If the control loop is inactive the modulation is still applied Waveform This button opens the Piezo Etalon Waveform see page 157 window Advanced Settings Figure 73 Advanced tab of the Piezo control dialog Piezo Etalon Control Setup Basic Advanced Dither Frequency Control Loop Feed Forward Oversampling Average Phase Shift 31 110 A TJ A y 100 4 100 Sample Rate Proportional Gain r rI J 32 kHz j E 150 e 150 150 150 Frequency Hz 1032 3 26 13 A Amplitude 210 8 A Waveform Close Matisse Commander 156 The advanced tab is divided into three sections each section controls a different aspect of the piezo etalon Oversampling and Sample Rate control the modulation frequency Average and Proportional Gain control the action of the control loop Phase Shift and Amplitude the action of the feed forward to the tweeter Oversampling This parameter determines how many samples are used to synthesize the modulation waveform The minimum value is 8 the maximum value is 64 samples per period Sample Rate This parameter determines the rate at which each of the sample points is transferred to the piezo etalon The combination of Oversampling and Sample Rate determines the frequency of the modulation f mod Sample Rate Oversampling Valid Sample Rates are 8 kHz 32 kHz 48 kHz 96 kHz Hence the limits for the modulation frequency are 125 Hz
22. check its appearance in the different tubing sections 13 Slowly close the needle valve on the circulator in order to increase the dye pressure In a first step only increase the pressure by 1 4 bar Wait for 5 minutes Increase the pressure by another 1 4 bar wait another 5 minutes Continue to increase the pressure in similar steps until the pressure reaches 2 5 bar Wait for 5 minutes While doing these steps of increasing pressure check the dye flow in the drain back from the dye catching tube towards the pump Note that the dye drain is only driven by gravity If ever you realize that the tube s position does not allow proper dye flow e g because tube s slope is not sufficient then immediately switch off the dye pump and change the position of the drain If too much dye accumulates in the tube and does not flow back to the pump properly then in the worst case the dye may flow backwards out of the dye catching tube in your laser 14 If the dye flows properly with a pressure of 2 5 bar then carefully increase the pressure in one single step up to 4 bar Wait for 5 minutes increase the pressure to 6 bar and wait another 5 minutes Depending on the type of dye solvent you use this pressure may already be sufficient to operate your laser Furthermore laser operation is usually not limited to a single pressure value but is rather possible in a certain pressure range of up to some bar If you start with a new solvent and or dye you shoul
23. executing the scan position the scan piezo at 0 3 set the PZETL baseline to 0 and optimize the BiFi and the Thin Etalon positions For a Matisse TS DS or higher also set the Slow Piezo to 0 35 and lock the laser Set Scan Range to 0 1 and Scan Speed to 0 001 and press the Measure button to start the scan All control loops have to be active otherwise the function will abort and give a corresponding warning The scan may take several minutes to complete It can be aborted with the Stop button After completion the ControlScan values for the various optical elements are calculated Pressing Set will set these values for the active configuration To make the change permanent you have to save the active configuration see Device Configuration see page 139 Matisse Commander 181 Motor Control Figure 90 Motor Control dialog The motors for the Thin Etalon and the Birefringent Filter can be controlled directly You can move a motor to an Absolute Position by pressing Goto Keys F5 to F8 Big Increment down Small Increment down Small Increment up Big Increment up will change the motor position relative to the current one The increments can be set in the Motor Control Options dialog see page 181 press the Options button The Home button will set the motor to its home zero position defined by a hardware switch Motor Control Options CO Motor Steps Birefringence Filter Motor Control Small Increment 110 a Big Increme
24. in scan speed terms Figure 85 Scan Setup dialog Figure 86 Scan Timing aes creen E rem om upper limit o rising falling o speed speed c volts sec volts sec b a to EE oc scc Ml A O EE lower limit gt time Matisse Commander 177 Scan Control switches the scan off or on Scan Mode allows you to define scan limits in three different ways Start Stop defines the scan by its upper and lower limits Start Range defines the scan by its lower limit and and scan range from which an upper limit can be calculated Position Range defines the scan using the current position and a scan range to calculate the following lower and upper limits current position range 2 and current position range 2 You can store different scan setups including Scan Mode to the Matisse Commander configuration file Available Scans shows all stored scans Its default value is SDEVICE i e it shows the current scan setup in the Matisse DSP controller When you select a stored scan setup the scan data will be shown in the respective fields the current scan position will not change With Set this scan setup will be sent to the Matisse controller You can create new scans with New prompting you for a scan setup name do not use names starting with a sign Save and Delete will do the corresponding actions for the displayed scan setup except in the case of SDEVICE C
25. in going beam path by a combination of a doubly passed quarter wave plate and a polarizing beam splitter to the Fast Diode In general photo diodes act as an intensity detector E square of the electrical field Having three different frequencies in the spectrum means that the resulting diode signal will not only contain a constant component but also beat signals with frequencies that corresponds to the various differences of the three optical frequencies Especially the beat signals having a carrier frequency of the EOM modulation frequency Vinos are now used for generating a suitable frequency error signal For that purpose the diode signal is mixed with the modulation signal for the EOM which filters out just the desired signals with the v u carrier As a complication there are actually two signals with this carrier frequency but only one of which is usable as an error signal Fortunately the two signal have carriers that have a oscillation phase shift of 7 2 i e they are mathematically orthogonal like e g a sine and a cosine wave By applying a tunable phase shift to the EOM modulation signal before the mixer only the desired signal can then be filtered out The resulting theoretical Pound Drever Hall error signal in dependance of the laser detuning to the used non confocal resonator with a free spectral range of 1320 MHz and a Finesse of about typically 250 to 300 and a modulation frequency for the EOM of 20 MHz is shown below Th
26. in stepper motor steps The third element in the graph is a red vertical line cursor indicating the original motor position before the scan was executed O Birefringent Filter Scan Thin Etalon Reflex Birefringent Filter Scan Total Power Mm 0 6 zu 0 5 Set e A 1 Motor Position 259663 x JD a 4 o o o a E 2 0 3 Zu zi us a E i to E h I np 0 07 I I I I I I 170 3 253000 254000 255000 256000 257000 258000 259000 260000 Birefr Filter motor position The blue curve has a step function form Within each step the Birefringent Filter might be set to an arbitrary position without changing the Matisse laser frequency If you change the motor position from one step to the next one the Matisse frequency will change normally by one Free Spectral Range of the Thin Etalon see the Single Frequency Tunable Laser Physics see page 34 chapter for more details Figure 40 Move the Birefringent filter to the position correspoding to maximum laser power without hopping onto another step of the blue curve Matisse Operation 101 The Birefringent Filter position can be set by moving the red vertical cursor shown in the graph Once the acquisition is finished move the mouse cursor on the red vertical line and drag the line by clicking on it with the left mouse button pressed Move the filter to about the center of the step of the blue curve where the original motor
27. in the Matisse Dye Ring Cavity In order to prevent the Matisse ring cavity to run at higher transversal TEM modes one needs to clip the cavity beam by inserting a ceramic aperture pinhole This 1s usually only required at a pump power of 10W or higher If a pinhole is delivered with a new Matisse laser it is to be found in the blue Matisse service box Required tools Metric Allen key set from the blue Matisse service box Powermeter Optical spectrum analyzer IMPORTANT The alignment procedure requires working within the running laser Be extremely cautious and especially make sure you do not interfere with the pump beam Start the installation procedure with a running and well adjusted laser If you are not familiar with the layout of the Matisse laser refer to the section Optical Set Up Matisse DR in the chapter Matisse Laser Description of your manual The pinhole mount will be fixed at one side of the thin etalon Thin E mount This will locate the pinhole between the thin etalon and the piezo etalon Piezo E This position is chosen because at this point in the ring cavity there is a second beam waist The pinhole is much bigger than the cavity beam to facilitate the alignment To suppress higher order laser modes it is sufficient to bring one edge of the aperture close to the cavity beam Matisse Installation 82 Close the shutter of your pump beam source Loosen the M6 Allen screw at the baseplate of t
28. limit the lower voltage limit either of them or neither of them Scan Control switches the scan off or on Once the scan is defined it can be started or stopped by simply clicking on Scanning in the Scan menu or on the Scan LED in the Matisse Commander window Matisse Operation 118 Shut Down Matisse T Switch off the pump laser Exit the Matisse Commander Switch off the Matisse electronics box and in the case of a Matisse X also the X Box controller Shut Down Matisse D O N O O Switch off the pump laser Open the Matisse top cover Loosen the fixing screw of the spray guard and move the guard to its lowest position The dye jet should be completely hidden inside the spray guard Open the needle valve on the dye circulator The dye will no longer flow to the sapphire nozzle but follow the bye pass Decrease the pressure to minimum 10 bar Switch off the dye circulator Close the laser cover Exit the Matisse Commander Switch off the Matisse electronics box and in the case of a Matisse X also the XBox controller CHAPTER 8 119 Matisse Maintenance Handling of Optical Components The good condition of all optical components mirrors beam splitters etc is an essential requirement for optimal performance of your Matisse laser Hence you should routinely check and clean all its optical components Avoid to touch optical elements with your fingers The fat persistent at the fingers collects on the sur
29. mm Matisse output port Beam Divergence 2 mrad Linewidth 20 MHz rms Amplitude Noise 3 5 rms Beam polarization horizontal Requirements Pump laser Millennia Pro Series or similar Pump laser power 5 20 W Matisse Laser Description 29 Ambient conditions constant temperature in the 20 25 C range non condensing humidity conditions Laboratory vibrational isolated optical table dust free air flow box Electrical 100 250 V max 2 5 Amps Computer control Windows 2000 or Windows XP system USB port Matisse Laser Description 30 Required Dye Solvents Required solvents to be used with the Matisse dye circulators are Ethylene Glycol EG Ethylene Glycol Phenyl Ether EPH and Propylene Glycol Phenyl Ether PPH because of their lubricant properties Other solvents will damage the dye circulators Use only EG which has a purity of at least 99 5 It 1s also very important that solvent s acidity is zero The dye concentration should be chosen in that way that at least 85 of the pump power is absorbed The following table contains solubility data g l for various dyes in the required solvents courtesy of Exiton Inc Solubility of Dyes in EG EPH PPH grams liter Matisse Laser Description 31 Rhodamine 560 Chloride Rhodamine 590 Chloride Kiton Red 620 Perchlorate E LDS698 099 LDS722 B i LDS751 LDS759 j LDS821 LDS867 AE 67 LDS925 LD700 Perchlorate Oxazine 750 Perchlor
30. range scan increment and the initial motor position can be set in the Thin Etalon Control Position Options see page 153 press the Options button or F2 The current motor position is shown as a cursor red line within the graph in the Thin Etalon Scan graph and in the Motor Position control You can change this position by changing the position control and pressing Goto Pressing Start will execute the scan that can be aborted by the Stop button Set will move the motor to the position the cursor in the graph points to and the control goal value will be set It is the ratio of the thin etalon s reflex and the total power at that position For keeping the Thin Etalon synchronized with the movements of the Piezo Etalon the reflection from one etalon facette is monitored and compared to the total laser intensity The TE control loop will adjust the TE position so that the ratio of these two signals is kept constant Figure 72 TE Control Position Options dialog Matisse Commander 153 Choosing the right control point is important for achieving stable modehop free single mode operation of the laser After a scan you should see a curve for the thin etalon reflex that consist of a succession of parabolas with minima Set the cursor by dragging it with the left mouse button pressed on the left flank of a parabola close to 1ts minimum and press Set if Flank Orientation is selected to be Left Set the cursor by dragging it with the left m
31. scan A typical result is shown below for a description of the graph s elements and the signal forms see the Thin Etalon and Birefringent Filter Optimization section see page 100 Figure 45 Result of a Birefringent Filter motor scan Blue curve thin etalon reflex Red curve total Matisse power Both in arbitrary units Matisse Operation 115 O Birefringent Filter Scan Thin Etalon Reflex ioe Birefringent Filter Scan Total Power om 0 6 0 5 C A I Motor Position J 259663 Thin Etalon Reflex C F c j j Bo AaiMOg 2301 e Nm 1 D 1 0 07 I I I I I I 170 3 253000 254000 255000 256000 257000 258000 259000 260000 Birefr Filter motor position Press Set and note down the wavelength frequency Now move the red cursor to the center of the next step of the Thin Etalon reflex signal and press Set again A comparison between the current and former frequency should reveal a difference with an absolute value of one FSR TE The change in frequency going from step to step in one direction is monotonous So what you have to do is to find the direction and motor position range step in which the absolute value of difference between current and desired frequency decreases and gets minimal This positioning procedure of the Birefringent Filter motor will allow you to set the laser within the range of 0 5 x FSR TE around the desired frequency for a standard configuration this corresp
32. selecting them with the left mouse button pressed With Open File Save Save As you can open or save files containing calibration table data Fit will fit the table data to the calibration function Wavelength WLOff WLFac sin 2 arctan LLen pos LOff Matisse Commander 150 The Coefficients have to fulfill certain conditions WavelengthOffset WLOff has to be greater than the maximum wavelength occurring in the table WavelengthFactor WLFac has to be negative Good start values might be maximum wavelength in table 50 for WavelengthOffset 400 for WavelengthFactor 2e 6 for LeverLength LLen and 100000 for LinearOffset LOff On opening the Calibration Table dialog the Coefficients indicator gives the current function parameters WLOff WLFac LevLen LinOff used by the Matisse controller After a fit is executed it will contain the newly calculated numbers together with the Maximum Deviation and the Mean Deviation of the fit result If Show Graph is ticked a graphical representation of the fit result and its errors is shown after a fit has been executed Set CalPar will program the displayed Coefficients into the Matisse controller To make this change permanent you have to save the active configuration see Device Configuration see page 139 available only with wavemeter support Birefr Scan will open the Birefringent Filter Calibration Table Birefr Filter Scan see page 150 dialog where a scan over
33. should use the Scan Device Calibration with Wavemeter procedure in the Wavemeter see page 141 menu because this gives also the sign of the conversion factor that is important for advanced function of the wavemeter plugin Determining the Conversion Factor in the general case for a Matisse and a wavelength frequency device is as follows define a a scan for the Matisse with a specific scan range e g 0 1 see Scan Setup dialog see page 176 Measure the laser frequency at the start of the scan execute the scan and measure the laser frequency at the end of the scan Divide the frequency difference in MHz by the scan range and enter the result into the Conversion Factor control Matisse Commander 179 ControlScan Setup ControlScan Setup Scan Device Slow Pieza Birefringent Filter 590 885 Calc BiFi Factor A Thin Etalon 3500 al Thick Piezo Etalon 3 599090 al Slow Piezo fe 2 Figure 88 ControlScan Setup dialog The ControlScan parameters are factors that are multiplied by the change of the nominal scan piezo voltage change and added to the position of the corresponding elements Birefringent Filter Thin Etalon Thick Piezo Etalon and the Slow Piezo the latter element is only of importance for Matisse models TS DS or higher These parameters are essential for fast scans scan speed of 1 GHz s The position changes will be executed even if the control loops for these elements are not active Th
34. signal for the transmitted light has a nominal value range from about 0 2 to 0 4 The signal maximum value should be lower than 0 25 Adapt the filters accordingly open the Fast Piezo Control Setup see page 160 dialog set the Setpoint to a value about half of the maximum peak signal seen in the Waveform display make sure the slow piezo baseline is in the middle of its range activate the lock by clicking on the RefCell Control LED indicator in the main window or ticking the Control On item in the RefCell Stabilization menu Troubleshooting If no lock can be obtained stop the RefCell Control loop Open Matisse gt Advanced Tools amp Options gt Control Loop Live View Set Protocol to FPZ The upper graph in this case will show the photo diode signal the red line corresponds to the FPZ Lockpoint Let this window open and switch on the RefCell Control loop Observe now the upper graph When you switch on the control loop and there is no lock then the slow piezo starts scanning the laser to find a resonance of the reference resonator You should see after a while in the upper graph the peaks of the resonator spectrum appear If you cannot see that the FPZ lock is setting in then you should decrease the Free Proportional Gain parameter in the Slow Piezo Control Setup see page 162 dialog This parameter determines the scan speed of the slow piezo If you see that the fast piezo control loop tries to lock to the setp
35. spectral range of FSR RefCell MHz and a finesse of Finesse These values have to be adapted to your Reference Cell for an X Matisse model the FSR has normally a value of 1320 GHz You also need the PDH Error Signal Maximum Intensity and PDH Error Signal Maximum Intensity values that can be determined with the PDH Error Signal Measurement see page 175 dialog The Maximum Deviation MHz and the RMS Deviation MHz gives you some statistical properties for the displayed sample series Matisse Commander 175 Pound Drever Hall Error Signal Measurement Only available for Matisse TX DX and TX DX light Pound Drever Hall Error Function Measurement E IOl xl Scan Device Reference Cell Piezo Measure Scan Range Jl 0 02 EI Scan Increment es A I I I l I I I 0 243 0 24325 0 2435 0 24375 0 244 0 24425 0 2445 0 24475 0 245 Scan Position w Min Max 0 131897 0 134033 Set Min Max Figure 84 PDH Error Signal Measurement Measure will perform a sampled scan with a range of Scan Range and an increment of Scan Increment with the current Scan Device either RefCell or Slow Piezo while measuring the PDH error signal value For the scan to be successful the positions of the Thick and Thin Etalon have to be optimized and the corresponding control loops have to be active beforehand In the case of the RefCell as scan device the RefCell control loops will be switched off automatically After closing t
36. state Matisse Commander 139 Matisse Tools and Options Device Configuration Figure 54 Device Configuration Menu Matisse Commander 1 2 S N 99 99 99 Birefringent Thin Etalon Piezo Etalon Scan Help Configuration Configuration Administration Advanced Options amp Tools gt Set Active as Default Conf Set Control Switch OFF Level Save Active Powermeter Load Configuration From File Motor Status Sawe Configuration Eo File Display Options Exit Ctrl 0 70 A device configuration comprises the various parameters for the control loops the Birefringent Filter calibration parameters the scan setup the switch off level etc that are stored on the Matisse DSP controller board Two different kinds of configurations are available Factory and User configurations Factory configurations are preset and can not be changed It is possible to have several user configurations that can be newly created changed and saved There is a default configuration that is used at every start up of the Matisse controller To fully administer the various device configurations see Device Configuration Administration see page 140 This menu lets you make the active configuration the default one save the active configuration to the Matisse DSP board or to a human readable text file Also you can load configurations from a file Note Saving the active configuration will interrupt the execution of the Thick Piezo Etalon control loop
37. the Birefringent Filter motor positions is executed simultaneously measuring the wavelength with the help of an external wavemeter Birefringent Filter Calibration Table Birefr Filter Scan only available with wavemeter support In this dialog a scan over the Birefringent Filter motor positions can be executed while simultaneously measuring the current wavelength with the help of an external wavemeter The scan start and end positions and increment can be set in the Birefringent Filter Calibration Table Birefr Filter Scan Options on page 150 press the Options button or F2 The range of motor position that is imported into the Calibration Table see page 149 1s determined by the two red cursor vertical red line in the Birefringent Filter Scan graph Change this range by dragging the cursors to other positions Pressing Start will execute the scan that can be aborted by the Stop button Birefringent Filter Calibration Table Birefr Filter Scan Options only available with wavemeter support These controls determine the Scan Start Scan Start and Scan Increment of the Birefringent Filter Calibration Table Birefr Filter Scan see page 150 Matisse Commander Thin Etalon Thin Etalon Control Setup 2 Thin Etalon Control Setup E Average rr A Proportional Gain Flank Orientation Left 4 Gain Parameter Scaling Thin Etalon Control C Figure 70 TE Control Setup dialog 151 In this dialog
38. to feed an external signal into the amplifier module 13 Thin etalon manual control Two way switch to control the stepper motor that controls the tilt of the thin etalon 14 Thin etalon indicator Lights up when the etalon motor is running LED 15 Thin etalon error Lights up when an error condition is present at the etalon motor controller unit LED 16 Birefringent filter manual control Two way switch to control the stepper motor that controls the rotation of the birefringent filter assembly 17 Birefringent filter indicator Lights up when the etalon motor is running LED 18 Birefringent filter error Lights up when an error condition is present at the etalon motor controller unit LED Figure 6 Rear view of the Matisse electronics box 1 X1 Connector This mixed signal sub D connector is used to connect the laser head to the control unit Matisse Laser Description 25 X2 Connector This mixed signal sub D connector connects the thin etalon stepper motor with the control unit X3 Connector This mixed signal sub D connector connects the birefringent filter stepper motor with the control unit AC Input Connector This connector also holds the fuse for the unit Rating 1 6 A 250 VAC Matisse Laser Description 26 Matisse TR Specifications This section summarizes the specifications of the Matisse TR laser Please note that specifications are subject to change without notice Tuning range Pump laser Op
39. was shipped in a container specially designed for this purpose Upon receipt of your system inspect the outside of the shipping container If there is any major damage insist that a representative of the carrier being present when you unpack the contents All Sirah laser containers are equipped with shock and tilt indicators Carefully inspect these indicators If any of them is actuated insist that a written confirmation 1s done on the shipping papers signed by the carrier If the transport boxes are in good condition and none of the shock and tilt indicators is actuated then carefully unpack and inspect the laser system and all accessory parts Each system is accompanied by a packing slip listing all the parts shipped Verify that your system is complete and undamaged In case of any problems like damaged or missing parts please immediately notify the carrier and your Sirah sales or service representative Addresses may be found in the Customer Service Chapter Keep the shipping containers If you file a damage claim you may need them to demonstrate that damage occurred during transport If you want to move your laser to another laboratory building or if you need to return the system for service the specially designed container assures adequate protection System Components Service Box The following components comprise the Matisse laser system Matisse laser head Matisse electronics box Matisse service box Matisse
40. you can determine the behavior of the Thin Etalon control loop by setting the loop s parameters like the Proportional Gain Integral Gain and Average which is the number of measurements the loop is averaging to compute the error signal Thin Etalon Control will switch the control loop on or off Flank Orientation determines on which flank of the Thin Etalon parabola structure in the Thin Etalon Scan see page 152 the laser is stabilized Gain Parameter Scaling enables the linear scaling of the two control loop gain parameters with the control loop setpoint set with the Thin Etalon Scan see page 152 procedure Changing the controls values has an immediate effect on the control loop Matisse Commander 152 Thin Etalon Scan C Thin Etalon Scan Thin Etalon Reflex Fa Thin Etalon Scan Tatal Power a STOP Set Motor Position 2118360 a Flank Orientation 5 Left d M n E 5 or co E cue i n a k Lu m E R E E 0 0 I I I I I I I I I I I I I I 0 3 7000 7200 7400 7600 7600 8000 8200 8400 s600 ss00 3000 9200 9400 9600 2800 10000 Thin Etalon motor position Figure 71 TE Control Position dialog In this dialog a scan over the Thin Etalon motor positions can be executed to set the control position for the Thin Etalon control loop T wo signals are recorded the total laser power and the intensity of the thin etalon s reflex The scan is centered around the current TE motor position The scan
