Doubly active Q switching and mode locking of an all-fiber laser

Abstract

Simultaneous and independent active Q-switching and active mode locking of an erbium doped fiber laser is demonstrated using all-fiber modulation techniques. A magnetostrictive rod attached to the output fiber Bragg grating modulates the Q-factor of the Fabry-Perot cavity, whereas active mode locking is achieved by amplitude modulation with a Bragg grating-based acousto-optic device. Fully-modulated Q-switched mode-locked trains of optical pulses were obtained for a wide range of pump powers and repetition rates. For a Qswitched repetition rate of 500 Hz and a pump power of 100 mW, the laser generates trains of 12-14 mode-locked pulses of about 1 ns each, within an envelope of 550 ns, an overall energy of 0.65 μJ and a peak power higher than 250 W for the central pulses of the train.