Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 6: Symposium: Ultrafast Nanooptics I

O 6.3: Hauptvortrag

Montag, 26. März 2007, 12:15–12:45, H38

Near-field second harmonic generation from single gold nanoparticles — •Giulio Cerullo, Michele Celebrano, Margherita Zavelani-Rossi, Paolo Biagioni, Marco Finazzi, and Lamberto Duò — Dipartimento di Fisica, Politecnico, Milano, Italy

Second-harmonic generation (SHG) from gold nanoparticles, both isolated and in high-density patterns, is investigated by a nonlinear scanning near-field optical microscope (SNOM). High peak power femtosecond polarized light pulses at the output of a hollow pyramid aperture allow efficient second-harmonic imaging, with sub-100-nm spatial resolution and high contrast. SHG on the nanoscale provides unique information on local field enhancement with respect to conventional linear SNOM and far-field microscopy. In particular, nanoscale SHG enhancement is shown to be very sensitive to localized surface plasmon resonances as well as to the morphology of the nanostructures. The combined analysis of linear and second harmonic SNOM images provides complementary information enabling to distinguish between near-field scattering, absorption and re-emission processes.