We propose and demonstrate a passively $Q$-switched Er-doped fiber laser based on pure water as the saturable absorber (SA). The SA is made of two optical ferrules matched with a cannula, and the gap between the end-facets is filled with pure water. The nonlinear response of this SA has been characterized, and stable $Q$-switching operation at 1558.03 nm has been achieved. The maximum output power is 21.1 mW with 65.0 kHz repetition rate. The duration is 1.44 μs, and the pulse energy reaches 324.8 nJ. To the best of our knowledge, this is the first demonstration of the passively $Q$-switched laser with pure water as the SA. It provides further evidence of the possibility of liquid as an effective SA for pulsed lasers.

中文翻译：

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被动Q基于纯水作为可饱和吸收-switched光纤激光器

我们主动提出并展示 $问$纯水作为可饱和吸收体（SA）的掺switch掺fiber光纤激光器。SA由两个与套管配套的光学插芯制成，端面之间的间隙充满了纯净水。该SA的非线性响应已被表征且稳定$问$-已经实现了1558.03nm的开关操作。最大输出功率为21.1 mW，重复频率为65.0 kHz。持续时间为1.44μs，脉冲能量达到324.8 nJ。据我们所知，这是被动展示的第一个例子。$问$用纯净水作为SA的激光。它提供了进一步的证据，证明液体有可能成为脉冲激光器的有效SA。