The vectorial nature of light-matter interaction is crucial for nanophotonic processes. However, a key requirement for experimental vectorial analysis—the controllable excitation and detection of different polarization components—remains challenging, especially in near-field optics, where the optical fields exhibit strong subwavelength spatial variations. Here the interaction of three orthogonal polarization components, represented by the three lowest-order surface plasmon polariton (SPP) modes of a silver nanowire (AgNW), with an edge of discontinuous refractive index is investigated. Selective excitation and collection of specific SPP modes via a fiber taper-AgNW hybrid probe reveals distinct modulations for different modes/polarization components. Reflection signals for two excitation modes exhibit subwavelength profiles, where the fundamental mode excitation realizes superresolution edge imaging. In transmission measurements, the far-field radiation patterns of all three modes are significantly modulated by the edge. We developed the local reflection and transmission models to quantitatively analyze these results, which show excellent agreement with both experimental measurements and numerical simulations. Our work not only provides insights into the nanoscale vectorial light-matter interactions but also establishes a platform with potential applications in areas such as near-field modulation, biosensing, optical communication, and superresolution optical edge imaging.

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• Light-matter interaction
• Photonics
• Surface plasmon polariton
• Waveguides
• Scanning near-field optical microscopy