Enhanced dispersive properties of graphene plasmons on substrates of composite materials

Graphene plasmons (GPs) have opened new perspectives for nanophotonic applications due to their intense fields and low losses at certain frequencies. In this work, we investigate transverse magnetic or p-polarized plasmonic modes supported by a doped graphene sheet cladded between a dielectric and a nanocomposite material in tera Hertz regimes. We show that if there is a certain mechanism to excite and couple localized surface plasmons (LSPs) on the surfaces of the metal-nanoparticles to GPs, this coupling leads to higher wave vectors for the GPs, which gives significant wave localization and intense fields near the surface. Along with dispersion relation, we discuss different properties of GPs supported by the waveguide geometry and its interaction with LSPs. Moreover, we compare the results with GPs supported by dielectric/graphene/dielectric geometry and discuss their tunability with different controlling parameters. We adopt realistic parameters to describe the geometry, therefore the study can be realized experimentally.