▎ 摘　　要

An active plasmonic device is designed to support multiple perfect absorption peaks using the highly confined graphene surface plasmons excited by silicon-based diffractive gratings. The physical origination corresponding to different absorption peaks is analyzed and the principle of impedance matching is used to explain perfect absorption. We show that the absorption spectrum is effectively controllable over a wide wavelength range by changing the Fermi levels, relaxation time of the graphene and geometric parameters of the device. This study could provide some possibilities facilitating the design of next-generation optical and photoelectronic structures by combining graphene and dielectric grating.