中文摘要：

从被动调Q四能级激光器的速率方程出发,通过引入光学参量振荡（OPO）有效转换截面的概念,建立被动调Q单谐振内腔光学参量振荡器（IOPO）的理论模型。推导考虑晶体吸收、走离效应、模式匹配等参数的单谐振IOPO增益表达式以及有效转换截面表达式。利用Runge-Kutta法数值模拟IOPO的动力学特性,讨论信号光脉冲的建立过程,分析耦合输出镜的信号光反射率对抽运光和信号光间的能量转换过程以及信号光脉冲的建立时间和脉冲宽度的影响,结果表明,信号光反射率存在一个最优值为0.85。将模拟结果和实验结果进行比较,两者的吻合度较好。对理解被动调Q单谐振IOPO的工作机理及IOPO系统的优化设计提供理论依据。

英文摘要：

Based on the rate equations for passively Q-switched four-level lasers, and by introducing the concept of optical parametric oscillator（OPO） effective conversion cross-section, a model for the passively Q-switched single resonant intracavity optical parametric oscillator（IOPO） is built. The parametric gain expression which taking account of the absorption loss of the material, walk-off effect, mode matching, etc., and also the OPO effective conversion cross- section expression are deduced. By using the Runge- Kutta method, the dynamic characteristics of the IOPO are simulated. Moreover, the buildup process of the signal pulse is discussed, and the impacts of the signal reflectivity on the energy conversion process and on the buildup time and pulse duration of the signal pulses are analyzed. The simulation results reveal that there is an optimal value for the signal reflectivity which is 0.85. Besides, the simulation results and experimental results are compared, and they match very well. The findings provide a theoretical basis for understanding the performance mechanism and optimization of the passively Q-switched single resonant IOPO.