Singh, L.; Maccaferri, N.; Garoli, D.; Gorodetski, Y. Directional Plasmonic Excitation by Helical Nanotips. Nanomaterials2021, 11, 1333.
Singh, L.; Maccaferri, N.; Garoli, D.; Gorodetski, Y. Directional Plasmonic Excitation by Helical Nanotips. Nanomaterials 2021, 11, 1333.
The phenomenon of coupling between light and surface plasmon polaritons requires specific momentum matching conditions. In the case of a single scattering object on a metallic surface, like a nanoparticle or a nanohole, the coupling between a broadband effect, i.e. scattering, and a discrete one such as surface plasmon excitation, leads to Fano-like resonance lineshapes. The necessary phase matching requirements can be used to engineer the light-plasmon coupling and to achieve a directional plasmonic excitation. Here we investigate this effect by using a chiral nanotip to excite surface plasmons with a strong spin-dependent azimuthal variation. This effect can be described by a Fano-like interference with a complex coupling factor that can be modified thanks to a symmetry breaking of a nanostructure.
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