Contents

• Mechanical and geometrical properties
  • Geometry of QC lasers
    • How are the axes of the laser defined, i.e. what is vertical?
    • What are the physical dimensions of laser carriers?
    • What materials are used for the laser carriers?
  • How to handle a QCL
    • How do I store a QCL?
    • How do I handle (carry) a QCL?
    • How to mount a QCL in an optical setup
    • Soldering wires to submount
  
  
• Electrical and optical properties
  • Electrical limits
    • What is the maximum allowed duty cycle?
    • What happens if I increase the duty cycle?
    • What is the lifetime of the laser (MTBF)?
  • Electrical properties
    • What impedance does a QCL show?
    • Can I check the impedance with an ohm-meter?
    • Where is the cathode of a QCL?
    • How do I drive a pulsed QCL? Can I use a standard laser driver?
    • How do I drive a CW QCL?
  • Optical properties
    • Mode characteristics
    • What is the polarisation of the emitted mode?
    • How do I collimate the beam?
    • How do I calculate the radiance?
  
  
• Starter Kit (pulser, temperature controller, etc...)
  • Operation of TE cooler
    • What is the dissipated heat of a pulsed QC laser?
    • What temperatures can be reached with the TCU-151?
  • Important points concerning LDD pulsers
    • What are the possible pulse lengths and duty cycles?
    • What is the "external power supply" used for?
  • Low-impedance line
    • How to connect the low-impedance line
  • Low-frequency bias current for modulation
    • What are function and purpose of a bias-T circuit?
    • What are the connections of the bias-T circuit?
    • Dangers and disadvantages of using a bias-T circuit
    • What has to be kept in mind before use?
    • What are the current and voltage ranges of the bias-T circuit?
  • Laser Laboratory Housing (LLH)
    • What is the distance of the laser die output facet from the window external facet?
    • What is the reflectivity of the LLH window?
  
  
• Operating QCLs in continuous wave mode
  • Thermal properties
  • Modulation of a CW mode operated QCL
    • Direct modulation of the DC source
    • Additional modulated supply
  
  
• General QCL questions
  • How to measure QC laser emission?
  • General emission characteristics
    • What wavelengths can be reached?
    • Why is such a large range obtainable?
    • How "CW" does a QCL look like in pulsed mode?
    • What optical powers can be expected?
    • How precise should emission be specified?
  • Tuning and linewidth
    • How does a DFB-QCL tune?
    • How much can a DFB-QCL be tuned?
    • Why is the line-width of a DFB-QCL limited?
    • How and how much does a FP-QCL tune?
  
  
• Glossary and Abbreviations