建立了激光晶体的热传导模型,通过求解泊松方程,得到激光晶体内温度和温度场分布,计算了由端面形变引起的光程差(OPD)和总的光程差,得到不同抽运功率下的热焦距,并通过实验进行了验证,实验结果与理论计算基本一致。当抽运功率为10 W,抽运光斑半径320 μm时,Nd:YVO4激光晶体端面形变引起的光程差占总的光程差的45%。抽运功率为24 W时,晶体热焦距为65.8 mm。提出激光晶体端面腔镜会加重激光晶体热透镜效应的结论。研究表明,对于大功率全固态激光器,由晶体端面形变引起的光程差对晶体热透镜效应有较大影响。对提高激光器的稳定性、研究晶体的热效应提供了理论依据。

The thermal conduct model of laser crystal was established. Using Possion equation, the temperature and temperature distribution in laser crystal were obtained, and the optics path difference (OPD) induced by end-face deformation and total OPD were caculated. Based on the former calculation, the focal length of laser crystal with different pumping powers was obtained. The experimental result agrees with the caculated result very well. When the pumping power is 10 W and the radius of pumping beam is 320 μm, the OPD induced by end-face deformation is 45% of the total OPD for Nd:YVO4 crystal. When the pumping power is 24 W, the focal length of crystal is 65.8 mm. The end-pumped resonators with one highly reflective coating directly on the laser crystal can aggravate its thermal effect. The study shows that, for the solid-state laser with high power, the OPD induced by end-face deformation has a large influence on thermal effect of laser crystal. This study provides a theoretical direction for improving the stability of laser and studying the thermal effect of laser crystal.