建立了描述内腔连续波单共振光学参量振荡器(ICCWSRO)的功率特性的高斯光束理论。将激光谐振腔内的二阶非线性相互作用视为激光器的一种输出损耗,求解描述激光器功率特性的方程,得到激光器的非线性反射率,进而得到内腔连续波单共振光学参量振荡器的信号波和闲置波的功率特性。分析中考虑了驻波腔结构、四能级激光增益介质的端面抽运特性、二阶非线性作用的平均场近似、相互作用的各光波的衍射效应。若不考虑激光增益介质中光束的衍射效应并同时采用一级近似,可以直接求解超越方程,得到激光器的非线性反射率。以Nd∶YVO4作为激光增益介质,周期极化LiNbO3(PPLN)作为二阶非线性晶体,给出了有关数值计算结果。

The Gaussian beam theory has been developed to describe the power characteristics of intracavity continuous-wave singly resonant optical parametric oscillator (ICCWSRO). The second-order nonlinear interaction in the resonant cavity of laser is treated as the output loss of laser. The nonlinear reflectivity of the laser and the power characteristics of the signal and idler waves are obtained, based on the solution for the equations describing the power characteristics of laser. The stand-wave cavity structure, the properties of the four-level, end-pumped laser gain medium, the mean-field approximation of second-order nonlinear interaction, the diffractive effect of the interacting waves are all considered in the derivations. If the diffractive effect in the laser gain medium is neglected and only the first-order approximation is retained, the nonlinear reflectivity of laser is obtained, based on the solution for the transcendental equation. In the numerical calculation, the Nd∶YVO4 is taken as the laser gain medium, and the periodically poled LiNbO3 (PPLN) is taken as the second-order nonlinear crystal.