Mode structure and orbital angular momentum of spatiotemporal optical vortex (STOV) pulses

TL;DR

This paper explores the modal structure and orbital angular momentum properties of spatiotemporal optical vortex pulses, revealing their unique OAM characteristics and agreement with experimental measurements.

Contribution

It introduces a modal theory for STOV pulses in dispersive media, highlighting their half-integer and integer OAM quantization based on symmetry and dispersion.

Findings

Symmetric STOVs in vacuum can carry half-integer OAM.

In dispersive media, asymmetric STOVs have quantized OAM depending on symmetry and dispersion.

The modal theory aligns well with experimental measurements of STOV propagation.

Abstract

We identify a class of modal solutions for spatio-temporal optical vortex (STOV) electromagnetic pulses propagating in dispersive media with orbital angular momentum (OAM) orthogonal to propagation. We find that symmetric STOVs in vacuum can carry half-integer intrinsic orbital angular momentum (OAM); for general asymmetric STOVs in a dispersive medium, the OAM is quantized in integer multiples of a parameter that depends on the STOV symmetry and the group velocity dispersion. Our results suggest that STOVs propagating in dispersive media are accompanied by a polariton-like quasiparticle. The modal theory is in excellent agreement with measurements of free space propagation of STOVs.