Suppression of supermode competitions in SOA fiber mode-locked ring laser

Summary form only given. An actively harmonic mode-locked fiber ring laser works at the modulation frequency which is an integral multiple of the fundamental cavity mode frequency spacing. As for harmonic mode-locking of erbium doped fiber lasers, relaxation oscillation and beating between supermodes are the main noise sources introduced by amplitude fluctuation and time jitter. However, a 10 GHz actively mode-locked fiber ring laser with semiconductor optical amplifier (SOA) as gain medium shows good amplitude stability compared with EDFA without active cavity length stabilization, where no relaxation oscillation was observed. In this paper, we analyse the beating between supermodes in a mode-locked fiber ring laser and present supermode competition suppression due to gain saturation in SOA and shorter recovery time compared with EDFA.