Joint effect of polarization and the propagation path of a light beam on its intrinsic structure

TL;DR

This paper investigates how the combined effects of polarization and the propagation path influence the intrinsic structure of a light beam, revealing new interactions between angular momentum components during fiber transmission.

Contribution

It introduces a new classification of spin-orbit interaction effects and experimentally demonstrates how polarization and fiber geometry jointly affect light's intrinsic angular momentum.

Findings

Light structure rotates with polarization sign change

Rotation angle depends on helix parameters

Results applicable to metrology and nanooptics

Abstract

The well-known effects of the spin-orbit interaction of light are manifestations of pair mutual influence of the three types of the angular momentum of light, namely, the spin angular momentum, the extrinsic orbital angular momentum and the intrinsic orbital angular momentum. Here we propose the convenient classification of the effects of the spin-orbit interaction of light and we observe one of the new effects in the frame of this classification, which is determined by the joint influence of two types of the angular momentum on the third type of the angular momentum, namely, the influence of the spin angular momentum and the extrinsic orbital angular momentum on the intrinsic orbital angular momentum. We experimentally studied the propagation of circularly polarized light through an optical fiber coiled into a helix. We have found that the spin angular momentum and the helix parameters affect the spatial structure of the radiation transmitted through the optical fiber. We found out that the structure of the light field rotates when changing the sign of circular polarization. The angle of rotation depends on the parameters of the helix. The results can be used to develop the general theory of spinning particles and can find application in metrology methods and nanooptics devices.