Studies on Surface Plasmon Dispersion Theory on the Bilayer Graphene Ribbon Arrays Metasurface

Graphene surface plasmon polaritons (SPP) provide a promising platform to develop a series of new photonic, plasmonic and optoelectronic devices from terahertz to optic spectrum owing to its excellent properties. In this paper, a new kind of graphene metasurfaces, i.e., bilayer graphene ribbon arrays separated by a dielectric gap is proposed. The general dispersion theory of SPP mode on the structure is investigated by a modal expansion method. Solving field expressions on different regions and using proper periodic boundary conditions, the analytical dispersion expressions of SPP mode are obtained on the bilayer graphene ribbon arrays for the first time. With this result, the SPP characteristics of dispersion and propagation loss can be calculated and analyzed with graphene and structural parameters. The proposed SPP modes on the bilayer graphene ribbon arrays metasurface can open up new ways to develop some functional devices such as low-loss sub-wavelength plasmonic waveguide, planar retroreflectors and the enhanced terahertz radiation source.