Split graphene nano-disks with tunable, multi-band, and high-Q plasmon modes

Abstract

We propose a new approach to directly tune spectral Q-factor of the graphene, which has remained challenging in these years. The remarkable tuning of optical properties is reported by splitting graphene disk resonators. In contrast to the single mode of the circular graphene disk, the split graphene nano-disks produce new emerged plasmonic resonant modes, which can be further modified by tuning structural parameters. Such split graphene nano-disks can not only strengthen the multispectral light-graphene interactions drastically but also improve the spectral Q-factor naturally. The spectral Q-factor shows an enhancement of 230–360% for the proposed split graphene nano-disks in comparison with that of the conventional graphene plasmonic mode. With increasing Fermi energy, the tri-band spectrum shows a further narrowing behavior for the resonant bandwidth. A maximal enhancement ∼400% for the spectral Q-factor is obtained. Moreover, the graphene plasmonic properties can be artificially modulated by polarization states of the illumination. This study will open up an avenue for effectively operating graphene photonic devices in the infrared range and pave a way for high-Q multispectral plasmonic graphene structures.