Subdiffraction Confinement and Non‐Diffractive Propagation of Optical Stokes Skyrmions Enabled by a Super‐oscillatory Metalens

ABSTRACT Optical Stokes skyrmions have garnered extensive interest due to their intrinsic topological robustness and potential in informatics. However, most research remains confined to paraxial, low‐numerical‐aperture (low‐NA) regimes, where their large transverse dimensions restrict broader applications. Under high‐NA focusing, the polarization texture typically degrades or transforms abruptly as the beam traverses the focal region, hindering topology‐preserving transport. In this work, a strategy is proposed to generate a skyrmion needle field that maintains both subdiffraction confinement and non‐diffractive propagation under high‐NA conditions, thus preserving their topological characteristics. Leveraging the polarization invariance of conventional optical needles, the Stokes skyrmion needle is realized using a single plasmonic metalens, which is designed to function as both a polarization filter and a super‐resolving focusing element. Experimental and simulation results verify non‐diffractive propagation over an extended depth of focus (up to 5), while the Stokes‐vector texture is retained at subdiffraction scales throughout propagation. This skyrmion needle not only addresses previous propagation constraints but also opens new avenues for diffraction‐unlimited information transport. Such skyrmion needles exhibit substantial potential in fields including light–matter interaction, optical metrology, and informatics.