Multifunctional polarization selectivity in a Sb₂S₃-based dichroism metasurface

Multifunctional polarization selectivity offers promising avenues for advanced applications in optical communications, sensing, holography, and so on. Here, we realized multifunctional linear and circular polarization selectivity empowered by q-BICs in a Sb₂S₃-based Z-shaped metasurface. The near-unity and reversible circular dichroism (CD) as well as linear dichroism (LD) could be selectively obtained by controlling the azimuth angles within the 90° range. The multiple dichroisms under various azimuth angles (CD_0° = -0.94, LD_45° = 0.87, CD_90° = 0.99) are supported by polarization selective excitation of magnetic dipole resonance, which is demonstrated by quantitative multipole decompositions and electromagnetic field distribution analysis. Furthermore, the strength of CD and LD could be dynamically tuned by changing the phase of Sb₂S₃, respectively.