Recent Advancement in Graphene-Based Metasurface Structures

Abstract

Surface plasmon polaritons (SPP) formed in graphene exhibits promising properties to become one of the mainstream research topics in nanophotonics. Graphene surface plasmons (GSPs) are excited most efficiently in periodic graphene-based devices, including diffraction gratings, graphene plasmonic crystals, corrugated graphene and conductivity gratings, etc. The metasurface is a strong candidate for electromagnetic wave modulation in optical systems because EM wave can be manipulated in terms of amplitude and phase. Metallic metasurfaces suffer from unwanted correlation between amplitude and phase control of the EM wave as one meta-atom has only one resonance condition. On the other hand, graphene metasurface can achieve tunable conductivity under the exposure of external biasing, chemical doping or stretching the graphene surface mechanically. Therefore, the graphene meta-atoms can achieve multiple resonance conditions within a single design, which further allows them to complete the wavefront’s complete control. Therefore, periodic graphene ribbons have been used independently on top of the 120dielectric, working as tunable terahertz (THz) metasurfaces. Graphene has been integrated with the metallic nanostructures as a hybrid combination to enhance the performance of existing metallic metasurface devices. Later, only graphene patterns have been employed to enhance SPP of the electromagnetic wave at the graphene-dielectric interface for several applications like cross-polarization converters, absorbers, and spatial filters etc. Periodic single-layer graphene patterns have been used in the metadevices for various applications in the THz domain. Recently, two separately patterned layers of graphene have been employed on the two opposite sides of a dielectric substrate for achieving maximum absorption possible of EM wave within the THz gap. The tunable surface conductivity of graphene makes it possible to attain versatile characteristics by altering the Fermi level in graphene.