Polarization-independent multi-band Terahertz metamaterial perfect absorber based on graphene and metal.

In this paper, a three-layer structure multi-band terahertz (THz) metamaterial perfect absorber (MPA) with the patterned layer formed by a frame graphene and a square copper, the silica dielectric layer and the copper metal bottom layer is designed and investigated. There are four absorption peaks when the Fermi energy level of graphene is 0.4 eV and relaxation time of graphene is 0.1 ps. The absorptivity at the frequencies of 2.77 THz, 5.41 THz, 7.48 THz, and 7.75 THz reached 99.99%, 99.09%, 97.13%, and 99.84%, respectively. The first absorption peak (peak I) of this absorber has a wide range of high absorption, and the second, third, and fourth absorption peaks (peaks II, III, and IV) have a high Q-factor. The absorber is polarization-insensitive, and the absorptivity of peaks I and II is still above 90% even when the incidence angle reaches 70°. Through exploring the absorption curve of different structures and electric field distribution and using impedance matching theory, the cause of absorption peak and the actual operation of the absorber parameter fault tolerance and tunability have been studied. It is found that the proposed absorber has many advantages such as low cost, simple structure, ease to manufacture and tunability. These explored generic properties of the proposed absorber emphasize its development potential in application areas, such as the design of sensors, wireless communication, controllable switch operation, modulators, etc. [ABSTRACT FROM AUTHOR]