基于能量均分方法, 根据经典热传导和热弹性理论, 建立了激光二极管端面抽运梯度浓度掺杂棒状激光介质的数值模型, 考虑到梯度浓度掺杂激光介质端面与空气的对流换热和激光介质材料的热力学参数的温度相关性, 运用有限元法, 得出了单一浓度掺杂、2阶阶变梯度浓度掺杂、5阶阶变梯度浓度掺杂和理想梯度浓度掺杂四种掺杂结构激光介质内吸收系数、抽运光吸收功率、温度、热应力和应变的空间分布。结果表明, 采用梯度浓度掺杂结构可以大大提高激光介质内抽运光吸收分布的均匀性, 5阶阶变梯度浓度掺杂激光介质的最高温度、最大主拉应力和最大主应变分别为单一浓度掺杂激光介质的42.6%、31.9%和28.1%, 可见明显减小了热效应的影响。理论分析结果可为激光二极管抽运梯度浓度掺杂激光器的合理优化设计提供数据理论支撑。

Based on the method of energy equipartition and thermal conduction equations and the thermal-elastic equations, a numerical model of the gradient dopant concentrations rod laser medium end-pumped by laser diode was set up. Considering the temperature correlation of the thermodynamic parameters of the material and heat transfer coefficient between air and medium, the distributions of absorption coefficient, absorption pump power, temperature, thermal stress and strain in the laser medium of constant doping, two stepwise gradient doping, five stepwise gradient doping and ideal gradient doping structures were calculated by a finite element analysis method. The results indicate that by using the gradient dopant concentrations laser medium, absorption pump power uniformity in laser medium can be improved greatly. And the maximum temperature and principal tensile stress and principal strain of the five stepwise gradient doping laser medium were respectively 42.6% and 31.9% and 28.1% of the constant doping laser medium. It is obvious that the thermal effects of the gradient dopant concentrations laser medium are greatly reduced. The theoretical results provide theoretical reference and experimental study for the design of solid laser pumped by laser diode.