Imaging the Hidden Modes of Ultrathin Plasmonic Strip Antennas by Cathodoluminescence

Edward S. Barnard, Toon Coenen, Ernst Jan R. Vesseur, Albert Polman, Mark L. Brongersma

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

We perform spectrally resolved cathodoluminescence (CL) imaging nanoscopy using a 30 keV electron beam to identify the resonant modes of an ultrathin (20 nm), laterally tapered plasmonic Ag nanostrip antenna. We resolve with deep-subwavelength resolution four antenna resonances (resonance orders m = 2-5) that are ascribed to surface plasmon polariton standing waves that are confined on the strip. We map the local density of states on the strip surface and show that it has contributions from symmetric and antisymmetric surface plasmon polariton modes, each with a very different mode index. This work illustrates the power of CL experiments that can visualize hidden modes that for symmetry reasons have been elusive in optical light scattering experiments. © 2011 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)4265-4269
Number of pages5
JournalNano Letters
Volume11
Issue number10
DOIs
StatePublished - Oct 12 2011
Externally publishedYes

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