SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 52: Poster Session IV: Poster to Mini-Symposium: Infrared nano-optics II
O 52.4: Poster
Dienstag, 2. März 2021, 13:30–15:30, P
Broken Symmetry of Surface Phonon Polaritons in Monoclinic β-Gallium Oxide — •Nikolai Christian Paßler1, Tom Folland2, Joseph Matson3, Xiang Ni4, Guangwei Hu4, Martin Wolf1, Andrea Alu4, Mathias Schubert5, Joshua Caldwell3, and Alexander Paarmann1 — 1Fritz-Haber-Institute of the MPG — 2University of Iowa — 3Vanderbilt University, Nashville — 4City University of New York — 5University of Nebraska
Materials with low crystal symmetry exhibit correspondingly high optical anisotropy - a critical component for manipulating the propagation, polarization, and phase of light. Specifically, polar crystals with strong optical anisotropy in their surface plane can support in-plane hyperbolic surface phonon polaritons (h-SPhPs), featuring highly directional polariton propagation in the surface plane. So far, the investigated material systems for the observation of h-SPhPs comprise uniaxial and biaxial polar crystals with orthogonal optical axes. Yet, in low symmetry Bravais lattices such as monoclinic and triclinic systems a new class of surface polaritons featuring low symmetry are observed. Here we present Otto-type prism coupling experiments of monoclinic β-gallium oxide demonstrating the intrinsic symmetry breaking of the polariton propagation general to this material class. Furthermore, we present a theoretical approach for the description of polaritons in monoclinic crystals, revealing additional directional symmetry breaking in the polariton propagation patterns. Our results offer significant opportunities for topological photonics, as well as for exploring the anisotropic electronic properties for high power electronic devices.