Controlled longitudinal spin-orbit separation of complex vector modes

TL;DR

This paper demonstrates a method to achieve controllable longitudinal spin-orbit separation of complex vector modes in free space using circular Airy Gaussian vortex vector modes, with potential applications in optical manipulation.

Contribution

It introduces a novel approach to manipulate spin-orbit coupling along the propagation direction of complex vector beams using CAGVV modes, combining numerical and experimental validation.

Findings

Successful numerical simulation of spin-orbit separation.

Experimental verification of controllable separation.

Potential applications in optical tweezers for particle manipulation.

Abstract

Complex vector modes, entangled in spin and orbital angular momentum, are opening burgeoning opportunities for a wide variety of applications. Importantly, the flexible manipulation the various properties of such beams will pave the way to novel applications. As such, in this manuscript, we demonstrate a longitudinal spin-orbit separation of complex vector modes propagating in free space. To achieve this we employed the recently demonstrated circular Airy Gaussian vortex vector (CAGVV) modes, which feature a self-focusing property. More precisely, by properly manipulating the intrinsic parameters of CAGVV modes, the strong coupling between the two constituting orthogonal components of CAGVV mode undergo a spin-orbit separation along the propagation direction namely, while one polarisation component, focuses at a specific plane, the other focuses at a different plane. Such spin-orbit separation, which we demonstrated by numerical simulations and corroborated experimentally, can be adjusted on-demand by simply changing the initial parameters of CAGVV modes. Our findings will be of great relevance, for example in optical tweezers, to manipulate micro- or nano-particles at two different parallel planes.