41. 2 Set the pin holes on the mirror side facing the crystal Adjust the pump beam with the help of the pair of pump mirrors PM1 and PM2 so that it passes through the centers of the two pin holes Make sure that the pump beam has the correct polarization p polarized Loosen the plastic screw at the half wave plate on the Matisse input and rotate it so that the power of the pump beam reflex from the Ti Sa crystal on the little beam blocking sheet is minimized Figure 24 Color Filter Figure 25 Overlap Tool Beam Matisse Installation 65 7 In the service box you will find a mounted green filter red glass 8 plate Put it into the laser between the crystal mount and the second folding mirror FM2 so that residual pump beam radiation circulating through the resonator is filtered out Align it perpendicularly so that the back reflected green spot hits the pinhole center on FM2 Increase pump power to about 1 W An IR viewer will help you in observing the fluorescence spots Note that the spots may not have the same size at different positions within the ring cavity Place the beam overlap tool between the output coupler M1 and the Brewster window at the output Make sure that the fluorescence spot originating from FM1 has got the correct height To adjust the height slightly adjust the height of the beam path through the two pinholes using PM1 and PM2 Place the beam overlap tool between the Piezo Etalon Thick
42. 4750 75000 75250 75500 75750 Birefr Filter motor position 0 9 0 8 e E I E e 1 Aai g e30 1 x E D a E S m E Lu aba 0 5 0 4 In this dialog a scan over the Birefringent Filter motor positions can be executed Two signals are recorded the total laser power and the intensity of the thin etalon s reflex The scan is centered around the current Birefringent Filter motor position The scan range and increment can be set in the Birefringent Filter Scan Options see page 148 press the Options button or F2 The current motor position is shown as a cursor vertical red line in the Birefringent Filter Scan graph and in the Motor Position control You can change this position by changing the position control and pressing Goto Pressing Start will execute the scan that can be aborted by the Stop button Set will move the motor to the position the cursor in the graph points to Achieving maximal laser output requires the Birefringent Filter to be positioned optimal in relation to the thin and thick etalon After a scan you should see a curve for the thin etalon s reflex that looks like a step function Set the graph s cursor by dragging it with the left mouse button pressed about into the center of such a step so the position coincides with a local maximum of the total laser power and press Set If Set is not used the motor will stay in the scan s end position when you close the dialog
43. E and the TGG plate TGG Adjust the beam height with the vertical adjustment of the tuning mirror mount TM Remove the beam overlap tool and using a small strip of paper make sure that the beam passes through the TGG plate and hits the middle of M3 This is especially important for the actively stabilized Matisse versions because there M3 1S rather small Figure 26 The Dummy Etalon Matisse Installation 66 10 Superimpose the propagation paths of the two fluorescence spots the 11 beam path from FMI to the output coupler M1 serves as the fixed path to which the beam from FM2 will be aligned using M1 and M3 Put the beam overlap tool between the Birefringent Filter B1F1 and the output coupler M1 Bring the spot from FM2 closer to the fixed spot using only M3 Then put the beam overlap tool between FMI and the Thin Etalon mount Thin E Overlap the spot from FM2 with the fixed spot using only MI Put the beam overlap tool back to the first position between BiFi and M1 and repeat the procedure To distinguish between the two spots as they get closer alternately block one of the beams while watching the overlap tool After some iterations a precise overlap of the two spots at both positions can be achieved Do a check by putting the beam overlap tool between FM2 and the Piezo Etalon If the adjustment is good the two spots will also be superimposed here Remove the color filter and the two pin holes Make sure that th
44. EE C E ELS NE Tr 181 Motor Control Pt OMS aia ses dae oni sont eu moo eate OUR oi dedo Code dork anta ooa ado NES osa ewan dee Ua dob o Rada eve do Qs aa UN 181 honus A 182 Scan Device Calibration with Wavemeterr cccccccsccecceccecceccscscecceccecceccsscescecescescescescscesceecs 182 Contents iv ERA 183 Matisse Electronics 184 DSPInput ChatcteEStC8 iii iia 184 Piezo Ampliier Board Inp t CharactettSteS netsh dee ee aes 184 Fast Piezo Amplifier Board Input Characteristics esessesessssseeeereresssssssssececrreeessssssssseceeresessssesseseeeeeee 185 Frequently Asked Questions and Troubleshooting 186 Customer Service 189 VY AM RIN UN lp tee ad ta cT PE NEN 189 Return or the Instrument TOt ROPA id 190 Snes BONN A E IO 191 Problems and Solutions A A A baa tbc us tede 193 Index 194 CHAPTER 1 Matisse Preface Thank you for purchasing the Sirah Matisse laser system This manual was written to show you how to safely install operate maintain and service your laser system An attempt was made to describe the laser both accurately and completely However due to the continuous progress in technical development discrepancies between the present manual and the delivered laser system may occur Before applying pump laser power to the laser system it is strongly recommended to read this manual thoroughly and to understand its content The present manual opens with a chapter on Laser Safety The Matisse
45. FORE the dye jet In any case you should make sure that the position of the three elements PM FM1 amp 2 does not deviate too much max 1mm from the predetermined mirror distances PM 29 FM1 37 5 FM2 52 5 If you gradually move the pump mirror towards the dye jet you will most likely reach a point where the laser becomes very unstable This position corresponds to the pump beam being focused to strong onto the dye jet a fact which leads to thermal induced refractive index inhomogeneities in the dye jet causing the cavity mode to break down When searching for the optimal focusing position every time you move the PM mirror back and forth one will notice a drop in power which can be compensated by tweaking the horizontal and vertical controls of the PM mirror Please note that for each position of the pump focusing mirror PM you will have to optimize the FMI 42 When approaching the critical point the symptoms will be increased sensitivity of the horizontal and vertical controls of the PM as well as strong flickering or even complete loss of lasing Also the mode structure will be scrambled beyond recognition Output Power vn Figure 44 Output Power versus Pump Focusing Distance Matisse Operation 113 The threshold at which this phenomenon occur depends on the pump power level and the dye flow rate dye circulator pressure The graph below illustrates the relationship between the output power and the pump focusing mirr
46. Matisse Look at the spot coming from mirror FM 1 hitting the laser housing between pump beam entrance and TM mirror mount Optical Setup Dye see page 21 Complex pattern or pattern dynamics in the central spot are the result of these instabilities Some dynamics on the spot fringes does not play any role Getting a better laser mode may require changing the distances between folding mirrors FM 1 and FM 2 and the gain medium with the help of the translation stages For the Matisse Dye changing the distance between pump mirror PM and the dye jet can also help Before you start using the translation stages make sure the knobs of the corresponding lead screws have marks so that you can clearly identify the amount of change you introduce If there is no clearly visible mark make one with e g a felt tip pen Note down the turns and their directions so that you can easily get back to original positions if necessary One full 360 turn of a knob will change the distance by an amount of 0 25 mm Turning knobs clockwise will decrease the corresponding distances mentioned above turning counter clockwise will increase them Ti Sa Matisse Decreasing the mirror distances will increase the laser mode volume and so mitigating saturation effects in the Ti Sa crystal Frequently Asked Questions and Troubleshooting 188 Start using the translation stage for mirror FM 2 Decrease the distances in steps of one full knob turn At each step
47. Matisse Commander 148 Birefringent Filter Scan Options e Birefringent Scan Options E Scan Range 1 3000 Scan Increment 150 all These controls determine the Scan Range and Scan Increment of the Birefringent Filter Scan Figure 68 Birefringent Filter Scan Options dialog 149 Matisse Commander Birefringent Filter Calibration Table Figure 69 Birefringent Filter Calibration Table Editor 06 017049 oo 192399 04 615674 B3 795573 az grs 02 406044 Bl1 592091 700 779069 10 53 40 780 211279 79 401189 78 582892 78 030611 77 222643 Brent 76 418739 75 616701 75 056293 774256857 127207 Coefficients max deviation al 843 910912 Derti KE mean deviation 0 086656 Set CalPar Show Graph a2 1 597 430108 ul a3 1 115709E 6 at i 198566 702983 A The laser s wavelength can be calculated to an accuracy of 1 nm if there 1s an adequate calibration function for the Birefringent Filter motor positions The calibration table represents the relationship between wavelengths and motor positions that will be used to calculate a corresponding function To get data set the laser to a known wavelength and enter it into the table Get MOTBI Pos will retrieve the current MOTBI position and fill it into the active row Click into a row to make 1t the active one Sort will sort the table row in descending order of the wavelengths You can Delete marked rows Mark rows by
48. Matisse User s Guide Version 1 10 Sirah und Plasmatechnik GmbH Contents Matisse Preface 5 Enytroni ental PEC sa E T ne anew N E A A 7 CE Electrical Equipment Requifetle lbs sordide ata 7 Environmental Conditions Re quite MENS ela 7 St NC AGS IS D 8 Unpackine and AAA E O 9 System COMPONEN aora cDopetutudu Lael tub eden en oS imd de ON T e edu lU Rs 9 Snap died C P 9 CE Declaratroncor G OBPFOFLTOIL i355 caterngs tases a eto e Use ra ento unde son doe dou noia ue eo aaue 11 Safety Precautions 13 Precautions for the Safe Operation of Class IV High Power LaserS ooooonnnnnccccnccnccnnononoocconccncnncncnnnonnnnnnos 13 Dangers Caused by Laser Dyes AMA SoLVetits 2 te ecd toad aclu na uo ase sesame ated totu De tad d ae Uu ip SU Rd Qd UE 15 Focused Back Reflection ange sucio i eee pe atm hore M Ded acu Sd PRO o dte T dede Die Dusa ee dead Us ludi duoqodr 16 Matisse Laser Description 17 Laser Head Titanum Sapphire Models SA pias weave V REN inn en alas 18 Laser Head Dye MOElS dalt 21 Controls Box Front and Rear Panel Pete a A das 23 Matisse TR Speci Nea nO ne a a E Qu oU UL Eedoa s 26 Matisse DR SPEC ICAU ONS ean inb dodudmsaidtushede Sao auedu taco bx lunsu din iocos eique iedestan tec au fb aca 28 R quitted Dye SolventSa quta A Aouad UI 30 Matisse Relerence C ellas Usen dono 32 Photodiode Attenuator SAS a 32 Single Frequency Tunable La
49. O e anak cua Te crus 86 The unidrtectronaldye CHECK Valve catador 90 Matisse Powe t Opu Zato e o o ISI do bete DUE 9 Cavity Minor O pOr te pean sederet A eei MeL cual om o epu ee 02 PICZO Etalon ODUNDIZdUOIL eoe toducue tato eed eo dad 93 Thin Etalon and Birefringent Filter Optimization oooonnnnnncncnnncncnnnnnnnnnnonnncnnnnnonnnnnnonononnnncnnnnncnnnnnos 100 Matisse Dye Ring Cavity Mode Optimization es riada 109 ANS A O A OE Nerone estare ai UuO 114 Fregene SC ANNO eH A da 117 SAUCEDO WA MAOUSSes Lis to a 118 Shut Down MadussesD sir ies to mites E E 118 Matisse Maintenance 119 Handlinv or Optucal COMPOREMS AA a 119 VIO EOS DOO tossed on S 121 Dye Exchange Procedure it SEA edd text botte PM du cilia a riduce audias 123 Exchangime The Matisse OpHos Seb MOS tada cou cua dedican a e C ta dd sa Uere d ua dud 130 Matisse Commander 133 A OI O 133 A istos dices cunt edunt Lo d d unb tem Ua S 133 Matisse Commander 126 adi o 133 Matisse Commander M M ES inci ea UN a habeas Dak A aaa 134 Matisse Commander Lodo rd 134 Genre roda ac OUS 134 Start Dio cU 135 Error DIOS io cee asa etc esti a cda 136 Key NAVA AON a RR 136 W AVEIMELET SUP POLE HE 137 Pam Ware Update 0 TP 137 Contents iii IVAW BO TTE Em HERUM 138 Matisse Tools and O DUODS os 139 D vice BUND Te 139 Advanced OpHOBS Ss TOO aos 141 Controls wie OI Loveless 144 Power me teh acter T ET T IM 145 Motor SCA GUIS so ctis E e e aia 145 DISPLAY ODIOS usd etes A Hooded to
50. This is especially true for solvents as e g benzyl alcohol DMSO dimethylsulfoxide p dioxane and methanol Therefore we highly recommend always to wear protective gloves laboratory overalls and a protective mask when handling laser dyes and solvents Your chemical supplier can give you further information concerning storage handling and waste management of laser dyes and solvents Almost all solvents are highly inflammable and volatile a fact that should always be remembered when handling these substances Especially smoking is strictly forbidden In the following list some further safety precautions for the handling of dye solutions are given If possible use an outlet for handling solvents and dye solutions Otherwise ensure a sufficient ventilation of the workshop place Do not eat drink and smoke during your work with solvents and dye solutions Avoid all kinds of open fire Repair damages or leakage in the dye circulator system immediately without modifying the technical construction of the pump systems Install a suitable fire extinguisher next to your dye laser Safety Precautions 16 Focused Back Reflection Danger Focused back reflections of the pump as well as the Matisse laser s beam represent a serious hazard for both your personal safety and optical components Remember that an uncoated glass surface reflects 496 of the impinging light and even with an appropriate anti reflective coating 0 5 o
51. al range that is determined by the configuration of output coupler birefringence filter and thin etalon To maintain the exact match of etalon and longitudinal mode the spacing of the etalon is dithered by an piezoelectric actor and a lock in scheme is used to control the etalon spacing Thin E Thin Etalon The thin etalon is used as a bandpass filter To provide tunability the tin etalon is attached to a motor driven mount A step motor controls the horizontal tilt angle of the etalon EOM Electro Optical Modulator The non resonant intra cavity electro optical modulator is used for fast change of the optical path length of the ring cavity The effect is used for high bandwidth correction of the Matisse s emission wavelength Note The device is only present in the Matisse DX TM Tuning Mirror The exact emission wavelength of the cavity is determined by it s length The tuning mirror is attached to a long stroke piezoelectric actor to allow the selection of this wavelength This device is used for low bandwidth woofer correction of the Matisse s emission wavelength when active wavelength control is enabled only available in Matisse DS and DX models DI Matisse Laser Description 23 Integral Diode The lock in control for the piezo etalon requires the measurement of the temporal behaviour of the integral intensity of the ring laser For this purpose the leak intensity on the backside of the out of plane mirror M2 is used DE E
52. al setting of the Phase Shift parameter you require an external optical spectrum analyser Changing the controls values has an immediate effect on the control loop To make changes permanent you have to save the active configuration see Device Configuration see page 139 Piezo Etalon Waveform C Piezo Etalon Waveform D a a T l l l l l Ou 4001 600 BOO 937 5u Time sec 1 032 Modulation Frequency kHz The graph shows the AC part of the total laser power The curve should be stationary when the Piezo Etalon control loop is on and should have a sine like w shaped harmonic form starting with a maximum S Stabilization Matisse Commander 158 only available for Matisse TS DS The Matisse laser frequency can be stabilized by locking the frequency to a mode of an external reference resonator using the side of fringe locking technique Pertubations that might destroy this lock are counteracted by an actively controlled laser cavity mirror mounted on a fast piezo actuator FPZ An actively controlled slow piezo SPZ acting on another laser mirror ensures that the FPZ will always have its full dynamical range to react on pertubations How to lock the Laser open the RefCell Waveform see page 163 display and set Scan Upper Limit to 0 1 Scan Lower Limit to 0 Oversampling to 128 and Sampling Mode to Average Optimize the adjustment of the laser beam into thee reference resonator The photo diode
53. alf wave plate The distance between pump laser and Matisse laser should not be too big about 10 to 30 cm You might find a beam tube grey plastic tube in your laser service box that should be installed between pump and Matisse laser to minimize perturbations caused by air flows Position the Matisse on your optical table so that the pump beam passes through the entrance opening and runs parallel to the Matisse housing The focusing pump mirror PM needs to be hit exactly in the middle Its distance should be about 40 mm from the pump spot in the dye jet The transmitted pump light should hit the beam dump next to the folding mirror FM 1 With these conditions fulfilled the beam may not pass exactly through the middle of the entrance opening If the height of the beam on PM is not right you may need to adapt the Matisse height loosen the counter nuts on the Matisse feet wrench size 17 mm and the adjust the height by turning the nuts near the bottom of the feet wrench size 10 mm One revolution corresponds to 2 mm of vertical movement Make sure you turn each of the nuts by the same amount to avoid instabilities and tilting of the Matisse housing Finally gently tighten the counter nuts without holding the nuts at the bottom of the feet For Matisse operation the pump beam path as well as the ring cavity beam path have to run at a height of 60 mm above the baseplate This height is marked by the center of the beam overlap too
54. aracteristics of the full internal waveform at the ADC the DSP is looking for finding Maxima Minima or computing the Average The two red cursors at the edges of the graph can be dragged inside or outside to adapt the scan limits interactively to have an optimal view on the corresponding waveforms The Autoscale Y Axis property determines whether to automatically adjust the maximum and minimum values of that axis If the property is set to false you can manually adjust these values by clicking onto the axis with the left mouse button and entering new numbers for the minimum and maximum values Matisse Commander 174 Pound Drever Hall Frequency Noise only available for Matisse TX DX and TX DX light C PDH Frequency Noise Frequency Deviation 0 08 0 06 FSR RefCell MHz 211320 E 0 04 Finesse 0 02 21260 E iu PDH Error Signal 0 02 Maximum Intensity 0 04 10 231323 1 A 0 06 PDH Error Signal 0 08 Minimum Intensity ry i 0 221191 0 1 a 2 E l l l l l l l l l lI es 800 6820 840 860 880 200 920 S40 J60 98582 Maximum Deviation MHz RMS Deviation MHz FPZ SetPoint 0 094195 n 0325394 0 0199737 os r4 ILI pe E m m I Dv a wi E D m Er T _ Tm Figure 83 PDH Frequency Noise display This dialog shows the relative Frequency Deviation from the current lock frequency of the Reference Cell calculated with the help of the PDH error function for a resonator with a free
55. ate ef ET m je e To prepare a dye solution with a concentration of x g l for operating the Matisse within a specific wavelength range dissolve an amount of 4 x grams of the dye of your choice to be found in the blue Matisse service box in 4 liters of solvent The solvent has to have a purity of at least 99 5 Matisse Laser Description 32 Matisse Reference Cell The Matisse Reference Cell contains a highly stable scannable optical resonator made of an INVAR rod serving as an external frequency reference in different frequency stabilization schemes for the Matisse S and X models The resonator itself is is evacuated The reasons are o prevent humidity related problems that degrade the piezoelectric actuator to minimize the acoustic transmission of noise to support a better thermalization Do not open the venting valve Photodiode Attenuator Stages Figure 7 Photodiode 1 with attenuation stage attenuator wheels 2 and ND filters 3 For the passively stabilized versions of the Matisse Laser there are two photodiodes which monitor the integral power and the thin etalon reflex Integral Diode and TE Diode Aditionally for the actively stabilized Matisse lasers the S Reference Cell is equiped with a Transmission Diode whereas the X Reference Cell possesses a Transmission Diode plus a Fast Diode Each of these photodiodes is equipped with an attenuation stage which comprises a neutral density glass f
56. available the functionality of the Matisse Commander can be enhanced provided that a corresponding software plug in can be created Further information concerning the software plug in can be found in the Matisse Programmer s Guide Remove Wavemeter C Remove Wavemeter Presssing OK will remove all Wwavemeter related data From the Matisse Control configuration File and the control program will terminate The integrated support for a wavemeter Integrate Wavemeter see page 142 will be removed 1 e the Matisse Commander program will not search for wavemeter plug ins at the start up Figure 60 Control Loop Live View Dialog Matisse Commander 143 Control Loop Live View Control Loop Live View Protocol PZETL Ordinal No 6509 Period ms Ju This dialog lets you view the internal variables used by the various control loops Process Controller and Setpoint value and can be used to optimize the control loop parameters It is a non modal window i e it runs in parallel to the main program From the Protocol control you can choose which control loop none Thin Etalon Thick Piezo Etalon Slow Piezo Fast Piezo is to be logged The logging process uses a 256 value ring buffer to record the data If the selected control loop is not active the ring buffer may hold random data There are two Sample Modes available Continuous or Snapshot Continuous will give a steady data stream Becaus
57. baseplate such that 1ts edges are parallel to the baseplate edges If this 1s not the case loosen the two M6 fixing screws and turn the unit until the edges are parallel Make sure that the cavity beam passes roughly through the middle of the thin etalon The motor moveable plate 1 of the thin etalon mount needs to be positioned approximately parallel to the fixed plate next to 1t 2 observe the gap at the top If this 1s not the case move the Thin Etalon motor either use the control switch on the motor controller card in the Matisse electronics box second card from the right or use the Thin Etalon gt Motor Control dialogue in the Matisse Commander software Note the approximate motor step number at this position Loosen the screw of the first aluminum mirror mount 4 use a 2 5 mm Allen Turn the mount clockwise until the mirror is parallel to the surface normal of the thin etalon This permits the reflection from the thin etalon to propagate further through the laser for adjustment Matisse Operation 106 4 Switch on your pump laser and set it to a power where you get 200 300 mW out of the Matisse Using the target beam tool and possibly an IR viewer for the T version of the Matisse locate the reflection from the etalon it should go towards the Ti Sa crystal mount for the T Matisse If 1t is hard to see increase the pump power but be careful as the reflection may be strong enough to burn the paper of the tool If neces
58. beam height throughout the cavity to be at 60 mm at all positions alternative tweak FM1 tilt accompanied by vertical PM adjust The optimization procedure consists of displacing the FM1 and FM2 alternately You should aim for an increased power level as well as for a mode with a good shape Besides a good shape which is relative as discussed above one should check that the output power is not fluctuating and the cavity runs single mode best checked with an external Fabry Perot cavity Start with FMI and move it by one full rotation of the silver knob which controls the linear stage The drop of power produced by the displacement of FM1 can be corrected compensated by adjusting the OC mirror Do the same with FM2 move FM2 into the same direction as FM1 Compensate the loss of power with the TM mirror One needs to reiterate these steps until you obtain a satisfactory mode and output power In several cases it might also be necessary to move the FMI amp FM2 closer or further apart rather than translating them to the left or to the right It is always a good idea to keep track of the number of rotations of the silver knob note the mark on it in case you might have to start anew or search for the better mode in a different direction Another important aspect that should be taken care of is focusing the pump beam onto the dye jet To achieve stable operation you should always make sure that the pump beam is focused using PM BE
59. cavity defined by a high reflectivity planar and a concave mirror which serves as frequency discriminator in the Pound Drever Hall stabilization scheme one of the high reflectivity mirrors is placed on a piezoelectric transducer PZT The cavity is evacuated and temperature stabilized 11 vacuum valve allows the evacuation of high finesse cavity Matisse Installation 15 12 transmission diode measurement of high finesse transmission spectra 13 aluminium mirror steering off the back reflected beam into the Fast Diode 14 high bandwidth diode Fast Diode converts the optical beats generated by the carrier and the sidebands into RF power 15 electrical connector supplies the electrical signals for the cavity PZT and the temperature stabilization A Setting up the Reference Cell Unit on the optical table Necessary Equipment Allen keys set Matisse beam tool Place the Reference Cell Unit next to the Matisse laser head such that the two units are parallel and equally displaced to the edge of the optical table Adjust the position of the Reference Cell Unit until the Matisse output beam runs horizontally through the middle of the glass substrate 1 The high power beam will then run although not exactly in the middle through the black beam tube mounted on the side of the Reference Cavity Check the beam height over the baseplate of the Reference Cell Unit using the Matisse beam tool If the beam is not a
60. ch motor error occurred and clear the error status if the Thin Etalon or the Birefringent Filter motor controller are in an error condition Matisse Commander 146 Display Options Display Options Position Display Mode nim Precision 5 Display On Figure 65 Display Options dialog The Position Display Mode control determines the physical unit the program uses to display the position of the laser device Precision sets the number of digits to be shown after the decimal point It has only an effectif a wavemeter is used otherwise the precision is fixed to one digit Display On switches the controls and indicators in the Main Window see page 138 on or off Birefringent Filter Goto Birefringent Filter Position CO Birefingent Position E Figure 66 Birefringent Filter Goto Dialog In this dialog you can move the laser to a new position in units determined by the Display Options see page 146 The position of the Birefringent Filter motor position is computed with the help of a calibration function the parameters of which can be calculated in the Birefringent Filter Calibration Table see page 149 Matisse Commander 147 Birefringent Filter Scan Figure 67 Birefringent Filter Scan dialog O Birefringent Filter Scan Thin Etalon Reflex Birefringent Filter Scan Total Power ma Set A Motor Position 75664 0 17 I I I l I l I I 70 7 73000 73250 73500 73750 74000 74250 74500 7
61. cking on TE Control and PZETL Control and additionally for the stabilized versions to enable the reference cell lock in the Matisse Commander window To define a scan open the Scan Scan Setup menu Scans are defined by the current Scan Piezo Position Start lower limit and Stop upper limit positions that have a nominal voltage range of 0 to 65 Set the voltage applied to the scan piezo and the upper and lower limits of the scan respectively The value written in the Position field when opening the Scan Setup represents the current voltage on the scanning piezo which is driving the scan piezo If you set the laser to a specific position e g the start frequency of the scan to be performed prior to opening the Scan Setup menu then you can easily deduce the piezo voltage corresponding to this laser frequency just by checking the Position value 4 E meras cp ger rR ANA a3 upper limit m rising falling 5 speed speed c volts sec volts sec N q a 5 o a lower limit gt time Rising Speed V s and Falling Speed V s are the voltage change per second see diagram above Scan Stop Mode determines if and when the scan stops at upper or lower limit There are eight pre defined scan modes first you may choose if the scan starts with increasing or decreasing voltage Additionally you may choose if the scan stops once it arrives at the upper voltage
