Dielectric Supercell Metasurfaces for Generating Focused Higher-Order Poincaré Beams with the Residual Copolarization Component Eliminated

The generation of focused vector beams using metasurfaces is important for developing classical and quantum applications and exploring the exotic structures of light fields. In this paper, we propose a dielectric supercell metasurface to generate the focused higher-order Poincaré (HOP) beams of improved quality by eliminating the central bright spot of the residual copolarization component. The supercell consists of a pair of complementary meta-atoms of rectangular nanopillars, whose output fields have the opposite propagation phases and orientations are set to be perpendicular. The copolarization and cross-polarization components of the output field of the supercell are eliminated and maximally superposed, owing to the destructive and constructive interferences, respectively. With the propagation and geometric phases forming the overall hyperbolic and helical phase profiles, respectively, the metasurface designs for focused HOP beams are made feasible and convenient. We designed and fabricated both supercell and single-meta-atom metasurface samples with the copolarization components eliminated and uneliminated, respectively, for comparison; the experimental results demonstrated a satisfactory improvement in the quality of the HOP beams produced by the proposed supercell samples. The study findings can significantly contribute to advancements in metasurface engineering in the related fields, including meta-holography, meta-imaging, and meta-device design.