A Metasurface Implementing Phased-Array-based Vortex Beam Divergence Control for Generating Four-Channel Equal Divergence Angle Vortex Beams

This paper proposes a dual-frequency polarization-multiplexed metasurface for Orbital angular momentum (OAM) divergence control using phased-array principles. Compared to FSS-loaded designs, the unit achieves ultrathin profile, full-phase coverage, and angle insensitivity. By implementing phased-array-based divergence tuning, we demonstrate four-channel high-purity vortex beams with equal divergence angles across modes. Fabricated prototypes validate the OAM control capability, showing good agreement between simulated and measured results. The design shows strong potential for vortex-beam communications and radar detection.