Orange-light passively Q-switched Pr^3+-doped all-fiber lasers with transition-metal dichalcogenide saturable absorbers

We experimentally demonstrated compact orange-light passively Q-switched praseodymium (Pr3+)-doped all-fiber lasers utilizing two-dimensional (2D) transition-metal dichalcogenides (TMDs, WS2 and MoS2) as saturable absorbers (SAs). The filmy TMDs SAs are fabricated by evaporating the composite of TMDs nanosheets and polyvinyl alcohol (PVA), and then inserted into an orange-light Pr3+-doped fiber laser cavity, which is designed by coating dielectric mirrors on fiber ends. Stable passively Q-switched orange lasers at 604 nm are successfully achieved. The passive Q-switching generated the short pulse duration of 435 ns and 602 ns, as well as the tunable repetition rate in the range of 67.3 ~132.2 kHz and 50.8 ~118.4 kHz, respectively. This is, to the best of our knowledge, the shortest-wavelength operation of 2D-material-based pulsed fiber lasers.