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    Using Active Surface Plasmons in a Multibit Optical Storage Device to Emulate Long-Term Synaptic Plasticity
    (Weinheim : Wiley-VCH, 2020) Rhim, Seon-Young; Ligorio, Giovanni; Hermerschmidt, Felix; Hildebrandt, Jana; Pätzel, Michael; Hecht, Stefan; List-Kratochvil, Emil J.W.
    Artificial intelligence takes inspiration from the functionalities and structure of the brain to solve complex tasks and allow learning. Yet, hardware realization that simulates the synaptic activities realized with electrical devices still lags behind computer software implementation, which has improved significantly during the past decade. Herein, the capability to emulate synaptic functionalities by exploiting surface plasmon polaritons (SPPs) is shown. By depositing photochromic switching molecules (diarylethene) on a thin film of gold, it is possible to reliably control the electronic configuration of the molecules upon illumination cycles with UV and visible light. These reversible changes modulate the dielectric function of the photochromic film and thus enable the effective control of the SPP dispersion relation at the molecule/gold interface. The plasmonic device displays fundamental functions of a synapse such as potentiation, depression, and long-term plasticity. The integration of such plasmonic devices in an artificial neural network is deployed in plasmonic neuroinspired circuits for optical computing and data transmission. © 2020 The Authors. Published by Wiley-VCH GmbH
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    Near-field interference map due to a dipolar emission near the edge of a monocrystalline gold platelet
    (Bristol : IOP Publ., 2022) Abbasirad, N.; Barreda, A.; Arslan, D.; Steinert, M.; Chen, Y.-J.; Huang, J.-S.; Staude, I.; Setzpfandt, F.; Pertsch, T.
    Point source excitation and point detection in the near-field provides new perspective to study the near-field optical phenomena of plasmonic nanostructures. Using the automated dual-tip scanning near-field optical microscope (SNOM), we have measured the optical near-field response of a dipolar emission near the edge of a monocrystalline gold platelet. The image dipole method was used to analytically calculate the interference pattern due to surface plasmon polaritons excited at the position of aperture tip and those reflected from edges of the gold platelet. The near-field enhancement was observed on the edges of the gold platelet. Our results verify that automated dual-tip SNOM is an intriguing technique for quantum plasmonic studies where deterministic coupling of quantum emitters and the detection of the near-field enhancement are of great interest.