侧面泵浦激光板条热变形量的简化计算方法

Simplified method for thermal distortion of side-pumped laser slab

泵浦光在激光晶体中产生的热效应是影响激光器工作性能和输出质量的主要因素之一。通常在研究激光晶体热效应时,先求解激光晶体中的温度分布,再对激光晶体的热应变进行积分来计算晶体的热变形量,这是一个既冗长又困难的过程。将求解热传导微分方程与热应变积分计算热变形量相结合,在激光板条冷却面恒温、其他侧面绝热的条件下,建立了板条热变形量满足的微分方程和边界条件,把复杂的两步计算过程简化为求解简单微分方程;得到了侧面泵浦激光板条的泵浦面和通光面热变形量的解析表达式;通过算例,验证了简化计算方法的正确性,并且分析了泵浦光分布对激光板条热变形的影响。

The thermal effect of laser crystal caused by pumping light is one of the main factors affecting the performance and the output quality of diode pumped solid state laser. Usually, the temperature field distribution in laser crystal is found,with the thermal distortion of crystal calcu- lated by integrating thermal strain along crystal,a redundant and difficult process. In the paper, under the condition that the cooling faces of laser slab have constant temperature and that other faces are adiabatic, solving heat conduction equation and integrating thermal strain are combined, with the differential equation and boundary conditions of slab thermal distortions set. Therefore, the ordinarily used two-step method was simplified to solve a simpler differential equation. The analytical expressions of thermal distortions of pumped-faces and laser output faces of the laser slab side-pumped by diode laser has been obtained. posed method,a computation example is given, with To demonstrate the correctness of the pro- the relations between thermal distortion and pumping light distribution analyzed.