DFB und DBR lasers for absoprtion measurements at ambient conditions

Wavelength tunable diode lasers enable qualitative and quantitative measurements of different substances and environmentally relevant gases. Despite high absorption bands being located in the mid-infrared spectral range, target samples such as water vapor and oxygen also provide sufficient absorption in the visible to near-infrared spectral range. Therefore, diode lasers realized at FBH can be applied for absorption measurements, e.g., for water vapor at ambient conditions.

  • Optical setup for measurements of water vapor
    [+] Optical setup for measurements of water vapor
  • Layout for a ns-MOPA light source
    [+] Layout for a ns-MOPA light source

Functional principle

For absorption measurements at ambient conditions emission from a narrow bandwidth, wavelength tunable DBR-RW laser is coupled into an integrating sphere. Within the sphere light is scattered multiple times before being detected by a photo diode. The effective propagation length within a 4" sphere is about 7 m. Such a simple setup allows for measurements of natural water vapor concentrations or high-resolution measurements of rotation relaxation bands. For power scaling, the same lasers can also be applied as master oscillators in pulsed ns-MOPA configurations. With an average power of up to 16 W the resulting spectrally stabilized emission is suitable for more demanding applications such as differe

Applications

  • Measurements of gas concentration for different molecules, e.g., H2O at 940 nm, O2 at 760 nm
  • Pulsed light sources for Micro-DIAL
  • Spectroscopic high-resolution measurements of molecules

Typical wavelengths

  • 760 nm
  • 940 nm

Technology and packaging

  • Diode lasers with vertical layer structures realized by MOVPE
  • Lateral laser structures with integrated gratings
  • Hybrid integration of laser diodes and electronics for pulsed operation