Relocking and Locking Range Extension of Partially Locked AMLL Cavity Modes with Two Detuned RF Sinusoids

Actively mode-locked fiber ring lasers (AMLLs) with loss modulators are used to generate approximately (Formula presented.) pulses with (Formula presented.) repetition. RF detuning around the fundamental frequency, (Formula presented.), causes a loss in phase lock (unlocking) of cavity modes and partial mode locking. Multiple RF inputs are shown, theoretically, to relock and extend the locking range of cavity modes in a detuned partially mode-locked AMLL. A custom-built Yb (Formula presented.) -doped AMLL with (Formula presented.), and operating wavelength of (Formula presented.), was used to experimentally verify the theoretical predictions. Two RF sinusoidal signals with constant phase and equal amplitude resulted in an extension of the range by (Formula presented.) in addition to the range (Formula presented.) with single input for the mode (Formula presented.). An increase in locking range was also observed for higher modes. Pulsewidth reduction to approximately (Formula presented.) from about (Formula presented.) was also observed in the AMLL.