title: Suppression of Radiative Damping and Enhancement of Second Harmonic Generation in Bull's Eye Nanoresonators.
abstract: We report a drastic increase of the damping time of plasmonic eigenmodes in resonant bull's eye (BE) nanoresonators to more than 35 fs. This is achieved by tailoring the groove depth of the resonator and by coupling the confined plasmonic field in the aperture to an extended resonator mode such that spatial coherence is preserved over distances of more than 10 μm. Experimentally, this is demonstrated by probing the plasmon dynamics at the field level using broadband spectral interferometry. The nanoresonator allows us to efficiently concentrate the incident field inside the central aperture of the BE and to tailor its local optical nonlinearity by varying the aperture geometry. By replacing the central circular hole with an annular ring structure, we obtain 50-times higher second harmonic generation efficiency, allowing us to demonstrate the efficient concentration of long-lived plasmonic modes inside nanoapertures by interferometric frequency-resolved autocorrelation. Such a light concentration in a nanoresonator with high quality factor has high potential for sensing and coherent control of light-matter interactions on the nanoscale.
authors.affiliation: Institute of Physics and Center of Interface Science, Carl von Ossietzky Universität Oldenburg , D-26129 Oldenburg, Germany.
authors.forename: Jue-Min
authors.initials: JM
authors.lastname: Yi
authors.affiliation: Institute of Physics and Center of Interface Science, Carl von Ossietzky Universität Oldenburg , D-26129 Oldenburg, Germany.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Smirnov
authors.affiliation: Photonic Systems Laboratory, School of Electrical Engineering, Seoul National University , 151-742 Seoul, Korea.
authors.forename: Xianji
authors.initials: X
authors.lastname: Piao
authors.affiliation: Photonic Systems Laboratory, School of Electrical Engineering, Seoul National University , 151-742 Seoul, Korea.
authors.forename: Jiho
authors.initials: J
authors.lastname: Hong
authors.affiliation: Institute of Physics and Center of Interface Science, Carl von Ossietzky Universität Oldenburg , D-26129 Oldenburg, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Kollmann
authors.affiliation: Institute of Physics and Center of Interface Science, Carl von Ossietzky Universität Oldenburg , D-26129 Oldenburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Silies
authors.affiliation: Institute of Physics and Center of Interface Science, Carl von Ossietzky Universität Oldenburg , D-26129 Oldenburg, Germany.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Institute of Physics and Center of Interface Science, Carl von Ossietzky Universität Oldenburg , D-26129 Oldenburg, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Groß
authors.affiliation: Institute of Physics and Center of Interface Science, Carl von Ossietzky Universität Oldenburg , D-26129 Oldenburg, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Vogelgesang
authors.affiliation: Photonic Systems Laboratory, School of Electrical Engineering, Seoul National University , 151-742 Seoul, Korea.
authors.forename: Namkyoo
authors.initials: N
authors.lastname: Park
authors.affiliation: Institute of Physics and Center of Interface Science, Carl von Ossietzky Universität Oldenburg , D-26129 Oldenburg, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Lienau
keywords: bull’s eye; nanoparticle; second harmonic generation; surface plasmon polaritons; ultrafast nano-optics