10 kW Fiber Amplifier Seeded by Random Fiber Laser With Suppression of Spectral Broadening and SRS

A 10 kW fiber amplifier seeded by the random fiber laser (RFL) with 1018 nm tandem-pumping scheme is reported in this letter. The amplified RFL centered at 1085 nm is seeded by the RFL with a full-open cavity. An array of chirped and tilted fiber Bragg gratings placed before the main amplifier prevent the stimulated Raman scattering with a suppression ratio of 55.8 dB. Control experiments prove that the fiber amplifier seeded by the RFL can suppress the spectral broadening during the amplification process effectively. We demonstrate experimentally that this phenomenon is due to the better temporal stability of the RFL compared with that of the fixed-cavity fiber laser. This fiber amplifier seeded by the RFL is the highest output power record for the amplified RFL to the best of our knowledge, and the spectral evolution suggests the potential for further power scaling-up.