Regensburg 2016 – scientific programme
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O: Fachverband Oberflächenphysik
O 33: Photonics and Nanooptics I: Infrared Spectroscopy
O 33.8: Talk
Tuesday, March 8, 2016, 12:15–12:30, H4
Surface Phonon Polariton Localization in SiC Nano Pillars Probed by Second Harmonic Spectroscopy — •Alexander Paarmann1, Ilya Razdolski1, Joshua D. Caldwell2, Alexander J. Giles2, Sandy Gewinner1, Wieland Schöllkopf1, Stefan A. Maier3, and Martin Wolf1 — 1Fritz-Haber-Institut, Berlin, Germany — 2Navy Research Laboratory, Washington D.C., USA — 3Imperial College, London, UK
Surface Phonon Polaritons (SPhP) have recently emerged as novel building block for mid-infrared nanophotonics, promising to possibly overcome the intrinsic loss problem of plasmonics associated with the short life time of plasmonic excitations [1]. SPhPs arise in polar dielectrics from optical phonon resonances causing negative permittivity between transversal and longitudinal optical phonon frequencies. Specifically, the long life times of optical phonons allow for remarkable degrees of SPhP localization in sub-wavelength nanostructures.
Here, we show that mid-infrared second harmonic generation (SHG) spectroscopy [2] provides the most direct experimental approach to study SPhP field localization. Our experiments employ intense, tunable, and narrowband mid-infrared pulses from a free-electron laser to acquire SHG excitation spectra from SiC nanopillars. We observe sharp enhancement of the SHG yield for various resonant modes of our nanostructures. Most importantly, the measurements show much increased sensitivity of the SHG yield to field localization, as compared to linear optical approaches. [1] Caldwell et al., Nanophotonics 4, 1 (2015), [2] Paarmann et al., APL 107, 081101 (2015)