对大口径有源反射镜式片状Nd∶LuAG陶瓷激光增益介质在高功率激光二极管(LD)抽运条件下的热效应及其引入的波前畸变进行了分析。片状Nd∶LuAG陶瓷尺寸为64 mm×6 mm，抽运峰值功率为58.5 kW，抽运光斑大小为32 mm×35 mm，在激光光束的入射角度为15°时对有源反射镜式片状Nd∶LuAG增益介质的热效应和波前畸变进行仿真分析。仿真结果显示在抽运状态时片状Nd∶LuAG陶瓷的最高温度为55.6 ℃; 水平方向和垂直方向引入的负焦距分别为FH=-65.78 m和FV=-77.28 m。模拟放大后激光波前畸变峰谷值为4.33λ(激光波长λ为1064 nm)，波前畸变主要为离焦量导致的像散。在此基础上搭建了相应的实验装置，测得抽运状态下Nd∶LuAG陶瓷的温度分布及引入的激光光束波前畸变。模拟分析数据与实验数据相吻合。模拟计算和实验分析结果为片状Nd∶LuAG陶瓷激光放大系统抽运均匀性的优化及激光光束质量的控制等提供了重要的参考依据。

The thermal effect of large aperture active mirror disk Nd∶LuAG ceramic laser gain medium under high power diode pump is analyzed and the wavefront distortions caused by the thermal effect is also studied. In simulation, the size of the disk Nd∶LuAG ceramic is 64 mm×6 mm, the peak pump power is 58.5 kW, the spot size of the pump is 32 mm×35 mm and the incident angle of laser beams is 15°. Simulation results show that the maximum temperature of disk Nd∶LuAG ceramic is 55.6 ℃ at pumping state, and the negative focal length is FH=-65.78 m and FV=-77.28 m in horizontal and vertical directions, respectively. The simulated wavefront distortions peak valley value is 4.33λ(the light wavelength λ is 1064 nm), which is caused by defocus mainly. On this basis, corresponding experimental facilities are set up to measure the temperature distribution of Nd∶LuAG ceramic and the wavefront distortions introduced by laser beams. Simulation results are in good agreement with the experiment. Simulative and experimental analysis results provide important references for the optimization of the pumping uniformity and the improvement of the laser beam quality of Nd∶LuAG ceramic laser amplifier system.