Design of multi-band metamaterial perfect absorbers with stacked metal–dielectric disks

Abstract

Simple periodic structures of stacked metal and dielectric microdisks can display very high absorbance over multiple bands at infrared frequencies (3–10 μm wavelengths). The stack can be envisaged as intersecting tri-layers, each tri-layer composed of metal–dielectric–metal disks that form independent impedance matched resonators, and give rise to large absorbance at different frequencies. Numerical simulations show that dual-band and multi-band absorbers with near unity absorbance on all their bands can be flexibly designed whereby the dielectric materials determine the absorption band of the metamaterial. The multi-band absorber is reasonably polarization insensitive and the absorbance remains large even with large angles of incidence. This approach of multi-layered stacked metamaterials is compared and shown to be superior to another approach to multiple-band metamaterial perfect absorbers having closely packed resonators within a unit cell.