Strategies for minimizing losses in negative phase velocity metamaterials

Abstract

Metamaterials demonstrating a negative phase velocity for light usually consist of arrays of wires and cut-ring structures. Such media are characterized by both the permittivity and permeability being negative. Calculations of the Ohmic loss associated with the wires alone indicate that dissipation can be minimized by making them of metal of the highest possible conductivity and by having the largest possible wire radius. Replacement of the cut-ring structures with a ferrite further reduces losses since ferrites can be less lossy than typical conductors. The upper limit to the wire radius is ultimately set by the requirement that the permittivity be negative. The calculations take into account the skin depth within the wires. Although bigger wires lead to more volume in which Ohmic losses are present, these wires are more effective in shorting out the electric field and thereby decreasing the Ohmic loss. An array made of large diameter and high conductivity wires leads to a strong electromagnetic response and a well defined plasma frequency for the wire array.