Mapping the Nanoscale Optical Topological Textures with a Fiber-Integrated Plasmonic Probe.

Topologically protected optical quasiparticles have garnered growing research interest due to their capacity to provide a novel degree of freedom for manipulating light-matter interactions while demonstrating significant potential in nanometrology and ultrafast vector imaging. However, the characterization of the full 3D vectorial structures of the topological textures at the nanoscale has remained challenging. We present a fiber taper-silver nanowire waveguide probe to achieve subwavelength mapping of the topological textures. Based on the selective plasmonic-optical mode coupling principle, the three orthogonal electric-field components in both the far field and the near field are directly collected and reconstructed without the need for postprocessing algorithms, enabling the visualization of topological textures formed in both free space and evanescent waves. The fiber-integrated probe further demonstrates broadband operation and mechanical robustness. This approach offers promising prospects for analyzing sophisticated optical-field topologies with potential advanced applications in optical data storage and information processing systems.