Kilowatt-level supercontinuum generation in random Raman fiber laser oscillator with full-open cavity

High-power supercontinuum (SC) sources are important for remote sensing, homeland defense, and scientific research. Despite recent advances in power scaling of the SC generation in optical fibers, the power record of SC fiber laser sources is still much lower than conventional high-power fiber lasers. Here we demonstrate a method for kilowatt-level SC generation based on the random Raman fiber laser (RRFL) with a full-open cavity. Theoretically, a model including cascaded Raman effect, modulation instability, and Rayleigh scattering is established to qualitatively highlight the dynamics of the kilowatt-level SC generation. Experimentally, injecting the amplified ytterbium-doped fiber laser and Raman fiber laser into the RRFL oscillator formed by a piece of long passive fiber, 3-kW-level SC spanning from 925 to 1862 nm is achieved. The experimental results suggest that the full-open-cavity RRFL is a promising approach for kilowatt-level SC generation and the theoretical model demonstrates the importance of Rayleigh backscattering during the SC generation.