从理论上分析了准三能级(Tm,Ho):YLF晶体的增益与温度关系,晶体温度的降低和长度的缩短有利于减小重吸收损耗对激光器运行性能的影响.在室温条件下,用2.7 W波长为792 nm激光二极管端面抽运Tm(原子数分数0.06),Ho(原子数分数0.004):YLF微片激光器,阈值抽运功率为450 W,当入射到晶体内的激光二极管功率为1.88 W时,2 μm激光最大输出功率为328 mW,斜率效率为22.5%,光-光转换效率达17.4%.为达到激光最佳运行条件,还探讨了激光二极管波长,抽运光偏振方向以及晶体温度对Tm,Ho激光器性能的影响.

The relation of gain coefficient to crystal temperature of quasi-three-level (Tm,Ho)∶YLF laser system was analyzed theoretically,with the conclusion that lower temperature and shorter crystal would reduce the reabsorption loss for lower threshold and high efficiency. A microchip Tm(0.06 in number fraction of atoms),Ho(0.004 in number fraction of atoms)∶YLF laser end-pumped by a continuous-wave laser diode with 2.7 W at 792 nm wavelength was conducted in experiment. Up to 328 mW of output power at 2.06 μm with TEM00 mode was obtained with 1.88 W pumping power onto (Tm,Ho):YLF crystal. The pumping threshold was 450 mW, the slope efficiency of the laser was 22.5% and total optical-optical conversion efficiency was 17.4%. To achieve the optimized condition, the effects of pumping wavelength, polarization direction, crystal temperature on the performance of laser were studied.