Experimental study of an actively mode-locked fiber ring laser based on in-fiber amplitude modulation

Abstract

We report an experimental study of an actively mode-locked fiber ring laser based on the development of an efficient in-fiber amplitude modulator. Intermodal coupling induced by standing flexural acoustic waves permits the implementation of broad bandwidth (1.5 nm), high modulation depth (72 %), low-insertion-loss (0.75 dB), in-fiber amplitude modulators, operating in the MHz frequency range. The experimental characterization of the laser as a function of the radio frequency voltage that controls the modulator, the length of the active fiber, and the optical bandwidth of an intracavity filter implemented with a fiber Bragg grating, has led to output optical pulses of 34 ps temporal width, 1.4 W peak power, 4.7 MHz repetition rate, at the emission wavelength of erbium.