Photonic Spin Hall Effect with Nearly 100% Efficiency

Photonic spin Hall effect (PSHE; i.e., spin‐polarized photons can be laterally separated in transportation) gains increasing attention from both science and technology, but available mechanisms either require bulky systems or exhibit very low efficiencies. Here it is demonstrated that a giant PSHE with ≈100% efficiency can be realized at certain meta‐surfaces with deep‐subwavelength thicknesses. Based on rigorous Jones matrix analysis, a general criterion to design meta‐surfaces that can realize 100%‐efficiency PSHE is established. The criterion is approachable from two distinct routes at general frequencies. As a demonstration, two microwave meta‐surfaces are fabricated and then experimentally characterized, both showing ≈90% efficiencies for the PSHE. The findings here pave the way for many exciting applications based on high‐efficiency manipulations of photon spins, with a polarization detector experimentally demonstrated here as an example.