▎ 摘　　要

Reduced graphene oxide (rGO) decorated with silver nanoparticles exhibits an enhanced nonlinear absorption effect compared with pure rGO. Using femtosecond time-resolved transient absorption spectroscopy, the enhancement mechanism and carrier dynamics of the composites are experimentally demonstrated. When the material is excited by laser pulses, the excited carriers in the conduction band of graphene will transfer to the d-band of silver before returning to the valence band. As the decay process (similar to 210 ps) is much longer than that of the relaxation time in pure graphene (similar to fs), the bleaching effect of valence band is prolonged, resulting in enhanced saturable absorption effect. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement