Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 76: Plasmonics and Nanooptics VII

O 76.4: Talk

Thursday, March 17, 2011, 15:45–16:00, WIL A317

Octave-wide Photonic Band Gap in Three-Dimensional Plasmonic Bragg Structures — •Richard Taubert and Harald Giessen — University of Stuttgart, 4th Physics Institute and Research Center SCoPE, Pfaffenwaldring 57, 70550 Stuttgart

We investigate radiative coupling of particle plasmons in various three-dimensional, stacked geometries of plasmonic oscillators. The arrays of gold nanowires with fixed dimensions and lateral periodicity are stacked on top of each other, separated by a dielectric spacer layer. The vertical distance as well as the number of layers is varied.

The dependence of the optical spectra on spacing distance is investigated in a system consisting of two layers. We show that the coupled system exhibits a superradiant mode when the vertical distance of the oscillators matches half their emission wavelength. This means that the Bragg criterion for the particle plasmonic resonance wavelength is fulfilled.

Upon increase of the number of radiatively coupled oscillators, the spectral width of the superradiant mode increases alongside with a change of the spectral shape from Lorentzian to stop-gap like. Eventually the superradiant mode evolves into a very broad photonic band gap which spans almost over one octave.

By changing the dimensions of the gold nanowires, keeping their aspect ratio constant, the oscillator strength is modified, and therefore the radiative damping rate can be tuned. This allows for a convenient tailoring of very broad photonic band gaps.