Filtering characteristics of a graphene ribbon with a rectangle ring in infrared region

We propose a structure of a graphene ribbon with a rectangle ring, which is deposited on SiO2 substrate. Our simulation results, conducted by finite element method, show that the transmission dips originate from the ring resonance of the fundamental edge graphene plasmons mode. By choosing specific parameters, the transmission dips of 6th and 4th order ring resonances can split into two, respectively, due to corner effect. Thanks to tunable permittivity of graphene by gate voltages, active control of filtering window is achieved. It is believed that our findings provide a smart way to design a tunable multiple window filter at infrared region.