Photonic torons, topological phase transition and tunable spin monopoles

TL;DR

This paper reports the experimental creation of photonic torons, complex topological light structures, and demonstrates their tunable topological phase transitions and spin textures, advancing topological photonics and information science.

Contribution

It introduces the first experimental realization of photonic torons with tunable topological states and monopoles, expanding the scope of topological light manipulation.

Findings

Demonstrated topological phase transitions among torons, hopfions, skyrmioniums, and monopole pairs.

Achieved continuous tuning of toron chirality and spin textures.

Established a platform for studying light-matter interactions with topological structures.

Abstract

Creation and control of topological complex excitations play crucial roles in both fundamental physics and modern information science. Torons are a sophisticated class of 3D chiral polar topological structures with both skyrmionic quasiparticle textures and monopole point defects, so far only observed in liquid crystal nonpolar models. Here, we experimentally construct torons with the photonic spin of vector structured light and demonstrate the topological phase transitions among diverse topological states: torons, hopfions, skyrmioniums and monopole pairs. We can also continually tune the toron's chirality and the helical spin textures of emerging monopole pairs. The birth of photonic torons and tunable monopoles opens a flexible platform for studying nontrivial light-matter interaction and topological informatics.