Microscopic analysis of spin-momentum locking on a geometric phase metasurface

We revisit spin-orbit coupling in a plasmonic Berry metasurface composed of rotated nanoapertures, which is known to imprint robust far-field polarization response. present scattering formalism that shows how spin-momentum locking emerges from the geometry unit cell without requiring global rotation symmetries. find and confirm with Mueller polarimetry measurements an approximate symmetry. The symmetry breakdown ascribed elliptical projection circularly polarized light into planar surface. This maximal when surface waves are excited, new set rules presented for this case.