▎ 摘　　要

We report a diode-pumped 2.78 mu m Er3+-doped ZBLAN fiber laser passively Q switched by a graphene saturable absorber, which was directly deposited onto a fiber dichroic mirror by the method of optically driven deposition. Stable Q-switched operation with a pulse duration of 2.9 mu s and a pulse energy of 1.67 mu J was achieved in a 10 m long gain fiber. The pulse duration was reduced to 1 mu s when the gain fiber length was shortened to 2 m. This Letter demonstrates that graphene is a promising and reliable saturable absorber for mid-infrared pulse generation at 3 mu m. (C) 2013 Optical Society of America