▎ 摘　　要

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 x 10(-7) (lambda(0)/n)(3) with a large Purcell factor of 1.7 x 10(8) 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. (C) 2016 Elsevier GmbH. All rights reserved.