Manipulations of vectorial-structured light by spatially interleaved metasurfaces of quarter-wave-plate meta-atoms

Metasurfaces of quarter-wave-plate (QWP) meta-atoms exhibit high flexibility and versatility in light-field manipulations; however, using them to generate multi-channel focused vector beams is challenging. This study proposes dielectric metasurfaces comprising two interleaving sets of QWP meta-atoms. Their parameters are adjusted based on the pre-set orders of the target vector beams to manipulate higher-order Poincaré beams and vortex superpositions in multiple channels. The metasurface phase profiles include hyperbolic, vortex, and gradient phases for focusing wavefronts, generating circularly polarized vortices, and deflecting vortices into two cross-polarization and one co-polarization channel. Four metasurface samples were designed to generate different order higher-order Poincaré beams in different channels, demonstrating the feasibility of QWP meta-atoms metasurface for manipulation of complicated vector light fields. Theoretical analysis, simulations, and experiments all demonstrate the feasibility of the proposed metasurfaces. Thus, this study is significant for compact, integrated, and multifunctional nanophotonic platforms with applications in high-capacity communication, image processing, quantum entanglement, and quantum communication.