Laminated Photonic Band Structures with High

We have developed a new transparent conductor based on one-dimensional metal-dielectric photonic band gap structures. Thin-film metal-dielectric filters containing at least 150nm of silver have been fabricated, with transmittance greater than 50% over the 500-600nm waveband, and sheet resistance of ∼ 0.1 Ohm/Square. Theoretical calculations predict at least 25% transparency levels for structures that contain 1/2 μm of silver, and transparencies that approach 80% for structures that have in excess of 100 nm of silver. Some applications for transparent, conducting films include antennas embedded in windshields, electrodes on flat panel displays, electromagnetic shielding, and solar window panes, to name a few. The study of electromagnetic wave propagation at optical frequencies in metals has never been tackled in the past because it was never thought to be very interesting. The reason is simple and well known: metals are highly reflective (and absorptive) at nearly all wavelengths of light. For example, static fields are rejected from the surface of a metal, while all other frequencies of interest, from microwaves to ultraviolet light, are reflected. One of the more significant optical properties of a metal is the skin depth [1,2]. The skin depth is a measure of the distance from the surface such that the magnitude of the electric field has decreased to approximately 1/3 of the value at the surface. Since metals are very dispersive, the skin depth is a strong function of frequency. For example, the skin depth of silver and other metals such as copper, aluminum, and gold, at optical frequencies is approximately 10nm. At microwave frequencies, the skin depth increases to approximately 1μm. It is therefore clear that metals attenuate electromagnetic waves very well, more so at high frequencies.