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在脉冲激光二极管(LD)泵浦的激光晶体中存在升降温的时变过程,为解决脉冲LD端面泵浦的激光晶体产生的热效应问题,基于热传导方程,采用特征函数法和常数变异法得到了脉冲超高斯光束端面泵浦Nd:YAG棒的时变温度场的一般解析表达式。同时定量分析了单脉冲和重复脉冲端面泵浦Nd:YAG棒的时变温度规律。研究结果表明,重复脉冲端面泵浦Nd:YAG棒时,棒内温度随时间呈锯齿状变化,经过一段时间后最终呈稳定的周期性分布;棒内温度也随泵浦脉冲束腰半径的减小和占空比的增大而增大;脉宽越宽时,棒内温度的波动幅度也越大。研究方法和所得结果还可以应用到激光系统的其他时变热问题的研究中,对解决激光系统的热问题具有理论指导作用。
There is a time-varying process of temperature rise and fall in the laser crystal pumped by a pulsed laser diode (LD). To solve the thermal effect caused by the pulsed LD end-pumped laser crystal, based on the heat conduction equation, the eigenfunction method and the constant- General Analytic Expression of Time - varying Temperature Field in Pulsed Super - Gaussian Beam End - pumped Nd: YAG Rods. The time-varying temperature laws of single-pulse and repetitive-pulse end-pumped Nd: YAG rods were quantitatively analyzed. The results show that the temperature in the rod changes serratically with time after repeated pulse end-pumped Nd: YAG rod, and finally changes periodically with a period of time. The temperature in the rod also decreases with the decrease of the pump pulse waist radius Small and increase the duty cycle increases; pulse width is wider, the greater the temperature fluctuations within the rod. The research methods and the results can also be applied to other time-varying thermal problems in laser systems, which have theoretical guidance for solving the thermal problems in laser systems.