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

基于棒状几何结构的高效二极管泵浦脉冲高功率激光系统将被开发为激光雷达系统的泵浦源。该激光器将是功率可扩展的，以100-1000 Kz的相对较低的重复频率和10-100 ns的脉冲持续时间提供超过400 W的平均输出功率。它将体现衍射受限的光束质量。通过注入种子技术获得了较小的带宽和较高的频率稳定度。利用偏振旋转和将激光棒相互成像来补偿激光棒中的热致双折射。在对激光系统进行功率调整的同时保持光束质量的挑战将被克服，例如通过光学相位共轭反射镜。潜在的激光材料有两种：Nd：YAG和Yb：YAG。他们将与其他具有较长上激光能级荧光寿命的材料进行比较。一项重要的成就将是将波长约1微米的激光倍频到绿光，效率超过50%。具有这些规格的二极管泵浦脉冲激光系统目前还没有推出，但它们作为下一代作战激光雷达系统的基本泵浦光源是必不可少的。

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.