We report on Czochralski growth, detailed ground- and excited-state absorption and emission spectroscopy and highly-efficient mid-infrared (∼2.3 µm) laser operation of a cubic potassium yttrium fluoride crystal, Tm:KY3F10. The peak stimulated-emission cross-section for the 3H4 → 3H5 transition is 0.34×10-20 cm2 at 2345 nm with an emission bandwidth exceeding 50 nm. The excited-state absorption spectra for the 3F4 → 3F2,3 and 3F4 → 3H4 transitions are measured and the cross-relaxation is quantified. A continuous-wave 5 at.% Tm:KY3F10 laser generated 0.84 W at 2331-2346 nm by pumping at 773 nm, with a record-high slope efficiency of 47.7% (versus the incident pump power) owing to the efficient action of energy-transfer upconversion leading to a pump quantum efficiency approaching 2. The first Tm:KY3F10 laser with ESA-assisted upconversion pumping (at 1048 nm) is also demonstrated. Due to its broadband emission properties, Tm:KY3F10 is promising for ultrashort pulse generation at ∼2.3-2.4 µm.

中文翻译：

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仔细观察立方Tm：KY3F10晶体，以实现3H4→3H5跃迁的高效激光发射。

我们报告了Czochralski的生长，详细的基态和激发态吸收和发射光谱以及立方氟化氟化钾钾晶体Tm：KY3F10的高效中红外（〜2.3 µm）激光操作。3H4→3H5跃迁的峰值受激发射截面在2345 nm处为0.34×10-20 cm2，发射带宽超过50 nm。测量3F4→3F2,3和3F4→3H4跃迁的激发态吸收光谱，并量化交叉松弛。连续波5 at。％Tm：KY3F10激光器通过在773 nm处泵浦在2331-2346 nm处产生0.84 W的功率，这归因于能量的有效作用，斜率效率达到了创纪录的47.7％（相对于入射泵浦功率）。 -转移上转换导致泵浦量子效率接近2。第一个Tm：还展示了带有ESA辅助上变频泵浦的KY3F10激光器（在1048 nm处）。由于其宽带发射特性，Tm：KY3F10有望产生约2.3-2.4 µm的超短脉冲。