Dual-band switchable terahertz metamaterial absorber based on metal nanostructure

In this paper, a tunable terahertz metamaterial absorber with two bands is proposed. It is composed of Au reflector, dielectric layer and periodic array of Au. By adjusting different materials and optimizing parameters, it can achieve the characteristics of both broadband and single peak absorption. In the range of 3.5–4.1 terahertz, the broadband absorption rate can reach over 90%, the relative bandwidth ratio is 17%, and the absorption peak at 7.15 THz can reach 98.9%. The coupling mechanism of broadband and unimodal absorption is studied by coupled mode theory. In addition, the designed absorber has broad application prospects in terahertz imaging and sensing due to its broadband and tunable characteristics.