Pseudovorticity of 2+1D optical solitons

TL;DR

This paper investigates pseudovorticity in 2+1D optical solitons, revealing complex rotational flow structures and hierarchies of pseudovorticity multipoles through experimental and numerical analysis.

Contribution

It introduces the concept of pseudovorticity in optical solitons and demonstrates its presence and structure in high-dimensional solitons via detailed phase and amplitude analysis.

Findings

Bright 2+1D solitons carry a pseudovorticity dipole.

Quadrupoles emerge during soliton fusion.

Stable high-dimensional solitons encode pseudovorticity multipoles.

Abstract

In the hydrodynamic representation of a quantum fluid or optical field, vorticity vanishes wherever the phase is well defined, and is instead localized at phase singularities, or quantum vortices. Pseudovorticity, by contrast, characterizes local rotational structures, even in regions without singularities or net orbital angular momentum. We study both experimentally and numerically pseudovorticity in photorefractive solitons and show that a detailed phase and amplitude analysis unveils a complex rotational flow dynamic: bright 2+1D solitons are found to carry a pseudovorticity dipole, while quadrupoles emerge in soliton fusion. The phenomenon, also explained using geometrical considerations, suggests a general picture according to which stable high-dimensional solitons naturally carry a hierarchy of pseudovorticity multipoles, encoded in the local perturbed phase and amplitude.