Noise reduction by harmonic injection locking of passively mode-locked erbium-doped fiber lasers.

Harmonic injection locking can generate pulse trains at high repetition rates from passively mode-locked lasers. We have examined experimentally the mutual interaction of noise with the locking process. For injected signals with large timing and amplitude noise, the mode-locked fiber laser generated a pulse train with reduced noise. Injected signals with low timing and amplitude noise were employed for the reduction of the internal noise of the passively mode-locked laser. The achieved output pulse-to-pulse timing jitter in the range of 20-2500 Hz was ~0.6 ps, comparable with that of actively stabilized fiber lasers.