Tunable excitation of surface plasmon polaritons on the graphene metasurfaces by electron beam

Abstract

Owing to its intense localized near-field and the versatile tunable capability, graphene surface plasmons(GSPs) provide an excellent platform to develop novel terahertz radiation source. Compared to the previous studies on terahertz radiation sources with complete grapheme sheet, graphene metasurface (such as periodical ribbon arrays) provide a new method by varying graphene ribbon width to tune output performance. In this paper, a terahertz radiation source based on the excitation of GSPs on the periodical graphene ribbon arrays by electron beam is proposed and studied both theoretically and numerically. First, the general dispersion relation of SSP mode on the graphene ribbon arrays which is deposited on a dielectric medium with a conducting ground metal plate is obtained by a modal expansion method. Besides, a terahertz radiation source on the graphene-dielectric-metal structure based on the interaction between GSPs and injected electron beam is modeled and implemented by particle-in-cell simulation. A tunable terahertz radiation source via different ribbon width is proposed and the output with different biased voltage is also analyzed. The presented studies based on gradient graphene ribbon arrays can provide a new way to develop tunable terahertz radiation source.