A Bandpass Graphene Frequency Selective Surface With Tunable Polarization Rotation for THz Applications

In order to achieve tunable polarization rotation of the transmitted wave and controllable bandpass response simultaneously, a new graphene frequency selective surface (GFSS) is proposed for terahertz applications. The GFSS is built up by sandwiching a high-resistivity Si-substrate with a graphene patch array and a graphene sheet, both of which are electromagnetically biased. The configuration is analyzed by using an equivalent tensorial surface conductivity and transmission matrices of graphene structures, which is validated by full-wave simulations. The transmission coefficient, axial ratio, and polarization rotation angle of the bandpass GFSS are captured. An observable polarization rotation angle is obtained with a relatively large transmittance, which is superior to the graphene sheet and bandstop patch-type structures. The passband frequency is found to be not sensitive to the incident angle for either TE- or TM-polarized incidence, while it can be shifted from 1.6 to 2.2 THz with the polarization rotation angle varying from 24° to 16° by changing the chemical potential from 0.6 to 1 eV. When the applied magnetic field is set up to 3 T, the maximum rotation angle of polarization reaches up to 30° for TM incidence and 45° for TE incidence while the passband remains around 2 THz.