Plasmon Resonances of Graphene-Assisted Core-Bishell Nanoparticles

Abstract We study the Localized Surface Plasmon Resonance (LSPR) in graphene-assisted core-bishell nanoparticles which consists of a graphene layer (outer shell) wrapped around a metal shell and either a dielectric or metal core. Small nanoparticles with a size much smaller than the wavelength of incident light are assumed, and the quasi-static approximation is applied to develop analytic equations to describe the absorption, scattering, extinction efficiencies in the core-bishell nanoparticles. The proposed nanostructures exhibit two LSPRs; one is in the visible range and corresponds to a plasmon mode of the core-inner shell composite while the second lies in the near infrared and is induced by the graphene plasmons excited at the outer shell. Interestingly, the latter LSPR of graphene has an ultra-narrow bandwidth and can be tuned in the NIR by altering the physical parameters of graphene, such as the Fermi energy and the number of graphene layers. Therefore, the LSPR peak of graphene is promising for medical applications. In addition, the LSPR of graphene can be tuned to the visible range near the position of the first LSPR, resulting in two narrow linewidth peaks. These resonance peaks could be beneficial for high-sensitive LSPR-based sensors.