Opt Express. 2023 Apr 24;31(9):14808-14820. doi: 10.1364/OE.487130.
We report on a bulk thulium laser operating on the H → H transition with pure upconversion pumping at 1064 nm by an ytterbium fiber laser (addressing the F → F excited-state absorption (ESA) transition of Tm ions) generating 433 mW at 2291 nm with a slope efficiency of 7.4% / 33.2% vs. the incident / absorbed pump power, respectively, and linear laser polarization representing the highest output power ever extracted from any bulk 2.3 µm thulium laser with upconversion pumping. As a gain material, a Tm-doped potassium lutetium double tungstate crystal is employed. The polarized ESA spectra of this material in the near-infrared are measured by the pump-probe method. The possible benefits of dual-wavelength pumping at 0.79 and 1.06 µm are also explored, indicating a positive effect of co-pumping at 0.79 µm on reducing the threshold pump power for upconversion pumping.
我们报告了一种基于钬到钬跃迁的块状掺铥激光器，采用掺镱光纤激光器进行纯上转换泵浦，泵浦波长为 1064nm（针对 Tm 离子的 F→F 激发态吸收（ESA）跃迁），在 2291nm 处产生 433mW 的功率，斜率效率分别为 7.4%/33.2%，相对于入射/吸收泵浦功率，激光呈线性偏振，这代表了从任何采用上转换泵浦的块状 2.3µm 掺铥激光器中提取的最高输出功率。作为增益材料，使用掺铥的钾镥双钨酸盐晶体。采用泵浦探测法测量了该材料在近红外波段的偏振 ESA 光谱。还探索了在 0.79μm 和 1.06μm 双波长泵浦的可能好处，表明在 0.79μm 处共泵浦对上转换泵浦的阈值泵浦功率有积极影响。
