Investigation and development of a pulsed laser system in rod geometry thought for pumping a lidar system for atmospheric research

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An efficient diode pumped, pulsed high power laser system based on a rod geometry will be developed as a pump source for a lidar system. The laser will be power-scalable and provide average output powers in excess of 400 W at relatively low repetition rates ranging from 100 - 1000 Kz and pulse durations in the range of 10 - 100 ns. It will embody a diffraction limited beam quality. Small bandwidth and high frequency stability are achieved via injection seeding technique. The thermally induced birefringence in the laser rods is compensated utilizing polarization rotation and in addition imaging the laser rods onto each other. The challenge to maintain the beam quality while power scaling the laser system, will be overcome, e.g. by optical phase conjugate mirrors. Potential laser materials are Nd:YAG and Yb:YAG. They will be compared to other materials with longer fluorescence lifetimes of the upper laser level. An important accomplishment will be the frequency doubling of the laser light around 1 µm wavelength to the green with an efficiency greater than 50 %. Diode pumped pulsed laser systems with these specifications are not available yet but they are essential as a fundamental pump source for operational lidar systems of the next generation.