Folding-assisted plasmonically induced transparency in coupled graphene nanodisks

Abstract

Abstract Plasmonically induced transparency (PIT), a classical analog of electromagnetically induced transparency in quantum systems, could offer an efficient way to engineer light–matter interaction and thus achieve particular manipulation of light. To realize PIT, the crucial point is the design of two strongly coupled modes, with one bright and the other dark. Common practice often takes dipole resonance as the bright mode, and higher-order resonance as the dark one. Here we present an alternative scheme to realize PIT in coupled graphene nanodisks through mechanical folding, where only fundamental dipole resonances are involved, and the dark mode is derived from two nondegenerate dipole resonances in a folded nanodisk. Two parameters (the folding angle θ and rotating angle φ ) arising from folding can be utilized to tune the PIT. They determine two different PIT windows separately. By varying either one of them, single-window PIT can be switched to double-window PIT, and vice versa. In addition to mechanical operations, the proposed PIT can also be actively tuned by electrostatic gating. To properly understand the mechanism, a theoretical model of two coupled harmonic oscillators is presented, from which the predictions show good agreement with simulations.