Chiral nanophotonic waveguide interface based on spin-orbit coupling of light

TL;DR

This paper demonstrates a chiral nanophotonic waveguide interface that uses spin-orbit coupling of light to control the direction of light propagation with high efficiency, enabling advanced light manipulation and sensing.

Contribution

It introduces a novel chiral waveguide coupler leveraging spin-orbit coupling to achieve directional control of light scattering at the nanoscale.

Findings

Up to 94% of light directed into a chosen waveguide direction

Broken mirror symmetry in light scattering by a nanoparticle

Potential for advanced integrated optical sensors

Abstract

Controlling the flow of light by means of nanophotonic waveguides has the potential of transforming integrated information processing much in the same way that conventional glass fibers have revolutionized global communication. Owing to the strong transverse confinement of the light, such waveguides give rise to a coupling between the internal spin of the guided photons and their orbital angular momentum. Here, we employ this spin-orbit coupling of light to break the mirror symmetry of the scattering of light by a single gold nanoparticle on the surface of a nanophotonic waveguide. We thereby realize a chiral waveguide coupler in which the handedness of the incident light determines the direction of propagation in the waveguide. Using this effect, we control the directionality of the scattering process and direct up to 94% of the incoupled light into a given direction. This enables novel ways for controlling and manipulating light in optical waveguides and nanophotonic structures as well as for the design of integrated optical sensors.