Mode-locked all-fiber lasers based on advanced acousto-optic modulators

Abstract

The development of efficient in-fiber amplitude modulators that operate in the MHz frequency range has enabled some recent advances in actively mode-locked all-fiber lasers. Our approach is based on the excitation of a standing acoustic wave along the fiber, which modulates the coupling between modes at twice the frequency of the acoustic wave. Among the remarkable features of these in-fiber modulators, we mention the high peak power damage, high modulation depth, broad bandwidth, easy tunability in optical wavelength and low insertion losses. The in-fiber modulation is crucial for the implementation of all-fiber compact and robust lasers. The experimental characterization of different cavity configurations as a function of the radio frequency voltage that controls the modulator, the length of the active fiber, the overall dispersion of the cavity, etc., has led to an improved operation of the lasers: output optical pulses of 34 ps temporal width, 1.4 W peak power and 4.7 MHz repetition rate, at the emission wavelength of erbium.