Continuous-Wave Mid-Infrared Gas Fiber Lasers

Efficient continuous-wave laser emission of acetylene molecules at 3.1 μm wavelength has been demonstrated in low-loss hollow-core fiber by optically pumping using a fiber-amplified diode laser around 1.53 μm. In this paper, we report and compare the continuous-wave laser performance of acetylene molecules in the cavity and single-pass configurations. The use of low-loss antiresonant hollow-core fiber makes the single-pass configuration ideal for high-power laser generation and enables over 1.1 W continuous-wave mid-infrared laser output with over 33% slope efficiency relative to the absorbed pump power. The systematic characterization of power-scaling and pump power absorption properties demonstrates that the molecular kinetics inside hollow-core fiber determines the laser performance, and that low fiber attenuation is key to high-efficiency continuous-wave output.