Spectrally efficient SBS suppression via seed laser current modulation

We report a novel approach to linewidth broadening of the seed laser spectrum for the suppression of Stimulated Brillouin Scattering (SBS) in high power fiber lasers. The seed laser linewidth is broadened through frequency modulation induced by current modulation of a Distributed-Feedback (DFB) laser, while the amplitude modulation is suppressed through a similar, out-of-phase current modulation of a Semiconductor Optical Amplifier (SOA). This approach produces an ideal, uniformly distributed seed laser spectrum for efficient suppression of SBS. SBS suppression is demonstrated on a 1kW fiber amplifier with 95% of output power within a 5.5GHz linewidth (5.7GHz FWHM).