Nonlinear Phonon Polariton Spectroscopy
September 12th, 2017 ALEX PAARMANN Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society

There has been much increasing interest recently in the mid-infrared spectral response of polar dielectric crystals due to a novel branch of photonics based on surface phonon polaritons (SPhPs), which arise at the surfaces and interfaces of these materials due to the optical phonon resonances in their dielectric response. Using our in-house free-electron laser as intense and tunable infrared light source, we have developed several new approaches of nonlinear solid state spectroscopy, focusing on phonon resonances in dielectrics. Specifically, mid-infrared second harmonic generation (SHG) spectroscopy is exemplified with a model study of SiC, and used to identify optical phonon hybridization in atomic-scale heterostructures. We also apply the technique to probe the optical field enhancement associated with resonantly excited SPhPs in sub-diffractional nanostructures, as well as prism-coupled propagating SPhPs using the Otto geometry. The latter approach enables mapping of the full SPhP dispersion which, for instance, reveals a new phenomenon of tunable, strong coupling between ultrathin film polaritons and SPhPs, demonstrated for AlN films on a SiC substrate.

Seminar, September 12, 2017, 14:00. Blue Lecture Room

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