Graphene Tunability for Transmission Type Terahertz Chiral Metamaterial

It is known that the combination of metamaterials (MTMs) and graphene leads to the tunable nanophotonic applications such as optical reflection modulation, wavefront tunability and absorbers. In this work, we attempt to use graphene as an interconnector between meta-atoms in order to control transmission characteristics of chiral metamaterial (CMM) for terahertz (THz) polarizers. A CMM exhibiting a broadband asymmetric transmission (AT) with the magnitude of more than 0.4 for linearly polarized electromagnetic waves in the range of 4.4 THz to 5.3 THz is tuned by varying Fermi Energy ( EF) of graphene. It is observed that graphene sheet with two possible orientations ( x and y) between meta-atom, tunes 20% and 7.3% cross-polarization conversion for transverse electric (TE) and transverse magnetic (TM) polarizations when EF is varied from 0.32 eV to 0.38 eV. We anticipate that this THz tunability of graphene in transmission type polarizer is inevitable in polarization control in THz imaging techniques.