Dresden 2009 – scientific programme
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O: Fachverband Oberflächenphysik
O 20: Nano-optics of metallic and semiconducting nanostructures (time resolved)
O 20.9: Talk
Tuesday, March 24, 2009, 12:30–12:45, SCH A216
Ultrafast optical nonlinearities in hybrid metal-J-aggregate nanostructures — •Parinda Vasa1, Robert Pomraenke1, Stephan Schwieger2, Erich Runge2, and Christoph Lienau1 — 1Carl von Ossietzky Universitaet, Institut fuer Physik, 26111 Oldenburg, Germany — 2Technische Universitaet Ilmenau, Institut fuer Physik, 98684 Ilmenau, Germany.
We report the first measurement of an ultrafast optical nonlinearity resulting from the strong interaction between Surface Plasmon Polaritons (SPPs) excited on a gold grating and excitons in a J-aggregated cyanine dye. The hybrid metal-J-aggregate nanostructure is fabricated by spin coating the dye solution on a gold grating fabricated using a focused ion beam. The hybrid structures are characterized using far-field linear reflectivity as well as photoluminescence measurements and exhibit enhanced SPP-exciton coupling in the linear optical regime. The nonlinearity is investigated by low-temperature, angle-resolved, ultrafast pump-probe spectroscopy with 20-fs-time resolution. The strong coupling results in a significant shift in the response wavelength and changes in the response time of the third order nonlinearity of the dye exciton are observed. Specifically, we observe, under certain resonance conditions, extremely strong, more than tenfold changes of the radiative lifetime of the dye exciton due to its coupling to SPP. Such a strong ultrafast nonlinear interaction between metal and excitons will be of key importance to amplify SPP excitations in such hybrid structures.