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O: Fachverband Oberflächenphysik
O 53: Plasmonics and Nanooptics IV
O 53.5: Vortrag
Mittwoch, 24. März 2010, 16:00–16:15, H32
Ultrahigh temporal and spatial resolution imaging of second harmonic fields in random zinc oxide nanostructure arrays — •Manfred Mascheck1, Slawa Schmidt1, Martin Silies1, Takashi Yatsui2, Motoichi Ohtsu2, David Leipold3, Erich Runge3, and Christoph Lienau1 — 1Carl-von-Ossietzky-Universität, Oldenburg — 2University of Tokyo — 3Technische Universität Ilmenau
Among the most prominent signatures of the weak (Anderson) localization of light in random dielectric media are an enhanced coherent backscattering and the localization of electromagnetic fields in both space and time. Light localization is particulary relevant in nano-photonic materials, where it can give rise to strong field localization and greatly enhanced optical nonlinearities.
Here, we explore this light localization in densely packed, random arrays of ZnO nanoneedles with tip diameters of less than 20 nm. A phase-stabilized pair of 6 fs laser pulses is focused to its diffraction limit of 1 µm2 onto the ZnO needles.
The generated surface second harmonic (SH) spectra are detected as a function of the lateral position of the laser focus and the delay between the two pulses. We observed a pronounced spatial localization of the SH signal in hot spots of less than 300 nm dimension. We show, by retrieving the time structure of the localized electric field from interferometric FROG traces, that light is stored in these hot spots for more than 100 fs. Such nanoneedle arrays therefore present a highly interesting new model system for exploring the rich physics of weakly localized light fields.
This document was translated from LATEX by HEVEA.