Broadband and polarization-insensitive terahertz absorber based on multilayer metamaterials

In this paper, a broadband, polarization-insensitive, and wide-angle terahertz metamaterial absorber is constructed by stacking multiple metal–dielectric layers with differently sized saw-shaped annular patch structures in the unit cell. The calculated results show that a broadband absorption above 70% is obtained for the frequency range from 0.76 THz to 0.96 THz, and the full absorption width at half maximum (FWHM) can reach 28%. The magnetic field distributions of the structure are discussed to look into the broadband mechanism. Moreover, the broadband absorption is insensitive to the polarization and incident angle of the TE and TM waves owing to the high-degree symmetry of structure. Importantly, the thickness of the four-layer patches is about 27 times smaller than the central working wavelength. Therefore, the proposed metamaterial provides a promising way to obtain a broadband absorber with a compact dimension, and such design also has potential applications in solar cell, detection, and imaging.