Spin-orbit interactions of the twisted random light

TL;DR

This paper investigates the complex interaction between spin and orbital angular momentum in twisted random light, revealing how the twist phase influences angular momentum transitions and transverse spin density, with implications for advanced optical applications.

Contribution

It introduces an asymmetry coherent-mode decomposition approach to explore spin-orbit interactions in twisted random light, a previously unexamined aspect due to the stochastic nature of the field.

Findings

Spin and orbit angular momentum transitions occur in tightly focused twisted random light.

Transverse spin density is controlled by the twist phase.

The effect is enhanced when the spin and twist phase chirality match.

Abstract

The twist phase of random light represents a nontrivial two-point phase, endowing the field with orbital angular momentum. Although the mutual transition of the spin and orbit angular momenta of coherent light has been revealed, the relationship between spin-orbital angular momentum interaction (SOI) and the twist phase has remained unexplored. This is because of the stochastic nature of random light, making it challenging to explore the properties of angular momenta that rely on well-defined spatial and polarization structures. This study addresses this gap from the view of the asymmetry coherent-mode decomposition for twisted random light to gain insight into the intricate interplay between the twist phase and the SOI within a tight focusing system. Our findings reveal that spin and orbit angular momentum transitions occur in the tightly focused twisted random light beam, yielding the transverse spin density controlled by the twist phase. This effect becomes more pronounced when the spin of random light and the chirality of the twist phase are the same. Our work may find significant applications in optical sensing, metrology, and quantum optics.