激光二极管端面泵浦Yb:YAG圆棒热效应研究

基于激光二极管端面泵浦Yb∶YAG棒工作特点的分析,提出了端面绝热、周边恒温的激光晶体热分析模型,采用了一种新的热传导方程求解方法,得到了超高斯光束端面泵浦Yb∶YAG棒温度场的一般解析表达式。同时分析了不同阶次、不同光斑半径、不同功率超高斯光束以及晶体参数改变时对于Yb∶YAG棒温度场分布的影响。研究结果表明,若准直聚焦到Yb∶YAG棒泵浦面42.5W的光束具有4阶超高斯强度分布时,掺Yb3+质量分数为10.0at.%、长度为2.5mm、半径为2mm的Yb∶YAG棒的泵浦面获得74.20℃的最高温升。新的热传导方程求解方法在研究激光棒温度场分布方面具有计算量小、精度高等特点。研究结果对减小激光晶体的热效应,提高全固态Yb∶YAG激光器性能提供了理论依据。

Thermal effect of Yb:YAG rod end-pumped by diode laser

Based on the working characteristic of Yb∶YAG rod with diode laser end-pumped,a thermal model of laser crystal with adiabatic end faces and a fixed boundary temperature is introduced.And a general temperature field analytical expression of Yb∶YAG rod end-pumped by super-Gaussian beam is obtained by a new solution of heat conductive equation.Meanwhile,some factors,such as the superGaussian beam with different orders,different spot radius,different power and the parameters changes of crystal rod,which influenced the temperature distribution of Yb∶YAG rod,are analyzed.The results show that when the power of the forth order super-Gaussian beam collimated and focused on the Yb∶YAG rod is 42.5W and the super-Gaussian radius is 400μm,the maximal temperature raise of Yb∶YAG rod(the length and the radius is 2.5mm and 2mm and the ytterbium doped concentration in Yb∶YAG rod is 10 %) is 74.20℃.The new method for solving heat conductive equation has the characteristic of smaller calculation amount and higher accuracy in the investigation of temperature distribution of laser rod.The results will provide a theoretical basis for reducing the thermal effect of laser crystal and improving the performance of all-solid-state laser.