title: Normal-Incidence PEEM Imaging of Propagating Modes in a Plasmonic Nanocircuit.
abstract: The design of noble-metal plasmonic devices and nanocircuitry requires a fundamental understanding and control of the interference of plasmonic modes. Here we report the first visualization of the propagation and interference of guided modes in a showcase plasmonic nanocircuit using normal-incidence nonlinear two-photon photoemission electron microscopy (PEEM). We demonstrate that in contrast to the commonly used grazing-incidence illumination scheme, normal-incidence PEEM provides a direct image of the structure's near-field intensity distribution due to the absence of beating patterns and despite the transverse character of the plasmonic modes. Based on a simple heuristic numerical model for the photoemission yield, we are able to model all experimental findings if global plane wave illumination and coupling to multiple input/output ports, and the resulting interference effects are accounted for.
authors.affiliation: Nano-Optics and Biophotonics Group, Department of Experimental Physics 5, University of Würzburg , Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Gary
authors.initials: G
authors.lastname: Razinskas
authors.affiliation: Department of Physics and Research Center OPTIMAS, University of Kaiserslautern , Erwin-Schrödinger-Str. 46, D-67663 Kaiserslautern, Germany.
authors.forename: Deirdre
authors.initials: D
authors.lastname: Kilbane
authors.affiliation: Department of Physics and Research Center OPTIMAS, University of Kaiserslautern , Erwin-Schrödinger-Str. 46, D-67663 Kaiserslautern, Germany.
authors.forename: Pascal
authors.initials: P
authors.lastname: Melchior
authors.affiliation: Nano-Optics and Biophotonics Group, Department of Experimental Physics 5, University of Würzburg , Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Geisler
authors.affiliation: Nano-Optics and Biophotonics Group, Department of Experimental Physics 5, University of Würzburg , Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Enno
authors.initials: E
authors.lastname: Krauss
authors.affiliation: Department of Physics and Research Center OPTIMAS, University of Kaiserslautern , Erwin-Schrödinger-Str. 46, D-67663 Kaiserslautern, Germany.|I. Physikalisches Institut, Georg-August-Universität Göttingen , Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Mathias
authors.affiliation: Nano-Optics and Biophotonics Group, Department of Experimental Physics 5, University of Würzburg , Am Hubland, D-97074 Würzburg, Germany.|Röntgen Center for Complex Material Systems (RCCM) , Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Bert
authors.initials: B
authors.lastname: Hecht
authors.affiliation: Department of Physics and Research Center OPTIMAS, University of Kaiserslautern , Erwin-Schrödinger-Str. 46, D-67663 Kaiserslautern, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Aeschlimann
keywords: Plasmon propagation; control; nanocircuitry; near-field imaging; photoemission electron microscope; plasmonic functional device