Photoelectron imaging of modal interference in plasmonic whispering gallery cavities

We use three-photon photoemission electron microscopy (PEEM) to investigate the interference of coherently excited dipolar and quadrupolar resonant modes of plasmonic whispering gallery resonators formed by circular grooves patterned into a flat Au surface. Optical scattering and cathodoluminescence...

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Bibliographic Details
Published in:Optics express 2015-12, Vol.23 (25), p.31619-31626
Main Authors: Melchior, Pascal, Kilbane, Deirdre, Vesseur, Ernst Jan, Polman, Albert, Aeschlimann, Martin
Format: Article
Language:English
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Summary:We use three-photon photoemission electron microscopy (PEEM) to investigate the interference of coherently excited dipolar and quadrupolar resonant modes of plasmonic whispering gallery resonators formed by circular grooves patterned into a flat Au surface. Optical scattering and cathodoluminescence spectroscopy are used to characterize the cavity resonance spectra for a wide range of cavity radii and groove depths. Using PEEM, we directly resolve the interference between the modal field distribution of dipolar and quadrupolar modes that are coherently excited at λ = 795 nm under oblique incidence. Characteristic asymmetries in the photoelectron images for both TM and TE excitation are a direct consequence of the coherent excitation of the resonant modes.
ISSN:1094-4087
1094-4087
DOI:10.1364/oe.23.031619