Plasmon polariton deceleration in graphene structures

Abstract

Surface plasmon-polariton waves with low-phase speed in carbon nanostructures can be utilized for the generation of coherent terahertz radiation through the Čerenkov mechanism, the effect being especially pronounced in bilayer and multilayer graphene. Using the many-body formalism and the tight-binding approach, we derived the dispersion equations of the surface plasmon-polariton waves in graphene. In single-layer graphene, the phase speed is about three to five times smaller than the speed of light in a vacuum. In bilayer graphene, inter-layer electron tunneling suppresses the reduction of the phase speed. Reduction of the phase speed by as much as 300 times is possible in a graphene structure with two spatially expanded monolayers, because inter-layer tunneling is suppressed, and the interlayer distance can be used to tune the plasmon frequency and the phase speed.