High efficiency mid-infrared passively Q-switched erbium-doped fiber laser pumped at 1.7 μm

We demonstrated a mid-infrared passively Q-switched erbium-doped fluoride fiber laser pumped at 1.7 μm experimentally for the first time to our knowledge. The Q-switched pulse generation is facilitated by a SnPSe₃ saturable absorber, noted for its outstanding nonlinear absorption characteristics at 2.8 μm. The fiber laser achieved a slope efficiency of 32%, a maximum output power of 435 mW, and a minimum pulse width of 384 ns, which is working at 2785 nm. The experimental results not only validate the 1.7 μm pumping scheme and the nonlinear optical properties of SnPSe₃ for mid-infrared nanosecond laser generation, but also provide a reference for improving the performance of mid-infrared passively Q-switched fiber lasers.