Watt-level single-frequency lasing enabled by an Er3+-doped fluoride fiber ring oscillator at 2.79 μm

-doped fluoride fiber platform, a unidirectional ring cavity has been employed to eliminate the detrimental spatial hole burning effect, thereby suppressing, to some extent, mode hopping and multi-longitudinal-mode behaviors, while a germanium etalon and a diffraction grating are incorporated into the cavity to realize single longitudinal mode selection based on their combined filtering effects. Ultimately, stable SF lasing at 2.79 μm with a maximum power of 1.16 W has been achieved, exhibiting a linewidth narrower than 500 kHz. This work highlights the great potential of the fluoride fiber ring oscillator for generating high-power SF MIR laser.