Numerical analysis and validation of an optical parametric oscillator considering crystal thermal effects

In this paper, a calculation model is proposed for the optical parametric oscillation (OPO) process considering the crystal thermal effects. Based on existing models, we combine a set of three-wave coupled equations with the Sellmeier equation. In order to optimize the calculation of the nonlinear process, a temperature variable t is introduced to describe the heat generated by the laser crystal during operation. The waveforms under different pump powers are analyzed. The effects of the reflectivity of the output mirror on the OPO threshold and inverse conversion are investigated. In addition, the optimal reflectivity under different pump powers can be estimated. Based on the simulation results, experiments are also performed in the near-infrared 1.57 µm band and mid-infrared 3.15 µm band. The experimental results are compared with the results of this model and a model that does not consider crystal thermal effects. The experimental results are consistent with the improved theoretical results, affirming that the proposed theoretical model can simulate the energy conversion process of OPO. This provides a theoretical basis for optimizing the parameters of the OPO output mirror and improving the efficiency of the parametric wave conversion.