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Mid-infrared trace gas detection using continuous-wave difference frequency generation in periodically poled
Applied Physics. B, Lasers and Optics
|January 5, 2002
Summary
A new tunable mid-infrared laser source was developed using a specialized crystal for difference frequency generation (DFG). This mid-infrared spectroscopic source shows promise for sensitive trace gas detection in ambient air.
Area of Science:
- Optics and Photonics
- Spectroscopy
- Laser Technology
Background:
- Mid-infrared (MIR) light sources are crucial for various spectroscopic applications.
- Developing tunable and efficient MIR sources remains a significant challenge.
Purpose of the Study:
- To report a novel tunable continuous-wave (cw) mid-infrared spectroscopic source.
- To demonstrate its capability for trace gas detection.
Main Methods:
- Difference Frequency Generation (DFG) in a quasi-phase-matched periodically poled RbTiOAsO4 (PPRTA) crystal.
- Mixing two cw single-frequency Ti:Al2O3 lasers (713 nm and 871 nm) to generate MIR radiation.
- Utilizing a 20-mm long PPRTA crystal with 300 mW pump power.
Main Results:
- Generated 10 microwatts of DFG power around 4 micrometers.
- Achieved a quasi-phase-matched infrared wavelength-tuning bandwidth (FWHM) of approximately 12 cm-1.
- Demonstrated a temperature tuning rate of 1.02 cm-1/degree C.
Conclusions:
- The developed PPRTA-based DFG source is tunable in the 3.4-4.5 micrometer region.
- The source shows feasibility for trace gas detection, specifically CO2 absorption spectroscopy in ambient air.