62. d In the case of the RefCell as scan device the RefCell control loops will be switched off automatically After closing the dialog the original control loops status will be restored Analyze will call up the RefCell Spectrum Analysis dialog see page 166 that will calculate the above mentioned conversion factor as well as the Finesse of the Ref Cell cavity and other properties that will be needed for the Ref Cell Frequency Noise display see page 164 For the analysis to be successful the spectrum has to contain at least two peaks Figure 79 RefCell Spectrum Measurement Analysis with Fit Matisse Commander 166 RefCell Spectrum Analysis Only available for Matisse TS DS E RefCell Spectrum Analysis Peak Table Position Amplitude dh 0 001567 0 176245 0 000261 l 0 009046 0 143146 0 000235 Peak width Alo AA O A O OA x Airy Fit Scan Conversion Factor Fit RerCell Finesse Amplitude Maximum Intensity 34 0 170776 0 201965 A Phase Scale Factor Offset Off Set Intensity a 039 33 0 0163223 0 017571 rd Phase Offset 1 30982 E FPZ SetPoint 10 109772 Set RefCell Prop The Peak Table contains the position amplitude and the full width at half maximum FWHM value for each found transmission peak of the RefCell spectrum measured in the RefCell Properties Measurement dialog see page 165 If more peaks are found than there are clearly visible ones increase the value for Peak Width until the co
63. d with the fast piezo crystal in case of the actively stabilized models TS TX DS and DX S 1h 3v The Mirrors M1 and M3 are adjustable even with the top cover of the Matisse closed by means of the four tuning knobs shown above Knob S lv tunes mirror M 1 in the vertical sense Knob S 1h tunes mirror M 1 in the horizontal sense Knob S 3h tunes mirror M 3 in the horizontal sense Knob S3v tunes mirror M 3 in the vertical sense For a fast optimization of a laser already running close to its maximum power it is sufficient to tune one of the two mirrors M 1 or M 3 Observe the Matisse power on your power meter Then very carefully either tune knobs S lv and S 1h or tune knobs S 3v and S 3h in order to maximize the Matisse power In general the necessary amount of tuning will be very small in the order of a knob rotation of only 1 2 degrees or even less If you turn too far the Matisse will stop lasing In this case immediately come back to the starting position in order to re obtain laser operation and re start optimizing Matisse Operation 93 Piezo Etalon Optimization If the cavity mirror optimization does not give you the expected or usual laser power within a range of 10 to 15 for the current wavelength 1t may be necessary to adjust the Piezo Etalon Before adjusting this etalon with the help of the two big micrometer screws as shown in the Matisse Ti Sa Optical Setup see page 18 note down the c
64. d carry out a series of tests of laser operation at different pressures to find optimal conditions and parameters The aim is to obtain high output power which is as stable as possible 1 e there should be no flickering visible within the output beam Note that changing the pressure during the adjustment can slightly alter the shape of the dye jet so you may also have to change the pumping position and or the location of the focus with the pumping mirror PM in order to regain optimal laser output If you increase the pressure continue in similar steps as before 1 e wait 5 minutes after each increase of up to 2 bar Do not increase the pressure in bigger steps than 2 bar at once and do not forget to watch the dye backflow 15 During the first minutes of operation characteristic noise from the nozzle indicates the presence of air bubbles in the dye If the increase in pressure is done slowly enough then the number and size of these bubbles will be at a minimum The bubbles will vanish with time When the final pressure is reached do not continue working before at least 15 minutes of bubble free operation Bubble free operation means that you do not hear any gurgling or splashing of dye under the spray guard 16 Lift the spray guard to its upper position and fix it there as shown in the first figure Carefully clean remaining spilled dye with a Q tip Take great care not to cross the dye jet with the Q tip Strong dye spray all over the la
65. dentification of possible error sources Finally if you encounter any difficulty with the content or the style of this manual please let us know For your convenience a fax form has been added at the end of this manual which will aid in bringing such problems to our attention Matisse Preface 7 Environmental Specifications CE Electrical Equipment Requirements AC power input 100 240 VAC 50 60 Hz Power Consumption max 700 W Environmental Conditions Requirements The environmental conditions under which the laser system will function are listed below Indoor use Altitude maximum of 3000 m Temperature 15 C to 35 C Humidity 30 to 60 non condensing conditions Insulation category 1 Pollution degree 2 Matisse Preface 8 Standard Units The following units abbreviation and prefixes are used in Sirah Manuals Quantity Unit Abbreviation mass kilogram kg length meter m time second S frequency Hertz Hz force Hewton N energy Joule J power Watt W electric current Ampere A electric charge Coulomb C electric potential Volt V resistance Ohm Q temperature degree Celsius C pressure Pascal Pa Prefixes tera 10412 T deci 10 1 d nano 10 9 giga 1049 G cent 104 2 c pico 104 12 mega 106 M milli 104 3 m femto 104 15 kilo 1043 k micro 104 6 u atto 10 18 Matisse Preface 9 Unpacking and Inspection Your Sirah laser system was assembled checked and packed with great care It
66. distance between FM1 and FM2 will take values within 113 115 mm range Please beware of the fact that it 1s also possible to obtain lasing outside of the optimal distance range i e when the distance between the two folding mirrors is 117 120 or 112 mm Even if the output power might suffice however in this configuration any optimization would deliver no results and render the laser highly unstable with only half the expected power the ring cavity is outside its stability configuration First you should aim for a nice round shaped TEMOO Its size should be approximately the same as that of the opening for the pump beam where the optional half wave plate may be mounted see the picture below Please note that the quality of the cavity mode can only be assessed by using a CCD camera and or by performing an M2 measurement using a beam profiler If the shape projection of the cavity mode on the housing see picture below does not look round e g outer ring outer structures present it does not necessarily imply that the real mode as measured with a CCD camera is bad The mode projected on the housing should only serve as a rough guide for the eye A thorough mode optimization procedure can only be carried out online by observing the mode on a CCD camera Matisse Operation 112 You can observe the mode on the right hand side of that opening at the same height with the opening if the height differs you will have to check the
67. dye circulator system only for dye laser version Further components may be supplied together with the laser system according to the packing list Each Matisse laser is delivered together with a service box containing some laser accessories and service tools for your everyday work with the laser as well as some spare parts The following items are included in your service box Installation Accessories 1 x Matisse Laser Manual x Matisse Commander Installation CD ROM Matisse Preface 10 1 x Mains cable x USB cable 4 x Laser fixing clamps 1 x Filter for purging the laser head x Beam tube to be installed in between pump laser and Matisse 2 x Laser warning signs Service Accessories 1 x Set of metric Allen head keys 1 5 2 2 5 3 4 5 mm 1 x Set of neutral density filters for Matisse laser head diodes 1 x Tool 1 Pump mirror pinholes 1 x Tool 2 Lyot filter dummy 1 x Tool 3 Thick etalon dummy 1 x Tool 4 Beam overlap tool 1 x Tool 5 Pump beam filter Ti Sa laser only 1 x Tool 6 Mirror mount ring Spare parts x Set of spare O rings 25 mm x 1 5 mm and 25 1 mm x 1 6 mm for mounting of mirrors Additionally depending on the configuration of your laser the service box may contain further items which are indicated in a list included in the box Matisse Preface 11 CE Declaration of Conformity Manufacturer Sirah Laser und Plasmatechnik GmbH Ludwig Erhard Str 10 41564 Kaarst Germa
68. e PDH Multipexer Input window in the PDH Waveforms menu of the X Stabilization menu of the Matisse X versions Carefully adjust the position of the L shaped pinhole mount horizontally while monitoring the spectrum analyzer display and the powermeter Two conditions need to be fulfilled a the laser runs single mode and b the power loss is minimal Note that the laser may temporarily run multi mode 1f the control loop of the Piezo Etalon is switched off At optimum alignment a power loss of about 596 1046 will occur Figure 30 Picture of the installed ceramic aperture front view Figure 31 Picture of the installed ceramic aperture back view Matisse Installation 84 CHAPTER 7 85 Matisse Operation The present chapter deals with the standard start up procedure This procedure applies for systems which are well installed and have been used under the same operating conditions in the near past This holds true if you switch off your system in the evening and switch it on again the next morning at the same wavelength CW lasers in general are temperature sensitive Therefore if the air conditioning in your laboratory is not running continuously take care to switch on the air conditioning and wait for thermal equilibrium before switching on your laser The best results will be obtained if your air conditioning is continuously running with temperature variations of no more than 1 K Start Up Matisse Ti Sa
69. e values determined here correspond to a change of the scan piezo by the full nominal range of 1 Calc BiFi Factor will calculate the corresponding factor using information from the calibration function for the Birefringent Filter see Calibration Table see page 149 and the conversion factor for the current scan device see Scan Device Configuration see page 178 There are different sets of ControlScan parameters depending on the selection of the Scan Device see Scan Device Configuration see page 178 Pressing OK will set these parameters for the active configuration To make changes permanent you have to save the active configuration see Device Configuration see page 139 Matisse Commander 180 ControlScan Values Measurement Figure 89 ControlScan Values Measurement E ControlScan Values Measurement Scan Device Slow Piezo Measure Piezo Etalon Scan Speed 3 59999 STOF a 0 001 Thin Etalon 3500 Measurement Progress Close The ControlScan parameter values see ControlScan Setup see page 179 for the active Scan Device see Scan Device Configuration see page 178 can be measured by executing a scan over a range of Scan Range with a speed of Scan Speed while calculating the position change for the Thin Etalon Thick Piezo Etalon and in the case of a Matisse TS DS or higher the Slow Piezo as well at the start and end During the scan all ControlScan parameters are set to zero Before
70. e Cell The fiber coupled Matisse S Reference Cell confers the Matisse S lasers flexibility allowing the user to design his her experiments in an optimal manner Nevertheless to make the most of its stabilization properties the Reference Cell should be placed on the same optical table with the Matisse Laser Head in a quiet environment away from any major noise source chillers compressors vacuum pumps etc In the following section a thorough description of the fiber coupling features of the Matisse s output into the Reference Cell as well as a standard optical alignment procedure for the fiber coupled reference cell is presented 1 The Fiber Coupling Unit For the fiber coupled version of the reference cell a fiber coupling unit is placed in the Matisse laser head It consists of a quartz plate 1 also used as an output beam exit window a small aluminium mirror 2 and a fiber coupler 3 L mount XY mirror mount and an adjustable colimator with a 8 mm focal length lens The principle is based on splitting a small fraction of the Matisse output beam delivered through the output coupler and directing it with the help of the quartz plate 1 and the metallic mirror 2 onto the 8 mm focal length lens into the single mode optical fiber EET E i Matisse Installation 71 to obtain an efficient coupling through the fiber we recommend to remove the mirror mount which holds the 8 mm lens and to project the Matisse output
71. e Current Position of the laser Display Options dialog see page 146 and a time chart of the total Laser Power Clear Chart will erase the time chart history Thin Etalon and Piezo Etalon Control are simultaneous indicator control displays determining the status of the corresponding control loops for the Thin and the Piezo Etalon Thin Etalon Signal displays the Thin Etalon reflex signal and the Piezo Etalon Baseline indicator control gives the voltage baseline applied to the piezo element If this voltage exceeds critical values the numerical indicator will start blinking red In this case use the slider to reset value Changing this value might cause a shift in the laser frequency The Scan indicator control displays the current scan status and there is also the Scan Piezo Voltage shown With the Direction indicator control the scan direction up or down can be quickly toggled For Matisse models TS or higher the main window contains also the Stabilization indicator control display with which you can turn on or off the locking of the laser to the reference cavity For this control loop the voltage applied to the slow piezo given by the Slow Piezo Voltage indicator control is of importance It should not exceed critical values if the slider 1s at the limits of the control use the slider to reset the value The Laser Locked indicator control indicates if the locking state is reached and maintained Clicking on it will toggle the Stabilization
72. e a geometrical rotation of the beam polarization The combination of M2 and the TGG plate forms an optical diode that supports laser activity in a defined direction M3 Tweeter Mirror M3 This mirror is mounted on a piezoelectric actor Changing the voltage applied to the actor will change the position of the mirror and ultimately the optical path length of the cavity The effect is used for mid bandwidth correction of the Matisse s emission wavelength Note The Matisse TR has no active control of the emission wavelength in this case the mirror is fixed directly to the mount TGG TGG Plate The TGG plate is made from Terbium Gallium Garnet and acts as a Faraday rotator when exposed to a strong magnetic field The combination of M2 and the TGG plate forms an optical diode that supports laser activity in a defined direction Note The magnetic field is generated by two powerful permanent magnets Be careful when using tools close to the device Piezo EPiezo Etalon The piezo etalon selects a single longitudinal mode from the spectral range that is determined by the configuration of output coupler birefringence filter and thin etalon To maintain the exact match of etalon and longitudinal mode the spacing of the etalon is dithered by an piezoelectric actor and a lock in scheme is used to control the etalon spacing Matisse Laser Description 20 TM Tuning Mirror The exact emission wavelength of the cavity is determined by it s length The t
73. e of the different time scales the control loops are working on you may have a real live view for the slower loops or just a sampling view for the faster ones An indicator which kind of behavior you experience is the Ordinal Number If it stays the same all the time or increase only slightly over time the current control loop values are read out if 1t increases rapidly you only have a time sampled view of the control loop The debug view behavior can be influenced by changing the Period time interval with which the logging buffer is read out Options will open the Control Loop Live View Options dialog see page 144 where the default values for the period times can be changed Choosing too small a period value may lead to communication errors due to the parallel access to the Matisse device by the status data gathering loop of the Matisse Commander The Snapshot mode will wait until the ring buffer contains new data and will display therefore a fully real time snapshot of the control loop behaviour regardless of the time scale it it working on Snap will trigger another snapshot Clear will erase the data displays Figure 61 Hardware Configuration dialog Matisse Commander 144 Control Loop Live View Options These controls determine the delay time for the continuous read out of the various control loops data in the Control Loop Live View dialog see page 143 Device Hardware Configuration Hardware Configuration E Hardwa
74. ed Lower numbers mean higher signal value Adapt the filters so that you have good signal to noise ratio set the Multiplexer control to Mixer Output Choose a scan interval and decrease its size about 0 03 so that you can clearly see the PDH error waveform with the biggest amplitude Adapt the value of the DSP Offset so that the signal s baseline outside of the PDH error signal is around zero The mixer signal has a nominal value range from 0 5 to 0 5 The PDH error signal should be in the range of 0 2 to 0 2 open the Fast Piezo Control Setup see page 160 dialog set the Lock Point to either a value slightly lower than the maximum of the PDH error signal or to a value slightly higher than the minimum value Set Setpoint to 0 make sure the slow piezo Baseline is in the middle of its range Activate the lock by clicking on the Ref Cell Control LED indicator in the main window or ticking the Control On item in the PDH Stabilization menu Troubleshooting Matisse Commander 169 If no lock can be obtained stop the RefCell Control loop Open Matisse gt Advanced Tools amp Options gt Control Loop Live View Set Protocol to FPZ The upper graph in this case will show the PDH error signal the red line corresponds to the FPZ Lockpoint Let this window open and switch on the RefCell Control loop Observe now the upper graph When you switch on the control loop and there is no lock then the slow piezo starts scanning t
75. en Coupler Reference Cell The reference cell in this case is a confocal resonator with a free spectral range of 600 MHz and a Finesse of about typically 15 to 20 The Airy Transmission spectrum is shown in the figure below normalized to 1 Transmitted Intensity Figure 19 Airy Transmission Spectrum Matisse Frequency Stabilization Schemes 51 Airy Transmission signal for a resonator with FSK 600 MEz and Finesse 17 1 1 1 1 I 1 1 1 1 I 1 1 1 era 1 1 I 1 1 I 1 1 1 1 I 1 1 H 1 I 1 1 I 1 1 I 1 1 I 1 1 1 1 PO A eurer s AE O enema som 1 1 1 1 I 1 1 I 1 1 1 1 I 1 Ps I 1 1 1 1 I I i I I T I I I T I I pom ipe ec ee ee ee e 800 600 400 200 0 200 400 600 800 Detuning MHz The Fast Piezo control loop works as follows any frequency deviation of the laser in relation to the reference resonator shown as blue arrows in the figure above will cause a change in the transmitted intensity green arrows This intensity difference to the desired transmitted intensity the setpoint in this case 0 5 is then taken as an error signal for the FPZ control loop There is also a control loop for the Slow Piezo that manages the tasks for this piezo as explained above One drawback of this frequency stabilization method is its sensitivity to laser intensity noise Because an intensit
76. equency Setting 114 Frequency Selective Elements 37 Frequently Asked Questions and Troubleshooting 186 G General 134 Goto Birefringent Filter Position 146 H Handling of Optical Components 119 Installation 133 Installation Requirements 57 Installing Ceramic Apertures in the Matisse Dye Ring Cavity 81 Integrate Wavemeter 142 Interactive Shell 141 K Key Navigation 136 L Laser Head Dye Models 21 Titanium Sapphire Models 18 Laser Principle 35 Main Window 138 Matisse Tools and Options 139 Matisse Commander 133 Matisse Commander 1 6 133 Matisse Commander 1 8 134 Matisse Commander 1 8 1 134 Matisse Dye Ring Cavity Mode Optimization 109 Matisse Electronics 184 Matisse Frequency Stabilization Schemes 49 Matisse Installation 57 Matisse Laser Description 17 Matisse Maintenance 119 Matisse Operation 85 Matisse Power Optimization 91 Matisse Preface 5 Matisse Reference Cell 32 Matisse DR Specifications 28 Matisse TR Specifications 26 Millenia Legs 61 Mirror Exchange 121 Motor Control 181 Motor Control Options 181 Motor Status 145 O Optical Alignment Guidelines for the Fiber Coupled Matisse S Reference Cell 70 Optical Alignment Procedure Matisse Dye 67 Matisse Ti Sa 62 Optical Alignment Procedure for the Matisse X Reference Cell 74 Optical Alignment Procedures 62 Optical Diode Unidirectional
77. ere is no obvious dust on the optics where the pump light is inciding or going through If there is dust refer to Chapter Handling of Optical Components for cleaning Increase the pump power to at least 5 W 12 If the laser is not already lasing observe the fluorescence shapes in the laser output Carefully pull at the mirror knobs at the laser output side M1 and M3 to see if there is a short laser flash and adjust the respective mirrors to reach lasing 13 If you have trouble getting lasing action it might be necessary to remove the Piezo Etalon and to replace it with the Dummy Etalon a block of glass of a cuboid shape placed on a metal block which was provided to you with the blue Service Box Please note that the Dummy Etalon should be placed in the beam path at a Brewster angle A good guidance for the eye is that the longer edge should be positioned parallel to the Birefringent Filter see photo below 14 Repeat the procedure described at step 10 Matisse Installation 67 Optical Alignment Procedure Matisse Dye This section gives a procedure how to align the various optical components of the Matisse Dye laser to achieve lasing The optical components are described in the Matisse Dye Optical Setup see page 21 section 1 The pump radiation has to be p polarized Your laser might have a half wave plate installed in the entrance opening for rotation of the polarization Step 6 below describes how to adjust the h
78. erence Cell Transmission Cy Diode Q Di M aa Se 20 MHz Modulation Fast Amplifier lt Slow Amplifier Variable DSP Attenuator High Pass Pound Drever Hall Unit First of all there are two lenses acting as a telescope to mode match the Matisse laser beam to the fundamental mode of the non confocal reference resonator Then follows an Electro optical Modulator EOM acting as a phase modulator which is modulated sinusoidally with a frequency of Vos With this modulation the frequency spectrum of the laser beam after the EOM has now essentially three components Vo Viu Vo Vo Vao Assuming that the reference cell is about resonant with the fundamental laser frequency v and its finesse is so high that the frequencies Vo v and Vo Vma are well outside of the resonator linewidth only the laser radiation part with the fundamental frequency can effectively interact with the resonator 1 e exciting a field inside the resonator Part of this excited field will be coupled out back by the first reference cell mirror The sideband parts are effectively just reflected back by the first reference resonator mirror a u Error Signal Figure 21 Theoretical PDH Error Signal Matisse Frequency Stabilization Schemes 53 The quantity that is now observed with a photo diode is the light reflected back from the reference resonator The reflected light is deflected from the
79. ering any change in polarization and hence no losses This situation would definitely lead to problems in operating the ring laser continuously tunable and mode hope free The problem can be solved by using a set of resonator mirrors with high reflectivity only for a limited wavelength range For example the MOS 1 works from 690 to 780 nm and thus according to the graph above one can only use the 4th mode Stacking a couple of quartz plates three for the design presented here with thickness equal to a multiple of the thickness of the first plate on top of each other yields a narrower bandwidth For each of the three plates the dependence of the output wavelength versus the phase difference can be described to a first approximation by a quadratic sinusoidal function The transmission profile bandwidth of the Birefringent Filter can be calculated by multiplying the individual transmission curves of each plate The design of the Birefringent Filter used with the Matisse Laser consists of three plates having thicknesses in the ratio of 1 3 15 In general for different optics sets Birefringent Filters with different plate thicknesses have to be used distinguished by the thickness of the thinnest plate For MOS 2 the thickness 1s 280 um for MOS 5 300 um MOS 1 MOS 3 and MOS 4 share the same filter with a 325 um thick plate The calculated transmission profile of a three plate Birefringent Filter oriented at an angle p 45 with plates thickne
80. ermine the emission wavelength of the ring laser The filter assembly 1s rotated by a stepper motor OC Output Coupler The output coupler forms the exit for the laser beam A fraction of the beam will be emitted by the laser the rest will be directed back into the ring cavity The beam polarization 1s horizontal M2 Out Of Plane Mirror M2 This mirror is mounted at a different beam height level This will introduce a geometrical rotation of the beam polarization The combination of M2 and the TGG plate forms an optical diode that supports laser activity in a defined direction M3 Tweeter Mirror M3 This mirror is mounted on a piezoelectric actor Changing the voltage applied to the actor will change the position of the mirror and ultimately the optical path length of the cavity The effect is used for mid bandwidth correction of the Matisse s emission wavelength Note The Matisse DR has no active control of the emission wavelength in this case the mirror is fixed directly to the mount TGG TGG Plate The TGG plate is made from Terbium Gallium Garnet and acts as a Faraday rotator when exposed to a strong magnetic field The combination of M2 and the TGG plate forms an optical diode that supports laser activity in a defined direction Note The magnetic field is generated by two powerful permanent magnets Be careful when using tools close to the device Piezo EPiezo Etalon The piezo etalon selects a single longitudinal mode from the spectr
81. ermined with the RefCell Properties Measurement see page 165 dialog The Maximum Deviation MHz and the RMS Deviation MHz gives you some statistical properties for the displayed sample series Matisse Commander 165 RefCell Properties Measurement Only meaningful for Matisse TS DS CO RefCell Properties Measurement Scan Device Reference Cell Piezo p Eur Ll ou LL ui D Ul Lu n o r3 a I 0 06 Ug IT LC ji J man lan H BLOOT d 2E 5 i 0 271 qm Figure 78 RefCell properties measurement l l l l I 0 272 0 273 0 274 0 275 0 276 Scan Range 210 02 Scan Increment Scan Position Measure will perform a sampled scan with a range of Scan Range and an increment of Scan Increment with the current Scan Device either RefCell or Slow Piezo while measuring the transmitted intensity of the Reference Cell The result will be the transmission spectrum of the Reference Cell that should have 2 or more peaks separated from their neighbor peaks by the Free Spectral Range FSR that can be used to calculate a scan range frequency factor for the current scan device For the scan to be successful the positions of the Thick and Thin Etalon have to be optimized and the corresponding control loops have to be active beforehan
