▎ 摘　　要

The large-area and high-quality monolayer graphene saturable absorber with a sandwich structure is prepared by the chemical vapor deposition technique. Using graphene saturable absorber, the mode locking operation of a diode-pumped Yb,Y:CaF2 laser is demonstrated. Without extra negative dispersion elements, 4.8 ps pulses are yielded at 1051 nm. The pulse repetition rate is 60 MHz. (C) 2015 Elsevier Ltd. All rights reserved.