Coupling of Whispering-Gallery Modes in the Graphene Nanodisk Plasmonic Dimers

In this paper, we proposed plasmonic dimers consisted of two evanescent field coupled graphene monolayer nanodisks. The electromagnetic properties including the split modes with non-degenerate wavelengths, enhancement of the quality factors (Q factors) and mode areas, and the coupling between the fundamental and the first-order whispering-gallery modes are numerically predicted and analyzed systematically. Compared with the single graphene nanodisk, the Q factor of TM4,1 reaches 356 in a dimer with a radius of 5 nm of each nanodisk and an inter-disk gap of 0.4 nm, where the corresponding mode area is as small as 6.88 × 10‐ 5(λ 0)2. In addition, the enhanced performances of size-mismatched coupled graphene plasmonic dimers are investigated. This graphene monolayer plasmonic dimer could be one of the fundamental components in the future ultra-high density plasmonic circuit technique, on-chip plasmonic interconnect, and transformation plasmonics. It also could be used as the test-beds for added explorations of cavity quantum electrodynamic experiments.