Suppression of stimulated Brillouin scattering induced by the compensating signal in all-optical gain-clamped EDFA

In an all-optical link-controlled wavelength-division multiplexing system, the compensating signal generated by a ring-laser structure in the first EDFA may induce strong stimulated Brillouin scattering (SBS) through intermittent bursts of single longitudinal mode oscillation. However, it can be suppressed effectively by an acousto-optic modulator (AOM) inserted in the lasing loop. Multiple longitudinal mode oscillation of compensating light is constantly kept by random interplay between phonons and photons, leading to much higher SBS threshold power.