晶体二阶有效非线性系数在全卦限中的对称性

Symmetry Property of Second Order Nonlinear Optical Coefficients in Crystals

从分析二阶有效非线性系数公式入手，针对各类单轴、双轴晶体，讨论了其二阶有效非线性系数在其折射率主轴坐标系八个卦限中的变化情况，给出了相应的对称性结果．为寻求晶体中的最佳相位匹配方向提供了理论依据．

For second order nonlinear optical (NLO) interactions in the bulk of a crystal, the incident wave vector K is generally confined in the first quadrant of the refractive index surfaces.After analyzing variations of the second order effective NLO coefficients when K is set in one of the other quadrants,we obtain the independent quadrants for both of the uniaxial and biaxial crystals.The results suggest that when NLO interactions in crystals with few symmetry operations, the NLO effects may be further increased when K is set in one of the other quadrants.