DFB-RW Laser for Measuring of Water Vapor under Atmospheric Conditions
Functional principle
The laser beam of a tunable DFB-RW laser with a small spectral line width is directed into an integrating sphere. The actual distance of the diffuse scattered light between the entrance of a 4 inch integrating sphere and the photodiode is 7 m.
This simple setup needs no multi-reflection cells and provides detection limits for water vapor in naturally concentrations. Even single rotation-vibration lines can be spectrally resolved.
- Scheme of the Laboratory Setup for Measurements of Water Vapor
Applications
- Quantitative measurement of gas concentrations of various molecules, e.g. H2O at 940 nm, O2 at 760 nm, etc.
- Highly resolved spectroscopic molecular analysis
Wavelength
- 940 nm
Technology and Mounting
- Semiconductor structures with MOVPE
- Laser structures with internal grating
Know-how
- Laser technology
- Highly resolved molecular spectroscopy
- Gas detection
Typical data
- Optical output power up to 0.5 W at 940 nm
- Tuning range up to 7 nm
- Temperature tuning 0,8 cm-1/K
- Side-mode suppression ratio better 40 dB
- Spectral line width smaller 2 MHz
- Suitable for sub Doppler spectroscopy [Poster, pdf]