Anisotropic graphene metasurface waveguide supporting plasmonic TM and TE modes

Abstract

Isotropic graphene metasurfaces can only support surface plasmon polariton (SPP) waves in either transverse magnetic (TM) or transverse electric (TE) modes. To overcome this limitation, we introduce what we believe to be a novel metasurface design based on an anisotropic graphene patch (AGP) unit cell, enabling the simultaneous propagation of both SPP-TM and SPP-TE mode waves. First, we use the transmission-line model and transverse resonance technique to derive the dispersion equation for TM and TE modes on a graphene sheet with a diagonal impedance tensor. Then, we develop an equivalent circuit representation for the AGP unit cell, which allows us to readily extract the characteristics of SPP wave propagation along the AGP metasurface. The results demonstrate that SPP-TM and SPP-TE modes can propagate along the AGP metasurface, provided the unit cell dimensions are within a specific range. These findings are then applied to the design of three metasurface waveguides tailored to different applications.