Terahertz dynamic polarization-multiplexed vortex based on VO 2 metasurface

Abstract Metasurfaces provide an effective approach for manipulating terahertz (THz) waves, offering unparalleled advantages over traditional optical components. Their subwavelength scale enables compact integration into terahertz systems, while their design flexibility allows precise tailoring of wavefront shaping including amplitude, phase, and polarization via careful arrangement of meta-atoms. Through elaborate structural design and precise parameter tuning, previous studies have successfully demonstrated static manipulation of terahertz waves. However, dynamic control of wavefronts, especially polarization-multiplexed wavefronts, remains a significant challenge. Here, we present a dynamic metasurface facilitating generating polarization-multiplexed THz vortex beams (VBs) according to phase change property of VO 2 . To be specific, under incidence of a 0° linearly polarized (LP) wave, with VO 2 in metallic state, this metasurface reflects 0° and 90° LP VBs with respective topological charges (TCs = 1, 2). When VO 2 transitions to insulator, reflected 45° and 135° LP VBs have TCs = − 1, −2, respectively. Thus, metasurface capable of generating polarization-multiplexed VB not only achieves multichannel wavefront manipulation but also possesses dynamically tunable characteristics. Furthermore, our research introduces an innovative strategy for information encryption and decryption.