A Titanium Sapphire laser, a Raman laser and a garnet laser are investigated and compared concerning the performance as a laser transmitter for a space born water vapor Differential Absorption Lidar (DIAL) in the 940 nm wavelength region. The Titanium Sapphire laser is currently the most mature transmitter system for a water vapor DIAL and has already been used in the 815 nm region. In the 940 nm region the spectral requirements are realized and pulse energies > 100 mJ at this wavelength have been reported. Assuming high conversion ratios of 20% from 808 nm to 1064 nm, 60% to 532 nm and 25% to 936 nm a maximum overall optical efficiency of the TISA laser of 3% can be estimated. The other two transmitter systems have the potential to deliver a higher efficiency due to less frequency conversions, but the simultaneous fulfillment of the spectral requirements is far from trivial and still needs to be demonstrated. An optical efficiency of 20% with a compact design should be possible with a Garnet laser. This transmitter technology is however presently only usable for Water Vapor DIAL. The Raman technology will not provide as high efficiencies as the garnet laser for the 935 nm wavelength, but can also be used for the generation of 1570-1610 nm wavelengths for a CO2 DIAL. For Stokes conversion the total optical conversion efficiency can be as high as 10%. In conclusion, garnet lasers are seen as the most promising option for future developments.
Transmitter technologies for space born water vapor DIAL systems in the 940 nm region
2006
3 Seiten, 3 Bilder, 1 Tabelle, 9 Quellen
S. 1-3
Conference paper
English
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