Demirbas Umit, Thesinga Jelto, Beyatli Ersen, Kellert Martin, Pergament Mikhail, Kärtner Franz X
Opt Express. 2022 Nov 7;30(23):41219-41239. doi: 10.1364/OE.471288.
We report detailed experimental data aiming for rigorous investigation of Tm:YLF laser performance, especially with a focus on tuning behavior. Continuous-wave (cw) lasing performance of Tm:YLF crystals with thulium dopings in the 2-6% range is investigated under diode and Ti:Sapphire pumping at 792 nm and 780 nm, respectively. While employing the c-axis, we have achieved cw lasing thresholds below 20 mW, laser output power up to 1.42 W, and laser slope efficiencies as high as 70% with respect to absorbed pump power. The passive loss of the Tm:YLF crystal is estimated to be as low as 0.05% per cm, corresponding to a crystal figure of merit above 10000. Via employing this low-loss crystal and a 2-mm thick off-surface optical axis birefringent filter (BRF) with strong sideband rejection, a record cw tuning range covering the 1772-2145 nm interval is demonstrated (except a small gap between 1801-1815nm region). Detailed lifetime and emission cross section measurements have been performed to explain the observed performance, and strategies for further performance enhancement are discussed.
我们报告了详细的实验数据，旨在对Tm:YLF激光性能进行严格研究，尤其侧重于调谐行为。分别在792 nm的二极管泵浦和780 nm的钛宝石泵浦下，研究了铥掺杂浓度在2%-6%范围内的Tm:YLF晶体的连续波（cw）激光性能。在采用c轴时，我们实现了低于20 mW的连续波激光阈值、高达1.42 W的激光输出功率以及相对于吸收泵浦功率高达70%的激光斜率效率。Tm:YLF晶体的无源损耗估计低至每厘米0.05%，对应晶体品质因数高于10000。通过使用这种低损耗晶体和具有强边带抑制的2毫米厚离表面光轴双折射滤光片（BRF），展示了覆盖1772-2145 nm区间的创纪录连续波调谐范围（1801-1815 nm区域之间有一个小间隙除外）。已经进行了详细的寿命和发射截面测量以解释观察到的性能，并讨论了进一步提高性能的策略。
