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

一种高效的二极管泵浦脉冲高功率激光系统基于棒的几何结构将被开发作为激光雷达系统的泵浦源。该激光器的功率可扩展，在相对较低的重复频率（100 - 1000 Kz）和脉冲持续时间（10 - 100 ns）范围内提供超过400 W的平均输出功率。它将体现出衍射受限的光束质量。通过注入播种技术实现了小带宽和高频率稳定性。热诱导双折射在激光棒是补偿利用偏振旋转和另外成像激光棒彼此。当激光系统的功率缩放时，保持光束质量的挑战将被克服，例如光学相位共轭镜。潜在的激光材料有Nd:YAG和Yb:YAG。它们将与其他具有较长荧光寿命的材料进行比较。一个重要的成就将是激光波长在1µm左右的绿光频率翻倍，效率超过50%。具有这些规格的二极管泵浦脉冲激光系统尚未可用，但它们是下一代操作激光雷达系统必不可少的基本泵浦源。

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.