以半解析热分析理论为基础,研究超高斯分布激光二极管(LD)端面抽运背冷式微片Nd:YAG晶体的热效应。通过对超高斯分布激光二极管端面抽运背冷式微片Nd:YAG晶体工作特点分析建立热模型,利用热传导方程新的求解方法得出微片Nd:YAG晶体内部温度场、热形变场、附加光程差(OPD)半解析计算表达式; 利用附加光程差得出微片Nd:YAG晶体的热焦距计算表达式。研究结果表明,当使用总功率为24.2 kW,10%占空比4阶超高斯分布激光二极管抽运时,微片上获得70.36 ℃最高温升,0.465 μm最大热形变,0.836 μm最大附加光程差。

Based on the theory of semi-analytical thermal analysis, the thermal effects of the diode-end-pumped Nd:YAG microchip crystal with back surface cooling were investigated. A thermal model that matches actual working state of the laser crystal is established by analyzing the working characteristics of the Nd:YAG microchip crystal. Through using a new method to solve the heat conduction equation of isotropic material, a general expression of temperature field, thermal distortion field and additional optical path differences (OPD) within Nd:YAG microchip crystal was obtained respectively. Calculation expression of thermal focal length of the Nd:YAG microchip crystal was obtained by analyzing the additional OPD caused by heat. Research results show that a maximum temperature rise is 70.36 ℃, a maximum thermal distortion is 0.465 μm and a maximum additional OPD is 0.836 μm when the LD pump light is fourth rank of super-Gaussian distribution, the total power is 24.2 kW,and the duty cycle is 10%.