Regensburg 2022 – scientific programme
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O: Fachverband Oberflächenphysik
O 37: Plasmonics and Nanooptics 1
O 37.7: Talk
Wednesday, September 7, 2022, 12:15–12:30, H3
Observation of Hyperbolic Shear Polaritons in Monoclinic Crystals — •Giulia Carini1, Nikolai C. Passler1, Xiang Ni2, Guangwei Hu2,3, Joseph R. Matson4, Martin Wolf1, Mathias Schubert5, Andrea Alù2, Joshua D. Caldwell4, Thomas G. Folland6, and Alexander Paarmann1 — 1FHI, Berlin, Germany — 2CUNY, NY, USA — 3NUS, Singapore, Singapore — 4Vanderbilt University, Nashville, TN,USA — 5University of Nebraska, Lincoln, NE, USA — 6University of Iowa, Iowa City, IA, USA
Surface phonon polaritons, light-matter coupled waves, have recently attracted much attention due to their versatility in nanophotonic applications in the infrared. In particular, highly anisotropic materials have been shown to support hyperbolic polaritons, which enable a deep sub-wavelength confinement of light [1,2].
In our contribution, we investigate the emergence of a new class of hyperbolic surface waves, that we call hyperbolic shear polaritons (HShPs), in the monoclinic crystal β-gallium oxide (bGO) [3]. The symmetry breaking in the in-plane hyperbolic propagation is directly linked to the frequency dependence of the optical axis directions within the monoclinic plane, resulting in shear phenomena in the non-diagonalizable dielectric permittivity tensor. We experimentally demonstrate the hyperbolic in-plane dispersion of these new polariton modes by means of Otto-type prism coupling.
[1] J. D. Caldwell, et al., Nat. Commun. 5, 5221 (2014).
[2] W. Ma, et al., Nature 562, 557-562 (2018).
[3] N. C. Passler, et al., Nature 602, 595-600 (2022).