▎ 摘　　要

A passively Q-switched nanosecond Tm-doped fiber laser at 1957 nm wavelength was demonstrated using a graphene-based saturable absorber. The absorber was fabricated with graphene grown by chemical vapor deposition and transferred onto a high-reflection mirror. Stable Q-switched laser pulses were observed with the shortest pulse width of 760 ns, a repetition rate of 202 kHz and a maximum average output power of 96 mW. Our experimental results suggest that graphene is suitable for a Q-switcher near 2 mu m wavelength.