受激旋转喇曼散射效应对强紫外激光聚焦特性的影响

Effect of Stimulated Rotation Raman Scattering on Focal Characters of High-Power Ultraviolet Laser

采用Maxwell-Bloch-Langevin方程,建立了强紫外激光在空气传输中的瞬态受激旋转喇曼散射(SRRS)效应模型;利用相位均方根(RMS)梯度描述的随机相位屏表示低频相位畸变,用扰动幅度表征的随机相位屏描述中、高频相位畸变,建立了相位畸变模型.讨论了强紫外激光在空气长程传输中所产生的受激旋转喇曼散射(SRRS)效应对其聚焦光斑形态的变化,定量分析了焦斑半径随入射强紫外激光的空间相位畸变及传输距离的变化.研究结果表明:当传输距离超过阈值条件时,焦斑半径随传输距离的增大而明显增大,且相位畸变越大,焦斑半径也越大.

Based on the Maxwell-Bloch-Langevin equation,the model of transient stimulated rotation Raman scattering （SRRS） for high-power ultraviolet laser beams passing through long air paths was built up. The model of the phase perturbation was also given, where the RMS Gradient and random phase perturbation were introduced to describe the low and the high frequency phase noise, respectively. The SRRS effect on the shape of focal spot has been discussed. The variation of focal spot size with the spatial phase perturbation and propagation distance has been analyzed quantita of focal spot increases with the propagation distance if once the t radius of focal spot increases with the spatial phase perturbation tively. The results indicate that the radius hreshold condition the high-power fulfilled. Moreover, the ultraviolet laser.