Enhanced graphene-light interaction assisted by magnetic plasmons in metallic nanogroove arrays

Abstract

Combining graphene with plasmonic nanostructures has attracted great interest for enhancing graphene-light interactions. Here, we report an intensive experimental study on the strong interaction of graphene with plasmon-induced magnetic resonances, i.e., magnetic plasmon (MP) supported by simple one-dimensional (1D) metallic nanogroove arrays. We demonstrate that the absorption of graphene, which covers only 10% of the groove surface, is dramatically enhanced by one order of magnitude compared with the 2.3% light absorption for the pristine graphene monolayer. The strong graphene-MP interaction also enables a considerable suppression of Ohmic loss in the metallic groove array. Importantly, we demonstrate that limited metal-graphene charge transfer at the directly contacting interface leads to a reduced Fermi level of graphene, thus giving no contribution to the shift of magnetic resonances, which is in contrast to other reported graphene-plasmonic systems with considerable resonance shift. We also evaluate the influence of local dielectric change on graphene-plasmon interaction, confirming that the observed considerable MP resonance shift results from the small variation of the dielectric environment inside the grooves, which is further supported by numerical simulations. Such a hybrid nanostructure with a 1D flat nature and efficient enhancement of graphene-light interaction is expected to open exciting perspectives within highly integrable plasmonics for light-harvesting, photodetection, and sensing applications.