LAUSR

In this Letter, we propose a scheme to use a temporally stable pump source in a high-power random distributed feedback Raman fiber laser (RRFL) with a half-open cavity. Different from conventional pump manners, the pump source is based on an Yb-doped fiber amplifier, seeded by a temporally stable phase-modulated single-frequency fiber laser for suppressing the spectral broadening and second-order Raman Stokes generation in the output laser. Using a piece of 50-m-long 20/400 µm passive fiber, the maximum output power of 1570 W was obtained with a pump power of 2025 W. The conversion efficiency with respect to the pump power was 77.5%. To the best of our knowledge, this is the highest output power ever reported in a RRFL to date. This work could provide a novel method for power scaling of RRFLs.