Negative index and mode coupling in all-dielectric metamaterials at terahertz frequencies
Institut d'Electronique Fondamentale, Univ. Paris-Sud, Universite Paris-Saclay,
2 UMR 8622, CNRS, 91405 Orsay, France
* Corresponding author: e-mail: firstname.lastname@example.org
Received in final form: 10 July 2018
Accepted: 18 July 2018
Published online: 24 October 2018
We elucidate the role of the mode coupling of the Mie resonances in all-dielectric metamaterials to ensure a negative effective index at terahertz frequencies. We perform a study as a function of the lattice period and of the frequency overlapping of the modes of resonance. We show that negative effective refractive index requires sufficiently strong mode coupling and that for even more strong mode coupling, the first two modes of Mie resonances are degenerate; the effective refractive index is then undetermined. We also show that it is possible to obtain near-zero, or even null, effective index with a judicious adjustment of the mode coupling. Further, we discuss the mode coupling effect with hybridization in metamaterials.
Key words: All-dielectric metamaterials / Negative index / Mode coupling / Near-zero refractive index
© E. Akmansoy and S. Marcellin, published by EDP Sciences, 2018
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.