Graphene plasmon guided along a nanoribbon coupled with a nanoring

The propagation properties of edge mode graphene surface plasmon polaritons (EGSPs) guided along a nanoribbon coplanar waveguide coupled with a nanoring are investigated, both in parallel and serial cascades. Strong coupling of EGSPs between the nanoribbon and nanoring appears at the resonance frequencies. Further investigation shows that EGSPs can be supported by nanorings, even though the radiuses are very small. The resonance frequencies can be tuned by the geometric parameters and the doping level of graphene. A Y-shape switch based on parallel coupled structures is presented as an application. Various potential planar devices are expected to derive from the prototype coupled structures. (paper)