Veselago lens and plasmonic nanostructures at optical frequencies

Summary form only as given. We describe various designs of metamaterials for Veselago lens that may potentially perform at optical frequencies. Plasmonic periodic metallic nanostructures present one interesting possibility for both 2D and 3D negative index medium (NIM) systems. NIM is a system having opposite group and phase velocities in a particular frequency range and thus supporting ´negative´ refraction and ´backward´ propagating waves. It is known since 1940s that crystals with strong spatial dispersion may exhibit negative refraction.