▎ 摘　　要

A tunable dual-band bandstop filter (BSF) in the far-infrared region is proposed based on a graphene surface plasmon. The BSF consists of a graphene waveguide and two graphene-ribbon resonators on the SiO2/Si substrate, supporting waveguide mode and edge mode, respectively. The influence of graphene structure parameters on transmission spectra is numerically investigated, which shows that the resonant properties are sensitive to the lengths of the graphene-ribbon resonators, and each stopband of dual-band BSF can be individually designed and tuned without affecting the other stopband. Moreover, the center frequencies of the two stopbands can be actively tuned independently by respective chemical potential of graphene-ribbon resonators. The proposed filter structure is promising to be utilized in future photonic integrated circuit applications as an ultracompact dual-band BSF.