端面泵浦热传导各向异性激光棒的温度场

为了解决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:YVO_4晶体热模型.考虑到Nd:YVO_4为热传导各向异性材料,而光纤耦合LD输出光束有超高斯分布的特点,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Nd:YVO_4晶体温度场的影响.研究结果表明,若LD输出功率为50 W,光学聚焦耦合器的传输效率为82%,用四阶超高斯光束端面泵浦掺钕离子质量分数为0.5%的Nd:YVO_4晶体时,泵浦面可获得528.95 ℃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,对于提高激光器性能具有理论指导作用.

Temperature field characteristics of thermal conductive anisotropic laser rods by LD end-pumped

With the aim to solve the thermal effect problem of thermal conductive anisotropic laser media end-pumped by LD, a thermal model of Nd:YVO_4 crystal with adiabatic end faces and a cooling circumference was established. As the Nd:YVO_4 crystal is a thermal conductive anisotropic material and the output beam of the fiber-coupled LD has the characteristics of super-Gaussian distribution, a general analytical temperature field expression of the 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 influences of the super-Gaussian beam with different orders, spot radius and powers on the temperature field of the Nd:YVO_4 crystal were quantitatively analyzed. The results show that when the output power of LD is 50 W and the transmission efficiency of the optical focusing coupler is 82%,the end-face of the Nd:YVO_4 crystal (the weight percent of neodymium ion doped in the crystal is 0.5%) end-pumped by the forth order super-Gaussian beam can get a maximum temperature rise of 528.95 ℃. The results can be applied to the design of thermally stabilized cavity of the all-solid-state laser with thermal conductive anisotropic laser medium end-pumped by LD, and will play theoretically a directional role in improving the performance of lasers.