Multifunctional metasurface based on vanadium dioxide in the terahertz frequency.

As metasurface technology has been developing rapidly over the past decades, multi-multiplexing and tunability are evolving into hot spots in its development. Here, a metasurface fit for vortex beam generation, beam focusing, linear-to-circular polarization conversion, and absorption is proposed in this study, contingent upon the phase change properties of vanadium dioxide. When the temperature is 25°C, the vortex beam and focusing generated when the circularly polarized wave is incident on the metasurface, the calculated outcomes demonstrate that the cross-polarization reflective coefficient is close to the co-polarization coefficient at the frequency range of 0.5-0.9 THz and 1.2-1.5 THz, implementing the linear-to-circular polarization conversion. When heated up to 68°C, it functions as an absorber at 1.55 THz when the y-polarized wave is incident vertically on the metasurface. The designed metasurface is likely to be used in the fields of terahertz communication and imaging systems.