A Folded Vector Vortex Beam Generator Based on Energy‐Allocatable Spin‐Decoupled Metasurface

ABSTRACT In recent years, vector vortex beams (VVBs) have attracted significant attention and enable revolutionary applications. In this article, a folded vector vortex beam (VVB) generator is demonstrated based on an energy‐allocatable spin‐decoupled metasurface (EASDMS). The meta‐atom of EASDMS is adapted as a receiver‐transmitter structure, comprising top receiving and bottom transmitting patches with a middle phase‐delay line connecting them. Under left‐hand circularly polarized (LCP) incidence, energy allocation of transmitted LCP and right‐hand circularly polarized (RCP) waves can be controlled by adjusting the polarization characteristics of the transmitter. The spin‐decoupled phase control is realized by combining the geometric phases of the transmitter with the propagation phase of the phase‐delay line. Under RCP incidence, EASDMS can achieve the function of full co‐polarized reflection. The superposition of LCP and RCP vortices with different topological charges, phase differences, and amplitude ratios can be flexibly controlled by EASDMS, enabling the generation of arbitrary VVBs. The simulation results validate that the proposed VVB generator can achieve VVBs of arbitrary points on the hybrid‐order Poincaré sphere (HOPS) of different orders. Two proof‐of‐concept prototypes for different VVB generations are fabricated and measured, and the results are consistent with the simulation results.