Quantum Instruments Cascade Laser Starter Kit manual What has to be kept in mind before use?

Page 58

Starter Kit Instruction Manual

Appendix

57

Dangers and disadvantages of using a Bias-T circuit

•Since a Bias-T only allows to heat the laser, the emission wavelength can only be increased (or emission wavenumber decreased), and out- put power will decrease with increased Bias current, due to the additional heating.

This means that the laser should be operated initially at lowest possible temperature

•Heating of the active zone will increase ther- mal stress of the laser, therefore the expected lifetime will decrease more rapidly compared to increasing the temperature of the laser sub- mount and base in total.

If operation at only a ﬁxed wavelength is needed, this should be adjusted with the overall tem- perature control.

•Too high a DC Bias current can immediately destroy the laser due to catastrophic thermal roll-over. Therefore set-up of the Bias current has to be done only by instructed personnel, and after checking with Alpes Lasers SA for allowed parameter ranges; otherwise warranty will be lost.

What has to be kept in mind before use?

•All use of a Bias-T on a speciﬁc QC laser has to be accepted by Alpes Lasers SA before; otherwise all warranty will be lost.

•The Bias-T should never be used at the high- est speciﬁed current or output power, other- wise the risk of thermal roll-over failure is im- minent.

•If optical output power can be monitored, this should be used during set-up of the Bias-T to make sure that thermal roll-over is not reached: Temporary increasing of the pulse current must always result in increased optical power out- put, otherwise the DC Bias current is already too high.

Image 58

Contents Quantum Cascade Laser Starter Kit Instructions Manual Web versionContents Maintenance Overview InstallationTroubleshooting UseAppendix Limited waranty IdentiﬁcationDocument ManufacturerGeneralities GeneralChapter overview ComplianceProduct GlossaryPersons PersonnelTypographic conventions Commands styleProcedure style Description styleSee page x-y Troubleshooting style ProblemProcedure eﬀects style Possible causePage Non-compliance with the safety regulations Safety InstructionsImportance of safety instructions IntroductionEnvironmental conditions General safety instructionsCompliance and informa- tion Description System CompositionDescription DFB and FP Quantum Cascade LasersIf no conﬁguration is speciﬁed, the DN pad is used Geometry of QC lasersSpeciﬁcations Electrical model characteristics Electrical modelLaboratory Laser HousingLLH100 LLH100 external view descriptionLaboratory Laser Housing internal view LLH100 internal viewSpeciﬁcations of the Peltier connector Thermo-Electric Cooler TEC and PT100 connectionsSpeciﬁcations of the measurement connector Measurement connectionQCL pulser switching unitLDD100 QCL pulser switching unit front and rear viewMeasured voltages QCL pulse switching measuring unitGeneralities Timing dataLaser peak current Duty cycle calculationAverage dissipation Laser peak voltageAccuracy considerations Trigger and logic output signals Ω TTL driver circuit QCL pulser timing unit TPG128QCL temperature controllerTCU151 Peltier and PT100 connectionsGeneral InstallationChapter overview Packing list Standard itemsProcedure Setting the appropriate AC voltage on TCU151110-120V, 60Hz USA 220-240V, 50Hz Europe Installing the starter Kit Before beginningConnecting Starter Kit Use QCL pulse timing unit com- mand descriptionTCU151 command description TCU151 temperature controler front panelOverview Laser utilisationProceedings Starting the TPG128 Procedure Interlock utilisation Interlock utilisationDC power supply is not ﬂoating TroubleshootingPower supply reaches max cur- rent for a very low voltage PrincipleQCL laser is not used with the LLH and is grounded Laser draws current but gives no lightLaser does not draw current There is no contact with the laserHow to remove the covers of TCU151 and TPG128 MaintenanceOverview Replacement procedures Quantum Cascade Laser replace MentFacet on the case, it is extremely fragile + LLH100 connectionQCL UP and DN position Exchange Exchanging the laserIf the ambient atmosphere is humid this is HumidityBefore beggining interlock set Ting TCU151 temperature con Troller interlock settingProcedure interlock setting Needed material1 TPG128 calibration Calibaration proceduresProcedure calibration GeneralitiesTPG128 main board TPG128 main board 2 TCU151 temperature controller calibration Procedure +5V/-5V power supply checkSensing level and range adjustement = 1.22 toTemperature Reference oﬀset adjustment Oscillator check Current/Voltage ratio adjustmentSetting LCD screen should display 1.00 a7V = 70 C If needed, adjust it with the trimmer P92 Starting the power section of the instru Ment→ Value displayed ≤ 1A Current adjustment→ Value displayed should tend to the deﬁned value Threshold on Miscellaneous functions testing Temperature Limit testing→ The temperature displayed 2 should be 035 C → The red LED 1 should turn oﬀDirect absorption Application notesDetection techniques Frequency modulation technique TildasPhotoacoustic detection Photoacoustic techniqueBias Circut Bias-T AppendixGeneral Utilisation What has to be kept in mind before use? Current and voltage ranges of the Bias-T cir- cuit Avoid reverse polarity on the inputUnpacking NS laser from its transportation box Unpacking instructions for NS submounts