Opt Lett. 2018 Dec 15;43(24):6109-6112. doi: 10.1364/OL.43.006109.
The bottleneck in Ho:I5→I52.9 μm laser emission, where the upper-level lifetime (I5) is significantly shorter than that of the lower-level (I5) lifetime, is overcome by co-doping Ho and Pr ions. A novel kind of Ho,Pr:YLIF (Ho,Pr:YLF) crystal is fabricated by optimizing the doping concentration ratios. By using as-grown Ho,Pr: YLF crystals with doping concentrations of 0.498 at. % Ho, 0.115 at. % Pr and 0.489 at. % Ho, 0.097 at. % Pr as gain media, both high-efficiency and continuous-wave 2.9 μm laser operations are realized under 1150 nm fiber laser pumping, respectively. With the 0.498 at. % Ho, 0.115 at. % Pr: YLF crystal, a maximum output power of 1.27 W with a corresponding slope efficiency of 28.3% is yielded under a 4.48 W absorbed pump power, which is the highest output power among the Ho-doped 2.9 μm lasers ever reported, to the best of our knowledge. The results well reveal the great potential of Ho,Pr:YLF crystals in developing high-power, high-efficiency 2.9 μm mid-infrared lasers.
Ho:I5→I52.9μm 激光发射的瓶颈是上能级寿命（I5）明显短于下能级寿命（I5），通过共掺 Ho 和 Pr 离子克服了这一瓶颈。通过优化掺杂浓度比，制备了一种新型的 Ho、Pr:YLIF（Ho、Pr:YLF）晶体。使用生长的 Ho、Pr:YLF 晶体，掺杂浓度分别为 0.498 原子%Ho、0.115 原子%Pr 和 0.489 原子%Ho、0.097 原子%Pr 作为增益介质，分别在 1150nm 光纤激光泵浦下实现了高效率和连续波 2.9μm 激光运转。在 0.498 原子%Ho、0.115 原子%Pr:YLF 晶体中，在 4.48W 吸收泵浦功率下，获得了 1.27W 的最大输出功率，相应的斜率效率为 28.3%，这是迄今为止报道的最高的 Ho 掺杂 2.9μm 激光输出功率，据我们所知。结果充分显示了 Ho、Pr:YLF 晶体在开发高功率、高效率 2.9μm 中红外激光器方面的巨大潜力。
