Switchable dual-broadband to single-broadband terahertz absorber based on hybrid graphene and vanadium dioxide metamaterials
Dan Hu, Nan Jia, Qiaofen Zhu
Abstract
Abstract Switchable and tunable broadband perfect absorbers have drawn great interest in a wide range of applications, including modulation, energy harvesting, and spectroscopy. Here, we propose a switchable and tunable terahertz (THz) metamaterial absorber with dual-broadband, single-broadband perfect absorption using graphene and vanadium dioxide (VO 2 ). Simulation results show that, when VO 2 is in the insulated state, this design behaves as a dual-broadband absorber with over 90% absorption in 0.73 THz–1.53 THz and 3.03 THz–3.64 THz under normal incidence. When VO 2 is in the metallic state and the graphene Fermi energy is set as 0.01 eV, this design acts as a single-broadband absorber with over 90% absorption in 1.00 THz–3.55 THz and the fractional bandwidth reaches 112%, which is much larger than the previously reported values. The absorption rate can be dynamically tuned by individually changing the conductivity of VO 2 and the Fermi energy of graphene. Moreover, this design exhibits polarization-insensitive and wide-incident-angle behaviors for both TE and TM waves. Such a design may have potential applications in many fields, such as thermal detectors, modulators, and stealth technology.