VO2-based terahertz multifunctional spin-decoupled reflective coding metasurface

Achieving independent control of left- and right-handed circularly polarized waves remains a significant challenge in current research. In this study, we propose a spin-decoupled multifunctional coding metasurface based on VO2. The design integrates two traditional approaches, Pancharatnam-Berry (PB) phase coding and propagation phase coding, it can independently manipulate left- and right-handed circularly polarized waves. In addition, VO2 is introduced into the metasurface unit patch, and three different functions can be performed by changing the ambient temperature and the type and frequency of the incident electromagnetic wave. At temperature below 68 °C, the metasurface deflects incident left-handed circularly polarized waves and generates a vortex beam with topological charge l = 2 for right-handed circularly polarized waves. At temperatures above 68 °C, the metasurface focuses incident linearly polarized waves. The proposed metasurface exhibits frequency multiplexing, miniaturization, and multifunctionality, holds significant potential for applications in wireless communication and related fields.