▎ 摘　　要

High-quality monolayer graphene as large as 1.2 x 1.2 cm(2) was synthesized by chemical vapor deposition and used as a transmitting saturable absorber for efficient passive mode-locking of a femtosecond bulk solid-state laser. The monolayer graphene mode-locked Cr:forsterite laser was tunable around 1.25 mu m and delivered sub-100 fs pulses with output powers up to 230mW. The nonlinear optical characteristics of the monolayer graphene saturable absorber and the mode-locked operation were then compared with the case of the bilayer graphene saturable absorber. (C) 2011 Optical Society of America