Open AccessQuasi-confined ENZ mode in an anisotropic uniaxial thin slab
Author(s) -
Simon Vassant,
JeanPaul Hugonin,
JeanJacques Greffet
Publication year - 2019
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.012317
Subject(s) - slab , optics , anisotropy , electric field , dielectric , metamaterial , physics , condensed matter physics , materials science , perpendicular , electromagnetic field , optoelectronics , geometry , quantum mechanics , geophysics , mathematics
In this paper, we present a numerical modal study of a simple slab, made of an uniaxial anisotropic material having an "epsilon-near-zero" (ENZ) dielectric function, surrounded by vacuum. We use two Drude models with a different plasma frequency for the direction parallel and perpendicular to the slab surface as toy models to study the effect of uniaxial anisotropy of type I (∊ ‖ > 0, ∊ ⊥ < 0) and type II (∊ ‖ < 0, ∊ ⊥ > 0) on the different electromagnetic modes of the system. In addition to the so-called ENZ mode, studied in detail by Campione et. al [ Phys. Rev. B91, 121408(R) (2015)], the slab can support quasi-confined (QC) mode in the type I and type II anisotropy frequency ranges. We show that those modes exhibit a strong electric field enhancement, caused by the ENZ character of the dielectric function. In strong contrast with the ENZ mode, QC modes can have a strong electric field enhancement for thick slabs, with a Fabry-Perot-like electromagnetic field distribution spanning over the whole slab thickness. This opens the way for large electric field enhancement in thick slabs with QC ENZ modes. Thick slabs also allow metamaterial designs, giving the possibility to engineer the anisotropy of the effective dielectric function, opening interesting perspectives for the control of field enhancement of the ENZ QC modes and their integration in operating devices, such as detectors, sources, or modulators.