高斯光束非线性“热像”效应研究

Study of nonlinear hot image effect of Gaussian optical beams

高功率激光系统中非线性"热像"强度可能达到光学元件损伤阀值,从而对系统的安全运行造成威胁.以往的非线性"热像"现象研究都是基于无限大平面光波背景,但实际系统中传输的是有限束宽光束.本文以高斯光束为例,基于无像差自聚焦理论分析了有限束宽光束的"热像"形成规律.结果表明,高斯光束"热像"的强度与位置在光束腰斑较小时与平面光波情况有明显不同,但光束腰斑较衍射物大得多时,高斯光束可以近似当作平面光波处理.

In high-power lasers, nonlinear hot image is likely to damage expensive optics. The location and intensity of hot image of plane light wave has widely been studied. However, in the operating lasers, the light beam possesses a limited spatial width. Based on the aberrationless model of self-focusing, the location and intensity of hot image of Guassian optical beams is investigated. It is shown that the location and intensity of hot image greatly differ from those of plane light wave when the Guassian beam has a small beam waist, while they approximately equal those of plane light wave for a very big beam waist.