Phase singularity or skyrmion? Surprise: it’s both!

In structured light, optical vortices are celebrated as scalar beams carrying orbital angular momentum, whereas skyrmions are hailed as three-dimensional vector textures with non-trivial topology. Until now, the two concepts were thought to belong to separate worlds: optical vortices arise from phase singularities [Ref: Light: Sci. & Appl. 8:90 (2019)], optical skyrmions from engineered superpositions of differently polarized modes [Ref: Adv. Opt. Photonics 17(2) 295-374 (2025)].

 

Writing in Physical Review Letters, the authors overturn this separation. They show that a plain Laguerre-Gaussian vortex already contains a complete skyrmionic texture once Maxwell’s longitudinal field is retained. At the dark core the transverse field vanishes, forcing the usually neglected z-component to dominate. The surrounding polarization ellipses therefore tilt out of plane, mapping every point on a newly defined Gauss-Stokes Poincaré sphere whose poles are pure transverse and pure longitudinal polarization. A stereographic projection of this sphere onto the transverse plane yields a skyrmion with topological charge exactly one—no interferometric alignment, no multi-mode synthesis.

 

The team confirmed the texture experimentally with a single dielectric metasurface that both imparts vorticity and focuses the beam. Interferometric polarimetry around the phase singularity directly images the skyrmion, retrieving the predicted integer topological charge.

 

Because the texture is born from a solitary scalar mode, it is intrinsically robust against perturbations and naturally compatible with planar photonics. Replacing bulky vector-beam generators by one ultrathin element, the work paves the way for high-dimensional OAM communication, topologically protected routing and on-chip quantum memories.

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