Research on temperature distribution and thermal stress of laser crystal from self-Raman yellow laser

Abstract

In the process of laser excitation of the solid laser, the laser crystal is exposed to the cooling of the surrounding medium while being irradiated and heated by the pump light. So that an uneven temperature distribution is formed in the laser crystal, leading to the thermal stress, stress birefringence, thermal lens effects, partial refraction effects, and even fractures that seriously affect the stability of laser resonators, laser output power, output beam quality, conversion efficiency, and laser lifetime. Therefore, studying the distribution law of temperature and thermal stress in the laser crystal and its effect on laser performance has become one of the hot topics in the field of solid-state lasers. In this dissertation, based on the mathematical model of the thermal conduction and thermal stress of the orthogonal anisotropic laser, the temperature distribution and thermal stress distribution in the laser crystal are numerically calculated, and the location where thermal cracking occurs is analyzed. A solid self-Raman yellow laser was used to verify the experiment. The thermal cracking position of the laser crystal was consistent with the theoretical analysis. The changes of the laser output power before and after the thermal cracking of the laser crystal were measured, and the degree of influence of thermal cracking on the output power of the laser was qualitatively studied. The experimental results show that the maximum power of the 1064nm fundamental frequency laser output before and after thermal cracking is reduced from 2.2W to 1.7W, while the yellow laser power is reduced from 200mW to 26mW.