▎ 摘　　要

Using large-area graphene sheets of 1-10 layers prepared by the improved liquid phase exfoliation technique, the mode locking operation of a diode-pumped Yb:KGW laser was demonstrated. Near-transform-limited 428 fs pulses were yielded at 1031.1 nm with an output power of 504 mW, corresponding to the slope efficiency of 27% and peak power of 13.8 kW. The output power ratio and the slope efficiency ratio of mode locking to free running were as high as 93% and 100%, respectively. This demonstration may open a proper way to achieve low-cost and efficient femtosecond bulk laser. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3672213]