Beyatlı Ersen, Kaya Fatma, Bilici Hatıce
Appl Opt. 2020 Sep 20;59(27):8247-8252. doi: 10.1364/AO.402113.
In this paper, we report self--switched (SQS) and three-color operation of an all-solid-state Tm:LuAG laser for the first time to our knowledge. In the experiments, a low-cost 3 W AlGaAs laser diode was used to end-pump the Tm:LuAG crystal inside a four-mirror x cavity. In typical continuous-wave (cw) operation, as high as 754 mW output power was obtained with 49% power efficiency at 2023 nm. Three-color and SQS operations were initiated by fine tuning of the curved mirror separation within the stability range of the resonator. In the three-color regime, the Tm:LuAG laser produced two extra, i.e., 2019 and 2033 nm, wavelength oscillations in addition to on at 2023 nm. As high as 542 mW output power was observed in this regime. To the best of our knowledge, this is the first stable three-color laser operation obtained with an isotropic gain medium without having any birefringent elements in the cavity. Furthermore, the SQS operations were also observed at other curved mirror separations. In the SQS regime, the Tm:LuAG laser produced as fast as 13.3 kHz repetition rate pulses and as high as 42.5 µJ pulse energy. Analysis of power-dependent repetition rate data gave an estimated value of 2% for the round-trip saturable loss of the crystal. As far as we know, this is the first cw-pumped stable SQS 2 µm laser that contains an ordered isotropic gain medium as well as the highest pulse energy obtained in any cw-pumped SQS laser.
据我们所知，本文首次报道了全固态Tm:LuAG激光器的自调Q（SQS）和三色运转。实验中，使用低成本的3W AlGaAs激光二极管对四镜x腔体内的Tm:LuAG晶体进行端面泵浦。在典型的连续波（cw）运转中，在2023nm波长处获得了高达754mW的输出功率，功率效率为49%。通过在谐振腔稳定范围内微调曲面镜间距来启动三色和SQS运转。在三色运转模式下，Tm:LuAG激光器除了在2023nm处有振荡外，还产生了另外两个波长的振荡，即2019nm和2033nm。在此模式下观察到高达542mW的输出功率。据我们所知，这是首次在各向同性增益介质中实现稳定的三色激光运转，且腔内没有任何双折射元件。此外，在其他曲面镜间距下也观察到了SQS运转。在SQS运转模式下，Tm:LuAG激光器产生了高达13.3kHz的重复频率脉冲和高达42.5µJ的脉冲能量。对功率相关重复频率数据的分析给出了晶体往返饱和损耗的估计值为2%。据我们所知，这是首个连续波泵浦的稳定SQS 2µm激光器，它包含有序各向同性增益介质，也是所有连续波泵浦SQS激光器中获得的最高脉冲能量。
