Optical hopfions from a single metasurface

Three-dimensional topological light fields extend singular optics beyond isolated phase and polarization defects to particle-like textures distributed throughout a finite propagation volume. Optical hopfions are a prominent example, characterized by linked polarization preimages and a nontrivial phase–polarization mapping onto the optical hypersphere. However, their experimental realization has so far relied on bulky, alignment-sensitive optical systems. Here, we introduce for the first time a compact platform for the generation and continuous reconfiguration of optical hopfions using a single dual-functional metasurface. The device independently controls the right- and left-circular polarization channels, encoding optimized modal amplitudes through phase equalization, and simultaneously providing the focusing phase required for volumetric field synthesis. The input ellipticity is fixed to establish the relative spin-channel weights and generate the target hopfion at focus, while reconfiguration is achieved simply by rotating the input polarization ellipse. We experimentally reconstruct the three-dimensional polarization Hopf fibrations associated with generalized (m, n) = (1, −1) and (1, 2) textures, while full-field propagation simulations reveal localized signed Skyrme densities with integrated degrees of 0.99 and −1.99, respectively. By integrating spin-decoupled control, amplitude equalization, and focusing within a single flat optical element, our approach provides a practical and scalable route to reconfigurable particle-like topological light and its application in optics and photonics.