Switchable THz Bi-Functional Device for Absorption and Dual-Band Linear-to-Circular Polarization Conversion Based on Vanadium Dioxide-Graphene.

This academic paper proposes a terahertz (THz) device featuring dynamic adjustability. This device relies on composite metamaterials made of graphene and vanadium dioxide (). By integrating the electrically adjustable traits of graphene with the phase transition attributes of , the suggested metamaterial device can achieve both broadband absorption and dual-band linear-to-circular polarization conversion (LCPC) in the terahertz frequency range. When is in its metallic state and the Fermi level of graphene is set to zero electron volts (eV), the device shows remarkable broadband absorption. Specifically, it attains an absorption rate exceeding 90% within the frequency span of 2.28-3.73 terahertz (THz). Moreover, the device displays notable polarization insensitivity and high resistance to changes in the incident angle. Conversely, when shifts to its insulating state and the Fermi level of graphene stays at 0 eV, the device operates as a highly effective polarization converter. It attains the best dual-band linear-to-circular polarization conversion within the frequency ranges of 4.31-5.82 THz and 6.77-7.93 THz. Following the alteration of the Fermi level of graphene, the device demonstrated outstanding adjustability. The designed multi-functional device features a simple structure and holds significant application potential in terahertz technologies, including cloaking technology, reflectors, and spatial modulators.