Independently tunable concentric graphene ring resonators based ultrathin broadband THz absorber

An ultrathin structure of graphene-based absorber is implemented and numerically analyzed. The absorber is designed with the usage of graphene ring resonators and graphene reflector in the lower terahertz (THz) frequency ranges. The geometry of the absorber can be implemented with the thickness as small as λ /193; ( λ : free space wavelength). A number of resonances is generated using concentric graphene ring resonators which can individually tuned over frequency using chemical potential of graphene for merging and achieving the broad absorption band. An absorption of more than 90% is achieved over the frequency range of 10.34–16.23 THz and more than 80% in the frequency range of 9.89–16.77 THz. The proposed absorber provides the polarization independent geometry with the allowed incident angle up to 50°. The ultrathin geometry of the proposed absorber can provide a way to implement the absorber with broad absorption bandwidth.