Investigation of the tunable plasmonic whispering gallery mode properties for graphene monolayer nanodisk cavities

Tunable graphene plasmonic whispering gallery mode nanodisks formed by nanoscale chemical potential variation on an infinite freestanding graphene monolayer at near-infrared wavelength range are proposed and numerically investigated in this paper. The Q-factor of a high-order whispering gallery mode of 136 and an extremely small mode volume of 4.8 × 10−7 (λ0/n)3 with a large Purcell factor of 1.7 × 108 is achieved in a cavity radius of 10 nm. This graphene based nanodisk cavity structure with an ultrasmall mode volume and large Purcell factor is a promising candidate for high efficiency plasmonic emitting sources, filters, or a key component in the fields of transformation plasmonics and plasmonic integrated circuits technique in the future.