Twisted Spatiotemporal Optical Vortex Random Fields

Milo Hyde

doi:10.1109/jphot.2021.3066898

Abstract

We present twisted spatiotemporal optical vortex (STOV) beams, which are partially coherent light sources that possess a coherent optical vortex and a random twist coupling their space and time dimensions. These beams have controllable partial coherence and transverse orbital angular momentum (OAM), which distinguishes them from the more common spatial vortex and twisted beams (known to carry longitudinal OAM) in the literature and should ultimately make them useful in applications such as optical communications and optical tweezing. We present the mathematical analysis of twisted STOV beams, deriving the mutual coherence function and linear and angular momentum densities. We simulate the synthesis of twisted STOV beams and investigate their free-space propagation characteristics. We discuss how to physically generate twisted STOV fields and lastly conclude with a summary and brief discussion of future research.

Highlights

30 years have passed since Allen et al.’s seminal paper showing that Laguerre-Gaussian beams possess orbital angular momentum (OAM) [1]
We present the mathematical analysis of twisted spatiotemporal optical vortex (STOV) beams, deriving the mutual coherence function and linear and angular momentum densities
We introduced twisted STOV beams

Summary

Introduction

30 years have passed since Allen et al.’s seminal paper showing that Laguerre-Gaussian beams possess orbital angular momentum (OAM) [1]. Much of the OAM beam research has focused on fields with wavefront twists or vortices coupling their transverse (to the direction of propagation) spatial dimensions. This results in beams with axial or longitudinal (parallel to the propagation direction) OAM. There has been significant interest in generating optical fields which possess transverse angular momentum. It has been known for decades that evanescent waves excited by total internal reflection and tightly focused Gaussian beams carry transverse spin angular momentum (SAM), called photonic wheels [30]–[32]. More information on light that possesses transverse SAM and potential applications can be found in Refs. [18], [30]–[32], [37]

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Conclusion