Diode-pumped 1-W Er-doped fluoride glass M-profile fiber laser emitting at 2.8 mum

We report a novel short-length diode-pumped cw fiber laser with high output power at a wavelength of 2.8mum . The system combines continuous-wave diode pumping at 970 nm, a high doping concentration (5-mol. % ErF(3)) of the active fiber, and an annular geometry of the laser medium, an M-profile fiber. Output powers in excess of 1 W with a slope efficiency of 25% were obtained.