高功率KTP晶体光参量振荡器热效应

Thermal effect of high-power KTP crystal optical parametric oscillator

采用有限元分析方法对KTP晶体内部3维温度分布情况进行了精确计算。根据参量过程满足的能量守恒条件和动量守恒条件,利用KTP晶体的热光色散方程计算了参量过程中温度对相位匹配角、光波走离角、允许角及晶体的有效非线性系数的影响。结果表明:晶体内温度分布不均匀;在沿着通光方向上晶体截面温度分布不同;加强晶体表面冷却效果,可有效降低温度对相位匹配角、光波走离角、允许角及晶体的有效非线性系数的影响。

The temperature distribution inside KTP crystal was calculated by finite element analysis accurately. The phase matching angles,walk-off angles,tolerance angles and effective nonlinear coefficient of type Ⅱ KTP crystal were calculated according to the conservation of mass and phase matched for parametric process and the thermo-optic dispersion of KTP crystal. The results showed that the distribution of temperature inside the crystal was non-uniform. Along the direction of light,temperature distributions of crystal sections were different. Strengthening the cooling effect of crystal can effectively reduce the temperature influences on the phase matching angles,walk-off angles,tolerance angles and effective nonlinear coefficient of crystal.