Bi-Channel Switchable Broadband Terahertz Metamaterial Absorber

In this letter, a novel and simple design of switchable broadband terahertz metamaterial absorber is theoretically proposed and numerically demonstrated. The electrically adjusting material of graphene and the temperature-related phase-change material of vanadium dioxide (VO2) are combined in such multi-channel manipulation design. When VO2 is set to be the state of dielectric, the designed platform serves as a broadband absorber with an absorption rate exceeding 90% in the range of 1.31-3.18 THz, and simultaneously the absorption rate can be artificially adjusted from 5.3% to 99.0% at 2.8 THz by adjusting the Fermi energy level of graphene from 0 to 1 eV. When VO2 is set to be the state of metal, the absorber can achieve broadband perfect absorption in the large frequency range of 4.45-8.40 THz. It should be noted that such two broadband absorption windows are remarkably separated in the spectral range, indicating the impressive promise for switching operation during the applications. Due to the symmetry of the structure, the broadband absorber is insensitive to the polarization angle and has good performance in the range of high incidence angle. The design and the findings hold potential applications in the terahertz wave technologies, such as intelligent switching and tunable filtering.