Theoretical and experimental study on PRBS time-domain characteristic effects: stimulated Brillouin scattering in silica-based optical fiber

In this paper, we theoretically and experimentally investigate the impact of pseudo-random binary sequence (PRBS) time-domain characteristics on the properties of stimulated Brillouin scattering (SBS) in silica-based optical fiber. It is shown that, when PRBS-modulated injection lasers at the front end in optical fibers reach the SBS threshold, the SBS-induced Stokes light exhibits periodic temporal variations accompanied by high-intensity pulses. By using numerical simulations and experimental validations based on three-wave coupling equations and a fiber laser platform, we demonstrate that the temporal instability in backward light stems from the inherent dwell time of PRBS. To reduce the impact of PRBS dwell time on the suppression of SBS, we generated two modified PRBS-9 sequences using an arbitrary waveform generator and applied them to a master oscillator power amplifier-structured fiber laser amplification platform at a clock frequency of 5 GHz. Upon reaching the SBS threshold, the forward output power reached 1120 W, representing a 6.66% power enhancement compared to the unmodified PRBS-9 sequence.