Two-dimensional tunable polarization-dependent absorptions for binary and ternary coding

Polarization coding is of great importance because of its applicability to information processing, storage, and security devices. In this paper, we numerically demonstrated a binary and ternary polarization coding scheme using a cross-shaped graphene/Au hybrid metasurface with two-dimensional (2D) electrical tunability. The C4 symmetry broken of the cross-shaped structure, caused by different lengths of Au bars in x- and y-directions, allows 2D tunability for x- and y-polarized waves at one biasing condition. For x-polarized wave incidence, the proposed structure generates near-zero or near-unit absorption by switching the graphene's Fermi energies, corresponding to the binary codes of '0' and '1'. Due to 2D tunability, the combination of two absorptions excited by x- and y-polarized waves at 2.45 THz are encoded into ternary codes with the states of '1', '0', or '1' by gating voltages. The compatibility for binary and ternary coding in the tunable metasurface opposes huge potentials in artificial intelligent devices. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement