端面抽运Tm,Ho:YLF激光器热转换系数及热透镜效应的研究

根据激光二极管纵向抽运Tm,Ho:YLF激光器的能级跃迁和能量传递过程，在考虑能量传递上转换和基态重吸收的前提下，建立了准三能级速率方程理论模型.给出了Tm,Ho:YLF激光器的热转换系数的解析表达式，讨论了抽运光斑半径与激光束腰半径的比值对热转换系数的影响.实验上得到了热焦距随抽运功率的变化关系，并将其与理论结果进行了对比，发现符合较好.关键词：TmHo:YLF晶体能量传递上转换速率方程热转换系数

Fractional thermal loading and thermal lensing in end-pumped Tm,Ho:YLF lasers

Based the energy transfer between ions and the transition between energy levels of diode-end-pumped Tm,Ho:YLF laser, and considering the energy transfer up-conversion and ground state re-absorption, the rate equations are set up. The analytical formula of fractional thermal loading is deduced from the rate-equations, and the results show that the fractional thermal loading critically depends on the pump-to-mode size ratio. The focal length of the thermal lens as a function of pump power is obtained in experiment. The experimental results are compared with theoretical results, which shows that the theoretical results are reasonable.