Dynamic Consequences of Optical Spin-Orbit Interaction

TL;DR

This paper investigates how optical spin-orbit interaction during scattering can induce a lateral force on objects, revealing a new non-conservative force component influenced by interfaces and unstructured light.

Contribution

It demonstrates the existence of an anomalous lateral force caused by spin-orbit interaction during scattering near interfaces, expanding understanding of optical forces.

Findings

Lateral force acts perpendicular to incident wave propagation.

Interface presence enables the anomalous force.

Unstructured light beams can produce this non-conservative force.

Abstract

When circularly polarized wave scatters off a sphere, the scattered field forms a vortex with spiraling energy flow. This is due to the transformation of spin angular momentum into orbital one. Here we demonstrate that during this scattering an anomalous force can be induced that acts in a direction perpendicular to the propagation of incident wave. The appearance of this lateral force is made possible by the presence of an interface in the vicinity of scattering object. Besides radiation pressure and tractor-beam pulling forces, this lateral force is another type of non-conservative force that can be produced with unstructured light beams.