Graphene-based programmable coding metasurface for manipulation of THz wave

Abstract

In this paper, a method for the design of graphene-based programmable coding metasurface is proposed for beam controlling at terahertz frequencies. The unit cell of the designed metasurfaces consists of two separate graphene parts (graphene patch and ring) where the corresponding chemical potentials may be varied independently. Therefore, a 2-bit unit cell is obtained which is employed in different arrays for beam splitting and beam steering applications. A theoretical approach based on the generalized Snell's law is also investigated to explain the results more conceptually. The desired angle of the reflected beam depends on the phase differences along the x and y directions within the lattice which are proportional to the numbers of the unit cells in the lattice. Therefore beam steering application is realized by changing the size of lattice in a simple method. The numerical simulation and the theoretical approach have good agreement which validate the design method.