A dynamically tunable terahertz perfect absorber based on surface patterned graphene nanofilm

Abstract

This article propounds a wideband, multi-peak and tunable terahertz (THz) absorber composed of symmetrically patterned graphene-dielectric-metal (SPG-d-M) structures. The findings from the show that the absorptivity of the proposed SPG-d-M structure at 2.33 to 6.10 THz exceeds 90 % when the Fermi level E_f = 1.05 eV. Furthermore, by modulating the external bias voltage applied to graphene, it is possible to modify its Fermi level from 0 eV to 1.25 eV, resulting in a change in absorptivity from 9.86 % to nearly complete absorption. The comparison of various top-layer graphene patterns demonstrates the superiority of our proposed SPG. We elucidate the physical mechanism of wide-band absorption by analyzing the field distribution of the structure at various peak frequencies. The SPG-d-M absorber achieves polarization angle insensitivity, and the absorption efficacy is maintained even at oblique angles of incidence. Consequently, the absorber demonstrates considerable potential for applications in the domains of medical imaging and stealth technology.