  Recent advances in nano-fabrication techniques allow for the manufacture of
optical metamaterials, bringing their unique and extra-ordinary properties to
the visible regime and beyond. However, an analytical description of optical
nano-plasmonic metamaterials is challenging due to the characteristic optical
behaviour of metals. Here we present an analytical theory that allows to bring
established microwave metamaterials models to optical wavelengths. This method
is implemented for nano-scaled plasmonic wire-mesh and tri-helical
metamaterials, and we obtain an accurate prediction for their dispersive
behaviour at optical and near-IR wavelengths.
