Influence of eccentricity on temperature field of rectangular doubling-frequency crystal

In order to solve the problem that frequency-doubled conversion efficiency of nonlinear crystal is influenced by the non-uniform temperature rise, a thermal model of rectangle nonlinear crystal was built. In the thermal model some factors, such as fundamental frequency laser having Gaussian distribution, nonlinear crystal's peripheral temperature invariableness and end-faces satisfying approximate adiabatic condition, were considered. In response to the requirement of nonlinear crystal with intracavity doubling frequency, the definition of fundamental frequency laser radiation eccentricity of rectangle nonlinear crystal was introduced. Based on the heat conduction equation, a general analytic solution of temperature distribution in rectangle nonlinear crystal eccentric-radiated by fundamental frequency laser was obtained. The temperature fields of rectangle nonlinear crystal center-radiated and eccentric-radiated by fundamental frequency laser were analyzed. The result shows that when the radiation eccentricity increases to 0.75, the temperature rise of nonlinear crystal can be reduced by 21.1%.