Focused linearly-polarized light scattering from a silver nanowire: Experimental characterization of optical spin-Hall effect

TL;DR

This study experimentally investigates the spin-Hall effect of light caused by scattering from a silver nanowire, demonstrating enhanced signals with Hermite-Gaussian beams and providing insights into spin-orbit interactions for photonic applications.

Contribution

The paper presents the first experimental observation of spin-Hall effect of light from a silver nanowire using focused beams, highlighting the enhancement with Hermite-Gaussian modes and linking it to longitudinally spinning fields.

Findings

Significant spin-Hall signals observed in scattering from silver nanowire.

Enhanced spin-Hall effect with Hermite-Gaussian beams compared to Gaussian beams.

Numerical simulations support experimental observations.

Abstract

Spin-orbit interactions (SOI) are a set of sub-wavelength optical phenomenon in which spin and spatial degrees of freedom of light are intrinsically coupled. One of the unique example of SOI, spin-Hall effect of light (SHEL) has been an area of extensive research with potential applications in spin controlled photonic devices as well as emerging fields of spinoptics and spintronics. Here, we report our experimental study on SHEL due to forward scattering of focused linearly polarized Gaussian and Hermite-Gaussian ($\textrm{HG}_{10}$) beams from a silver nanowire (AgNW). Spin dependent anti-symmetric intensity patterns are obtained when the polarization of the scattered light is analysed. The corresponding spin-Hall signal is obtained by computing the far-field longitudinal spin density ($s_3$). Furthermore, by comparing the $s_3$ distributions, significant enhancement of the spin-Hall signal is found for $\textrm{HG}_{10}$ beam compared to Gaussian beam. The investigation of the optical fields at the focal plane of the objective lens reveals the generation of longitudinally spinning fields as the primary reason for the effects. The experimental results are corroborated by 3-dimensional numerical simulations. The results lead to better understanding of SOI and can have direct implications on chip-scale spin assisted photonic devices.