All-fiber integrated saturable absorber-tunable wavelength filter for Q-switching laser in both C- and L-bands.

ABSTRACT

We proposed and experimentally demonstrated combining a nonlinear optic saturable absorber and a wideband-tunable spectral filter in a single graphene oxide (GO) film deposited fiber optic device. The GO film was prepared on the cleaved facet of an optical fiber applying two sequential processes the electrical deposition to make a thick GO film using an arc fusion splicer, followed by the laser pulse drilling to form a multi-layered GO film. The GO deposited fiber facet and a pristine fiber facet formed an asymmetric Fabry-Perot interferometer (FPI), whose spectral response was flexibly controlled by adjusting the air gap between them. An all-fiber ring laser cavity was built using the proposed device as a tunable saturable absorber along with erbium-doped fiber as a gain medium in the L-band. Stable Q-switching laser pulse trains were successfully generated, whose pulse duration was in the order of a few microseconds and its peak wavelength was tunable over 40nm from 1564 to 1604nm covering both C-and L-bands. At a certain condition, we also obtained Q-switching pulses simultaneously lasing at the double wavelengths, 1573.3 and 1586.7nm. Detailed device fabrication processes and laser characteristics are described to elucidate the high potential of 2-dimensional material films in nonlinear optics.