We present an all-passive efficient KGW Raman laser with an external-cavity configuration in the 2 µm spectral regime. The Raman laser was pumped by a passively ${Q}$-switched Tm:YAP laser emitting at 1935 nm. Due to the bi-axial properties of the KGW crystal, the laser exhibits stimulated Raman emission at two separate spectral lines: 2272 nm and 2343 nm. The output energies achieved at these two lines are 340 µJ/pulse and 450 µJ/pulse, accordingly. The seed to Raman laser conversion efficiencies achieved of 19.2% and 23.5%, respectively, are comparable to actively ${ Q}$-switched laser arrangements. To the best of our knowledge, this is the first time an efficient Raman laser in the 2 µm regime is demonstrated in a completely passive configuration.

中文翻译：

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高效全固态被动调Q SWIR Tm：YAP / KGW拉曼激光器

我们介绍了一种全被动高效KGW拉曼激光器，其外腔配置在2 µm光谱范围内。拉曼激光器由在1935 nm处发射的无源$ {Q} $切换的Tm：YAP激光器泵浦。由于KGW晶体的双轴特性，该激光器在2272 nm和2343 nm这两个单独的光谱线上表现出受激拉曼发射。在这两条线上获得的输出能量分别为340 µJ /脉冲和450 µJ /脉冲。从种子到拉曼的激光转换效率分别达到19.2％和23.5％，可与主动$ {Q} $转换激光装置相媲美。据我们所知，这是首次在完全无源配置中展示2 µm范围内的高效拉曼激光器。