Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 7: Plasmonics and Nanooptics I
O 7.7: Vortrag
Montag, 18. März 2024, 12:00–12:15, MA 043
Spectroscopic and Interferometric Sum-Frequency Imaging of Strongly Coupled Phonon Polaritons in SiC Metasurfaces — •Niclas S. Mueller1, Richarda Niemann1, Sören Wasserroth1, Guanyu Lu2, Martin Wolf1, Joshua D. Caldwell2, and Alexander Paarmann1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany — 2Department of Mechanical Engineering, Vanderbilt University, Nashville, USA
Phonon polaritons enable waveguiding and localization of infrared light with extreme confinement and low losses. Here, we introduce sum-frequency spectro-microscopy as a tool to image phonon polaritons in infrared metasurfaces with sub-wavelength spatial resolution and highly-resolved spectral resonance information.1 This is implemented by resonantly exciting polaritons using a tunable infrared free-electron laser and wide-field microscopic detection of the upconverted light. We employ this technique to image hybridization and strong coupling of localized and propagating surface phonon polaritons in metasurfaces of SiC micropillars. Spectro-microscopy allows us to measure the polariton dispersion simultaneously in momentum space by angle-dependent resonance imaging, and in real space by polariton interferometry. Notably, we directly visualize how strong coupling affects the spatial localization of polaritons, inaccessible with conventional spectroscopic techniques. We further observe the formation of edge states at excitation frequencies where strong coupling prevents polariton propagation into the metasurface.
[1] R. Niemann, N.S. Mueller et al. arXiv 2311.13284 (2023)