晶体球法是近年来在国际上发展起来的一种测量非线性系数的新方法。根据聚焦高斯光束二次谐波产生的孔径方程理论,分析了晶体球中的第1类非相位匹配二次谐波产生过程,讨论了晶体球中第1类非相位匹配二次谐波最佳聚焦参数的选择。报道了LiNbo3晶体球中皮秒激光脉冲抽运的非相位匹配二次谐波实验。所得结果与理论预计相符。

The sphere method is a newly developed technique for mesurement of nonlinear optical coefficients in crystals. Based on the theory of aperture function of the focused Gaussian beam SHG, the non phase matched (NPM) SHG process in a crystal sphere is analyzed, and the optimum focus condition of type Ⅰ NPM SHG is discussed. The experiment of NPM SHG in a LiNbO 3 crystal sphere pumped with a pico second laser pulse is reported. The experimental results agree well with the theoretical prediction.