Invisible nanowires with interfering electric and toroidal dipoles

Abstract

By studying the scattering of normally incident plane waves by a single nanowire, we reveal the indispensable role of toroidal multipole excitation in multipole expansions of radiating sources. It is found that for both p-polarized and s-polarized incident waves, toroidal dipoles can be effectively excited within homogenous dielectric nanowires in the optical spectrum regime. We further demonstrate that the plasmonic core–shell nanowires can be rendered invisible through destructive interference of the electric and toroidal dipoles, which may inspire many nano-wire-based light–matter interaction studies, and incubate biological and medical applications that require non-invasive detections and measurements.