Thermal effect of high-power KTP crystal optical parametric oscillator

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．