▎ 摘　　要

In this paper, a tunable triple-band plasmonic switch based on an array of graphene rings has been studied in the far-infrared region. The performance of the structure is based on the absorption mechanism and the value of absorption has been improved due to the excitation of graphene surface plasmons. The structure has three resonance peaks with the absorption of more than 83%. By changing the chemical potential of graphene rings and making the switching capability, the high extinction ratio of 19.62 dB has been obtained at the wavelength of 17.87 mu m. Also, the structure has an ultrafast response time of 1.2 ps. The effects of geometrical parameters, chemical potential and relaxation time of graphene on the absorption characteristics have been also investigated. To validate the results of finite element simulation, the equivalent circuit model of the switch has been extracted. Due to the simplicity, tunability and narrow-band absorption spectrum of the suggested switch, it can be also used as modulator, sensor, and logic gate.