Berreman Embedded Eigenstates for Narrow-Band Absorption and Thermal Emission
Zarko Sakotic, Alex Krasnok, Norbert Cselyuszka, Nikolina Jankovic, Andrea Alú
Abstract
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 nonorthogonal modes in periodic structures. In this work, we demonstrate a class of embedded eigenstates based on Berreman modes in epsilon-near-zero layered materials and propose realistic silicon carbide structures that support high-Q ($\ensuremath{-}{10}^{3}$) resonances based on these principles. The proposed structures demonstrate strong absorption in a narrow spectral and angular range, giving rise to quasicoherent and highly directive thermal emission.