82. eroretical PDH error signal for a resonator with FSR 1320 MHz Finesse 250 Modulation frequency Ofog 20 MHz PDH error signal Detuning MHz Matisse Frequency Stabilization Schemes 54 The interesting part of this graph is the relatively steep slope around the detuning of 0 MHZ giving a very sensitive measure for the laser detuning in relation to the reference resonator resonance The fundamental principle producing this signal form is the following assuming the laser frequency is exactly resonant with the reference resonator then the beat signal terms of the fundamental frequency with the equidistant left sideband and the right sideband will cancel out because the sidebands have a phase difference of x giving a PDH signal of O If the laser is slightly off resonant the exited field in the reference resonator will have an optical phase shift in comparison to the laser field The sidebands are then no longer equidistant in relation to the resonator field frequency to be precise you have to look at the optical phases resulting in non zero terms for the PDH signal The Pound Drever Hall method actually detects optical phase shifts rather than frequency shifts making it very sensitive The PDH stabilization method is insensitive to laser intensity noise The catching range for this method is given by the modulation frequency Vin Together this makes the Pound Drever Hall stabilization a highly sophisticated tool for locking
83. ersion Factor MHz full nominal scan range of 1 utilizing the Free Spectral Range MHz information for the RefCell the Number of FSR and the Scan Range Set Conv stores the calculated conversion factor into the Matisse Commander s configuration file to be used by the Scan Setup dialog see page 176 X Stabilization Matisse Commander 168 only available for Matisse TX DX and TX DX light The Matisse laser frequency can be stabilized by locking the laser frequency to an external reference resonator using the Pound Drever Hall control scheme Fast perturbations that might destroy this lock are counteracted by an intra cavity electro optical modulator EOM Slower perturbations are cancelled by an actively controlled laser cavity mirror mounted on a fast piezo actuator FPZ An actively controlled slow piezo acting on another laser mirror ensures that the FPZ will always have its full dynamical range to react on perturbations How to lock the Laser optimize the mode matching of the laser beam into the reference resonator open the Pound Drever Hall Waveforms see page 172 display and set Scan Upper Limit to 0 1 Scan Lower Limit to 0 Oversampling to 128 and Sampling Mode to Average Set the Multiplexer control to Diode Signal Minimize the signal strength by adjusting the mirror reflecting the back reflected light from the resonator onto the photo diode The signal has a nominal value range from 0 5 to 0 5 and is invert
84. esonance of the reference resonator to lock the laser to if the lock was lost Slow Piezo Control will switch the control loop on or off Changing the controls values has an immediate effect on the control loop RefCell Waveform Figure 76 Waveform display RefCell Matisse Commander 163 only available for Matisse TS DS RefCell Waveform Scan Upper Limit o i E Scan Lower Limit 210 07 ae Oversampling 1128 TE A y Sampling Mode J O Fl r Maximum E 2 5 LITT TT i tt l I l l l l l 10 0 30 40 50 60 o 8 Time FPZ Setpoint 0 103057 I ol 30 100 110 le Autoscale v Axis The graph shows the transmission spectrum for the confocal reference cell A scan over the cell s piezo actuator voltage is performed within an interval determined by Scan Upper Limit and Scan Lower Limit values are in a range of O to 0 7 The Oversampling parameter gives the number of sampling points It cannot be higher than 512 The Sampling Mode decides which characteristics of the waveform the DSP is looking for finding Maximums Minimiums or computing the Average using the full internal waveform at the ADC The Autoscale Y Axis property determines whether to automatically adjust the maximum and minimum values of that axis If the property is set to false you can manually adjust these values by clickin
85. et www sirah com Customer Service 192 gt Japan East Spectra Physics KK East Regional Office Daiwa Nakameguro Building 4 6 1 Nakameguro Meguro ku Tokyo 153 Telephone 81 3 3794 5511 Fax 81 3 3794 5510 gt Japan West Spectra Physics KK West Regional Office Cycnas Building 2 19 Uchihirano Cho Chuo ku Osaka Telephone 81 3 6941 7331 Fax 81 3 6941 2700 gt United States and Export Countries Spectra Physics Lasers 3635 Peterson Way Santa Clara CA 95054 USA Telephone 1 800 456 2552 Service 1 800 775 5273 Sales Fax 1 650 964 3584 E mail service O splasers com sales O splasers com Customer Service 193 Internet www spectra physics com Problems and Solutions This form should encourage you to tell us about difficulties you have experienced when using your Sirah instruments or this manual problems that did not require a formal call or letter but which you should feel free to communicate We are always interested in improving our products and manuals and we appreciate your suggestions Thank you gt From Name University Company Institute Department Address gt Instrument Type Serial Number Date of installation gt Problem Please give as much details as possible Mail to Sirah Laser und Plasmatechnik GmbH Ludwig Erhard Str 10 10 D 41564 Kaarst Germany Email to info sirah com Or fax to Si
86. f in contrast your Matisse laser is not yet operating carefully check the entire pump beam path Matisse Operation 86 Start Up Matisse D Figure 32 View of the dye jet nozzle and the dye catching tube The spray guard is fixed at its upper position Switch on your pump laser and allow for sufficient warm up time Please check your pump laser manual for details about the exact procedure and the necessary warm up time During this time take care that the pump beam is blocked before entering the Matisse laser If present use the internal shutter of your pump laser or any other suitable external beam dump In the case of a Matisse DX first switch on the XBox Controller Switch on the Matisse electronics box and start up the Matisse Commander program Open the Matisse top cover Place a power meter or any other suitable beam dump at the Matisse output port Move the spray guard to its upper position see Figure below Verify that the dye catching tube situated underneath the dye nozzle is centred with respect to the nozzle If not slightly move the dye drain which should be screwed down to the optical table to a different position In order to avoid the transmission of vibrations to the laser base plate the dye catching tube is not screwed to the laser It is just squeezed in its holder by some foam Therefore moving the dye drain slightly will allow to re centre the catching tube with respect to the nozzle atii c
87. f pure solvent the kind you will be using with the new dye EG EPH or PPH For the rinsing to be efficient one must run the procedure 2 times NOTE the rinsing cleaning procedure is based on the so called progressive dilution and therefore it is more efficient to clean the circulator two times with 1 liter than just one time with 2 liters Pour 1 liter solvent in the circulator and let it run for approx 10 min at a pressure of around 6 bar All this time the cooling system must be switched off or else there will be considerable water condensation on the cooling coils of the circulator Matisse Maintenance 125 When the rinsing 1s complete just repeat the drainage procedure described in section A IMPORTANT Make sure you close the red valve as well as the Allen screw before you start the rinsing procedure During the rinsing procedure described above it is advisable to keep the spray guard in the lower position in order to avoid unnecessary contamination of the optical components in the laser head C Replace the dye filter The old dye filter in the circulator will need to be replaced with a new one remove the hose 3 going to the nozzle use a wrench tool size 12mm as depicted below Matisse Maintenance 126 disconnect the filter from the bypass 4 pipe of the circulator Use the same wrench tool size 12mm as for the hose removal above remove the 3 Allen screws on top of the dye filter housing Ma
88. f reflection are normal These reflections may be focused from both convex and concave surfaces depending on the orientation of the surface to the direction of light In the focus the light intensity is often high enough to damage the surfaces of other optical components and to represent a serious hazard for eyes and skin The optical design of your Matisse laser has been set up very carefully by Sirah Laser und Plasmatechnik GmbH If you intend to make any modifications to the pump laser beam path or to the Matisse laser beam path then thoroughly check beforehand whether a focused back reflection may occur Warranty does not cover damages due to focused back reflection 17 CHAPTER 3 Matisse Laser Description The present chapter gives a brief description of the optical set up of the Matisse as well as its main specifications For a discussion of optical details including step by step instructions for system optimizations please refer to the next chapters Matisse Laser Description 18 Laser Head Titanium Sapphire Models Figure 1 Top view of a Matisse TX laser head FW Nr Ma T PM z 3 m PM2 Figure 2 Optical layout of a Matisse PMI D Pump Beam Mirror 1 Re directs the pump laser beam onto the Titanium Sapphire laser second pump beam mirror PM2 The mirror is used for steering the pump laser beam PM2 Pump Beam Mirror 2 Focusses the pump laser beam into the crytsal thro
89. faces of the optical elements from which it can hardly be removed In particular visually non perceptible layers may remain that considerably increase the losses in your laser cavity thus reducing the laser output power or destroying the surface itself The first condition to keep the optics clean and make your laser work at highest power is to always keep your laser under a permanently operating flow box Additionally from time to time you should wipe the optical surfaces with a soft clean Q tip Only apply very gentle pressure in order not to scratch the surface with the dry cotton The advantage of dry cleaning is to avoid smears from residual cleaning liquids on the optics but once again dry cleaning supposes only very gentle pressure In the case of important dust on the optics you may clean them by using isopropanol spectranalyzed or equivalent grade e g spetranal and lens cleaning paper e g Kodak lens cleaning paper In this case if ever possible you should remove the optics from their mounts in order to have easy and full access to the surface A part of the lens cleaning paper is wetted with isopropanol and wiped over its surface with low pressure In the ideal case it is sufficient to draw the wetted paper over the surface In this case the cleaning effect is caused by adhesion Be careful when cleaning half wave plates They are relatively thin and tend to break if too strong pressure is applied The best solution is to rem
90. g onto the axis with the left mouse button and entering new numbers Set Setpoint will set the setpoint of the Fast Piezo control loop see page 160 to the displayed FPZ Setpoint The value is calculated to be the amplitude value at the Full Width At Half Maximum points of the currently displayed transmission spectrum Matisse Commander 164 RefCell Frequency Noise Figure 77 RefCell Frequency Noise display only available for Matisse TS DS CO RefCell Frequency Moise Frequency Deviation FSR RerCell MHz 0 1 D 075 gt he Y 0 05 Finesse 0 025 33 9766 E do RefCell Spectrum 0 025 Peak Intensity P 0 05 J 0 201965 Lie JE lE Bs D m pu a o E n Lr m ES LL 0 075 RefCell Spectrum eps Intensity Offset h ri 0 017578 0 1257 I I I H E 225254 225300 225550 25400 225455 Sample Maximum Deviation MHz RMS Deviation MHz FPZ SetPoint 0 117728 0 040535 1 0 10975 This dialog shows the relative Frequency Deviation from the current lock frequency of the Reference Cell calculated with the help of the inverse Airy function for a resonator with a free spectral range of FSR RefCell MHz and a finesse of Finesse These values have to be adapted to your Reference Cell for an 5 Matisse model the FSR has normally a value of 600 GHz You also need the RefCell Spectrum Peak Intensity and RefCell Spectrum Intensity Offset values that can be det
91. hanging the controls values except Position has an immediate effect on an active scan Matisse Commander 178 Scan Device Configuration 2 Scan Device Configuration E Scan Device F1 Reference Cell Piezo a Conversion Factor 184348 41 MHz scan range of 1 a Laser Position nimi ab 775 3555 Figure 87 Scan Device Configuration This dialog lets you select the Scan Device that is used during a scan Possible devices are Reference Cell Piezo Slow Piezo or No Device Slow Piezo means that the intra cavity piezo is scanned which will cause a direct change of the laser s frequency Matisse TR DR setup Reference Cell Piezo means shifting the transmission spectrum of the Reference Cell which will cause an indirect change of the laser s frequency via the locking of the laser to the cell For the scan to be effective in this case the RefCell Control Loop has to be active Only meaningful for Matisse TS DS or higher You can also set a Conversion Factor that gives a relation between the nominal scan piezo range and the effective laser frequency change If you have a Matisse TS DS you can measure this factor with the help of the Reference Cavity see RefCell Properties Measurement see page 165 If you have a wavemeter and a corresponding Wavemeter plugin e g the HighFinesse wavemeter plugin available at the Sirah website integrated into the Matisse Commander then you
92. hat is on the resonance or far awway from the resonance Hence the laser will first lock to a non zero value determined by the Lock Point parameter that is only present at a resonance After the lock is attained the laser will be smoothly moved from the Lock Point to the Setpoint Fast Piezo Control The Fast Piezo Control button will switch the control loop on or off Changing the controls values has an immediate effect on the control loop Matisse Commander 162 Slow Piezo Control Setup only available for Matisse TS DS and TX DX Slow Piezo Control Setup E Setpoint 210 5 A Free Proportional Gain Al i P Locked Proportional Gain 3 rh Tj 2 Locked Integral Gain H 3 Slow Piezo Control Figure 75 Slow Piezo Control Setup dialog In this dialog you can determine the behavior of the Slow Piezo control loop by setting the loop s parameters The Setpoint defines the point in the nominal voltage range of the Fast Piezo from O to 0 7 to which the Fast Piezo is kept with the help of the Slow Piezo It should be set to 0 5 so that the Fast Piezo has the full dynamical range available to react on pertubations to keep the laser locked to the reference resonator The Lock Proportional Gain and the Lock Integral Gain are the control loop parameters used when the laser is in the lock The Free Proportional Gain determines the scan speed of the slow piezo for the scan that 1s executed to find or regain a r
93. he dialog the original control loops status will be restored Set Min Max will store the Min and Max values of the PDH error signal that are needed for the PDH Frequency Noise display see page 174 Matisse Commander 176 Scan Scan Setup Scan Setup Available Scans Position Rising Speed Y s Rising Speed MHz s DEVICE 0 31095 10 005 0 05 a al a Start Falling Speed fhis Falling Speed MHzJs 210 25 0 005 0 05 Stop Range Scan Range GHz 1 0 45 0 2 D A Scan Mode Start Stop equal Speeds a Scan El Stop Mode C gt l increase voltage stop at neither limit gt 4 This dialog determines the scan behavior Position Start and Stop have a range of O to 0 65 and set the voltage applied to the scan piezo and the upper and lower limits of the scan respectively Rising Speed V s and Falling Speed V s are the voltage change per second see diagram below The Stop Mode determines if and when the scan stops at upper or lower limit Rising Speed MHz s and Falling Speed MHZ s are about values for the frequency change per second These serve as a hint for the order of magnitude of the change Scan Range GHz gives the frequency range that corresponds to the scan range between Upper and Lower Limit To calculate the frequency quantities there has to be a conversion factor that can be set in the Scan Device Configuration see page 178 dialog Equal Speeds determines if the scan is symmetric
94. he laser to find a resonance of the reference resonator You should see after a while in the upper graph PDH error waveforms appear If you cannot see that the FPZ lock is setting in then you should decrease the Free Proportional Gain parameter in the SPZ Control Setup see page 162 dialog This parameter determines the scan speed of the slow piezo If you see that the FPZ control loop tries to lock to the PDH error signal but looses the lock quickly than you have to increase the FPZ PID loop parameters in the FPZ Control Setup see page 160 e g multiply the values by a factor of 2 Optimizing the lock open the Frequency Noise display goto the Fast Piezo Control Setup see page 160 dialog increase the Integral Gain for the fast piezo control loop by factors of 2 until you see an increase in the displayed frequency noise There is a threshold for this parameter above which the control loop starts to oscillate and frequency noise is increased Decrease the Integral Gain until you find this threshold value Choose a value that is about 10 smaller than the threshold value If you cannot find a threshold you might have already started above it so decrease the Integral Gain until you will find a decrease in the frequency noise goto the Pound Drever Hall Control Setup see page 170 dialog decrease the Attenuator value by steps of 5 until you see an increase in the displayed frequency noise There is a threshold for this
95. he optical table Since there will be a lateral displacement of the beam position when the Piezo Etalon is inserted in the beam you should make sure the target can be moved laterally In case you do not have a HeNe laser at your disposal the alignment can also be carried out by using the output beam of Matisse You would only have to make sure that the beam is running parallel to the optical table you should however consider the beam height difference between the Matisse and Piezo etalon 90 mm and place the etalon on a pedestal or lower the Matisse laser beam As a short explanatory notice one should keep in mind that the Piezo Etalon consists of an assembly of 2 Littrow prism with an 8mm air gap between them one of the prism being fixed while the other one is attached to a piezo The assembly is embedded in a solid metal mount which is attached to a stable ground plate The two silver micrometer screws on the front control the position of the two prisms with respect to each other while the two plastic knobs on the rear control the position orientation of the prism assembly with respect to the ground plate see also the section on Piezo Etalon Description Chapter Single Frequency Tunable Laser Physics in the current Manual Matisse Operation 95 2 proceed by inserting the Piezo Etalon in the HeNe Matisse laser Figure 36 Schematic of the Piezo Etalon orientation with respect of the target and laser source To the targe
96. he power diode Piezo Etalon Control Setup Gleichung 1 Basic setup or piezo etalon f ples Piezo Etalon Control Setup Advanced Amplitude Phase Shift A i2 12 6648 SO ET y Ue 100 X 100 150 f 150 Control Loop Active 180 180 CA J 5 81 waveform Close Matisse Commander 155 This dialog has two tabs Basic and Advanced Amplitude This parameter controls the amplitude of the sine modulation that is applied to the piezoelectric actor The value for the Amplitude should never exceed 50 Depending on the actual etalon values between 5 and 25 should work for almost all cases Bigger values make for a cleaner waveform less amplitude noise but might decrease the power output of the laser Too big values for the Amplitude will show up as more than one mode per FSR in the monitor spectrum Phase Shift This parameter controls the phase shift that is applied before the convolution of modulation waveform and waveform detected at the integral diode is calculated You should find a range of values or just one value where for each value the Piezo Etalon Waveform is stationary i e its form stays the same apart from some amplitude noise Choose a value from the center of the range Note The Phaseshift parameter can only be changed in discrete steps of 180 oversampling points Control Loop Active This button controls if the action that is calculated by the control loop is
97. he thin etalon mount shown in the middle of the picture below using the Allen key size 5 from the Matisse service box Put the adapter piece in its place and fix 1t on top of the baseplate using the long M6x25 screw supplied with the kit Open the shutter of your pump beam source Place the L shaped pinhole mount in its position and observe the fluorescence spot on the pinhole body If necessary adjust the height of the pinhole until it is located approximately in the middle of the fluorescence spot m M m Bp e fluorescence h A P Matisse Installation 83 Slide the L shaped pinhole mount horizontally to find the position where the laser starts lasing Fix the M4 screw at the bottom of the pinhole mount loosely using the ballpoint tip of the allen key size 3 from the Matisse service box Fine adjust the horizontal and vertical location in little steps until the cavity beam passes exactly through the middle of the pinhole Some amount of straylight visible on the pinhole body is normal At this point the laser output should be the same as 1t was without pinhole Set up an external optical spectrum analyzer to monitor the mode structure of the laser Alternatively you can look at the transmission spectra of the Reference Cell which is available in the Matisse Commander open Ref Cell Waveform window in the S Stabilization menu for the S versions of Matisse or switch to the Iransmission Diode mode in th
98. hich is polarized perpendicular to the optical axis fast axis and the extraordinary ray polarized along the optical axis slow axis The two rays ordinary and extraordinary will see different refraction indices and hence will propagate with different phase velocities in the same time experiencing a slight displacement with respect to each other The main effect will however be given by the fact that the two orthogonal components will grow out of phase as they propagate through the quartz plate To understand the way in which a BiFi operates we are only considering the case of a single quartz plate oriented at Brewster s angle with respect to the incoming beam As already mentioned there are no reflection losses for the p polarized light The polarization of the incoming light assumed to be p is rotated to a certain degree depending on its wavelength For a certain orientation of the optical axis with respect to the polarization of the incoming beam there are only a finite number of wavelengths for which the polarization will remain unchanged for these wavelengths the quartz plate acting as a full wave plate Accordingly the light oscillating with one of these wavelengths will come out of the quartz plate and see no losses whereas the remaining wavelengths will encounter great losses due to the Brewster s angles in the ring laser cavity Tuning the laser wavelength with the BiFi is achieved by rotating the quartz plate with an angle p with re
99. hickness of 280 300 and 325 um and by replacing eq 3 in eq 1 and solving as a function of A for different values of m 3 4 5 6 one obtains a set of curves as depicted below Single Frequency Tunable Laser Physics 41 1150 1050 950 E 850 E 750 D S 650 550 450 EE 350 0 15 30 45 60 75 90 Rotation Angle deg Figure 11 Calculated Spectral Range of the 1150 Matisse 280 Birefringet Filter Dislplayed are the 1050 tuning curves for four different orders in a 990 descending order E m 3 4 5 6 E 99 750 D S 650 gt 550 450 350 0 15 30 45 60 5 90 Figure 12 Calculated Spectral Range of the Matisse 300 Birefringet Filter Dislplayed are the tuning curves for four different orders in a descending order m 3 4 5 6 Rotation Angle deg Single Frequency Tunable Laser Physics 42 1150 1050 950 850 750 Wavelength nm 650 550 450 350 0 15 30 45 60 75 90 Rotation Angle deg Figure 13 Calculated Spectral Range of the Matisse 325 Birefringet Filter Dislplayed are the tuning curves for four different orders in a descending order m 3 4 5 6 Transmission 55 Single Frequency Tunable Laser Physics 43 In each of the above graphs one can observe that by changing the angle p there will always be a position of the quartz plate for which the resonance conditions delivers solutions for multiple modes that is several wavelengths will pass through without encount
100. hin the range of f 0 5 x FSR PZETL where FSR PZETL 20 GHz is the free spectral range of the Thick Piezo Etalon Finally tuning the PZETL will allow you to set the laser to the desired frequency f The recommended method for this last step is to scan the laser to the goal frequency instead of manipulating the baseline voltage directly Fine frequency adjustments of the Matisse are only possible by using an external frequency reference either a high resolution wavemeter or the atomic line or any other frequency selective phenomenon of your experimental set up The Matisse laser is delivered with a rough calibration for the Birefringent Filter This calibration is accurate enough to set the laser wavelength with an accuracy of about 1 nm to the desired value If the laser wavelength is already in the range of the calibration accuracy skip the next step Otherwise open the Goto Position dialog in the Birefringent menu of the Matisse Commander program Type the desired laser position in THz nm or 1 cm in the respective field You can choose whether to indicate the laser position in THz nm or 1 cm in the Display Options dialog in the Matisse menu For further tuning the Birefringent Filter and the Thin Etalon a procedure very similar to the one for the Thin Etalon and Birefringent Filter Optimization is applied For tuning the Birefringent Filter setting open the Birefringent gt Scan dialog and execute an corresponding motor
101. hysics 46 Horizontal Alignment This screw controls the horizontal tilt of the entire etalon assembly Vertical Alignement This screw control the vertical tilt of the entire etalon assembly Piezo Voltage SMA connector that connects to the piezoelectric actor Vertical Etalon Alignment This differential micrometer screw controls the vertical alignment of the two prisms that form the etalon to each other Horizontal Etalon Alignment This differential micrometer screw controls the horizontal alignment of the two prisms that form the etalon to each other Prism The etalon is formed by two prisms The resonator beam enters and exits under Brewster s angle Single Frequency Tunable Laser Physics 47 Piezo Etalon Dither Prism moved Fixed Prism by Piezo Beam exit and entrance under Brewster s angle Piezo Element Surfaces forming the Etalon Figure 16 Piezo etalon principle Apart from further narrowing down the frequency range of possible laser modes the piezo etalon has also to ensure that one of its mode s frequency coincides with the resonator mode s frequency of the laser This is done by modulating the distance between the prisms with the help of the piezo actuator so that the frequency spectrum of the etalon is slightly modulated This results into a small intensity variation that is monitored and used as the input for a control loop that keeps the center frequency of the piezo etalon mode at the freque
102. i 280 MOS 3 Matisse Bifi 325 MOS 4 Matisse BiFi 325 MOS 5 Matisse BiFi 300 In the following we describe a step by step routine for switching from one optics set MOS to another Preferably start the change procedure with a running and well adjusted laser Changing the components one after each other always maximizing the output power in between eliminates the risk of losing the optimum adjustment NOTE Jf you want to change between MOS 1 and MOS 3 it is highly advised to take an intermediate step via MOS 2 Set the laser wavelength to a position where two optics sets overlap 1 e approx 770 nm for changing between MOS 1 and MOS 2 and approx 860 nm for changing between MOS 2 and MOS 3 Use the Birefringent gt Goto menu in the Matisse Comander to set the laser wavelength Matisse Maintenance 131 If you are not familiar with the mirror exchange procedure see the paragraph Mirror Exchange in the current chapter of the manual Note that some mirrors may have a slightly different diameter so the rubber o ring used will either not fit when you try to squeeze it in or it will be too loose In this case you can find two different o rings to choose from in the service box 25 0 x 1 5mm and 25 1 x 1 6mm First change the HR mirrors TM M2 Do this one by one and re adjust the respective mirror mount after every change maximizing output power When changing the 26 HR mirror M2 re adjust with both M1 a
