Optical performance of a dielectric-metal-dielectric antireflective absorber structure

The absorption of electromagnetic radiation by a planar structure, consisting of a three-layer dielectric-metal-dielectric coating on a metal backreflector, is analyzed. The conditions for total absorption are derived. Our analysis shows that, in contrast with bi-layer structures, the calculated layer thicknesses are feasible to fabricate for any metal. The proposed absorber design is of potential use in infrared, terahertz, and longer wavelength detectors and for radiant energy harvesting devices.