Abstract

Optical activity is a phenomenon ubiquitous across natural and artificial structures and is generally understood in terms of the coupling between electric and magnetic dipoles [1]. Usually, this dipole approximation is sufficient to explain optical activity in most media. In metamaterials however, engineering of the structure allows for designs where a conventional multipole (electric and magnetic dipole) response is suppressed in favour of more exotic excitations typically excluded from the standard multipole expansion. Here, we report on the first computational study of optical activity in a metamaterial that cannot be attributed to conventional multipoles, and can only be accounted for by the inclusion of the toroidal dipole.

© 2015 IEEE