偏心度对方形倍频晶体温度场的影响

Influence of Eccentricity on Temperature Field of Rectangular Doubling-Frequency Crystal

为了解决非均匀温升对非线性晶体倍频转换效率影响的问题,建立了方形非线性晶体模型.该模型在建立中考虑了基频光具有高斯分布,方形倍频晶体具有周边恒温、端面满足近似绝热等特点.根据非线性晶体腔内倍频的实际需要,给出了方形非线性晶体基频光辐射偏心度的定义,并利用热传导方程,得到了方形非线性晶体受基波偏心辐射时温度场分布的一般解析表达式,解决了在温场模式研究中将倍频使用的方形晶体近似为圆柱形晶体所带来的问题.实验结果表明:当基频光辐射偏心度增大到0.75时,倍频晶体的最高温升下降了21.1%.

In order to solve the problem that frequency-doubled conversion efficiency of nonlinear crystal is influenced by the nonuniform 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 conduc tion 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 %.