Direct observation of the enhanced photonic spin Hall effect in a subwavelength grating supporting surface plasmon resonance

TL;DR

This paper demonstrates the enhanced photonic spin Hall effect in a subwavelength grating supporting surface plasmon resonance, showing both experimental and theoretical insights into spin-dependent and spin-independent shifts.

Contribution

It provides the first combined experimental and theoretical observation of enhanced in-plane PSHE in a SPR-supported subwavelength grating, including control of shifts via polarization.

Findings

Enhanced in-plane PSHE observed with angular splitting of circular polarizations

Switching between spin-independent and spin-dependent shifts by changing polarization

High purity of spin separation achieved at optimal conditions

Abstract

The photonic spin Hall effect (PSHE) in surface plasmon resonance (SPR) structures has great potential for various polarization-sensitive applications and devices. Here, using optical weak measurement, we observe spin-dependent and spin-independent angular shifts of the reflected beam, enhanced by SPR in a subwavelength nickel grating. An enhanced in-plane photonic spin Hall effect manifested in the angular splitting of circularly polarized photons with opposite helicity signs is demonstrated. We theoretically and experimentally demonstrate that angular in-plane shifts can be changed from spin-independent (Goos-H\"anchen shift) to spin-dependent (PSHE) when the incident beam polarization state changes. The SPR-induced depolarization of light and the mixing of polarization states are detected. High purity of spin separation and a high degree of circular polarization are achieved with an optimal polarization state (preselection angle) and a resonance angle of incidence. The spineless spatial separation of two orthogonal components of the field with diagonal linear polarizations is demonstrated.