Surface polaritons in magnetic metamaterials from perspective of effective-medium and circuit models
File(s)
Published version
Author(s)
Hadjicosti, K
Sydoruk, O
Maier, SA
Shamonina, E
Type
Journal Article
Abstract
Surface waves are responsible for many phenomena occurring in metamaterials and have been studied
extensively. At the same time, the effects of inter-element coupling on surface electromagnetic waves
(polaritons) remain poorly understood. Using two models, one relying on the effective-medium
approximation and the other on equivalent circuits, we studied theoretically surface polaritons
propagating along an interface between air and a magnetic metamaterial. The metamaterial comprised
split rings that could be uncoupled or coupled to each other in the longitudinal or transverse directions
(along or perpendicular to the propagation direction). A metamaterial without inter-element coupling
supported a single polariton. When a moderate longitudinal coupling was included, it changed the
wave dispersion only quantitatively, and the results of the effective-medium and the circuit models
were shown to agree at low wavenumbers. However, the presence of a transverse coupling changed
the polariton dispersion dramatically. The effective-medium model yielded two branches of polariton
dispersion at low values of the transverse coupling. As the coupling increased, both polaritons
disappeared. The validity of the effective-medium model was further tested by employing the circuit
model. In this model, surface polaritons could exist in the presence of a transverse coupling only if the
boundary layer of the metamaterial included additional impedances, which could become non-Foster.
The results reveal that the inter-element coupling is a major mechanism affecting the properties of the
polaritons. They also highlight the limitations of using bulk effective-medium parameters for interface
problems in metamaterials.
extensively. At the same time, the effects of inter-element coupling on surface electromagnetic waves
(polaritons) remain poorly understood. Using two models, one relying on the effective-medium
approximation and the other on equivalent circuits, we studied theoretically surface polaritons
propagating along an interface between air and a magnetic metamaterial. The metamaterial comprised
split rings that could be uncoupled or coupled to each other in the longitudinal or transverse directions
(along or perpendicular to the propagation direction). A metamaterial without inter-element coupling
supported a single polariton. When a moderate longitudinal coupling was included, it changed the
wave dispersion only quantitatively, and the results of the effective-medium and the circuit models
were shown to agree at low wavenumbers. However, the presence of a transverse coupling changed
the polariton dispersion dramatically. The effective-medium model yielded two branches of polariton
dispersion at low values of the transverse coupling. As the coupling increased, both polaritons
disappeared. The validity of the effective-medium model was further tested by employing the circuit
model. In this model, surface polaritons could exist in the presence of a transverse coupling only if the
boundary layer of the metamaterial included additional impedances, which could become non-Foster.
The results reveal that the inter-element coupling is a major mechanism affecting the properties of the
polaritons. They also highlight the limitations of using bulk effective-medium parameters for interface
problems in metamaterials.
Date Issued
2015-04-28
Date Acceptance
2015-04-14
Citation
Journal of Applied Physics, 2015, 117 (16)
ISSN
1089-7550
Publisher
American Institute of Physics (AIP)
Journal / Book Title
Journal of Applied Physics
Volume
117
Issue
16
Copyright Statement
Copyright © 2015 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in J. Appl. Phys. 117, 163910 (2015) and may be found at https://dx.doi.org/10.1063/1.4919072
Subjects
Science & Technology
Physical Sciences
Physics, Applied
Physics
WAVES
PERMITTIVITY
Publication Status
Published
Article Number
163910