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 degrees to 16 degrees 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 degrees for TM incidence and 45 degrees for TE incidence while the passband remains around 2 THz.