Transmissive and reflective switchable terahertz metasurface for phase modulation based on vanadium dioxide

Abstract

Abstract Metasurfaces provide a powerful ability to control electromagnetic waves, but most metasurfaces only work in transmission or reflection mode. In this paper, a transmissive and reflective switchable metasurface is designed. The unit structure consists of two split-rings and vanadium dioxide (VO2) film. Utilizing the phase change characteristics of VO2, the designed metasurface works in transmission mode at 25 °C, while works in reflection mode at 68 °C. It can transform the incident circularly polarized wave at the frequency of 0.47 THz, achieving transmission cross-polarization conversion amplitude greater than 0.8 and reflection cross-polarization conversion amplitude greater than 0.9. By rotating the split-rings, full 2π gradient phase distribution is achieved. The switchable metasurface has the potential to design multifunctional devices. To prove the concept, anomalous refraction and reflection, single-foci and dual-foci focusing metalens are designed. The proposed metasurface provides an effective method to design temperature controlled meta-devices and other systems in terahertz communications.