Graphene-based, 50 nm wide-band tunable passively Q-switched fiber laser

We demonstrated a wide-band tunable passively Q-switched fiber laser by using a graphene-based saturable absorber (SA). The graphene SA was prepared through the optically driven deposition method. The Q-switched operation was initiated with a low pump threshold of about 33 mW. The wavelength tunable operation was obtained with a narrow bandwidth tunable filter. Experimentally, the stable Q-switched pulse with a tunable range from 1519.3 to 1569.9 nm was achieved, covering a wavelength range of over 50.6 nm.