双轴晶体主平面上倍频的相位匹配参量

根据折射率椭球方程及双光轴晶体中光波的传播与偏振特性，分析双轴晶体在主平面内激光倍频相位匹配的特性与方法，导出光波在主平面上传播时倍频的相位失配关系；给出双轴晶体中容许相位匹配倍频的相位匹配角及混频的有效非线性系数deff的表达式。利用可相位匹配的类型、相位匹配角公式和有效非线性系数deff表达式的表，容易对任意一具体晶体在一给定波长求出实际能实现相位匹配的类型或偏振组合，算出相位匹配角，比较不同的相位匹配类型或偏振组合的有效非线性系数，选择最佳的相位匹配类型与方向。从相位失配关系可以计算晶体主平面内倍频的接收角、接收光谱宽度等特性参量。

Phase Matching Paramiters for Doublings in Principal Planes of Biaxial Crystals

Based on index ellipsoid equation and characteristics of optical wave propagation and polarization in a biaxial crystal, methods of the collinear phase matching (PM) permitted for frequency doubling in principal planes of biaxial crystals are discussed and analysed. The general expressions of the effective nonlinear coefficients d eff and phase mismatchs for all the allowed PMs are derived for all kinds of biaxial crystals. By using the Table, in which possible PM types or polarization combinations, respective PM angle formula and effective nonlinear coeficients are involved, realizable PM methods may be found and respective PM angles can be calculated. Finally effective nonlinear coeficients for allowed PMs can be compared and optimal PM types or directions can be selected easily.