Dresden 2009 – scientific programme
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O: Fachverband Oberflächenphysik
O 20: Nano-optics of metallic and semiconducting nanostructures (time resolved)
O 20.5: Talk
Tuesday, March 24, 2009, 11:30–11:45, SCH A216
Ultrafast Coherent Control of Third-Harmonic Generation in Plasmonic Nanostructures — •Tobias Utikal1,3, Mark I. Stockman1,2, Albert P. Heberle1, Markus Lippitz3, and Harald Giessen1 — 14. Physikalisches Institut, Universität Stuttgart — 2Department of Physics and Astronomy, Georgia State University, USA — 3MPI für Festkörperforschung, Stuttgart
We present a new technique to coherently control ultrafast nonlinear plasmonic effects on a nanometer scale. By using a nonlinear four-photon process (third-harmonic generation) our detection is not limited to the local optical intensity in the system, but additionally supports phase information. The nanostructure under investigation consists of a 1-D gold wire grating on top of a dielectric slab waveguide. The coupling of particle plasmons, optically excited in the wires, to photonic waveguide modes leads to plasmon-polaritonic eigenstates, characterized by long dephasing times, whose dynamics can be coherently controlled on a femtosecond timescale. In the experiment one polaritonic eigenstate is excited by a first sub-8 fs laser pulse (start pulse). A subsequent second pulse (control pulse) follows the start pulse after a few tens of femtoseconds. Dependent on the exact phase delay, the control pulse either stops the polariton oscillation or re-excites it again. A third pulse (probe pulse), which is aligned at a small angle to the start and control pulse, is continuously shifted in time. Photons of the probe pulse together with photons of the start and control pulse create a nonlinear third-harmonic signal depending on the coherently controlled polarization of the polariton.