Light localization, photon sorting, and enhanced absorption in subwavelength cavity arrays

A periodically patterned metal-dielectric composite material is designed, fabricated and characterized that spatially splits incoming microwave radiation into two spectral ranges, individually channeling the separate spectral bands to different cavities within each spatially repeating unit cell. Further, the target spectral bands are absorbed within each associated set of cavities. The photon sorting mechanism, the design methodology, and experimental methods used are all described in detail. A spectral splitting efficiency of 93-96% and absorption of 91-92% at the two spectral bands is obtained for the structure. This corresponds to an absorption enhancement over 600% as compared to the absorption in the same thickness of absorbing material. Methods to apply these concepts to other spectral bands are also described.