Dresden 2011 – scientific programme
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O: Fachverband Oberflächenphysik
O 11: Plasmonics and Nanooptics I
O 11.8: Talk
Monday, March 14, 2011, 16:45–17:00, PHY C213
Size, gap, shape, and material dependence of third harmonic generation from bowtie nanoantenna arrays — •Mario Hentschel1,2, Tobias Utikal1,2, Markus Lippitz1,2, and Harald Giessen1 — 14th Physics Institute and Research Center SCoPE, University of Stuttgart, D-70569 Stuttgart, Germany — 2Max-Planck-Institute for Solid State Research, Heisenbergstr. 1, D-70569 Stuttgart, Germany
We investigate third harmonic generation from gold bowtie nanoantenna arrays. We fabricated 9x11 arrays of 125x200 nanoantennas each, varying continuously the gap size as well as the bowtie size. Both structural parameters determine the resonance wavelength of these plasmonic dimers, leading to a wide range of resonance positions from 690 nm to 1020 nm. The linear transmittance spectra are measured by an FTIR microscope. 8 fs broadband laser pulses with a center wavelength of 820 nm are utilized to generate the third harmonic signal. We find that surprisingly the third harmonic signal does not scale with shrinking gap size as expected, but is rather a function of resonance energies in the hybridized plasmonic dimer. The third harmonic signal is strongest for maximum overlap of the extinction spectrum of the nanostructures and the laser spectrum, as well as when the plasmonic oscillator strength is largest. Furthermore we study variations of the nanoantenna system in order to gain further insight in the harmonic generation process. We are going to present resent results on the THG conversion efficiencies for different antenna designs, such as rod-, sphere-, and gap-antennas, as well as for different antenna materials.