1212 nm high-efficiently-pumped 2 µm Tm/Ho-co-doped fiber laser Q-switched by graphene

We report a high-efficiently-pumped Tm-Ho co-doped fiber laser Q-switched by graphene saturable absorber. The home-made 1212 nm Raman fiber laser with output power of ~200 mW was directly launched into a short 30 cm Tm-Ho co-doped fiber for providing laser gain. The solution-based graphene was grafted with polymer and then made into film for fabricating fiber compatible Q-switcher. The passively Q-switched laser has a center wavelength of 1976 nm, tunable repetition between 32.2 to 43 kHz and shortest pulse width of 1.41 μs. The experimental results suggest that the graphene Q-switched 2 μm laser can be obtained efficiently using 1212 nm wavelength pumping.