Chapter 7 - Graphene on epsilon-near-zero metamaterials as perfect electromagnetic absorber

Abstract

The concept of electromagnetic metamaterials is reviewed with a special emphasize put on how artificial materials with near-zero refractive index can be designed. Among them, epsilon-near-zero (ENZ) metamaterials are specially designed structures whose effective dielectric permittivity is close to zero in a given frequency interval. For terahertz frequencies and below, such structures can be realized by microfabrication. These metamaterials have interesting properties related to the fact that they do not propagate the displacement field D for thick ENZ metamaterials. Accordingly, an ideal lossless planar ENZ material is a perfect reflector for incident plane waves. It can transform in a perfect absorber of the electromagnetic radiations when its surface is covered by a thin conducting layer, provided the conductance of the overlayer be close to ɛ0c. The sheet conductivity of graphene produced by chemical vapor deposition is precisely of the right order of magnitude in the subterahertz domain. Calculations illustrate how nearly perfect absorption of electromagnetic radiations in this frequency range can be achieved by having a few-layer graphene deposited on top of an ENZ metamaterial.