Graphene-Gated Control of Ag Nanowire Infrared Polaritons

Surface plasmon polaritons (SPPs) at dielectric-metal interfaces are of significant interest in nanophotonic devices owing to their unique field localization behaviors. Low-dimensional metal structures like metal nanowires generate strong SPP modes, yet dynamic SPP modulation, particularly in the mid-infrared (IR) range, is still underdeveloped, hindering progress in reconfigurable SPP-based devices. Here, we demonstrate active control of mid-IR SPPs in silver nanowires (AgNWs) through electric field gating, taking advantage of a graphene monolayer substrate and its gate-tunable dielectric properties in the mid-IR range. Through IR near-field nanoimaging and numerical simulations, we explore the resulting range of the spectral tuning behavior of the AgNW SPP response. Furthermore, we identify a new gate-dependent decay channel in which SPPs in AgNWs directly dissipate into graphene SPPs. Our findings highlight the potential for utilizing the electrical characteristics of graphene for manipulating SPPs in metal nanowires, paving the way for the development of advanced nanophotonic devices.