Quasi-kilowatt random fiber laser

The random distributed-feedback Raman fiber laser (RRFL) is a new approach to obtain a high-power laser. In this Letter, we report a RRFL with quasi-kilowatt output power for the first time based on a half-open cavity. It consists of a piece of a large-mode-area passive fiber with a core diameter of 20 mu m and a high-reflectivity fiber Bragg grating (FBG). By optimizing the fiber length to be 90 m, a 919 W random laser at 1150 nm is achieved in the forward output end. Due to the nonlinear Kerr-effect-induced spectral broadening, the spectrum of the generated random laser exceeds the bandwidth of the FBG, resulting in a 66 W random laser emitting from the backward direction at the maximum power. To the best of our knowledge, it is the first quasi-kilowatt random fiber laser, and it is also the highest power reported of a 1150 nm laser. This work provides a rather simple structure to obtain a kilowatt-level, stable random laser output. (c) 2019 Optical Society of America.