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O: Fachverband Oberflächenphysik
O 43: Plasmonics and Nanooptics III: Periodic Structures and Theory
O 43.6: Vortrag
Dienstag, 17. März 2020, 11:45–12:00, WIL A317
Polar semiconductor heterostructures as hyperbolic metamaterials — •Christopher J. Winta1, Daniel C. Ratchford2, Martin Wolf1, Joshua D. Caldwell3, and Alexander Paarmann1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany) — 2U.S. Naval Research Laboratory, Washington, D.C. (USA) — 3Vanderbilt University, Nashville, TN (USA)
We present a novel approach towards engineering the infrared dielectric response of polaritonic materials by means of atomic-scale superlattices of polar semiconductors. [1] With layer thicknesses on the order of just a few atomic monolayers, new optic phonon modes arise at the many interfaces, resulting in a unique and strongly anisotropic dielectric response of the heterostructure.
We show experimentally that these crystalline hybrids exhibit multiple spectral regions where the principal dielectric components have opposite signs. These so-called hyperbolic bands support hyperbolic phonon polariton (h-PhP) modes, i.e., large-momentum states with rigid directionality, facilitating, e.g., subdiffractional imaging by means of hyperlens designs. [2] We employ transfer-matrix calculations [3], simulating the h-PhP dispersion, showing that these modes are highly dispersive, as well as finite elements calculations, revealing their rigid directionality. The crystalline hybrid approach presents itself as a versatile platform for user-designed hyperbolic metamaterials.
[1] Ratchford, Winta et al., ACS Nano 13, 6730-6741 (2019)
[2] Liu et al., Science 23, 1686 (2007)
[3] Passler, Paarmann, JOSA B 34, 2128-2139 (2017)