Dual-Band Polarization-Independent Terahertz Absorber Based on F-Shaped Multimode Structure

In this letter, a dual-band polarization-independent terahertz (THz) metamaterial absorber (MA) based on metal-insulator-metal (MIM) configuration is proposed and measured. The flexible material polyimide is chosen as the substrate. The periodic metal array cell on the top surface is fabricated utilizing four F-shaped metal strips, and due to the high symmetry of the structure, the designed absorber is insensitive to polarization. Furthermore, the impact of structural parameters on the absorption characteristics is numerically investigated, and the results indicate that the absorption peak can be flexibly adjusted by changing the length of the top metal strip. The proposed MA achieves near-perfect absorption at 0.555 THz and 0.797 THz under normal TE and TM polarized incidence, with Q-factors of 23.56 and 45.28, respectively. This work provides a new design strategy for the realization of multi-band THz MA.