激光二极管抽运氦气冷却钕玻璃叠片激光放大器热致波前畸变和应力双折射的数值模拟和实验研究

摘要

Thermal effect is still the most serious problem: it restricts the high power and high beam quality of solid laser to be further enhanced. The efficient thermal management is an important approach to suppress the thermal effect. In this paper, the thermal effect in a gas-cooled laser diode pumped multislab Nd:glass amplifier operating at a repetition rate is investigated in detail both theoretically and experimentally. The three-dimensional distributions of temperature, stress, strain, and birefringence are calculated by a finite element analysis. Based on these data, the thermally induced wavefront distortions and depolarization losses are determined with considering six slabs and one laser head. It is revealed that the theoretical data are in good agreement with the experimental results: the total wavefront distortion is 6.77λand a depolarization loss of more than 90%accumulates over six slabs when the heat deposition is 0.7 W/cm3.%热效应仍是限制激光放大器向高功率、高光束质量进一步发展的瓶颈问题,高效的热管理是抑制热效应的重要技术途径.研究了基于激光二极管抽运氦气冷却的钕玻璃叠片激光放大器的热效应.利用有限元数值模拟的方法,分析了钕玻璃的温度、应力应变和应力双折射分布,并计算了热致波前畸变和退偏损耗,与实验结果符合得较好,在热沉积为0.7 W/cm3的条件下,6片钕玻璃总的热致波前畸变为6.77λ,最大退偏量大于90%.