Tailoring toroidal and magnetic dipole excitations with the same dielectric structure.

Abstract

The toroidal dipole (TD) and magnetic dipole (MD) are usually overlooked due to their relatively weak coupling to the electromagnetic fields. However, recent investigations have shown that they can play an important role in the optical response from some designed nanostructures. Different nanostructures have been designed for tailoring TD and MD excitations. Here we demonstrate that a single structure can be designed to tailor both TD and MD excitations. Near-perfect TD and MD excitations from the same structures have been realized by using various electric dipoles, which is very beneficial for designing optical functional devices such as nanoantennas and sensors.