Tunable narrow-linewidth surface plasmon resonances of graphene-wrapped dielectric nanoparticles in the visible and near-infrared

We investigate the plasmon resonance in the light interaction with a graphene nanoshell which consists of graphene wrapped around a low − loss dielectric core. In this work, Polystyrene (PS) and Titanium dioxide (TiO2) cores are proposed. This study is restricted to small nanoparticles with diameters significantly smaller than the wavelength of incident light. Therefore, we adopt the quasi − static approach that provides in− depth insights into the plasmon resonance of core− shell nanoparticles. The proposed graphene nanoshell can support two localized surface plasmon resonances (LSPRs). These plasmon resonance modes correspond to the symmetric and antisymmetric dipole-like modes described in the hybridization theory. The observed resonance modes are characterized by a narrow bandwidth and a broadband resonance tunability in the visible to near-infrared (NIF) range. The impacts of the optical properties of graphene, core material, and nanoshell geometry on surface plasmon features are explored. We show that the features of each plasmonic resonance meet the demands for specific nanoscale applications such as biosensing, photothermal therapy, and in vivo imaging.