▎ 摘　　要

We propose a simple method to fabricate graphene saturable absorber (GSA) through drop casting the graphene dispersion prepared by liquid-phase exfoliation of graphite onto quartz plate and realize the passively mode-locked of an Erbium-doped fiber laser by this saturable absorber (SA). In contrast with previous GSAs, due to the incorporation of additional free space alignment from the SA component, we are able to deliberately control the laser radiation spot size and location on GSA, leading to flexibility in mode-locked performance. Finally, we can obtain stable soliton pulse emission with central wavelength at 1564.42 nm, 3 dB bandwidth of 1.02 nm, and pulse duration of 2.89 ps, and also note that soliton parameters (pulse energy, central wavelength, and pulse duration) sensitively depend on the position of GSA, which could be traced back to nonuniformity of saturable absorption from the nonhomogeneous morphology of the as-prepared graphene sample. (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.OE.51.8.084203]