Tunable terahertz polarization conversion and absorption devices based on metamaterials

Abstract

Metamaterials, as novel materials, have electromagnetic behaviors that can be realized by rationally designing the unit structure. It plays an important role in the research of terahertz functional devices. Switchable terahertz devices are constructed by flexibly combining the excellent properties of graphene and vanadium dioxide (VO2) with the application potential of terahertz technology. When the VO2 is in the metallic state and the graphene Fermi energy level is 0 eV, the device behaves as a broadband polarization switching device. It can realize cross-polarization conversion for the incident electromagnetic wave in the range of 2–4.2 THz. When the VO2 is in the insulating state and the graphene Fermi energy level is 0.9 eV, the device is an absorption device. The absorption rate can reach more than 99% at 4 THz. In addition, the polarization conversion ratio (PCR) as well as the absorption rate of the device can be tuned independently. This actively tunable switchable terahertz device provides ideas for dynamically controlling terahertz, bringing more possibilities for various applications such as terahertz imaging, stealth, and communication.