Broadband terahertz absorber integrating polarization conversion and filtering functions

In this paper, a terahertz metamaterial absorber based on graphene and vanadium dioxide (VO2) is proposed incorporating three functions: broadband absorption, linear cross-polarization conversion, and bandpass filter. When VO2 is metallic, the proposed structure can be switched between broadband absorption (7.54-9.89 THz) and linear polarization transition (4.62-8.16 THz) by adjusting the Fermi energy level of graphene. When VO2 is transformed into an insulating state, the proposed structure can function as a bandpass filter offering a bandwidth of 2.39 THz. Compared with the previously reported devices of the same type, this design not only achieves considerable performances of absorption and polarization conversion with a simple structure but also integrates the filtering function. Therefore, it is possible to optimize the performance of communication systems and improve imaging quality, giving it great potential for development in electromagnetic shielding, communication, imaging, and signal processing.