Generation of Vectorial Optical Fields with Polarization Variation along Propagation Paths via Dielectric Metasurfaces

Tailoring vectorial optical fields (VOFs) with polarization singularity along the propagation path advances the development of fundamental physics and optical communications. This study demonstrates that spin-multiplexing metasurfaces can introduce a seamlessly varying propagation path related phase difference, enabling the generation of VOFs with longitudinally evolving polarization distributions. By superposing two orthogonal circularly polarized components, we achieve dynamic polarization evolution from radial to azimuthal polarization along the optical path. Experimental results confirm that the observed polarization distributions along the propagation path align with the evolution trajectory on the higher-order Poincare spheres. The design strategy offers substantial flexibility for crafting longitudinally varying VOFs with arbitrary polarization orders. Further, we show the generation of dual VOFs with distinct polarization evolution along the propagation axis. This approach opens new avenues for applications in light-matter interactions, complex structured light generation, and advanced polarization engineering.