Topological Charge Constrained Photonic Skyrmion Defects in Split Plasmonic Vortices

We report the formation of photonic skyrmion defects in split plasmonic vortices upon the broken rotational symmetry of the electromagnetic field in the presence of spin–orbit interaction. By employing the interaction between light and a partially chiral metallic structure, we demonstrate the split of high order plasmonic vortices to the one with unit topological charge, where antivortices in the Poynting vector are assigned at the vicinity, giving rise to the spin reversal and construction of skyrmion defects with antiskyrmionic topology. In addition, we reveal the topological charge constraints for skyrmion defects from the conservation of angular momentum and vortex winding, manifesting the stability of skyrmions induced by plasmonic vortex with different order. The results provide new insights on spin–orbit interaction and photonic topological textures, which may pave the way for their applications in optical metrology, sensing, and storage.