Broadband all-dielectric absorber based on supercell cylindrical metamaterials

Abstract

Based on the cylindrical array microstructure of doped silicon, we propose an all-dielectric terahertz-band broadband absorber. First, we design an absorber with a cylindrical structure in a unit cell. Due to the electromagnetic dipole resonance characteristics, the absorber has an absorption efficiency of over 99.97% at a single frequency of 1.24 THz. In order to obtain wide-bandwidth angular absorption characteristics, we propose a kind of superstructure absorber with a single unit cell containing multiple cylinders with different diameters. The results show that the optimally designed absorber has wide-bandwidth angular absorption characteristics under different polarization states and different incident angles of terahertz waves. In order to further improve the absorption bandwidth, we propose a superimposed superstructure absorber. After optimized design, the absorption efficiency reaches more than 90% in the broadband frequency range of 1.42 THz–4.5 THz. At the same time, different structural parameters have different effects on the peak absorption efficiency.