Suppressing the stimulated Brillouin scattering in high power fiber amplifiers by dual-single- frequency amplification

We demonstrate the suppression of stimulated Brillouin scattering (SBS) in high power fiber amplifiers by a dual-single-frequency amplification. The output power of dualsingle-frequency fiber amplifiers in all-fiber configuration is boosted to 275 W with seeds central wavelength of 1063.7 and 1064.4 nm, respectively. The power conversion efficiency is 76.6%. The maximum output power is limited by the pump power and no significant SBS has been detected even at the highest output power. The effect of the delivery fiber length, the optical output spectra and polarization of the amplified laser are also studied experimentally. The relative magnitude of the two single-frequency signals is maintained in the amplification process and the maximal output power of dual-single-frequency amplifiers can be increased by a factor of more than 2 compared with single-frequency amplification. O u tp u t p o w e r, W 300