Metallic negative index nanostructures at optical frequencies: losses and effect of gain medium

One of the most important modern problems in modern electromagnetics is a design and study of negative index metamaterials that may enable sub-wavelength imaging at optical frequencies. Plasmonic periodic metal-dielectric nanostructures present one interesting possibility for both 2D and 3D negative index medium (NIM) systems. The displacement current near plasmonic resonance excitations may produce both negative permittivity and negative permeability (most difficult) in a NIM with e.g. “fishnet” metal-dielectric composite type structure. One obvious problem with a metallic NIM is that the response is strongly dispersive and lossy. Both of these effects are detrimental to sub-wavelength imaging. One way of mitigating losses is to use a gain medium. We address the question of sub-wavelength resolution in the fishnet NIM with and without gain medium.