103. ibrational isolated optical table together with the corresponding pump laser The Matisse housing is equipped with legs designed for vibrational isolation allowing to set the height of the entrance for the pump laser beam to a value between 140 155 mm for the Ti Sa model and to a value between 145 155 mm for the Dye model In a first step you have to set your pump laser in such a way that its beam runs in a height within these limits and parallel to the plane on which the Matisse is to be mounted Advantageously you perform this setting before mounting the Matisse Matisse models TS and TX are equiped with a reference cell This cell requires additional space of about 450 mm x 360 mm 58 Shipping Locks In the Matisse laser head the baseplate is suspended on four ceramic balls and does not have any further solid mechanical connections to the Matisse housing Hence its position is fixed by its weight The gap between baseplate and housing is filled with special acoustically insulating foam This special design minimizes transmission of low frequency noise from the environment to the inside of the Matisse laser The baseplate 1s secured for shipping by tightening the four black plastic nuts on top of the threaded rods of the feet Furthermore white plastic bushings are put onto the rods into the gap between the rods and the baseplate Matisse Installation 59 To achieve best insulation from environmental noise the b
104. id purchase order to Sirah covering all transportation and subsistence costs For warranty field repairs the customer will not be charged for the cost of labour and material Material not under warranty may be returned to Sirah for repair or replacement Sirah will advise you of the cost and delivery time to repair the equipment before beginning work on it Customer Service 190 Return of the Instrument for Repair Before any return of instrument please contact your local Sirah service or sales centre for shipping instructions or an on site service appointment You are responsible for the one way shipment of the defective instrument to the Sirah service centre Always use the original packing boxes for shipment If shipping boxes have been destroyed or lost we recommend you to order new ones We will return instruments only in Sirah transport boxes Customer Service 191 Service Centres gt Central Europe Spectra Physics Europe Guerickeweg 7 D 6429 Darmstadt Telephone 49 0 6151 708 0 25 Dutch spoken 257 French spoken Fax 49 0 6151 708 217 Europe and Middle Eastern Countries Spectra Physics Guerickeweg 7 D 6429 Darmstadt Telephone 49 006151 708 219 Fax 49 0 6151 708 217 Germany Sirah Laser und Plasmatechnik GmbH Ludwig Erhard Str 10 D 41564 Kaarst Telephone 49 0 2131 512 78 20 Fax 49 0 2131 512 78 40 E mail info Osirah com Intern
105. iginal position half a clockwise rotation and then gently turning the micrometer controls by hand 7 If the laser beam passing through the Piezo Etalon shows only a comet tail shape on the target try to bring it to a round shape by iteratively tweaking the two micrometer screws You will notice constructive bright and destructive dark interference on the spot An optimal alignment is attained when the micrometer screws are tweaked for constructive interference maximum brightness Matisse Operation 98 8 It might by that the height of the superimposed spots now differs from the one you had at the beginning of the adjustment procedure in this case one should slightly change the orientation of the prism assembly This can be achieved by loosening the two M4 screws which are fixing the Littrow prism assembly window placed on the micrometer screw side of the etalon see picture below x i A amp 9 The height of the beam should than be adjusted to its original value by moving the position of the prism window by hand subsequently followed by tightening the screws which are fixing the window Please note that you may notice now again the 4 laser point constellation pattern which you will have to get rid of by coarse turning of the micrometer screws if the etalon has only a slight misalignment of the prism assembly one would then only notice the comet tail like structure Also here by turning the micrometer
106. ill hit the first pump mirror PM1 rather on its edge that in its center Figure 23 Pin Holes Matisse Installation 64 4 For Matisse operation the pump beam path as well as the ring cavity beam path have to run at a height of 60 mm above the baseplate This height is marked by the center of the beam overlap tool see Fig 73 below if it is placed on the baseplate To determine whether the Matisse height is set correctly set your pump laser to the lowest possible output level Right after the Matisse pump beam input further attenuate the beam to avoid damage to the beam overlap tool This may be done using the mount from the color filter see figure below and mounting one of the spare neutral density filters from the service box instead Put the beam overlap tool into the attenuated beam and check whether it has got the correct height If the Matisse height needs to be adapted loosen the counter nuts on the Matisse feet wrench size 17 mm and the adjust the height by turning the nuts near the bottom of the feet wrench size 10 mm One revolution corresponds to 2 mm of vertical movement Make sure you turn each of the nuts by the same amount to avoid instabilities and tilting of the Matisse housing Finally gently tighten the counter nuts without holding the nuts at the bottom of the feet In the service box you will find two pin holes that can be set on the two half inch mirrors directly located at the Ti Sa crystal FM1 and FM
107. ilter and a variable attenuator wheel The attenuator wheel can be set to eight different positions of which six will provide attenuation of the incoming beam i e each contains a neutral density filter Turning a wheel clockwise seen from the direction of the incoming beam increases the filter values ND values 0 5 1 1 5 2 2 5 3 There are dots on the side of the wheel indicating the respective positions Matisse Laser Description 33 The photodiodes and the attenuator wheels must always be operated with a fixed glass ND filter 34 CHAPTER 4 Single Frequency Tunable Laser Physics This chapter intends to give a concise and simple introduction into the physics and technologies used to operate the tunable single mode continuous wave Matisse laser Single Frequency Tunable Laser Physics 35 Laser Principle As the acronym Light A mplification by S timulated E mission of R adiation indicates one crucial part of a laser is an amplifying medium This gain medium has in general to be exited pumped by a adequate sources to act as an amplifier for electromagnetic radiation The spectral bandwidth of a laser medium can be relatively small e g just one atomic resonance or very large covering a wavelength range of under 700 nm to over 1000 nm in the case of Titanium doped Sapphire Ti Sa or a range of some 10 nm for various dyes The second prerequisite for a laser is an optical resonator being in a simple case a
108. imizing the control loop s gain parameters see either the S Stabilization see page 158 and X Stabilization see page 168 sections Integral Gain The Integral Gain determines the magnitude of the controller action that is applied to the fast piezo Low Integral Gain will result in a slow reaction of the piezo and not all perturbations of the laser will be compensated Excessive Integral Gain will result in overshoot and uncontrolled oscillations of the fast piezo Setpoint This value defines the control goal for the fast piezo control loop The control loop will try to stabilize the laser at a wavelength that corresponds to the Setpoint value at the DSP input Matisse TS DS Use a position in the centre of the transmission flank as value for Setpoint See Reference Cell Waveform see page 163 on how to determine this point For Matisse TS DS systems the Lock Point will be automatically set to the same value as the Setpoint Matisse TX DX The Setpoint defines the point on the steep flank of the Pound Drever Hall mixer signal see page 172 to which the laser s wavelength is stabilized Choose a value that has has the same value as the signal has far from any resonance Matisse Commander 161 Lock Point This value defines an initial Setpoint that will be used when the laser starts a lock or re lock process The Lock Point is useful for Pound Drever Hall systems where it is not possible to distinguish between a laser system t
109. irst make two pencil marks on the bottom of the lens mounts indicating their original setting Usually the position of the second diverging lens 4 will remain more or less unchanged while the position of the first focusing lens 3 needs to be adapted to increase or decrease the total distance between the two lenses By moving one of the lenses back and forth look for a better suppression ratio Note that after each displacement of the lenses it is necessary to re align the beam as described at the previous point D Optimize the signal on the Fast Diode Trace back the reflection from the high finesse cavity and make sure it hits the small metallic mirror 13 at approximately 2 3 of its length using a narrow stripe of paper make sure the reflecting beam is centered on the Fast Diode opening Matisse Installation 80 to optimize the alignment launch the Matisse Commander and open the X Stabilization menu Click on PDH Waveforms and set the PDH Multiplexer to Diode Signal Minimize the signal strength by turning the two screws SI and S2 in the picture above on the mirror The signal has a nominal value range from 0 5 to 0 5 and is inverted lower numbers mean higher signal value Adapt the attenuator wheel such that you have a good signal to noise ratio Extensive information on how to lock the laser can be found in the Matisse Commander Chapter Section X Stabilization 81 Installing Ceramic Apertures
110. l see figure above 1f 1t 1s placed on the baseplate Set the distance between the two folding mirrors FM 1 and FM 2 to about 113 115 mm The distance between the pump spot in the dye jet and FM 1 should be about 50 52 mm and the distance between the pump spot and FM 2 should be about 62 64 mm In the service box you will find two pin holes that can be set on FM1 and FM2 Put the pin holes on the mirror side facing the dye jet Set the pump laser to the lowest possible output and put the beam overlap tool between FM1 and the dye drain mount Adjust the height of the transmitted pump beam using the vertical adjustment of PM so that the center of the spot is in the middle of the beam overlap tool Matisse Installation 68 Make sure that the pump beam has got the correct polarization p polarized Loosen the plastic screw at the half wave plate on the Matisse input and rotate 1t so that the power of the pump beam reflex off the dye jet visible on the little beam blocking sheet on the dye nozzle mount is minimized The nozzle height should be adjusted so that the pump spot is about 3 to 5mm underneath the nozzle Adjust the nozzle s horizontal position so that the dye jet enters the drain tube at reasonable distances from the tube edges to avoid turbulences in the drain Increase the pump power to max 1 W Locate the two fluorescence spots one going from FMI to the output coupler M1 and one going from FM2 to the beam displacement rho
111. lack nuts have to be unscrewed and the white bushings have to be removed during installation After the nuts and bushings have all been removed make sure that the baseplate is still in 1ts middle position indicated by a visible gap around the threaded rods of the feet The linear adjusting stages of some of the cavity optics FM 1 FM 2 PM 2 are each secured with two counter nuts for shipping i ee es x En ee ram A a A men o AN AA HU Ts EH L HTML 2 E Matisse Installation 60 These counter nuts should be opened unscrewed for cavity optimization during the installation procedure Millenia Legs Matisse Installation 61 The Millennia Legs have a 8 32 thread which fits into three threaded holes in the Millennia baseplate The Millennia Legs have a ceramic ball bearing system incorporated to reduce the transmission of possible low frequency vibrations from the table to the Millennia pump laser The same design principle is used for the feet of the Matisse laser head the Matisse Reference Cell and the Wavetrain Legs Please note that in contrast to these three feet leg types the Millennia Legs height can not be adjusted Due to the ceramic ball bearing construction principle the feet legs consist of two parts which can move with regard to each other as long as there is no weight applied This is done on purposely so thus the Millennia Legs are shipped pre adjusted and ready to use If weight i
112. laser in combination with a powerful pump laser is a class IV high power laser Its laser radiation represents a serious hazard for your health as it can permanently damage your eyes and skin Moreover inadequate operation of the laser system may damage other laboratory equipment e g by ignition of combustible substances or by laser sputtering of surfaces as well as the laser system itself e g by focused back reflections To minimize the risks connected to laser operation read this Chapter thoroughly and carefully follow the instructions The Laser Safety Chapter should be read by all persons working in the laboratory where laser radiation occurs even by those not directly involved in laser operation The next chapter contains a general Laser Description with some details about the optimum performance range of your Matisse An concise introduction into Single Frequency Tunable Laser Physics and the techniques used for Frequency Stabilization follows The Matisse Installation chapter describes the procedures that need to be followed when the laser is installed for the first time The instructions therein are also helpful in case you have to move your Matisse laser to a different location The operation of your Matisse laser on a day to day basis is described in detail in the next chapter This chapter contains both basic operation hints necessary for your everyday work with the laser system as well as more detailed alignment and op
113. ling coils should be covered for at least 2 3 of their height which corresponds to about 3 liters of dye solution A minimum of 1 liter is necessary for proper operation of the dye circulator 130 Exchanging The Matisse Optics Set MOS For each version of the Matisse laser Dye and Ti Sapphire there are a couple of optical sets MOS which allow the Matisse user to access a certain wavelength range Due to a special design of the optics mounts one can replace the optics without causing a severe misalignment of the ring cavity Essentially the process of exchanging the optical sets involves replacing 2 two high reflective HR mirrors and the output coupler M1 Please note that it is possible to use the same Birefringent Filter over a broad range of wavelengths one only needs to choose the appropriate order For example the wavelengths from 695nm to 850nm can be covered within the same order of a 325 Birefringent Filter At the end of this section you will find a plot with the calculated spectral range for each Birefringent Filter This should help you decide which Birefringent Filter suits to a specific operation wavelength Exchanging the Birefringent Filter is ONLY necessary when maximum output power in a certain wavelength range is desired In this regard below is a listing of which Birefringent Filters correspond to each MOS Matisse Optical Set MOS Birefringent Filter MOS 1 Matisse Bifi 325 MOS 2 Matisse Bif
114. ll observe one of the patterns depicted in figure a or b or c below The goal here is to minimize the size of the observed pattern as much as possible until it will shrink down to a single bright point figure d This can be achieved by iteratively tweaking the mirrors 6 and 7 start with the horizontal controls then switch to the vertical off axis on axis a 9a a Pii 4 a x n a 4 e dm Cas a b d Observe the back reflections from the quarter wave 9 plate and of the polarizing beam splitter cube 8 on the output side of the EOM 5 They should be set such that they are visible close to the output aperture but they must not go right back into the aperture You can distinguish between the spots of the back reflections by gently bending the fixed L shaped mounts and watching the spots move Matisse Installation 77 By rotating the quarter wave plate maximize the back reflection towards the little metal mirror 13 which directs the beam downwards onto the fast photo diode simply hold a piece of paper in front of the mirror Alternatively minimize the back reflection visible on the output side of the EOM 5 The rotation of the quarter wave plate is done by turning the mount using the long screw C Mode matching Note Before you proceed to the procedure described in this section you should connect the two cables from the Reference Cell to the Matisse X Power Supp
115. lon and Birefringent Filter Optimization 100 Thin Etalon Control Position Options 153 Thin Etalon Control Setup 151 Thin Etalon Scan 152 Thin Etalon Signal Monitor 142 Transport 62 U Unpacking and Inspection 9 Using your own reference for stabilizing 56 V Version Changes 133 W Warranty 189 Wavemeter 182 Wavemeter Support 137 X X Stabilization 168 Index 196
116. lter Single Frequency Tunable Laser Physics 38 The Birefringent Filter uses the effect of birefringence and the polarization selective property of the laser resonator to achieve frequency selection This filter serves as the main broad range tunable element determining the approximate wavelength where the Matisse laser will operate To achieve single frequency operation two additional etalons are necessary as described in the next section The frequency range in which lasing modes could exist is narrowed down to approximately 50 GHz by the Birefringent Filter the Free Spectral Range of the Birefringent Filter amounts to 130nm The Birefringent Filter used with the Matisse laser also known as Lyot Filter or BiFi consists of a three quartz plates stack oriented at Brewster Angle with respect to the incident light The principle of the BiFi 1s based on the birefringent properties of the quartz plates which are acting as a retardation plate and thus rotate the polarization of the incoming beam If the BiFi is properly aligned then the optical axis of the three plates must be parallel On the other hand the BiFi works as a polarization filter the incoming p polarized light sees no reflection at the Brewster s angle whereas the s polarized light will encounter high losses due to reflection Light travelling through an uniaxial positive birefringent crystal like crystalline quartz is resolved into two orthogonal components an ordinary ray w
117. ly also called X Box and to the Matisse Laser Head respectively Switch on the Matisse Control Unit and the X Box Necessary Equipment oscilloscope function generator SMA to BNC adaptor To obtain good quality mode matching we suggest to use an external function generator to drive the Reference Cell piezo during the optical alignment procedure Connect the output of the Function Generator to the RefCell External Input SMA connector on the front the applied signal Matisse Installation 78 The amplitude must not exceed 500mV peak to peak and the signal has to be in the positive voltage range If these limitations are not obeyed the piezo can be damaged Trigger the oscilloscope externally using the Function Generator TTL signal outlet Using the SMA to BNC connector connect the output of the Transmission Diode 12 to one of the oscilloscope channels Now you should be able to observe several transmission peaks of various intensities n order to attain a good mode matching the goal now is to get as few peaks as possible The peaks should exhibit maximum intensity To identify the peaks corresponding to the fundamental modes of the high finesse cavity you need to make sure that you sweep over at least one free spectral range of the cavity You can carefully increase the amplitude while watching the transmission spectra displayed by oscilloscope As the peaks are squeezed together increase the time
118. m going through the etalon shows only the comet tail shape Fig 2 right than jump to step 6 Note In each of the above cases you will observe a lateral displacement of the laser beam that should amount to 8mm For an optimal alignment you will have to move the target laterally such that the brightest biggest point in the two patterns described above will be again positioned in the center of the target Figure 38 The 4 laser 5 Loose the lateral plastic screws on each of the micrometer screws by point constellation inserting a 1 5 Allen key and gently turning it by half a rotation observable from a missaligned etalon left and the comet tail pattern right Matisse Operation 97 6 Using a size 3 Allen key that goes into the micrometer screw do a coarse overlapping of the multiple laser spots The overlapping procedure consist in bringing together all the spots by iteratively turning the lower and the upper screw which will produce a vertical respectively a horizontal displacement of the laser spots During the overlapping process you will notice that the laser spots will take the shape of a comet tail shortly before becoming one spot Once you reduced the multiple spots to a single one the final and fine adjustment 1s realized by turning the micrometer screws until the spot displaces maximum brightness The final adjustment can be best done by tightening the small screws on the side of the micrometer controls to their or
119. ma is 146 SIPC IAM SCNT Mets siia ete ORPeEe nee O 146 Goto Brretrineent Filter PoSIUOD na cis 146 Biren ce nt lle Ca di 147 Biretrinecat Filter C alt bration Table ii 149 Tr sire tH EM 151 hans Etalon C OBUbOL Seal Nau cV Ve d E Did cU Gu culo tu D oT ad 151 Italo Celada ica 152 AAN A NN 154 Piezo Falom Contool Se UD ada 154 Advanced Seios N P E A ion aora ovs Delta irpo E E Dee su Rc OB erence 155 Piczo Etalonm WaVelOLIE ci osea oe tace rods oua Pes Since tex drive itu ep dcus ess Leder nd bam tadocedunode dines ba emot 157 A T DL Dt 158 Last Pieza Control Se UPD iae o lid 160 Slow Pezo C onttol SSP o 162 RETCCUM Wave 163 dies Messi NOE RT r TP 164 IcetGell Properties Measure tie tll ooo cales dote E EHE da 165 A SPADE Z AU OM EOI ER Aeneae es Etna ue Ges gaseous catene a ich a ia eode invnlusul a Das seg uutir eaa 168 Pound Drever Hall Control Setup pudet A Pa ted eges ded te A AA A 170 Pound Drevet Hall Wavetotiiso ia 172 Pound Drever Hall Frequency INOISE 2 5 0899009 aa 174 Pound Drever Hall Error Signal Measurement eeeseeeseessesesseeeeeeeee enne nennen nennen 175 EA 1 A S A MAE estate we acca and acta Seah dad vias E E E acetic TE E ese eat wack E A T EA 176 CASE E P E 176 Scan DEVE COnN OTa OM esse eee a a ae e A A AAA 178 Controbscar Seear A A A Rode da PORes feque Focus 179 ControlScan Valles Measure mentene are aa es ue Dao tut baie wun 180 MOOC ONTO PER
120. mb PS Make sure that their height is 60 mm by putting the beam overlap tool between PS and the tuning mirror TM and then between MI and the output opening If the height is not right correct it using the vertical adjustment of PM If you notice clipping of the spots at the rhomb or at the Birefringent Filter BiFi correct it using the horizontal adjustment of PM Put the beam overlap tool between TM and the Thin Etalon mount Thin E and check the beam height Correct it using the vertical adjustment of TM Remove the beam overlap tool and using a small strip of paper make sure that the beam passes through the TGG plate and hits the middle of M3 This is especially important for the actively stabilized Matisse versions because there M3 is rather small 10 Superimpose the propagation paths of the two fluorescence spots the 11 beam path originating from FM2 and going from the tuning mirror TM to M3 serves as the fixed path to which the beam from FMI will be aligned using M1 and M3 Put the beam overlap tool between the TGG plate TGG and the Thick Piezo Etalon Thick E Bring the spot from FMI closer to the fixed spot using only MI Then put the beam overlap tool between TM and the Thin Etalon mount Thin E Overlap the spot from FM1 with the fixed spot using only M3 Put the beam overlap tool back to the first position between TGG and Thick E and repeat the procedure To distinguish between the two spots as they get closer
121. mmy Mode The Dummy Mode is useful for getting familiar with the control program without needing an actual physical device or using it as a test environment for software plug ins for the Matisse Commander see the Matisse Programmer s Guide for further details This mode tries to simulate the Matisse controller box with an idealized laser but it does not completely implement all device commands so you might encounter error messages in some dialogs Error Dialog Figure 52 Error Dialog Key Navigation Matisse Commander 136 Error Error Message Matisse Error 50 motor errar Display OFF Command MOTBI Command Motor Error 7 position out of range Error Shack Matisse AFI Motor Get Status vi lt Matisse API If an error occurs this dialog will display basic error information Details will provide more information Display Off will switch off the controls on the Main Window see page 138 This may be helpful if the error occurs repeatedly in the data gathering loop for the various indicators You can switch on the display again in the Display Options dialog see page 146 You have to choose if you wish to Continue with the application execution or if you want to Exit Matisse Commander Matisse Commander and all its dialogs follow a key navigation standard Key s Function Enter Execute Function Change Settings Esc Abort Dialog Function Fl Show context sensitive Help F2 Open Dialog Opti
122. n fix it again to move it What should be avoided is to still have a signal at quite a big angle of the moveable plate 1 e when the etalon is set almost perpendicularly to the resonator beam Higher motor positions mean that you get closer to this condition The middle of the signal range should approximately coincide with the mechanical middle setting you determined in step 2 109 Matisse Dye Ring Cavity Mode Optimization For most applications of the Matisse Laser it is desirable to have the ring cavity mode very close to the TEMoo mode If properly adjusted the ring cavity of the Matisse laser delivers a TEMoo mode with an M2 parameter equal to 1 1 Aside from a good alignment the M2 value also depends on many other factors pump power level dye solvent used dye jet pressure As far as the alignment is concerned there are two critical parameters within the Matisse ring cavity which determine the quality of the cavity mode 1 the positioning of the pump focusing mirror PM with respect to the dye jet and 2 the positioning of the folding mirrors FM1 FM2 with respect to each other AND with respect to the gain medium dye jet In a normal case the Matisse laser will be delivered with an optimized cavity However if the type of the pump laser is different or the Matisse is pumped with other power levels than those used for optimization it might be necessary to adjust the above parameters The symptoms for non optimal alig
123. ncy of the laser resonator mode The control loop principle is shown in the following figure Etalon aligned to cavity mode Etalon out of alignment Cavity Mode Cavity Mode g WV detected amplitude variation detected amplitude variatior Etalon Transmission Peak dither signal dither signal Figure 17 PZETL Phase Locked Loop Principle l l l l l Having the etalon aligned to the cavity mode is essential not only for getting the maximum laser power but also in the case of scanning the laser Scanning is achieved by changing the laser resonator length continuously with the help of one of the resonator mirrors mounted on a piezo actuator So when the laser frequency changes the piezo etalon control loop will make sure that the piezo etalon s mode frequency will follow by adapting the thickness of the air gap Single Frequency Tunable Laser Physics 48 Optical Diode Unidirectional Device Because the Matisse is a ring laser two counter propagating modes with the same frequency could co exist To prevent this an optical diode is also part of the optical set up It consists of a TGG crystal plate mounted in a strong magnetic filed that will rotate the polarization vector of the electric field by some degrees irrespective of the propagation direction Faraday effect The M3 Matisse mirror of the three mirror assembly is an out of plane mirror causing also a rotation of the polarization vector of the electric field b
