Invited Paper
Plasmonics at the Space-Time Limit

Martin Aeschlimann Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Kaiserslautern, Germany

The optical response of metallic nanostructures exhibits fascinating properties: local field interference effects that lead to strong variations of the near field distribution on a subwavelength scale, local field enhancement, and long lasting electronic coherences. Coherent control in general exploits the phase properties of light fields to manipulate coherent processes. Originally developed for molecular systems these concepts have recently been adapted also to nano-optical phenomena. Consequently, the combination of ultrafast laser spectroscopy, i.e. illumination with broadband coherent light sources, and near-field optics opens a new realm for nonlinear optics on the nanoscale.

To circumvent the experimental limitation of optical diffraction we use a photoemission electron microscope (PEEM) that has been proven to be a versatile tool for the investigation of near field properties of nanostructures with a spatial resolution of only a few nanometers and that allows for new spectroscopy techniques with ultrafast time resolution [1,2].

In this talk it will be shown that the excitation of nanostructures with broadband laser pulses and the control of the near field properties open the route for logical processing elements on a nanometer and femtosecond scale whereas the time resolved spectroscopy technique gives deeper insight into the underlying microscopic processes [3].

In standard PEEM systems, a grazing angle of incidence has to be used for illumination. However, asymmetric illumination causes phase retardation effects and complex intensity distributions because of the superposition of higher order plasmonic modes. As a result, the complexity of the observed photoemission behavior makes the interpretation of the observed photoemission pattern and dynamic behavior challenging. We present the observation of plasmonic excitations and the real space and time tracking of surface plasmon polaritons with a novel NI PEEM setup where the sample is now illuminated under normal-incidence [4].

[1] M. Aeschlimann et al, Nature 446, 301 (2007)

[2] M. Aeschlimann et al, PNAS 107 (12), 5329 (2010)

[3] M. Aeschlimann et al, Science 333, 1723-1726 (2011)

[4] P. Kahl et al,, Plasmonics 9, 1401 (2014)

ma@physik.uni-kl.de









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