Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 76: Plasmonics & Nanooptics V: Nanostructures and Nanoantennae
O 76.6: Vortrag
Donnerstag, 4. April 2019, 11:45–12:00, H8
Near-field characterization of plasmonic slot waveguides in single-crystalline gold films — •Mike Prämassing1, Hans-Joachim Schill1, Matthias Liebtrau1, Stephan Irsen2, and Stefan Linden1 — 1Physikalisches Institut Universität Bonn, D-53115 — 2Center of advanced european studies and research (caesar), Bonn, D-53175
Plasmonic slot waveguides (PSW’s) consist of a sub-wavelength gap engraved in a thin metal film. PSW’s support guided plasmonic modes with a lateral confinement siginificantly below the diffraction limit, while sustaining propagation over several microns. Therfore PSW’s are attractive canditates e.g. as building blocks for integrated optoelectronic circuits [1], or for enhanced coupling to quantum emitters [2]. Here, we investigate the dependency of the the effective mode index neff and the propagation length Lp on the slot width. For the first time, we use focused ion beam milling on chemically grown 50 nm thick single-crystalline gold flakes to fabricate down to 50 nm wide PSW’s. We utilize scattering-type scanning near-field optical microscopy (s-SNOM) in transmission mode configuration with an interferometric detection scheme for amplitude- and phase-resolved measurements. A 2D model-function is fitted to the measured near-field distributions in order to extract neff and Lp. Our experimental results are in accordance with finite element simulations. The presented results may offer design rules to optimize PSW’s for potential future applications.
[1]Gramotnev, and Bozhevolnyi. Nature photonics 4, 83 (2010).
[2]Jun et al. Phys. Rev. B 78, 153111 (2008).