Reexamining the anomalous spin–orbit interactions of light around Fresnel coefficient singularities

Using a full-wave theory to analyze the light beam scattering at sharp interfaces, we reexamine the anomalous spin-orbit interaction (SOI) around the Fresnel coefficient (FC) singularities. We evaluate the spin-dependent beam shifts near the singularity for three typical optical interfaces, comparing our results with existing ones. Existing theories neglect the contribution of the wave vector component <i>k</i> <i>y</i> <i>i</i> near the FC singularities, potentially leading to erroneous results. In contrast, our approach comprehensively considers <i>k</i> <i>x</i> <i>i</i> and <i>k</i> <i>y</i> <i>i</i> contributions in the FC without any approximation. Our analysis reveals significant deformations in scattered light intensity patterns near the FC singularities, causing both out-of-plane and in-plane spin-Hall shifts, uncaptured by prior theories. These findings offer a comprehensive understanding on the spin-orbit interactions at generic optical interfaces.