Direct observation of photonic spin Hall effect in Mie scattering

TL;DR

This paper reports the first direct experimental observation of the photonic spin Hall effect in a single superscattering particle, achieved by symmetry breaking and mode coupling, significantly enhancing spin-dependent light-matter interactions.

Contribution

It introduces a novel mechanism based on symmetry breaking and mode coupling to observe the PSHE directly in a single scatterer, overcoming previous limitations of weak signals.

Findings

Enhanced spin Hall shift and scattering intensity by nearly two orders of magnitude.

First direct observation of PSHE from a single superscattering particle.

Accessible PSHE at convenient angles without complex measurement protocols.

Abstract

The photonic spin Hall effect (PSHE), a hallmark of spin-orbit interaction of light, has long been considered a promising route toward spin-controlled functionalities in nanophotonics. Yet, its practical realization has been severely limited by the inherently weak spin-orbit coupling in typical systems, resulting in vanishingly small transverse shifts and extremely low scattering efficiency. This fundamental trade-off has rendered the PSHE observable only through complex weak measurement protocols and signal amplification-approaches that come at the cost of further intensity loss, particularly in nanoscale systems. In this work, we overcome this longstanding challenge by introducing a novel mechanism based on symmetry breaking and mode coupling in a standalone scatterer, which unlocks a regime of Friedrich-Wintgen superscattering with strong near-field spin-orbit interaction. This allows for simultaneous enhancement of both the photonic spin Hall shift and the far-field scattering intensity-boosting the latter by nearly two orders of magnitude compared to conventional dipolar particles. Through tailored multipolar interference, the PSHE is made accessible at experimentally convenient angles, enabling post selection-free detection. We report the first direct experimental observation of the PSHE from a single superscattering particle, achieved in the microwave regime via polarization-resolved far-field measurements. Our findings not only validate a new physical pathway for enhancing spin-dependent light-matter interactions, but also establish a robust, scalable platform for spin-based photonic technologies. This breakthrough opens new avenues in precision optical metrology, advanced imaging, LIDAR systems, and integrated photonic circuitry, bridging a critical gap between fundamental spin optics and real-world applications.