Continuous-wave laser emission of 10.4 W, 4.16 μm from HBr-filled hollow-core fiber

Abstract We report here the characteristics of a high-power continuous-wave mid-infrared (mid-IR) fiber light source based on nested anti-resonant hollow-core fiber (AR-HCF) filled with HBr gas. A homemade hundred-watt-level 2 μm narrow-linewidth fiber laser is constructed as the pump source. The pump source is forward injected into the AR-HCF through a single-pass configuration. A maximum output power of 10.4 W at 4.16 μm with excellent beam quality ( M 2 ) of approximately 1.05 is achieved in a 4.8 m long AR-HCF at gas pressure of 9.9 mbar, with a slope efficiency of 20% relative to the absorbed pump power. The mid-IR light source maintains good stability during long-term operation. To the best of our knowledge, this is the highest output power for silica-based fiber light sources beyond 4 μm. This work demonstrates the significant capability of power scaling in a gas-filled AR-HCF mid-IR light source.