124. nd M3 IMPORTANT If you posses a R version of the Matisse no active stabilization hence no mirror mounted on a fast piezo you also have to replace the M3 mirror Change the output coupler M1 When re adjusting the mirror mount note that your final output power may be significantly different from the value you had before due to different reflection properties Finally change the birefringent filter Once removed any existing birefringent calibration motor position vs wavelength will be void Note that there is a pencil mark on the filter which should line up with the upper allen screw of the birefringent filter mount if seen from above see picture If a birefringent filter which was shipped with the laser is mounted in such a way the actual lasing wavelengths will roughly match the calibration data stored in the respective factory configuration of the DSP This method will provide a preliminary calibration until a fine calibration is done using an external frequency reference either a high resolution wavemeter or an atomic line or any other frequency selective phenomenon of your experimental set up Matisse Maintenance 132 Loosen the two allen screws with a 2 mm wrench and carefully take out the filter The second allen screw on the side is easier accessible when the birefringent motor is moved to a low step motor position as shown in the picture above e g position 50000 Insert the new birefringent filter
125. nd its vertical axis Pictures were made with Matisse dye version so the spot is easily visible The weaker side spot is of no importance Matisse Operation 107 Top view 7 Mount the monitoring Photodiode Unit back in its place Make sure it is mounted straight to the edges of the plate Matisse Operation 108 8 Increase the pump power to the value you normally use Do a scan of the thin etalon with the Matisse Commander software Choose a scan range so big that you can see the entire range where there is a signal from the Thin Etalon monitoring Photodiode You may need to change the attenuator wheel setting or the neutral density filters mounted in front of the monitoring Photodiode Unit the maximum signal level should not be much higher than 0 5 9 The bigger your signal range is the easier will be the wavelength selection This 1s especially important 1f you work with a HighFinesse wavemeter and want to use the Matisse Commander plug in for automatic wavelength setting With the modified optics you should get a sequence of at least 20 parabola structures in the signal range possibly some more To optimize the range there are two possibilities a use the micrometer screw on top of the mount do one turn in either direction then do a scan to see whether the signal range has changed and b very slightly rotate the mount of the first mirror around its vertical axis 1t may already suffice to just loosen the screw and the
126. nds to about 10 GHz If you cannot get close to this value please have a look at the full range of TE motor positions where there is a TE reflex signal and try to find a parabola with a frequency difference in the stated range Before doing the final approach to your frequency f you have to optimize the position of first the Birefringent Filter and then the Thin Etalon as described in the Thin Etalon and Birefringent Filter Optimization section see page 100 Finally scan the laser to the desired frequency see the following section In most cases the procedure described above allows a direct approach to the selected frequency In some cases however the interaction of Birefringent Filter Thin and Piezo Etalon leads to an unstable optics configuration In this case more stable operation can be achieved by tuning the Birefringent Filter and Thin Etalon settings described above more than once Matisse Operation 117 Frequency Scanning Figure 47 Scan Timing The Matisse is scanned by acting on the logical scan piezo For the Matisse R version this is the long travel piezo the tuning mirror TM is mounted on for the stabilized Matisse versions this 1s the reference cell piezo Before starting a scan you need to optimize the Birefringent filter the Thin and the Thick Piezo Etalons at the scan reference frequency as described in previous sections Take care to activate automatic tuning of the Thin and Thick Piezo Etalons by cli
127. nment of the folding mirrors include scrambled mode shape fluctuating output power astigmatic cavity beam a thick cavity beam flickering as well as multi mode operation Before you start the optimization procedure described below please check that the cavity optics is not contaminated and the cavity is peaked for maximum power It is also of equal importance that the dye solution is not too old or contaminated Also make sure you use only high quality solvent see Chapter Matisse Laser Description section Required Dye Solvents It is of outmost importance that the pump beam be centered on the focusing pump mirror Matisse Operation 110 If the cavity was subjected to major tweaking which resulted in gross misalignment you should consider checking the distances depicted in the picture above A set of good starting values is FMI to dye nozzle cladding the silver not the anodized part 37 5 mm FM2 to dye nozzle cladding 52 5 mm PM to dye nozzle cladding 29 mm Alternatively you can consider using the template provided in the Service Utility Box Make sure the focused pump beam is centered on the dye jet The width of the dye stream jet is 4mm In the vertical plane the optimal distance between the edge of the dye nozzle and the pump beam is 2 mm The height of the nozzle can be adjusted using the two M4 allen screws on the mount Matisse Operation 111 Also in an optimal configuration the total
128. nsate these drifts an absolute frequency reference like an atomic resonance is needed The following figure shows a possible Matisse setup using the absorption fluorescence signal of a gas exited by the laser radiation as an error signal for the laser frequency detuning This signal is digitized by a DAQ card and processed by a software extension of the Matisse Commander control program In reaction to the error signal this software extension will act via the Matisse controller on the reference cell piezo actuator to keep the master resonator on the atomic resonance Drift Compensation PC Photodetectors Extension Controller Pump Laser Small Linewidth This setup scheme does not need a stabilized Matisse to work The drifts of lasers of the Matisse R type can be compensated as well The LabVIEW framework for the Matisse Commander extension 1s available on request Matisse Frequency Stabilization Schemes 56 Using your own reference for stabilizing Instead of using the reference cell that comes with the stabilized Matisse versions you can also use your own reference generating an adequate error signal for the laser frequency deviation For this the DSP controller card has an external input for your error signal so you can take advantage of the control loop logics already implemented for the Fast and Slow Piezo The section DSP Input Characteristics see page 184 gives the technical details and constrains f
129. nt 100 Big Increment and Small Increment sets the steps a motor will be moved relative to its current position in the Motor Control dialog see page 181 Figure 9 Motor Control Options dialog Matisse Commander 182 Wavemeter only available with Wavemeter Support see page 137 If the Use Wavemeter menu entry is ticked the Current Position display in the main Matisse Commander window will show the wavemeter readout Scan Device Calibration with Wavemeter only available with Wavemeter Support see page 137 Scan Device Calibration with Wavemeter acl xj Scan Device Reference Cell Piezo Measure Scan Range 10 05 A Scan Speed 0 001 A Set 5 077630E 8 i i Conversion Factor 0 2 0 21 0 22 0 23 0 24 0 25 0 26 MHz scan range of 1 Scan Position 194949 E Figure 92 Scan Device Calibration with Measure will perform a scan with a range of Scan Range and a speed of Wavemeter Scan Speed with the current Scan Device either RefCell or Slow Piezo while measuring the laser frequency over the current scan position After completion of the scan the Conversion Factor MHz scan range of 1 can be calculated Set stores the conversion factor into the Matisse Commander s configuration file to be used by the Scan Setup dialog see page 176 For the scan to be successful the positions of the Thick and Thin Etalon have to be optimized and the corresponding con
130. ny Phone 49 2131 512 78 0 Fax 49 2131 512 78 40 Product Name Matisse Product Types TR DR TS DS TX DX Directive Council Directive 73 23 EEC Low Voltage Council Directive 89 336 EEC Apendix I Electromagnetic Compatibility Applicable Standards EN 61010 1 2004 Safety requirements for electrical equipment control and laboratory use EN 60825 1 2001 Safety of laser products Part 1 Equipment classification requirements and user s guide EN 61326 1 1997 EN 601326 1 1998 Electrical equipment for measurement control and laboratory use EMC requirements We herewith declare in exclusive responsibility that the above specified instruments were developed designed and manufactured to conform with the above Directives and Standards Dr Sven H drich Gesch ftsf hrer Sirah Laser und Plasmatechnik GmbH Kaarst November 30 2005 Matisse Preface 12 CHAPTER 2 13 Safety Precautions Precautions for the Safe Operation of Class IV High Power Lasers The use of a dye laser system may cause serious hazards 1f adequate precautions are not taken Most of these hazards can be avoided by appropriate operation of the laser device However after a period of problem free operation many users tend to become careless with safety precautions Hence you should ensure that all safety rules described in the following section and of course those prescribed by law are observed The Sirah Matisse laser 1s o
131. o the experimental set up All laser beams for which the set up itself does not provide a suitable beam stop have to be terminated with a beam dump Operate the laser only inside distinctly marked areas The laser should only be operated inside a room distinctly marked with respective warning signs and warning lamps The access to this room has to be restricted to personnel properly trained Do not install the laser in a height that the output is at eye level Maintain a high ambient light level in the laser operation area Eye s pupils remain constricted and thus are less sensitive to scattered laser light Mark the laser operation area by prominent warning signs Safety Precautions 15 Dangers Caused by Laser Dyes and Solvents The physical chemical and toxicological properties of organic dyes are not well characterized Just as the solvents they should be treated as poisonous Thus an extreme caution is required in handling these substances During the work with laser dyes eating and drinking are strictly forbidden inside the laboratory Always wear protective gloves and a protective mask when weighing out the laser dye Following these measures an inadvertent ingestion of any dye can be excluded A more likely hazard is the potential for absorption of solvent or dye solution through the skin Even if the solvent itself is not extremely dangerous some solvents can penetrate the skin easily and carry the toxic dyes into the body
132. oco e EZ ye jot EI p nozzle Pa uc E Dye catching tube 6 Set the spray guard back to the lower position see Figure below Figure 33 View of the spray guard in its lower position to avoid dye spray during the start up procedure of the jet Figure 34 View of the Matisse dye circulator The dye jet pressure might be varied by adjusting the needle valve 9 Matisse Operation 87 AS pray guard Mtixins screw On the dye circulator make sure that the dye by pass is completely open The by pass 1s open 1f the needle valve shown on the next figure is turned counter clockwise as far as possible In this case when switching on the dye pump the main fraction of the dye will follow the by pass and no pressure will build up in the circulator system Main switch 10 Switch on the dye pump The cooling loop in your dye reservoir 11 should be connected in series to the chiller of the pump laser and thus already be operational If you are using an external cooling system then check that this system is operational Even with the by pass open some dye will enter the tube leading to the dye nozzle Carefully observe the dye flowing towards the nozzle Wait until the dye reaches the nozzle Once the entire tube from the circulator to the nozzle is filled with dye wait for another 5 minutes before proceeding Matisse Operation 88 12 DO NOT open the spray guard to watch the dye arriving in the nozzle only
133. oint but looses the lock quickly than you have to increase the fast piezo control loop parameters in the Fast Piezo Control Setup see page 160 e g multiply the values by a factor of 2 Optimizing the lock Matisse Commander 159 open the RefCell Properties Measurement dialog see page 165 Measure the spectrum and choose about half of the maximum peak signal seen in the spectrum graph as the new Setpoint for the fast piezo control loop open the Frequency Noise display increase the Integral Gain for the fast piezo control loop multiply by factors of 2 until you see an increase in the displayed frequency noise There is a threshold for this parameter above which the control loop starts to oscillate and frequency noise rises strongly Decrease the Integral Gain until you find this threshold value Choose a value that is about 10 smaller than the threshold value If you cannot find a threshold you might have already started above it so decrease the Integral Gain until you will find a decrease in the frequency noise Matisse Commander 160 Fast Piezo Control Setup only available for Matisse TS DS and TX DX Fast Piezo Control Setup E Integral Gain 2299 5 iF Setpoint D 109757 d Lack Point 0 109757 Fast Piezo Control tara Figure 74 Fast Piezo Control Setup dialog In this dialog you determine the behavior of the Fast Piezo Tweeter control loop by setting the loop s parameters For opt
134. onds to about 125 GHz The tuning procedure for the Thin Etalon is analogous to the one for the Birefringent Filter Open the Thin Etalon gt Control Position Scan dialog and execute a motor scan resulting in the figure below Set Thin Etalon Control Position Thin Etalon Reflex 1 4 Thin Etalon Scan Total Power mn D 8 0 5 e ai 1 Motor Position 20000 Thin Etalon Reflex 430d 2301 iV C A 0 07 I I I I I I I I I 170 3 15000 18200 18400 18600 18800 19000 19200 19400 19600 19800 20000 Thin Etalon motor position Figure 46 This window indicates the power reflected from the thin etalon as well as the total laser power for different positions of the thin etalon Matisse Operation 116 Press Set and note down the wavelength frequency Now move the red cursor to the minimum of the next parabola of the Thin Etalon reflex signal and press Set again A comparison between the current and former frequency will normally reveal a difference with an absolute value of one FSR PZETL The change in frequency going from parabola to parabola in one direction is not necessarily monotonous There can be differences of up to one FSR TE Finding a parabola by going from one to the next one that has a minimal absolute value for the frequency difference 1s here the goal It should be possible to approach the desired frequency within a range of 0 5 x FSR PZETL for a standard configuration this correspo
135. ons Matisse Commander 137 Wavemeter Support Firmware Update The functionality of the Matisse Commander software can be enhanced by using devices capable of measuring the laser s current wavelength further referred to as wavemeters New functions like a Goto Wavelength routine that sets the laser to any desired wavelength position within its tuning range could be implemented Wavemeter support for the Matisse Commander program which is developed with LabVIEW is achieved by using LabVIEW application libraries plug ins for different kinds of wavemeters that conform to a specific interface Further details are given in the Matisse Programmer s Guide available on the Sirah website www sirah com http www sirah com The firmware of the hardware controller can be updated via the Firmware Updater program available on the Sirah website http www sirah com http www sirah com Matisse Commander 138 Main Window Figure 53 Main Window C Matisse Commander 1 8 S N 99 99 99 Matisse Birefringent Filter Thin Etalon Piezo Etalon 5 Stabilization Scan Help Current Position 200 0 a Laser Locked Laser Power 0 62 0 70 Clear Chart d Thin Etalon m Pieza Etalon P Scan Direction Stabilization Thin Etalon Signal Piezo Etalon Baseline Scan Piezo Voltage Slow Piezo Voltage EA L l l L L L D 0 25 0 13398 0 00000 0 10000 0 35000 A A The window contains an indicator for th
136. or to the nozzle cladding distance Pump Focus Distance vs Output Power Matisse Dye Lal FP Output Power 12 bar W Output Power 14 bar W Output Power 18 bar VW 0 28 300 20 400 28 500 286 500 28 700 20 800 286 900 29 000 29 100 Pump Mirror Distance mmy In order to set the PM to an optimal position it is recommended to find the break down point and then progressively walk away from it back off the PM by roughly one turn of the silver screw of the translation stage A higher dye jet pressure higher dye jet flow rate will produce a better mode and more output power The drawback is an increased frequency jitter larger linewidth Please bear in mind that for each value of the dye jet pressure there is an optimal position of the three elements PM FMI amp 2 Matisse Operation 114 Frequency Setting Setting the Matisse to a specific frequency needs a step by step setting and optimization of Birefringent Filter Thin Etalon TE and Thick Piezo Etalon PZETL In order to approach a specific frequency f you first need to set the Birefringent Filter Doing so will allow you to set the laser wavelength within a range of f 0 5 x FSR TE where FSR TE 250 GHz is the free spectral range of the Thin Etalon This is the standard value it might be different for your laser Older Matisse lasers were shipped with a TE with a FSR TE 130 GHz Then you need to set the Thin Etalon resulting in a laser frequency wit
137. or your signal When you connect your error signal to the DSP s external input and set the switch from Intern to Extern you replace the internal error signal from the Matisse Reference Cell with your own signal There is exactly one control loop DSP task that uses this error signal to act on the Fast Piezo So you can either stabilize on your reference or on the Matisse reference cell but not on both at the same time You have to adapt the Fast Piezo and Slow Piezo control loop parameters to the characteristics of your error signal CHAPTER 6 57 Matisse Installation The first installation of your Matisse 1s done by a Sirah or other qualified service engineers This includes the mechanical set up as well as the adjustment of the pump optics and the Matisse laser beam path Therefore the installation procedure described in the present chapter is not intended for your everyday work with the Matisse but for those users who have to move their laser to another location and to re install it afterwards e g in another laboratory Your Matisse is mounted in an extremely stable housing and transport does not cause any major problem Installation is also quite simple if the transport has been well prepared So please do not touch your system before having read the present chapter completely Installation Requirements The installation of the Matisse laser requires an area of about 1050 mm x 360 mm The laser needs to be mounted on a v
138. ore eventually changing the wavelength or the pump power During transport your laser is exposed to unavoidable vibrations which might cause damages to the laser system 1f no adequate precautions are taken One precaution is to install transport safeties for the four linear translations and for the Birefringent Filter lever inside the Matisse laser Do not forget to remove the transport safeties when reinstalling the laser Optical Alignment Procedures Optical Alignment Procedure Matisse Ti Sa This section gives a procedure how to align the various optical components of the Matisse Ti Sa laser to achieve lasing The optical components are described in the Matisse Ti Sa Optical Setup section see page 18 1 The pump radiation has to be p polarized Your laser might have a half wave plate installed in the entrance opening for rotation of the polarization Step 6 below describes how to adjust the half wave plate 2 The distance between pump laser and Matisse laser should not be too big about 10 to 30 cm You might find a beam tube grey plastic tube in your laser service box that should be installed between pump and Matisse laser to minimize perturbations caused by air flows Matisse Installation 63 3 Position the Matisse on your optical table so that the pump beam will pass through the center of the entrance opening Align the long side of the laser base plate so that it is parallel to the pump beam direction The pump beam w
139. ouse button pressed on the right flank of a parabola close to its minimum and press Set if Flank Orientation is selected to be Right If Set is not used the motor will stay in the scan s end position when you close the dialog Thin Etalon Control Position Options 2 Thin Etalon Scan Options E Initial Motor Postion y T 1 2 Scan Range 11500 A These controls determine the Scan Range and Scan Increment of the TE Control Position setting procedure The Initial Motor Position is the position the TE motor is moved to when you call the TE Control Goal dialog If it is set to a negative number the motor will not not be moved Matisse Commander 154 Piezo Etalon The thick piezo etalon ensures that all except one longitudinal mode have so high losses that laser emission is not possible Therefore the spacing of the etalon must be matched to an multiple of the favored longitudinal mode s wavelength Because of the tight spacing and in order to be able to perform a scan the spacing 1s actively controlled The control loop is based on a lock in technique and the etalon spacing is varied by a piezo drive The lock in measures the response of the laser to an externally introduced perturbation The perturbation is a slight modulation of the etalon spacing The modulation follows the amplitude of a sine wave with a modulation frequency f mod The response of the laser is the variation in the total laser power measured at t
140. ove dust by applying a gentle flow of clean air or nitrogen rather than wiping the surface of these plates Of course you should clean the optics of your laser system only when not operated That means no pump laser beams should be applied to the Matisse and the entire system should be protected against unintended application of the pump laser In case you are removing optics for cleaning please remove them one by one and switch on and re optimize the laser between two successive optics removals In that way switching on the laser again and keeping its full output power is relatively straight forward Do not forget to completely block the pump beam before removal of each Matisse optics Matisse Maintenance 120 If you observe a significantly increased level of scattered light in your laser that cannot be reduced by thorough cleaning check your laser optics for defects In case of damages caused by wrong adjustment of your laser optics you should make sure to correct the alignment to avoid further damaging right before changing the defect optical elements 121 Mirror Exchange Figure 46 Matisse mirror squeezed in a metal ring The mirror will not fall even when the ring is turned upside down The Matisse has been designed with the aim to keep mirror exchange as simple as possible Depending on the specific configuration as dye or Titanium Sapphire laser five mirror sets which include the mirrors TM and M 1 through M
141. pair of parallel spherical mirrors which acts as a feedback loop for the amplifier medium This system of an amplifier with feedback can produce self exited electromagnetic fields in the form of laser beams which have well known special properties First they have a very high spatial coherence 1 e they have a very small spotsize when focused they are the best practical approximation to an idealized light ray etc The simplest laser beam has a transverse intensity profile in form of a Gaussian distribution Second they can have a very high temporal coherence i e the field has a relatively small frequency spectrum For the latter property some conditions have to be fulfilled Optical resonators have discrete resonances with well defined frequencies separated in the case of a ring resonator by a frequency difference of Av c d c velocity of light d mirror distance this is called the Free Spectral Range FSR These resonances are called resonator eigen modes If you have a gain medium with a relatively small bandwidth compared to the FSR of the optical resonator and one of the resonator modes frequencies coincides with the center frequency of the medium your laser will emit radiation only with just this frequency you then have a single mode laser In the case of the Ti Sa with its very large gain bandwidth a vast number of modes could in principle oscillate for any practical resonator length To achieve single mode laser opera
142. parameter below which the control loop starts to oscillate and to increase the frequency noise increase the Attenuator until you find this threshold value Choose a value that is about 3 lower smaller than the threshold value If you cannot find a threshold you might have already started above it so increase the Attenuator until you will find a decrease in the frequency noise Matisse Commander 170 Pound Drever Hall Control Setup Only available for Matisse TX DX and TX light These control parameters influence the various input and output signals of the Pound Drever Hall unit 2 Pound Drever Hall Control E Basic Advanced Phaseshift AS a DSP Offset ias d Attenuator A a DE 5 dB POH Multiplexer Input Slow Side EOM 2 Sideband Madulatian On Intra Cavity EOM actives Figure 80 Pound Drever Hall Control Basic Parameters Setup basic parameters DSP Offset will change the baseline of the Phase Mixer signal Choose a value so that the baseline 1s around zero The Phaseshift determines the phase between the 20 MHz sine modulation and the detector signal This phase will determine the shape of the PDH error signal Choose a value that results in an symmetric error signal with a steep slope in its center The Attenuator value determines how strong the intra cavity EOM will react on deviations from the zero crossing of the PDH signal All above mentioned quantities have a range of O to 255 except the
143. perated in combination with a powerful pump laser Nd YAG or Ar laser The laser power of the Matisse depends on the pump laser power and on the selected wavelength In any case the laser beam of the pump laser as well as the Matisse laser beam have an extremely high power density Hence both lasers are able to cause severe eye and skin damages Due to the high powers involved even scattered or specularly reflected laser light are sufficient to produce such injuries Furthermore absorbing and flammable material inadvertently used as a beam stop poses a fire hazard Thus working with such laser systems utmost precautions have to be taken Pay special attention to all advice given by the manufacturer of your pump laser In the following some general safety rules for the usage of lasers are given These recommendations are by no means complete rather they constitute the bare minimum of precautionary measures necessary to avoid laser induced dangers and damages Each person working with the laser or present in its operating room should wear laser radiation safety goggles Note that the safety goggles should give protection against the radiation of all lasers used in the operating room which are in each case the pump and the Matisse laser but also radiation generated by up or down conversion of the laser light Keep the laser closed This means not only to keep the housing of the laser closed during laser operation but also to enclose the eme
