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We report here an efficient watt-level tunable 1.7 µm fiber gas Raman laser. Pumped by a homemade pulsed fiber amplifier around 1.5 µm wavelength, a tunable laser ranging from 1687 to 1723 nm is demonstrated in a hydrogen-filled hollow-core photonic crystal fiber (HC-PCF). A maximum average power of ∼ 0.8 W (pulse energy of ∼ 1.6 µ J ) is achieved on a 20-m-long HC-PCF filled with 16 bar of hydrogen gas, corresponding to a maximum Raman power conversion efficiency of 60%. A steady-state model of the rotational stimulated Raman scattering in hydrogen-filled HC-PCF, considering the pump pulse shape, is also established. The predicted output power and pulse shapes of the pump and Stokes waves are in good agreement with the experimental results. Our system offers an elegant solution for realizing efficient, tunable, and high-power fiber lasers operating at 1.7 µm wavelength range.

We conducted comprehensive theoretical research on rotational stimulated Raman scattering (SRS) of hydrogen molecules in hollow-core fibers. A reliable model for describing the steady-state rotational SRS of hydrogen was established and the influences of various factors was investigated. To verify the theoretical model, a single-pass fiber gas Raman laser (FGRL) based on hydrogen-filled hollow-core photonic crystal fibers pumped by a 1.5 µm nanosecond-pulsed fiber amplifier was constructed. Experimental results were congruent with simulation results. As the output powers and pulse shapes can be well calculated, the model can offer guidance for FGRL investigation, particularly for achieving high-efficiency and high-power FGRLs.