A nearly transform-limited, single-frequency $2~\mu \text{m}$ laser system with multi-stage of double-pass Tm:Ho:LuLiF₄ slab amplifiers was demonstrated. An amplified pulse energy up to 5.6 mJ at central wavelength of 2051.9 nm was achieved successfully with around 429.7 ns pulse width at a repetition rate of 10 Hz. The line-width of the laser spectrum detected by a heterodyne technique was about 1.24 MHz. The M² factors were less than 1.6 and 1.4 in the x and y directions, respectively.

中文翻译：

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5.6 mJ、单频、端泵浦 Tm:Ho:LuLiF4 平板放大器系统

一个几乎受变换限制的单频 $2~\mu \text{m}$ 演示了具有多级双通 Tm:Ho:LuLiF ₄板条放大器的激光系统。在 2051.9 nm 的中心波长下成功实现了高达 5.6 mJ 的放大脉冲能量，脉冲宽度约为 429.7 ns，重复率为 10 Hz。通过外差技术检测到的激光光谱的线宽约为 1.24 MHz。M ²因子在 x 和 y 方向分别小于 1.6 和 1.4。