Enhanced topological phase and spin Hall shifts in an optical trap

TL;DR

This paper demonstrates a simple optical trapping setup that significantly enhances the spin Hall shift of light, enabling controlled rotation of micro-particles through spin-orbit interaction manipulation.

Contribution

It introduces a straightforward method using a standard Gaussian beam in an optical trap to enhance spin Hall shifts via stratified media interference.

Findings

Achieved an order of magnitude increase in spin Hall shift

Controlled rotation of micro-particles with a fundamental Gaussian beam

Enhanced spin-orbit interaction effects in a simple optical setup

Abstract

The spin orbit interaction (SOI) of light has been in the focus in recent times because of fundamental consequences and potential applications in diverse systems ranging from inhomogeneous anisotropic media to engineered plasmonics and metamaterial strutures. Here we demonstrate perhaps one of the simplest means to realize SOI and the Spin Hall Shift (SHS) using a standard Gaussian TEM$_{00}$ beam in an optical trap. Our system exploits the versatility and interference generated in a stratified medium to control and manipulate SOI and transfer the resulting angular momentum to optically trapped micro-particles. We show that even such a simple setup can lead to an order of magnitude enhancement in the SHS compared to the sub-wavelength shifts typically obtained. Importantly, this leads to controlled rotation of mesoscopic particles using a fundamental Gaussian beam lacking any intrinsic angular momentum.