Optical metamaterials based on thin metal films: From negative index of refraction, to enhanced transmission, and to surface wave guidance

摘要

Optical metamaterials characterized by several unique properties are introduced and characterized. The structures comprise continuous metal films sandwiched between dense periodic arrays of optically thin metal strips or patches separated by a small distance. The structures' electromagnetic properties are described by means of a modification of the cavity model typically used to characterized microwave patch antennas. It is shown that the presented structures can operate as negative index metamaterials that comprise deeply subwavelength periodic unit cells, are tunable for operation in the near-infrared and visible spectra, and can be manufactured using standard methods and materials. In addition, the presented structures can operate as an optical filter that, due to the presence of several resonances, transmits fields for certain (controllable) wavelength bands, which are (nearly) independent of the angle of incidence and polarization. The presented structures also can support arbitrary polarized surface waves that can have a high wavenumber and can exhibit unusual dispersion relations.