Watt-level gain-switched fiber laser at 3.46 μm

We demonstrate a gain-switched fiber laser, yielding a maximum average power of 1.04 W at 3.46 mu m, which is the current record of a pulsed rare-earth-doped fiber laser at the wavelength beyond 3 mu m, to our knowledge. The corresponding pulse energy is 10.4 mu J with a repetition rate of 100 kHz. A dual-wavelength pumping scheme consisting of a home-made 1950 nm passively Q-switched fiber laser system with a mu s-scale pulse width. A 976 nm continuous wave laser diode was used to gain-switch a double-cladding Er-doped ZBLAN fiber laser cavity. Possible laser-quenching behavior during a single-pump pulse was circumvented for the moderate pump peak power and relatively large-pump pulse width. Synchronous gain-switched pulses were achieved with a tunable repetition rate at a wide range of 55 similar to 120 kHz, which is the highest gain-switching repetition rate at this band and only limited by our pulsed-pump source. Moreover, the significance of pump pulse width for repetition rate improvement is also discussed. These results provide an available way to produce high-power pulses at the mid-infrared range of 3 similar to 5 mu m. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement