Description | Quantum Instruments Cascade Laser Starter Kit guide

Starter Kit Instruction Manual

Description

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4.3 DFB and FP Quantum Cascade Lasers

4.3.1Description

Quantum Cascade Lasers (QCL) are unipolar lasers emitting in the mid-infrared from 4 to 17 microns. The laser is a ridge of InGaAs and AlInAs grown on InP providing gain and a Fabry-Perot cavity in order to build the laser oscillation up. Distributed- Feedback(DFB) Quantum Cascade Lasers are then obtained by adding a grating, forcing the laser to emit at the target wavelength.

4.3.2Geometry of QC lasers

Mountings

Lasers exist in two diﬀerent packages:

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Fig.3: ST submount

•ST mounting (1)

•NS mounting (2)

Axes of QC lasers

The vertical direction is the so called growth direc- tion.

Device are mounted on a copper carrier which has one or two ceramic pads carrying the bonding wires. The pads are yellow on top due to a layer of gold, and white around it and on the sides (colour of the ceramic). If these pads are placed upwards, the vertical for the laser is the same as the observer vertical direction.

If there are two ceramic pads present, they are named as follows:

Looking onto the front facet with the laser placed as described above, the pad left of the laser chip is called ”DN” (for DOWN), the one on the right of it ”UP”.

If no conﬁguration is speciﬁed, the ”DN” pad is used.

Never place the laser upside-down, since this will damage the bonds connecting the pads to the laser and possibly the laser itself!

The laser chips mounted on NS submounts pro- vided separately from a LLH100 are supplied in a round plastic box. For removing the laser from it, please follow the instructions as described in ap- pendix (appendix 10.2, p.59)

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Fig.4: NS submount

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Quantum Instruments Cascade Laser Starter Kit manual DFB and FP Quantum Cascade Lasers, Description, Geometry of QC lasers

Contents

Quantum Cascade Laser Starter Kit Instructions Manual Web version Contents Maintenance Overview InstallationTroubleshooting Use Appendix Limited waranty IdentiﬁcationDocument Manufacturer Generalities GeneralChapter overview Compliance Product GlossaryPersons Personnel Typographic conventions Commands styleProcedure style Description style See page x-y Troubleshooting style ProblemProcedure eﬀects style Possible causePage Non-compliance with the safety regulations Safety InstructionsImportance of safety instructions Introduction Compliance and informa- tion General safety instructionsEnvironmental conditions Description System Composition Description DFB and FP Quantum Cascade LasersIf no conﬁguration is speciﬁed, the DN pad is used Geometry of QC lasers Speciﬁcations Electrical model characteristics Electrical model Laboratory Laser HousingLLH100 LLH100 external view description Laboratory Laser Housing internal view LLH100 internal view Speciﬁcations of the Peltier connector Thermo-Electric Cooler TEC and PT100 connections Speciﬁcations of the measurement connector Measurement connection QCL pulser switching unitLDD100 QCL pulser switching unit front and rear view Measured voltages QCL pulse switching measuring unitGeneralities Timing data Laser peak current Duty cycle calculation Accuracy considerations Laser peak voltageAverage dissipation Trigger and logic output signals Ω TTL driver circuit QCL pulser timing unit TPG128 QCL temperature controllerTCU151 Peltier and PT100 connections General InstallationChapter overview Packing list Standard items 110-120V, 60Hz USA 220-240V, 50Hz Europe Setting the appropriate AC voltage on TCU151Procedure Installing the starter Kit Before beginning Connecting Starter Kit Use QCL pulse timing unit com- mand description TCU151 command description TCU151 temperature controler front panel Proceedings Laser utilisationOverview Starting the TPG128 Procedure Interlock utilisation Interlock utilisation DC power supply is not ﬂoating TroubleshootingPower supply reaches max cur- rent for a very low voltage Principle QCL 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 laser Overview MaintenanceHow to remove the covers of TCU151 and TPG128 Replacement procedures Quantum Cascade Laser replace Ment Facet on the case, it is extremely fragile + LLH100 connection QCL UP and DN position Exchange Exchanging the laser If the ambient atmosphere is humid this is Humidity Before beggining interlock set Ting TCU151 temperature con Troller interlock settingProcedure interlock setting Needed material 1 TPG128 calibration Calibaration proceduresProcedure calibration Generalities TPG128 main board TPG128 main board 2 TCU151 temperature controller calibration Procedure +5V/-5V power supply check Sensing level and range adjustement = 1.22 to Temperature Reference oﬀset adjustment Oscillator check Current/Voltage ratio adjustmentSetting LCD screen should display 1.00 a 7V = 70 C If needed, adjust it with the trimmer P92 Starting the power section of the instru Ment → Value displayed should tend to the deﬁned value Current adjustment→ Value displayed ≤ 1A Threshold on Miscellaneous functions testing Temperature Limit testing→ The temperature displayed 2 should be 035 C → The red LED 1 should turn oﬀ Direct absorption Application notesDetection techniques Frequency modulation technique Tildas Photoacoustic detection Photoacoustic technique General AppendixBias Circut Bias-T 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 input Unpacking NS laser from its transportation box Unpacking instructions for NS submounts