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为解决脉冲激光二极管端面泵浦Nd:YAG晶体产生瞬态热效应的问题,对激光晶体内的温场分布进行了解析分析与定量计算。通过对脉冲激光二极管端面泵浦激光晶体工作特点分析,建立了端面绝热、周边恒温的晶体热模型,考虑到Nd:YAG晶体导热系数与其温度的函数关系,引入弦截法求解含时热传导方程,得出了变热传导系数方形Nd:YAG晶体时变温度场的一般解析表达式。定量分析了变热传导系数方形Nd:YAG晶体在不同超高斯阶次和光斑半径下内部温度场时变情况。计算结果表明:使用平均输出功率为60 W的脉冲激光二极管端面泵浦掺钕离子质量分数1.0%的Nd:YAG晶体,若入射的3阶超高斯光束泵浦光光斑半径为400μm,则晶体尺寸为4 mm×4 mm×8 mm的Nd:YAG晶体在达到准热平衡状态时的最高和最低温升分别为364 K和337 K。研究结果为正确计算Nd:YAG晶体温度场分布提供了方法,并对解决激光晶体热效应问题提供了理论依据。
In order to solve the transient thermal effect of end-pumped Nd: YAG laser diode laser, the temperature distribution in the laser crystal was analyzed and calculated quantitatively. Considering the thermal dependence of the Nd: YAG crystal as a function of temperature, the chord-cut method is introduced to solve the time-dependent heat conduction equation, The general analytical expressions of time-varying temperature field of square Nd: YAG crystal with variable coefficient of thermal conductivity are obtained. The time-varying internal temperature field of square Nd: YAG crystals with different heat transfer coefficients under different super-Gaussian order and spot radius was quantitatively analyzed. The calculated results show that Nd: YAG Nd: YAG crystal with Nd: YAG content 1.0% can be end-pumped by a pulsed laser diode with an average output power of 60 W. If the incident 3rd-order Gaussian beam has a spot radius of 400 μm, the crystal size The maximum and minimum temperature rise of 4 mm × 4 mm × 8 mm Nd: YAG crystals at the quasi-thermal equilibrium are 364 K and 337 K, respectively. The results provide a method for correctly calculating the temperature field distribution of Nd: YAG crystal and provide a theoretical basis for solving the thermal effect of laser crystal.