Symmetry breaking in a plasmonic metamaterial

We numerically study the optical properties of metal lattices made from periodically arranged plasmonic molecules, i.e., coupled gold nanowire pairs. It is shown that the interaction between the metallic wires, which is directly controlled by the specific lattice geometry, leads to the formation of collective surface plasmon modes. Surface plasmon hybridization is discussed and the direct influence of near- and far-field interaction are highlighted. In particular, it is shown that the common hybridization schema can be reversed by tuning the wire-wire interaction. Moreover, optical activity of higher order modes is demonstrated in case of symmetry breaking. An additional degree of freedom is introduced by inserting a homogeneous metal film, i.e., taking into account wire-image coupling.