中文摘要：

对连续波光参量振荡器的转换效率进行了研究。光参量振荡器选用氧化镁掺杂的周期性极化铌酸锂（Mg O：PPLN）晶体为非线性晶体。实验中通过改变泵浦光功率和输出镜反射率改变腔内信号光波的光强，证明了腔内存在最佳信号光强，使得光参量振荡器达到最佳转换效率。根据此最佳信号光强，本文在 2.9 μm 波段实现了 8 W 的输出，闲频光输出效率 19.5%，在不加额外限制线宽器件的情况下，2.9 μm 输出线宽小于 0.68 nm。

英文摘要：

Optimal conversion efficiency of a continuous-wave optical parametric oscillator （OPO） is investigated experimentally. The nonlinear crystal of OPO is a magnesia-doped periodic polarization lithium niobate crystal. As the power density inside the OPO cavity is associated with the reflectivity of the cavity mirrors, different cavity mirrors are used. Experimental results show that the best intensity inside the cavity exists to obtain the best conversion efficiency. By the coupling of the pump power and the OPO cavity, 8 W idler output at 2.9 μm with the efficiency of 19.5% is achieved. The spectral width of the 2.9 μm laser is less than 0.68 nm without any additional bandwidth control elements.