Tunable C₄-Symmetry-Broken Metasurfaces Based on Phase Transition of Vanadium Dioxide (VO₂)

Coupling is a ubiquitous phenomenon observed in various systems, which profoundly alters the original oscillation state of resonant systems and leads to the unique optical properties of metasurfaces. In this study, we introduce a terahertz (THz) tunable coupling metasurface characterized by a four-fold rotation (C₄) symmetry-breaking structural array achieved through the incorporation of vanadium dioxide (VO₂). This disruption of the C₄ symmetry results in dynamically controlled electromagnetic interactions and couplings between excitation modes. The coupling between new resonant modes modifies the peak of electromagnetic-induced transparency (EIT) within the C₄ symmetric metasurfaces, simulating the mutual interference process between modes. Additionally, breaking the C₄ symmetry enhances the mirror asymmetry, and imparts distinct chiral properties in the far-field during the experimental process. This research demonstrates promising applications in diverse fields, including biological monitoring, light modulation, sensing, and nonlinear enhancement.