Dresden 2011 – scientific programme
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DS: Fachverband Dünne Schichten
DS 37: Plasmonics and Nanophotonics O-IV (jointly with HL and O)
DS 37.3: Talk
Wednesday, March 16, 2011, 11:45–12:00, WIL A317
Ultrafast optical nonlinearities in hybrid metal-semiconductor nanostructures — •Parinda Vasa1, Robert Pomraenke1, Giovanni Cirmi2, Elenora De Re2, Wei Wang1, Stephan Schwieger3, David Leipold3, Erich Runge3, Giulio Cerullo2, and Christoph Lienau1 — 1Institut für Physik, Carl von Ossietzky Universität Oldenburg, Germany — 2IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Milano, Italy — 3Institut für Physik and Institut für Mikro- und Nanotechnologien, Technische Universität Ilmenau, Germany
Understanding and manipulating the interactions between quantum emitters and surface plasmon polaritons (SPPs) is the key to designing and implementing novel nano-optical devices. We report the measurements of ultrafast optical nonlinearity resulting from the strong interaction between SPPs on a gold grating and excitons in either a semiconductor QW or a J-aggregated cyanine dye. The hybrid structures are characterized by linear reflectivity measurements and exhibit enhanced SPP-exciton coupling. The nonlinearity is investigated by low-temperature, angle-resolved, ultrafast pump-probe spectroscopy under different excitation schemes. Strong optical excitation drastically alters the hybrid nanostructure response by transiently changing the exciton density. A significant shift in the polariton resonance wavelength and changes in the response time are observed. The results are explained within a semi-classical density matrix formalism. Such a strong ultrafast nonlinear interaction between SPPs and excitons will be of key importance in adding active functionality to plasmonic devices.