在准连续激光二极管(LD)抽运的激光晶体中存在升降温的瞬态过程。为解决准连续LD端面抽运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准连续超高斯光束端面抽运Nd:YAG棒的瞬态温度场的一般解析表达式。同时定量分析了准连续抽运光束腰半径、脉宽以及频率对Nd:YAG棒瞬态温度场的影响。研究结果表明,准连续LD端面抽运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周期性分布,而且棒内温度也随脉宽和频率的增大而增大。研究方法和所得结果还可以应用到激光系统的其他瞬态热问题研究中。

The transient processes of temperature rise and fall exist in laser crystal pumped by quasi-continuous-wave (CW) laser diode (LD).In order to solve thermal effect of laser crystal end-pumped by quasi-CW LD,a general analytical transient temperature filed expression of Nd:YAG rod end-pumped by the quasi-CW supper-Gaussian beam is obtained by the methods of eigen-function and constant variation,based on the heat conduct equation.Meanwhile,the influence of the quasi-CW pump beam with different waist radii,pulse widths and frequencies on the transient temperature filed of Nd:YAG rod,are quantitatively analyzed.The results show that for quasi-CW LD end-pumped Nd:YAG rod,the temperature of the rod has sawtooth distribution with time,which shows periodically stable distribution after some time,and it increases with the increase of the pump width or pump frequency.The research methods and results can also be used to analyze other transient thermal problems in laser systems.