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Berreman Embedded Eigenstates for Narrowband Absorption and Thermal Emission
preprintposted on 2023-11-30, 19:35 authored by Zarko Sakotic, Alex Krasnok, Norbert Cselyuszka, Nikolina Jankovic, Andrea Alú
Embedded eigenstates are nonradiative modes of an open structure with momentum compatible with radiation, yet characterized by unboundedly large Q-factors. Traditionally, these states originate from total destructive interference of radiation from two or more non-orthogonal modes in periodic structures. In this work, we demonstrate a novel class of embedded eigenstates based on Berreman modes in epsilon-near-zero (ENZ) layered materials and propose realistic silicon carbide (SiC) structures supporting high-Q (~10^3) resonances based on these principles. The proposed structures demonstrate strong absorption in a narrow spectral and angular range, giving rise to quasi-coherent and highly directive thermal emission.