Regensburg 2007 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 13: Symposium: Ultrafast Nanooptics II
O 13.8: Vortrag
Montag, 26. März 2007, 17:15–17:30, H38
Ultrafast polariton dynamics in metallic photonic crystal superlattices — •Tobias Utikal1, Thomas Zentgraf1,2, Jürgen Kuhl2, Sergei Tikhodeev3, and Harald Giessen1 — 14. Physikalisches Institut, Universität Stuttgart, Germany — 2MPI für Festkörperforschung, Stuttgart, Germany — 3General Physics Institute, Moscow, Russia
We present time- and frequency-resolved nonlinear autocorrelation measurements of gold nanowire photonic crystal superlattices on a dielectric waveguide layer. In these structures an external light field can excite electronic and photonic modes at the same time. A strong coupling of the two resonances leads to the formation of a polaritonic state which can further be modified by introducing a periodically structured unit-cell into the lattice. The frequency resolved measurements show a rather complex behaviour of the third harmonic signal. It consists of several spectral components, which differ in intensity and time dynamics. To describe the nonlinear processes we use a simple model, in which each resonance in the fundamental extinction spectrum is considered as an eigenmode of the polaritonic system and can be described as a Lorentzian oscillator with a certain amplitude and lifetime. The resonance frequencies of these eigenmodes can mix in the nonlinear regime, leading to third harmonic and sum frequency generation. Within this model it is possible to relate the spectral components in the higher harmonic signal to the different third harmonic and sum frequency processes. We find dephasing times of the different polariton modes which range from 10 up to 60 fs.