Demonstration of a 150-kW-peak-power, 2-GHz-linewidth, 1.9-μm fiber gas Raman source

We report here for the first time, to the best of our knowledge, a 100-kW-peak-power, GHz-linewidth, sub-nanosecond, 1.9-μm laser source by gas stimulated Raman scattering (SRS) in hollow-core fiber. A H₂-filled, anti-resonance, hollow-core fiber is pumped with a sub-nanosecond, high-peak-power, 1064-nm microchip laser, generating a 1908-nm Stokes wave by vibrational SRS of H₂ molecules. A maximum peak power of about 150 kW (average power 55 mW, pulse energy 55 μJ) is achieved with a 1.4-m fiber length and only 3 bar H₂ pressure. The maximum quantum efficiency is about 54%, and the corresponding slope efficiency is about 37%. The linewidth of the Stokes wave is about 2 GHz, which decreases about 1-2 orders compared with the rare-earth-doped fiber lasers of the same peak-power level. Operation close to atmospheric pressure makes it more convenient in future applications. If a tunable pump laser is used, a high-peak-power, narrow-linewidth, broadly tunable, 2-μm fiber laser source can be easily achieved.