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O: Fachverband Oberflächenphysik
O 65: Plasmonics and Nanooptics IV: Waveguides and Antennas
O 65.1: Vortrag
Mittwoch, 18. März 2020, 10:30–10:45, WIL A317
Plasmonic nanfocusing spectroscopy: from local excitation to local detection of optical near fields — •Abbas Chimeh1, Sven Stephan1, Martin Esmann2, Anke Korte1, Jinhui Zhong1, Martin Silies1, Nahid Talebi3, and Christoph Lienau1 — 1Universität Oldenburg, Oldenburg, Germany — 2Centre de Nanosciences et de Nanotechnologies, Paris, — 3Universität Kiel, Kiel, Germany
The nanofocusing of light in tapered plasmonic waveguides efficiently confines electromagnetic radiation into volumes far below the wavelength, breaking the diffraction resolution limit of optical microscopy [1]. Selective delivery of the optical excitation to a specific point near the sample surface has made plasmonic nanofocusing an effective tool for spatially resolved spectroscopy on the nanoscale [2]. Here, we show that a tapered plasmonic guide is also capable of not only nanofocusing of light into nanometric volumes but also detecting light from them. We show by full-wave analysis of electromagnetic fields how surface plasmon polaritons (SPPs) nanofocused onto the apex of a gold nanotaper excite the near fields of a nanorod. These near fields are coupled back to the taper apex and launch back propagating SPPs. We detect the local light scattering spectra of nanorods from these back propagating SPPs and quantify line broadenings and spectral shifts induced by tip-sample coupling. Our finite-difference time-domain simulations are in a good agreement with experimental results. [1] D. K. Gramotnev et al., Nature Photon. 8, 14 (2012). [2] M. Esmann et al., Nature Nanotechnol. 6, 6040 (2019)