Spin-orbit interaction in a high-power laser irradiated micro-scale plasma waveguide

TL;DR

This paper demonstrates how high-power laser interactions with micro-scale plasma waveguides induce spin-orbit effects, generating optical vortices with orbital angular momentum in the extreme ultraviolet regime, revealing new relativistic plasma physics phenomena.

Contribution

It is the first to analyze spin-orbit interaction effects in relativistic laser-plasma interactions using 3D particle-in-cell simulations, showing spin-controlled chiral surface waves and harmonic photon OAM transfer.

Findings

Generation of intense optical vortices in EUV regime

Spin-controlled chiral surface wave formation

Orbital angular momentum transfer to reflected harmonics

Abstract

Light carries angular momentum as spin and orbital components. The spin-orbit interaction (SOI) of light refers to phenomena in which the spin (left or right circular polarisation) affects the spatial degrees of freedom. Recently, interest in SOI has surged, as it provides physical insight into the behaviour of polarised light at subwavelength scales, and allows for spin-controlled manipulation of light. Most studies are performed with low intensity, leaving the role SOI plays in the relativistic laser-plasma interaction, characterised by nonlinearity, less understood. Here, using 3D particle-in-cell simulations, we report SOI effects in this unprecedented regime. Specifically, a circularly polarised Gaussian laser irradiating a micro-scale plasma waveguide drives a spin-controlled chiral surface wave, allowing the reflected harmonic photons to gain orbital angular momentum (OAM). These effects produce intense optical vortices in the extreme ultraviolet regime - an area of significant fundamental and applied physics potential.