2 W monolithic fiber laser at 3.8 µm

We report a dual-wavelength-pumped all-fiber continuous-wave laser operating at the extended wavelength of 3.79 µm that reaches a record output power of 2.0 W. This represents, to the best of our knowledge, the highest output power reported at the longest spectral range for a fiber laser. The laser cavity, made of a heavily erbium-doped fluoride fiber and bounded by two photo-inscribed fiber Bragg gratings, reaches a slope efficiency of 46.5% with respect to the absorbed 1976 nm pump power. The system exhibits an absorption dependency of the 1976 nm pump on the launched 976 nm pump and a quenching behavior dependency on the output coupler reflectivity. The all-fiber design of the cavity allows significant power scaling of the laser and ensures its long-term stability.