Ultrafast Graphene Photonics and Optoelectronics

Coupled surface plasmon modes of graphene on a plasma layer are studied. Three coupled plasmon modes are found, and analytical equations for their dispersion characteristics are given in the long-wavelength limit. Symmetric and antisymmetric modes are identified between two strongly coupled modes, the antisymmetric mode is found to be more energetic than the symmetric mode. The great tunability, of plasmon characteristics is shown by changing the surrounding dielectric constant, the coupling distance, and the plasma frequency of the substrate.