Abstract

2-μm holmium (Ho) lasers resonantly pumped by thulium (Tm) emission for space-borne wind speed and CO₂ measuring lidar are interesting due to the advantages of high slope efficiency and minimal heating owing to the inherent low quantum defect between the pump and laser photons [1]. Apart from high efficiency and narrow linewidth, simple heat management and high reliability are the requirements of space-borne lidar because of complex space environment and limited space resources. Tm pumped Ho laser’s heat management includes temperature control of pump source diode laser and Tm, Ho-doped crystals (affect of temperature on laser performance due to thermal effects and Boltzmann occupation factors, especially for quasi-three-level Tm laser system [2]) usually. If laser performance degradation owing to crystal’s cooling can be accepted by overall lidar system during about 10 minutes working time of space-borne lidar per circle, the crystals’ refrigeration can be cancelled. Thus the heat management system would be simplified and system reliability would be improved.

© 2015 IEEE