以激光二极管端面抽运Nd:YAG激光器为例,采用有限元法数值计算了不同散热条件下晶体的温度分布;比较了两种散热方法(铜热沉加半导体制冷(TEC)器散热法和晶体侧面水流散热法)对晶体温度分布的影响,并提出晶体热透镜球差效应。根据温度分布的结果,采用光线追迹理论,定量比较两种散热方式对晶体不同径向位置热透镜焦距的影响。结果表明,采用铜热沉加半导体制冷器散热法时,晶体不同径向位置热透镜焦距较短,焦距差较小,球差效应较弱;采用晶体侧面水流散热法时,不同径向位置热透镜焦距较长,不同径向位置焦距差也较大,球差效应明显。最后模拟了两种散热方式下,晶体散热不对称时热透镜畸变的结果。

In laser diode end-pumped Nd:YAG lasers,temperature distributions in rods under different heat-dissipation methods are calculated by the finite element method. Influences of two heat-dissipation methods,such as copper heat sink conduction method and water flow method on temperature of rods,are compared. Spherical aberration of thermal lens is presented. Based on the calculation results and ray-tracing theory,influences of two heat-dissipation methods on focal length of thermal lens distribution are compared quantificationally. Results show that the thermal lens focal length is smaller,focal length differences are shorter and spherical aberration is weaker,when using the heat-dissipation method with copper heat sink and TEC. And the thermal lens focal length is longer but focal length differences are larger and spherical aberration is more obvious,when using the water flow heat-dissipation method,Using the two heat-dissipation methods respectively,thermal lens distortion of a rod is simulated when the heat-dissipation is asymmetric.