title: Hotspot-mediated ultrafast nonlinear control of multifrequency plasmonic nanoantennas.
abstract: Plasmonic devices have a unique ability to concentrate and convert optical energy into a small volume. There is a tremendous interest in achieving active control of plasmon resonances, which would enable switchable hotspots for applications such as surface-enhanced spectroscopy and single molecule emission. The small footprint and strong-field confinement of plasmonic nanoantennas also holds great potential for achieving transistor-type devices for nanoscale-integrated circuits. To achieve such a functionality, new methods for nonlinear modulation are required, which are able to precisely tune the nonlinear interactions between resonant antenna elements. Here we demonstrate that resonant pumping of a nonlinear medium in a plasmonic hotspot produces an efficient transfer of optical Kerr nonlinearity between different elements of a multifrequency antenna. By spatially and spectrally separating excitation and readout, isolation of the hotspot-mediated ultrafast Kerr nonlinearity from slower, thermal effects is achieved.
authors.affiliation: Department of Physics and Astronomy, Faculty of Physical Sciences and Engineering, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
authors.forename: Martina
authors.initials: M
authors.lastname: Abb
authors.affiliation: 1] Department of Physics and Astronomy, Faculty of Physical Sciences and Engineering, University of Southampton, Highfield, Southampton SO17 1BJ, UK [2] Nano Group, Faculty of Physical Sciences and Engineering, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
authors.forename: Yudong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Nano Group, Faculty of Physical Sciences and Engineering, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
authors.forename: C H
authors.initials: CH
authors.lastname: de Groot
authors.affiliation: Department of Physics and Astronomy, Faculty of Physical Sciences and Engineering, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
authors.forename: Otto L
authors.initials: OL
authors.lastname: Muskens