144. position was located so that it coincides with the corresponding local maximum of the total laser power red curve as shown in the figure below Click on Set in order to physically move the Birefringent Filter motor Thus the total laser power will be optimized without any influence on the current wavelength You need to hit Set even if the default position of the red cursor is the position you want to keep because otherwise the Birefringent Filter will stay in the utmost right position on the displayed motor position scale O Birefringent Filter Scan Thin Etalon Reflex 1 Birefringent Filter Scan Total Power ms 0 6 0 5 0 57 Set o E L Motor Position Jj 256413 x jo g HoH D o E N i4 2 0 3 0 4 3 m 2s a c aT o e U n3 l 0 1 0 07 I I I I I I 170 3 253000 254000 255000 256000 257000 258000 259000 260000 Birefr Filter motor position Thin Etalon Click on Control Position Scan in the TE Thin Etalon menu Press Start The Thin Etalon performs a scan in the vicinity of of its current position A typical result is shown in the figure below The power reflected from the Thin Etalon and the total laser power are measured simultaneously as function of the etalon position The third element in the graph is a red vertical line indicating the original motor position before the scan which will allow you to move the etalon in a well controlled way near a minimum of the curve repre
145. program requires Administrator privileges A USB port is needed to connect the laser to the PC First install the software by executing setup exe in the Matisse Commander Installer subdirectory then connect the laser to the computer Windows should detect the new device and ask for a driver Let Windows execute an automatic search The Matisse Commander is based on LabVIEW 8 6 for device communications National Instruments VISA software is used Corresponding required software LabVIEW runtime 8 6 VISA runtime 4 3 or higher etc will be installed or updated during the Matisse Commander installation 1f no appropriate software is already present on the computer Version Changes Matisse Commander 1 6 Matisse Commander 1 6 x rescales parameters with small values lt lt 1 by a factor of 10000 This is true for the FPZ and SPZ control loop gain parameters as well as for the PZETL modulation amplitude These parameters are rescaled only for display purposes The internally used values in the Matisse Controller stay the same Matisse Commander 134 Matisse Commander 1 8 Version 1 8 1s based on LabVIEW 8 6 The dialog window for the piezo etalon was re programmed to accommodate the new feed forward parameters and to clarify the usage of the control The fast piezo dialog was modified to reflect the changes in the firmware Matisse Commander 1 8 1 General Version 1 8 1 is based on LabVIEW 8 6 1 An error in the Read Configura
146. rah Laser und Plasmatechnik GmbH Fax 49 2131 66 80 95 Index A About 183 Advanced Options amp Tools 141 Aligning the Piezo Etalon outside the laser cavity 94 Aligning the Thin Etalon Monitor Diode to the intracavity beam reflection 104 B Birefringent Filter 38 146 Birefringent Filter Calibration Table 149 Birefr Filter Scan 150 Birefr Filter Scan Options 150 Birefringent Filter Scan 147 Birefringent Filter Scan Options 148 C Cavity Mirror Optimization 92 CE Declaration of Conformity 11 CE Electrical Equipment Requirements 7 Control Loop Live View 143 Control Loop Live View Options 144 Control Switch Off Level 144 Controls Box Front and Rear Panel Features 23 ControlScan Setup 179 ControlScan Values Measurement 180 Customer Service 189 D Dangers Caused by Laser Dyes and Solvents 15 Device Configuration 139 Device Configuration Administration 140 Device Hardware Configuration 144 Display Options 146 DSP Input Charcteristics 184 Dye Exchange Procedure 123 E Environmental Conditions Requirements 7 Environmental Specifications 7 Error Dialog 136 Exchanging The Matisse Optics Set MOS 130 194 F Fast Piezo Amplifier Board Input Characteristics 185 Fast Piezo Control Setup 160 Firmware Update 137 Focused Back Reflection Danger 16 Frequency Drift Compensation 55 Frequency Scanning 117 Fr
147. re Modules Slow Piezo DAC Reference Cell DAC Birefringent Filter Motor Controller Thin Etalon Motor Controller Fast Piezo Piezo Etalon _ Pound Drewer Hall Controller Intra Cavity EOM Controller The various Matisse models possess different electronic hardware components In this dialog you can activate or deactivate these components To make this change permanent you have save the active configuration see Device Configuration see page 139 Changes will come into effect at the next start of the Matisse hardware controller Control Switch Off Level Figure 62 Switch Off Level dialog Switch Off Level Switch OFF Intensity Level 10 1 A Cance The Switch Off Level is the total laser power level below which the control loops are deactivated Powermeter Figure 63 Powermeter Motor Status Figure 64 Motor Status Display Matisse Commander 145 ll Powermeter 0 4 05 0 6 0 2 0 3 a 0 8 0 1 Averaged Power 15 0 6996 The powermeter displays the total laser power and can be used for adjusting purposes gt Motor Status MOTTE Position MOTBI Position 90000 160000 EE Running EE Running Error Error Show Clear Error This windows display the current position and status of both the Thin Etalon and the Birefringent Filter motors It 1s updated every 500 ms and runs in parallel to the main program Show Clear Error will show you an error dialog indicating whi
148. red to the total laser intensity A control loop will adjust the TE position so that the ratio of these two signals is kept constant Single Frequency Tunable Laser Physics 45 Piezo Etalon Description Figure 14 Front view of the piezo assembly etalon The piezo etalon is formed by two prisms with parallel base sides functioning as a Fabry Perot interferometer with an air gap One prism is mounted to an piezoelectric actuator to control the air gap thickness The free spectral range of the interferometer 1s about 20 GHz and a Finesse of about 3 The piezo etalon ensures that all except one longitudinal mode have so high losses that lasing is not possible Therefore the spacing of the etalon must be matched to an multiple of the favored longitudinal mode s wavelength Because of the tight spacing and in order to be able to perform a scan the spacing is actively controlled The control loop is based on a lock in technique and the etalon spacing is varied by a piezo drive Prism The etalon is formed by two prisms The resonator beam enters and exits under Brewster s angle 2 Horizontal Alignment This screw controls the horizontal tilt of the entire etalon assembly 3 Vertical Alignement This screw control the vertical tilt of the entire etalon assembly 4 Piezo Voltage SMA connector that connects to the piezoelectric actor Figure 15 Side view of the piezo assembly etalon Single Frequency Tunable Laser P
149. reflection on a beam tool Note the position of the reflected beam and then by inserting the lens back try to hit the target beam tool in exactly the same point Keep in mind that due to its small focal length the lens will make the incoming beam diverge within a short distance therefore choose an appropriate distance where to place the beam tool acoarse alignment is done by unscrewing the L1 screw which will shift the hole mount on the vertical axis or the B1 which does the same on the horizontal now you can connect the fiber to the coupler A fine adjustment can be achieved by tweaking the H1 and V1 controls and observing the light which is coupled out the fiber A maximum intensity denotes an optimum coupling The ultimate adjustment must be carried out by looking at the transmission spectra of the reference cavity see the next section and maximizing the peak intensity 2 The Fiber Coupled Reference Cavity The reference cell is made up of three parts I fiber out coupling unit at the in coupling cavity end consists of an XY mount in which a 2mm lens is embeded the fiber from the Matisse Laser Head delivers the necessary laser beam into the reference cavity II evacuated and thermally stabilized confocal cavity of Finesse 30 40 used as frequency discriminator III the detector unit it comprises an attenuation stage a photodiode a pre amplification stage measures the transmission spectra of the cavity
150. rging laser beam e g in tubes where feasible and to terminate the beam with a suitable beam stop Keep the internal protection sheets and beam stops in place Under no circumstances look into the laser beam For security reasons even when the laser 1s switched off never look backwards in direction of the laser beam Avoid wearing reflective jewellery while using the laser Especially watches are excellent mirrors for laser radiation Do not risk to reflect the beam into your eyes by them Safety Precautions 14 Never place reflecting surfaces into the laser beam before having verified where the reflected beam will go Even absorbers and beam dumps may reflect a considerable amount of laser power which can be sufficient to cause severe injuries or damages at the power levels common in the operation of your laser The introduction of lenses into the laser beam requires special caution because its curved surfaces generate additional laser foci in the reflected beam which are able to destroy optical elements Use the pump laser at the lowest possible power level Especially for alignment purposes you should use the pump laser at a power level which is just slightly above the threshold power level of the Matisse laser Never expose your skin to the laser radiation All laser beams have to be terminated with a beam stop All experiments to which the laser is applied have to be designed in such a way that the laser beams are confined t
151. rrect number of peaks appear in the Peak Table With the information in the Peak Table it is possible to calculate the RefCell Finesse The Maximum Intensity and Off Set Intensity of the spectrum are given as well Airy Fit tab A Fit for the RefCell spectrum can be made according to the following function for the transmitted intensity Intensity Scan Piezo Position Offset Amplitude 1 2 x RefCell Finesse 7 Y x sin Phase Scale Factor x Scan Piezo Position Phase Offset 2 Matisse Commander 167 The best fit result is shown in the graph of the RefCell Properties Measurement dialog see page 165 If the fit does not lead to reasonable fit parameters press again Fit and see if the result improves If not press Init to initialize the start parameters again change the Phase Offset and repeat the fitting procedure Set RefCell Properties stores the calculated RefCell Finesse the RefCell s FSR the Maximum and the Off Set Intensity into the Matisse Commander s configuration file making it possible to calculate the frequency noise in the the Ref Cell Frequency Noise display see page 164 Also the setpoint of the Fast Piezo control loop see page 160 will be set to the displayed FPZ Setpoint value The value is calculated to be the amplitude value at the Full Width At Half Maximum points of the measured transmission spectrum Scan Conversion Factor tab Calculate Conv will perform the calculation of the Conv
152. s BUT should NOT be overlapped by overlapping them you might notice a substantial drop in power since the laser will start running in two directions Cd T e a the fine adjustment for getting maximal power is finally achieved by softly rotating the micrometer screws this should be done in an iterative manner too Matisse Operation 100 Thin Etalon and Birefringent Filter Optimization Figure 39 Result of a Birefringent Filter motor scan Blue curve thin etalon reflex Red curve total Matisse power Both in arbitrary units During laser operation especially when the laser wavelength is scanned the position of the thin etalon is actively controlled by the laser electronics The error signal for the electronics it the laser power reflected from the etalon as measured by diode D 2 divided by the total laser power as measured by diode D 1 This error signal is minimum for the optimum etalon position The set point of the thin etalon and also the position of the birefringent filter need to be checked and optimized for each wavelength Execute the optimization process in the following order Birefringent Filter Click on Scan in the Birefringent Filter menu of the Matisse Commander main window Start a Birefringent Filter scan A typical result is displayed in the next figure where the total laser power blue curve and the Thin Etalon reflection are shown as function of the Birefringent Filter motor position
153. s applied the orientation of the two parts will be stable In view of the relatively low weight of the Millennia laser head compared to the Matisse some guidelines need to be followed for a proper installation once the Millennia is set up in its final location and orientation make sure that the housing can not be bumped accidentally and that the umbilical s location and tension is not changed afterwards This is especially important if the Millennia is located at a side of the table where there is much lab traffic If the installation is done on a floating table float it for the installation the clamps for the Millennia Legs are the same as for the Matisse feet They have a flat head screw on their end The head of the screw needs to face down This results in a gap of equal width between the clamp and the table along the entire length of the clamp Transport Matisse Installation 62 The main condition to keep installation after transport easy 1s to start with a running system Before moving the system you should operate your laser at the wavelength of maximum power output of the current configuration This wavelength and the obtained power will be mainly defined by the mirror set and dye crystal your are using Optimize the system for that wavelength and take notes about pump power Matisse wavelength and obtained Matisse power After moving the system you should re install the laser for with the same configuration bef
154. s ND filters If the reflected beam is not properly aligned to the TE Unit scanning the Thin Etalon see the previous section will present spurious effects and a rather narrow scanning range under optimal alignment the TE scan should cover around 20 000 stepper motor steps A missalignment of the TE Unit might result in very low intensity on the monitoring Photodiode Unit which can be visualised on the Thin Etalon Signal Monitor Menu which in turn will affect the effectiveness of the TE Control Loop Start by making sure that the Matisse cavity is well aligned i e the output power at the desired wavelength is peaked Then proceed to shutter or block the pump beam Important Safety Notice The design of the Thin Etalon is such that the focused reflection from the thin etalon is directed upwards from the second aluminium mirror Under normal operation conditions the reflected beam is blocked by the silver coloured monitoring Photodiode Unit housing The alignment procedure described here involves removing of the Photodiode Unit housing in step 5 hence the beam can propagate free space upwards and poses a serious hazard to your eyes and skin Do not look directly down on the thin etalon unit when the Matisse is running If you however do so ALWAYS use a screen as described in step 6 to adjust the spot location Matisse Operation 105 Alignment Procedure 1 It is assumed that the thin etalon mount is fixed to the Matisse
155. sary use the micrometer screw on top of the thin etalon mount 5 to adjust the reflected beam height until it is in the middle of the target 1 e at 60 mm height Then rotate the mirror mount back to its original position so the thin etalon reflection is directed through the focusing lens Only fix the screw slightly for now Block the pump beam again 5 Remove the monitor Photodiode Unit in a silver coloured housing from the Thin Etalon Unit mount Use a 2 5 mm Allen key for the two screws You do not need to disconnect the electronic connectors if you carefully put the diode housing next to the Thin Etalon mount on the baseplate inside the laser 6 Switch on the pump laser again Beware of the cavity beam visible or IR which is directed upwards Prepare a little piece of paper or thin cardboard having one straight edge and draw a pencil line parallel to that edge at a distance of 10 mm about 0 394 Put the straight edge at the plate where the monitor diode was mounted Put it between the lens hole and the two holes for the screws for the monitor diode housing about 20 mm 0 787 underneath the two holes When the laser is running a spot will be visible through the paper The goal is to set the spot a on the pencil line and b to the middle position between the two holes if seen from above Adjustment a is done by rotating the second mirror mount around its horizontal axis for adjustment b the first mirror mount is rotated arou
156. schemes In the Matisse TX DX light versions the PDH error signal is used as the error signal for the Fast Piezo control loop achieving a significant improvement in the laser bandwidth in comparison to Matisse S models In the full Matisse TX DX versions an EOM is added to the laser resonator that will also use this signal after adequate signal conditioning as the error signal for its control loop Because the EOM has a much larger control bandwidth a further significant improvement in the laser bandwidth can be seen Detailed instructions for the various control loop settings can be found in the X Stabilization see page 168 section of the Matisse Commander chapter Matisse Frequency Stabilization Schemes 55 Frequency Drift Compensation Experiment Figure 22 Possible Matisse Setup using an atomic resonance to compensate frequency drifts Gas Cell Matisse Commander The frequency stabilization schemes described before will give small laser linewidths 1 e frequency fluctuations on time scales of several 10 or a few 100 ms are reduced When you look at the frequency behavior on time scales of several 10 s or minutes and some hours the center frequency of the laser can drift in the order of some 100 MHz depending on the ambient conditions of the reference cell environment The drifts are due to temperature changes or piezo actuator relaxation processes acting on the optical properties of the reference cell To compe
157. senting the reflected power Matisse Operation 102 Figure 41 This window indicates the power reflected from the thin etalon as well as the total laser power for different positions of the thin etalon Set Thin Etalon Control Position Thin Etalon Reflex Thin Etalon Scan Total Power Am D 8 0 5 A A Motor Position 0 4 lt 20000 0 07 I I I I I I I I I 170 3 18000 18200 18400 18600 18800 19000 19200 19400 19600 19800 20000 Thin Etalon motor position Dom D 430d 2301 x v t o a 9 m 2 lu de The blue curve looks similar to a sequence of parabolas with minima Changing the thin etalon s position within such a parabola will not change the Matisse wavelength If you change the motor position from one parabola to the next one the Matisse frequency will change normally by one Free Spectral Range of the Thick Piezo Etalon see the Single Frequency Tunable Laser Physics see page 34 chapter for more details Once the acquisition is finished drag the line towards the minimum of the parabola where the original thin etalon motor position was located Set the line on the left hand side of the minimum as shown in the next Figure Click on Set and the thin etalon will be moved to the stepper motor position indicated by the red cursor You have to hit Set even if the default position of the red cursor is the position you want to keep because otherwise the etalon will sta
158. ser Physics 34 E AAA II A E 35 Erequehcysselectro e Element ld bs 37 Biterripgent Pier xata ino a t dotato diets adire bee etui nb tede bept 38 Thit T a a me vasanceraeses ca vucnnacetnseisss sue wecaemenase A E te seteeeoaad 44 Pezo Etalon DESC pli cento soho a onec E cs ses satay Sonne wade eae eee 45 PICZO Btalom DIM de asa 47 Contents ii Optical Diode CU midivectiOnal Device iu ii deett uat one eda tado dodo aad dn i HUI 48 Matisse Frequency Stabilization Schemes 49 Side oL Ermege TTequenc v SCAD UM AIO IN tie 50 Pound Dtever Hall frequency stabilization auiiks eos casas A TH ER QEE QU Rae A C SH OUR D eO P DUE 22 Frequency Drit COMPE oo ias 55 Usine Y0ur owmtelerence Lor stabilizing A A AL pes 56 Matisse Installation 57 Installation Requirements airis 57 ROY AH pia LoS Tr EDAD 58 AE SINN uo X E NE 61 A T 62 Optical Alonment PEOCEQUEOS ion 62 Optical Ahlienment Procedure Matisse T1393 utei tette eu hate e hne docu a icxa eee 62 Opucal Altenment Procedure Matisse Dye uisiseede fabis etre tli eeu vea is 67 Optical Alignment Guidelines for the Fiber Coupled Matisse S Reference Cell 70 Optical Alignment Procedure for the Matisse X Reference Cell ooooonnnnnnncncccnnnnononocononncononnnnnnos 74 Installing Ceramic Apertures in the Matisse Dye Ring Cavity cccccccononnnooncnonccnnnnnnnnonononnnnnnnnncnnnncnnnnnonnnnnnos 81 Matisse Operation 85 ld A O 85 Cal eI ASSO Deui tue ow ex cele A
159. ser would be the consequence 17 Set your pump laser to a very low pump power 0 2 W or less Open the pump laser shutter or remove the external beam dump and apply pump power to the Matisse 18 Make sure that the pump laser is correctly coupled into the dye laser Matisse Operation 89 19 Close the Matisse top cover 20 Increase the pump power until the Matisse laser threshold is reached 21 The energy level necessary for the start of laser operation depends on the used dye and the wavelength As a rough indication if pumped with a 532 nm beam and used with a high gain red dye the Matisse should start lasing at about 1 5 W input power Slowly increase the pump power up to 5 W At this pump energy most pump Matisse laser configurations should result in an operating dye laser However for very low gain dyes or at wavelengths at the edge of the tuning range even higher pump power might be necessary Before further increasing the pump power please check again that the pump beam correctly enters the dye laser Then slowly increase the pump power until the Matisse starts lasing 22 Your Matisse dye laser should now operate In this case please refer to the following Sections for a quick optimization of the Matisse output power If your Matisse laser is still not operating then decrease the pump power to about 5 W and carefully re check the entire pump beam path Matisse Operation 90 The unidirectional dye check valve
160. spect to the plate s surface normal In this way the optical axis of the quartz crystal will also be rotated hence yielding new wavelengths of the incoming light for which there is no change of the polarization state and therefore no losses through reflection at Brewster s incidence Single Frequency Tunable Laser Physics 39 Figure 10 Single element Birefringent Filter The c axis is the optical axis of the plate Below is a sketch of a laser beam propagating through a quartz plate The beam is incident at a Brewster s angle on the surface of the plate The unity vectors e and e define the plane of polarization where the unity vector ep is parallel with the surface of the plate The internal Brewster s angle is denoted with D The propagation of the beam within the crystal is defined by the vector S C denotes the optical axis of the crystal with respect to which any incoming wavelength will see a finite refraction index o is the angle between the surface normal and the c axis The rotation of the quartz plate with respect to the surface normal is defined by the angle p Single Frequency Tunable Laser Physics 40 The resulting phase difference between the ordinary and the extraordinary ray 1s given by 2n t 2 EN n n Jsin y A cos p 1 with the angle y given by cos y cos D cos o sin p sin g cos p 2 and can be related to angles determined experimentally For crystalline quartz n 1 553 and n 1 544
161. ss of 0 325 0 975 and 4 55 mm is presented below O dL d LL Lu fe LL 1L ee eee ft O LL LM LLL lu A CL aL ECCL d Ll JL LE AL ul dL Ld Lb LU A HL A LA D ITA A A LAA ALT I I I I l I I 600E 9 650E 9 700E 9 750E 9 BOOE 9 850E 9 3900E 9 950E 9 1E 6 Wavelength nm 10 Thin Etalon Single Frequency Tunable Laser Physics 44 One of the main advantages of using the Birefringent Filter as a tuning element is given by its extremely wide tuning range as well as by the relatively small insertion losses theoretically zero for the case in which the filter 1s properly aligned at Brewster s angle The combination of the Birefringent Filter and the Thick Piezo Etalon is in general not sufficient to guarantee single mode single frequency laser operation Therefore there is another frequency filter a solid state Fabry Perot etalon called the Thin Etalon TE Its position in relation to the laser beam can be adjusted with the help of a motor controlled mount It has an FSR of about 250 GHz for the standard etalon and a relatively small Finesse The TE is in a way adjusted that will give no direct reflections from the etalon s facettes into the laser beam paths to avoid complicated laser intensity dynamics For the TE it also true that one of its mode s frequency has to be the same as the laser resonator mode s frequency For this purpose the reflection from one facette is monitored and compa
162. t 5 6 m Figure 37 Top view of 3 the Piezo Etalon orientation with respect to the target and laser source NS EE i y S beam The etalon must be positioned such that the plastic knobs are facing the HeNe laser while the side with the silver micrometer screws 1s oriented towards the target see the picture below The positioning should be done such that the ground plate of the etalon 1s parallel to the beam path also please do note that the laser beam should pass right through the middle the Littrow prisms When the positioning is satisfactory the etalon must be fixed to the optical table similar to the intra cavity operation mode Ty To the laser source 2 3 m The first alignment step consists of directing the back reflection from the prism assembly as parallel as possible to the incoming beam Localize the back reflection and by turning the upper and or lower black plastic knob bring it as close as possible to the laser source Please note that the back reflection should NOT overlap with the incoming beam but it must be positioned 1 2 cm to the side of it preferably at the same height Matisse Operation 96 4 Observe the laser beam on the target in case the Piezo Etalon is badly misaligned by inserting it in the beam path you will notice a 4 laser spot constellation with each spot having a different size see the photo below left follow the procedures described in step 5 If the bea
163. t 60 mm height adjust the height of the Reference Cell by turning screwing in or out the three threaded feet To be able to do so open the 17 mm counter nuts on the bottom of the baseplate first see photo below One complete rotation corresponds to a increase decrease in Reference Cell Unit height with 1 5 mm Matisse Installation 76 B Optical alignment of the Ref Cell coarse Using the mirrors 1 and 2 walk the low intensity laser beam such that it runs through the middle of the two mode matching lenses 3 4 fine Center the laser beam on the entrance respectively the exit aperture of the EOM 5 see EOM exit aperture picture on the next page Using the mirrors 6 and 7 make sure that the beam is passing approximately through the middle of the PBS 8 and the quarter wave plate 9 The aim of the next step is to ensure that the beam is propagating parallel to the axis of the high finesse cavity In order to do that remove the transmission diode 12 and by using a piece of paper and an IR viewer if you are working above 800 nm with the Ti Sapphire version of the Matisse laser look at the transmitted light Note normally the Reference Cell 1s pre aligned in the factory and thus the transmitted light will present a small and bright point like pattern figure d in the graphic below If the the alignment of the Ref Cell Unit has been subject of major changes due to maintenance etc you most probably wi
