Ho∶YLF晶体的5I7和5I8斯塔克能级分裂数较多,形成2047～2070 nm宽的增益谱带,对于可调谐2 μm激光及宽带激光放大器研究具有重要意义。理论上分析了(Tm,Ho)∶YLF晶体的能级结构,并对晶体掺杂浓度和长度进行了优化。实验研究了激光二极管抽运微片Tm(原子数分数0.06),Ho(原子数分数0.004)∶YLF激光谱线可调谐特性,调谐范围2.0656～2.0671 μm。利用(Tm,Ho)∶YLF晶体的宽增益谱特性,将其作为激光二极管抽运激光放大器,成功地将2.048 μm (Tm,Ho)∶GdVO4激光功率放大了2.5倍。实验上测量了(Tm,Ho)∶YLF晶体在强抽运条件下480～492 nm及530～550 nm可见波段的上转换蓝绿光荧光谱。

The tunability and high gain amplification of (Tm,Ho)∶YLF crystal with wide spectral band in the range from 2047～2070 nm are studied in theory and experiment. The crystal length and (Tm,Ho) doped concentration are optimized for room operation and high gain amplification. The microchip Tm(fraction of number of atoms 0.06),Ho(fraction of number of atoms 0.004)∶YLF laser is tunable from 2.0656～2.0671 μm under pumping power of 1.88 W at 792 nm. The 2.048 μm radiation from (Tm,Ho)∶GdVO4 laser is amplified by cryogenic Tm(8%), Ho(1.4%)∶YLF amplifier dual-end pumped by two 15 W fiber-coupled laser diodes, an amplification factor of 2.5 is achieved. The blue-green upconversion fluorescence spectral from (Tm,Ho)∶YLF laser under strong pumping condition are measured within the radiation range of 480～492 nm and 530～550 nm.