Skyrmionic spin textures in nonparaxial light

Abstract

Topological textures in optics such as skyrmions and merons are increasingly studied for their potential functions in light–matter interactions, deep-subwavelength imaging, and nanometrology. However, they were previously generated either in strongly confined guided waves or in paraxial beams. This has posed a significant challenge in constructing skyrmions in nonparaxial propagating waves due to the lack of symmetry-breaking in the optical field and difficulty in characterizing the full three-dimensional spin textures at the nanoscale. We theoretically propose and experimentally demonstrate the generation of skyrmionic spin textures in nonparaxial light, where skyrmionic textures with a Bloch-type scheme, including isolated skyrmioniums, skyrmion, and meron lattices are generated in free space. We introduce the interplay between the Hertz potentials to break the dual symmetry of light and build well-defined domains of skyrmions. We experimentally realized the topological textures by applying a hybrid polarized optical vortex and observed the complete three-dimensional spin distributions by a dual-mode waveguide probe. By bridging the gap in the skyrmionic group, we present a topologic diagram, showing how spin–orbit coupling of light governs the spin topology. These findings offer new insights into optical quasi-particles and electron–photon correspondence, potentially facilitating advanced applications in optical metrology, sensing, and storage.

Topics & Concepts