端面泵浦热传导各向异性激光棒温场特性研究

了解决LD端面泵浦热传导各向异性激光介质产生的热效应问题，建立了端面绝热、侧面冷却的Nd:YVO4晶体热模型。考虑到Nd:YVO4为热传导各向异性材料，而光纤耦合LD输出光束有着超高斯分布的特点，利用特征函数法和常数变异法得到了超高斯光束端面泵浦热传导各向异性激光介质温度场的一般解析表达式。并定量分析了超高斯泵浦光阶次、泵浦功率以及光斑尺寸对于Nd:YVO4晶体温度场的影响。新的各向异性介质热传导方程求解方法具有计算量小、精度高等特点。研究结果表明：若LD输出功率为30W，光学聚焦耦合器的传输效率为82%时，4阶超高斯光束端面泵浦掺钕离子质量分数为0.5%的Nd:YVO4晶体，泵浦面获得528.95C的最大温升。所得结果可用于LD端面泵浦热传导各向异性激光介质全固态激光器热稳腔的设计之中，对于提高激光器性能具有了理论指导作用。

Temperature Field Characteristic of Laser Rod with Anisotropic Thermal Conductivity by Diode-laser End-pumped

In order to solve thermal effect of thermal conductive anisotropic laser medium by LD end-pumped, a thermal model of Nd:YVO4 crystal with adiabatic end faces and cooling circumference was established. Considering that the Nd:YVO4 crystal is a thermal conductive anisotropic material and the output beam of LD coupled by fiber has the characteristic of super-Gaussian distribution, a general analytical temperature field expression of thermal conductive anisotropic laser medium end-pumped by the super-Gaussian beam was obtained by the methods of eigen-function and constant variation. Meanwhile, the temperature field influences of the super-Gaussian beam with different orders, spot radius and powers on the Nd:YVO4 crystal were quantitatively analyzed. The new method for solving heat conductive equation of anisotropic medium has the specialties of smaller calculation amount and higher accuracy. The results show that when the output power of LD is 10W, the transmission efficiency of optical focusing coupler is 82%，the end-face of neodymium doped yttrium orthovanadate crystal with 0.5% neodymium ion doped mass fraction end-pumped by the forth order super-Gaussian beam get a maximum temperature rise of 528.95C. The results can be applied to the design of thermally stabilized cavity of all-solid-state laser with thermal conductive anisotropic laser medium by LD end-pumped, and will play theoretically instructive effects at improving the performance of lasers.