Specially designed metal-dielectric composites can have a negative refractive
index in the optical range. Specifically, it is shown that arrays of single and
paired nanorods can provide such negative refraction. For pairs of metal rods,
a negative refractive index has been observed at 1.5 micrometer. The inverted
structure of paired voids in metal films may also exhibit a negative refractive
index. A similar effect can be accomplished with metal strips in which the
refractive index can reach -2. The refractive index retrieval procedure and the
critical role of light phases in determining the refractive index is discussed.Comment: 39 pages, 17 figures, 24 equation