164. talon Diode The control loop for the thin etalon requires the measurement of the back reflection of the entrance surface of the etalon This diode measures the reflected intensity Controls Box Front and Rear Panel Features Figure 5 Front view of Matisse control box N _ Power switch Turns the entire unit On and Off Voltage indicators Light up when the respective voltage 1s available in the control unit LED DSP signal input select Selects the internal or an external signal source for the digital signal processor DSP DSP external input SMA connector to feed an external signal into the DSP unit USB connector Connects the unit to the USB USB indicator Lights up when the USB is transferring data LED Tuning mirror input select Selects the internal or an external signal source for the piezoelectric actor that controls the tuning mirror Tuning mirror external input SMA connector to feed an external signal into the amplifier module Matisse Laser Description 24 9 Tweeter mirror input select Selects the internal or an external signal source for the piezoelectric actor that controls the tweeter mirror 10 Tweeter mirror external input SMA connector to feed an external signal into the amplifier module 11 Reference cell input select Selects the internal or an external signal source for the piezoelectric actor that controls the reference cell spacing 12 Reference cell external input SMA connector
165. te with the laser device using low level device commands Commands typed into the Command control followed by pressing lt Enter gt will be sent to the Matisse controller and executed The controller s response will be shown in the Response indicator A history of sent commands to choose from can be accessed by using the pull down menu of the Command control To send the current command repeatedly you have to press Send Again You can also arrange commands line wise in a text file and load this file via Batch File The text lines will be sent until an End Of File or the word END is encountered Figure 57 TE Signal display Figure 58 Wavemeter Integration dialog Figure 59 Wavemeter Removal Matisse Commander 142 Thin Etalon Signal Monitor TE Signal Monitor lx os 04 05 06 97 Oe 0 5 Averaged Signal 15 0 0818 The Thin Etalon s reflex signal is displayed to be used when adjusting the reflex on the corresponding detector Integrate Wavemeter Integrate Wavemeter IF vou possess a Wavemetker and a corresponding software plug in see Matisse Documentation Matisse Control can use the device to enhance its Functionality When vau press OK Wawvemetker relabed data will be added to Matisse Control s configuration File and the control program will terminate After you have restarted Matisse Control the new menu Wayemeter will be available If you have a wavelength measuring device wavemeter
166. the back reflections from the etalon prisms using the black plastic knobs facing the output side of the Matisse laser bring the two spots close together but make sure that they are slightly separated on the vertical axis If you overlap them you will Observe a very bright spot and a strong decrease in output power since the laser will be running in unwanted counter clockwise direction This effect occurs due to the formation of two separate cavities defined by the facets of the etalon prisms and other cavity components end mirrors Matisse Operation 94 Aligning the Piezo Etalon outside the laser cavity A misalignment of the Piezo Etalon may result from changes in the ambient temperature or 1t can occur during the transportation of the laser This section gives guidelines for aligning the Piezo Etalon outside the ring cavity Necessary equipment 3 mobile target you could use the beam tool provided with the service box laser source With regard to this we recommend using a He Ne laser whose beam could be run over a total distance of about 8 10 m One should keep in mind that a distance of at least 3 4 m should exist between the He Ne laser and the Piezo Etalon as well as another 5 6 m from etalon to the target a set of Allen keys Alignment procedure 1 align the HeNe laser source beam to the target without inserting the Piezo Etalon in the beam path For that make sure that the beam is running parallel to t
167. tics set Output range Millennia Pro 10s MOS 1 700 780 nm Millennia Pro 10s MOS 2 750 870 nm Millennia Pro 10s MOS 3 860 990 nm Power Output at approximately 780 nm Pump laser Specified power Millennia Pro 5s 800 mW Millennia Pro 10s 1800 mW General Characteristics Spatial Mode TEMOO Beam Diameter at typical 1 4 mm Matisse output port Beam Divergence 2 mrad Linewidth lt 10 MHz rms Amplitude Noise 1 5 rms Beam polarization horizontal Requirements Pump laser Millennia Pro Series or similar Matisse Laser Description 27 Pump laser power 5 20W Ambient conditions constant temperature in the 20 25 C range non condensing humidity conditions Cooling required for crystal 10 W Laboratory vibrational isolated optical table dust free air flow box Electrical 100 250 V max 2 5 Amps Computer control Windows 2000 or Windows XP system USB port Matisse Laser Description 28 Matisse DR Specifications This section summarizes the specifications of the Matisse DR laser Please note that specifications are subject to change without notice Tuning range Pump laser Optics set Output range Millennia Pro 10s MOS 4 550 660 nm Millennia Pro 10s MOS 5 650 780 nm Power Output at the output maximum of the Rhodamine 6G tuning curve Pump laser Specified power Millennia Pro 5s 550 mW Millennia Pro 10s 1600 mW General Characteristics Spatial Mode TEMOO Beam Diameter at typical 1 4
168. timization procedures for all relevant components of your laser To keep the laser working at optimum performance is quite easy as long as you do not totally corrupt the laser optical set up Some effort has been undertaken to illustrate the different laser optimization possibilities as step by step procedures Please always read the whole section corresponding to your task before doing the first step The Maintenance chapter will deal with all relevant maintenance tasks necessary for a stable long term operation of your laser system Matisse Preface 6 The following chapter serves as a description and reference for the Matisse Commander computer program with which the Matisse laser 1s controlled Matisse Electronics gives additional and more detailed information on the electronics The FAO and Troubleshooting chapter tries to help you solve some issues that you may encounter at some time working with a Matisse laser In the Customer Service section you will find the addresses of world wide Service and Sales Centres for Sirah instruments In case of any question remark or problem please do not hesitate to contact us Please read the whole manual before starting to work with your system We strongly recommend to keep a laser logbook You should note all changes of the mechanical or optical set up of your laser Regularly take notes about obtained laser powers together with the corresponding pump power These notes often simplify the i
169. tion for Ti Sa or dyes additional frequency selective elements have to be introduced into the resonator These elements will be explained in detail in the next section Single Frequency Tunable Laser Physics 36 Another important aspect for single mode laser operation is to choose a ring laser geometry instead of a standing wave resonator configuration With electromagnetic standing waves only part of the gain provided by the laser medium can used by a specific resonator mode at the locations of the wave s nodes the gain cannot be depleted spatial hole burning effect This can lead to a situation where another resonator mode having its anti nodes at the locations of the nodes of the former mode can start to oscillate and produce a multi mode laser operation case Ring resonators with their running waves do not suffer from this problem but there 1s the possibility for two modes with the same frequency but running in opposite direction to oscillate This case produces complicated intensity dynamics and can be avoided by introducing an unidirectional device optical diode to allow only modes in one propagation direction to oscillate Apart from adding new elements to the laser another way to reduce the number of modes is to use resonator mirrors that are highly reflective only for a certain range of wavelengths For the Matisse there are five different optical sets Matisse Optical Set Wavelength Range nm MOSI 690 780 Ti Sa
170. tion from File part of the commander was detected an removed The error affected the loading and saving of Pound Drever Hall unit specific settings on X and X Light systems With the help of the Matisse Commander program you can manipulate the positions of the frequency selective elements and the settings of control loops respectively to achieve maximal stable single mode output from the Matisse laser device Moreover this program allows you to configure and execute scans over the laser s wavelength The following chapters ordered in analogy to the menu structure of the program gives you information on the various functions of Matisse Commander References to indicators or controls of dialogs are set in bold type The following subsections provides information concerning Matisse Commander in general Matisse Commander 135 Start Up Figure 51 Device Not Found dialog At the start up of the program Matisse Commander will try to detect the presence of a Matisse laser device either with the help of information in the Matisse Commander s configuration file Matisse Commander ini or by directly accessing USB devices that have the correct Manufacturer and Model ID If no Matisse laser can be located the following dialog will appear requesting you to power up the Matisse controller box and restarting Matisse Commander or to choose the Dummy Mode Could not Find a Matisse device Please restart Ehe Matisse hardware Exit Du
171. tisse Maintenance 127 pull out the old filter replace the old filter with a fresh one Hold the filter mount as shown in the right hand side picture below Matisse Maintenance 128 when mounting the filter top to the housing make sure the black rubber O ring 5 is properly positioned in its groove like depicted in the picture below D Get the laser back in operation After mounting back the filter top to the housing and reattaching it to the hose as well as to the bypass pipe you can now pour the new dye solution into the steel dye reservoir For information about what type of solvent can be used as well as about the dye solubility you are strongly advised to consult the Matisse user s guide see the Required Dye Solvents sub section in the Matisse DR Specifications section chapter Matisse Laser Description Note that the data given is the maximum solubility of dyes in the respective solvent for information on required dye concentrations please contact Sirah Also in order to achieve good and stable lasing with a specific dye solution you must aim to have 90 absorption of the pump beam in the dye solution Now you can get the laser in back in operation by referring to the standard Start up Matisse Dye procedure described in in the Basic Matisse Operation Chapter Matisse Maintenance 129 IMPORTANT For laser operation use an adequate amount of dye solution to facilitate proper cooling the coo
172. trol loops have to be active beforehand About Figure 93 About dialog Matisse Commander 183 About Matisse Commander The About dialog displays System Information like the Model Name and the Serial Number S N of your Matisse Device as well as the DSP and Firmware version of the hardware controller This information 1s important in case of a support request The clickable www link www sirah com will open the Sirah homepage in the default web browser on your computer where you can find news about and updates for the Matisse laser systems and accompanying software 184 CHAPTER 10 Matisse Electronics DSP Input Charcteristics The external input of the DSP has the following electrical characteristics Parameter Value Connector Type SMA jack connector MIL C 39012 Voltage Range 5 0 5 0 Volts Input Impedance 3 4 KQ Piezo Amplifier Board Input Characteristics The external input of the Piezo Amplifier Boards for the Scan Device or the Thick Piezo Etalon has the following electrical characteristics Parameter Value Connector Type SMA jack connector MIL C 39012 Voltage Range 0 0 43 0 Volts Input Impedance gt 1 MQ Matisse Electronics 185 Fast Piezo Amplifier Board Input Characteristics The external input of the Piezo Amplifier Board for the Fast Piezo has the following electrical characteristics Parameter Value Connector Type SMA jack connector MIL C 39012 Voltage Range 0 0 4 0 Volts
173. ugh the backside of folding mirror FM1 FM1 Folding Mirror 1 Restores a parallel beam for the ring laser beam after amplification by the Titanium Sapphire crystal Matisse Laser Description 19 FM2 Folding Mirror 2 Focusses the ring laser beam into the Titanium Sapphire crystal for spatial mode matching with the pump laser focus TiSa Titanium Sapphire Crystal The laser gain medium The crystal is cooled by a temperature controlled water EOM Electro Optical Modulator The non resonant intra cavity electro optical modulator is used for fast change of the optical path length of the ring cavity The effect is used for high bandwidth correction of the Matisse s emission wavelength Note The device is only present in the Matisse TX Thin E Thin Etalon The thin etalon is used as a bandpass filter To provide tunability the tin etalon 1s attached to a motor driven mount A step motor controls the horizontal tilt angle of the etalon BiFi Birefringence Filter The birefringence filter is used as a coarse bandpass filter to determine the emission wavelength of the ring laser The filter assembly is rotated by a stepper motor OC Output Coupler The output coupler forms the exit for the laser beam A fraction of the beam will be emitted by the laser the rest will be directed back into the ring cavity The beam polarization 1s horizontal M2 Out Of Plane Mirror M2 This mirror is mounted at a different beam height level This will introduc
174. ulator on a pedestal such that you can fit a flask under the plastic drain pipe use the outlet with the red valve 1 on the right side underneath the reservoir by rotating it 90 anti clockwise you will allow the old dye solution to flow out For an efficient drainage at the end of the emptying process the circulator can be tilted to the left side while the red valve is kept open o drain the output side and the filter housing afterwards open the Allen screw 2 at the silver metal block on the left side underneath the reservoir Use the metric Allen key size 6 from the blue Matisse service box IMPORTANT Make sure you close the screw properly after draining since the full pressure of the circulator is on this side Matisse Maintenance 124 In case you posses an older model of dye circulator you can only use the outlet with the red valve 1 Optionally for a thorough removal of the old dye you can open the filter housing see Section C of this instructions and soak up the dye on the bottom of the filter housing using some paper towels IMPORTANT The removal of the black cooling tubes is not necessary However make sure you do not puncture damage them during the dye exchange operation B Rinse the circulator Note that a little amount of dye solution will always remain in the emptied circulator system due to construction reasons In view of this fact we strongly recommend you to rinse the circulator with 1 liter o
175. uning mirror is attached to a long stroke piezoelectric actor to allow the selection of this wavelength This device is used for low bandwidth woofer correction of the Matisse s emission wavelength when active wavelength control is enabled only available in Matisse TS and TX models DI Integral Diode The lock in control for the piezo etalon requires the measurement of the temporal behaviour of the integral intensity of the ring laser For this purpose the leak intensity on the backside of the out of plane mirror M2 is used DE Etalon Diode The control loop for the thin etalon requires the measurement of the back reflection of the entrance surface of the etalon This diode measures the reflected intensity Matisse Laser Description 21 Laser Head Dye Models Figure 3 Top view of Matisse dye laser head Figure 4 Optical layout of a Matisse dye laser PM Pump Beam Mirror Re directs and focusses the pump laser beam into the dye jet FM1 Folding Mirror 1 Restores a parallel beam for the ring laser beam after amplification by the dye jet FM2 Folding Mirror 2 Focusses the ring laser beam into the dye jet for spatial mode matching with the pump laser focus DJ Dye Jet The laser gain medium The jet is formed by a flow of dye solution that is pumped by the circulator system into the nozzle Matisse Laser Description 22 BiFi Birefringence Filter The birefringence filter is used as a coarse bandpass filter to det
176. urrent setting using the scale on the upper side of the two screws The upper screw determines the vertical adjustment the lower one the horizontal one Start adjusting the lower horizontal screw Observe the Matisse power on your power meter Then carefully turn the lower micrometer screw to maximize the Matisse power There should be one position where the laser power peaks There might be a slight hysteresis so maximize the power twice approaching the peaking point from the two different directions to see which direction gives the maximum power Adjusting the upper vertical screw can reveal the existence of two different peaking points having similar laser power not due to hysteresis Use the one with maximum power Here also a slight hysteresis may exist so apply the same procedure as described above If you turn too much the Matisse will stop lasing In this case immediately come back to the starting position in order to re obtain laser operation and re start optimizing After completing the optimization of the two micrometer screws now make sure the etalon prisms assembly is properly aligned with respect to the ring cavity Below are some guidelines use a piece of paper or a business card and place it to the right side of the output on the inside of the laser housing If you are working in the IR range you must use an IR viewer for the optimum Thick Etalon adjustment you will be able to see two spots which are
177. ut this time the direction of the rotation depends on the propagation direction For the counter clockwise running laser mode the effects of this mirror and the optical diode are canceled out For the clockwise running mode the effects sum up so that this mode will suffer additional losses at the various Brewster surfaces in the resonator CHAPTER 5 49 Matisse Frequency Stabilization Schemes For many laser applications is not only necessary to have a single frequency laser but also to have a very stable frequency itself i e a small effective laser linewidth It is possible to suppress laser intrinsic frequency noise by using external frequency references Frequency stabilized Matisse are using highly stable reference resonators that still allow to have a scannable laser by scanning the reference in contrast to using e g atomic frequency standards There are two stabilization schemes exploited with the Matisse for the TS DS version it 1s the side of fringe scheme for the TX DX and TX DX light version it is the Pound Drever Hall method These two schemes differ in their complexity and achievable stabilization results as will be described in the following sections Matisse Frequency Stabilization Schemes 50 Side of Fringe frequency stabilization The concept for this method is relatively simple when you scan the laser frequency and observe the transmitted light from the reference cell you can observe the well known Air
178. vide high performance scientific instruments but also to offer an excellent after sales service In case of any problem please feel free to contact your local service centre Addresses may be found at the end of the present chapter You will need your instrument model and serial numbers available when you call Service data will be promptly supplied Warranty conditions are defined in our General Sales Conditions They may be modified by agreements made in your specific sales order In case of any conflict between documents the terms and conditions of the sales order shall prevail Sirah warrants that the products except optics shall be free from defects in materials and workmanship under normal use and service for a period of twelve 12 months from the date of installation or from 30 days after shipment from Sirah Optics and filters are warranted for 90 days This warranty 1s subject to Sirah products being installed maintained and operated in accordance with the operating and maintenance instructions accompanying the shipment Warranty shall be void if Sirah products are modified by the customer or used in other than the recommended manner or applications In no case shall Sirah be liable for consequential or special damages Material under warranty will be repaired or replaced FOB our shipping point by Sirah Sirah will provide an on site field service representative in a reasonable amount of time provided the customer issues a val
179. will see two fluorescence spots which relative horizontal and vertical position to each other will change with turns of the corresponding screws There is normally a trade off situation for the adjustment of the Piezo Etalon orientation the closer the etalon gets to the perpendicular case the higher is the laser output power If it is too close the output for the counter clockwise running mode will sharply drop As a rule of thumb introduce a vertical separation of the fluorescence spots by 5 to 10 mm I experience spatial instabilities spatial mode fluctuations of the laser beam Frequently Asked Questions and Troubleshooting 187 A laser pumped with higher pump powers might show spatial mode instabilities if not adjusted well enough or because of saturation effects in the lasing medium causing decreased power and making single mode operation difficult You can easily check the laser mode quality by looking at the laser spot of the transmitted light of one of the laser cavity folding mirrors Ti Sa Matisse Look at the spot coming from mirror FM 1 and going through mirror PM2 Optical Setup Ti Sa see page 18 on the inner laser housing about 7 cm left to the pump beam entrance The laser spot is horizontally elongated because of the oblique angle under which it hits the housing When you use an infra red viewer pay attention to look at the Matisse laser spot and not at the pump laser spot that will be close by Dye
180. y change is taken as a measure for a laser frequency deviation intensity noise of the laser is wrongly interpreted as frequency deviations and actually transformed into real frequency noise To minimize this intensity sensitivity the Finesse of the used reference resonator could be increased i e the linewidth of the resonator decreased This would increase the laser frequency deviation sensitivity transmitted intensity change per frequency deviation and in this sense decrease the sensitivity to laser intensity noise But this will also decrease the catching range of the stabilization method defined as the maximal allowed frequency deviation without loosing the laser lock In this case it is about one quarter of the full linewidth of the reference resonator If this range is too small the laser lock becomes unstable This trade off situation finally limits the achievable laser bandwidth with the sside of fringe stabilization scheme Detailed instructions for the various control loop settings can be found in the S Stabilization see page 158 section of the Matisse Commander chapter Matisse Frequency Stabilization Schemes 52 Pound Drever Hall frequency stabilization To DSP Figure 20 Matisse TX Setup For the PDH stabilization scheme there are additional elements in the optical path leading to the reference resonator in comparison to the Matisse S setup The schematic setup is shown in the following figure Laser Head Ref
181. y choosing the PDH Multiplexer Input Modulation On indicates sets the status of the 20 MHz sideband generation and EOM active shows sets the control status of the intra cavity EOM PDH Multiplexer Input shows which signal is currently as output from the multiplexer Modulation On indicates sets the status of the 20 MHz sideband generation and EOM active shows sets the control status of the intra cavity EOM Basic Parameters DSP Offset will change the baseline of the Phase Mixer signal Choose a value so that the baseline is around zero The Phaseshift determines the phase between the 20 MHz sine modulation and the detector signal This phase will determine the shape of the PDH error signal Choose a value that results in an symmetric error signal with a steep slope in its center Advanced Parameters The Attenuator value determines how strong the intra cavity EOM will react on deviations from the zero crossing of the PDH error signal Matisse Commander 173 With the EOM Fast Offset and EOM Slow Offset controls offsets in the fast and slow control signal branch for the intra cavity EOM can be compensated A scan over the cell s piezo actuator voltage is performed within an interval determined by Scan Upper Limit and Scan Lower Limit values are in a range of 0 to 0 7 The Sampling Points parameter gives the number of points used to display the internal waveform It cannot be higher than 512 The Sampling Mode decides which ch
182. y function spectrum of the reference resonator The stabilization idea 1s now to set the frequency of the laser so that it corresponds to a point of the flank of one of the resonator s transmission resonances side of fringe A control loop adapts the laser s frequency in a way that keeps the transmitted intensity of the reference constant The laser frequency is then locked to one of the reference resonator s modes To achieve this locking a second laser resonator mirror is mounted on a piezo actuator the Fast Piezo This Fast Piezo has to counteract relatively fast perturbations to reduce the effective laser bandwidth The former scan piezo mirror the Tuning Mirror in the Matisse TR DR now becomes a kind of auxiliary piezo the so called Slow Piezo It has two tasks to fulfill first in the not locked case it will scan the laser to a resonance of the reference resonator Second when locking is achieved it will keep the Fast Piezo at the center of its dynamics range and so cancelling out slow drifts of the laser in relation to the reference cell The schematic setup is shown in the following figure Tuning Titanium Sapphire Thick Etalon Unidirectional Fast Reference M Mirror Crystal a As e Laser Figure 16 Matisse TS Setup Piezo Driven Device Piezo Cavity t E ni SN JD Photo Q Diode m Dm y 7 Thin Etalon Birefringent Filter Output Motor Driven 3 Plates Motor Driv
183. y in the utmost right position on the displayed motor position scale The software operates with the gradient of the reflected power therefore the cursor needs to be set well outside the minimum of the curve On the other hand setting the etalon too far away from the minimum of the blue curve will decrease the emitted laser power because the minimum of the curve indicating the reflection from the etalon coincides with the maximum of the laser power curve Set Thin Etalon Control Position Thin Etalon Reflex Thin Etalon Scan Total Power PSAL D 8 0 5 D 7 e e 1 Thin Etalon Reflex 430d 2301 Motor Position 0 4 lt J 19130 0 3 I I 15000 18200 18400 18600 18600 19000 19200 19400 19600 19800 20000 Thin Etalon motor position 0 0 Matisse Operation 103 Figure 42 Drag and When the cursor 1s properly set to a position corresponding to a reflection drop the red cursor on minimum leave the dialog window by hitting the respective button In the left hand side of a the Matisse Commander main window click on the TE Control indicator minimum of the blue The dark green indicator will switch to bright green as shown below curve indicating the indicating that the electronics is now continuously controlling the etalon power reflected from the position in order to minimize the reflection and maximize the laser thin etalon power The blue bar underneath the TE Control lamp labelled TE

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