Direct dark mode excitation by symmetry matching of a single-particle based metasurface

This paper makes evidence for direct dark mode excitation mechanism in a metasurface structure. The dark mode excitation mechanism is entirely determined by structures' symmetry and does not depend on near-field coupling between elements. In our examples, we consider single element based metasurface composed of two V antennas connected in an anti-symmetric arrangement. Both experimental and modeling results show an efficient excitation of magnetic dipolar mode in such structures. The direct dark mode excitation mechanism provides a design that is more robust with respect to technology imperfections. The considered approach opens promising perspectives for new type of nanostructure designs and greatly relaxes fabrication constraints for the optical domain.Comment: 21 pages, 5 figure

Structures périodiques et métamatériaux. Antennes et dispositifs électromagnétiques.

Ce manuscrit présente une synthèse de mes travaux de recherche effectués depuis l’obtention de mon doctorat en Novembre 2005. Il détaille les différents cadres de ces travaux, notamment si les projets ont été effectués en collaboration avec d’autres groupes de recherche universitaires ou industriels et si les projets se déroulaient sur le plan national ou international. S’y trouve aussi une liste détaillée des différents encadrements auxquels j’ai contribué, ainsi qu’une liste de mes publications en relations avec mes travaux de recherche. Les publications majeures de cette liste sont regroupées dans un document annexe.Mes travaux de recherche, qui sont effectués dans le domaine des microondes, sont regroupés sous deux thèmes bien distincts :1. Métasurfaces et antennes,2. Structures à gradient, antennes et dispositifs microondes

Ultra directive antenna via transformation optics

Spatial coordinate transformation is used as a reliable tool to control electromagnetic fields. In this paper, we derive the permeability and permittivity tensors of a metamaterial able to transform an isotropically radiating source into a compact ultradirective antenna in the microwave domain. We show that the directivity of this antenna is competitive with regard to conventional directive antennas horn and reflector antennas, besides its dimensions are smaller. Numerical simulations using finite element method are performed to illustrate these properties. A reduction in the electromagnetic material parameters is also proposed for an easy fabrication of this antenna from existing materials. Following that, the design of the proposed antenna using a layered metamaterial is presented. The different layers are all composed of homogeneous and uniaxial anisotropic metamaterials, which can be obtained from simple metal-dielectric structures. When the radiating source is embedded in the layered metamaterial, a highly directive beam is radiated from the antenn

Waveguide taper engineering using coordinate transformation technology

Spatial coordinate transformation is a suitable tool for the design of complex electromagnetic structures. In this paper, we define three spatial coordinate transformations which show the possibility of designing a taper between two different waveguides. A parametric study is presented for the three transformations and we propose achievable values of permittivity and permeability that can be obtained with existing metamaterials. The performances of such defined structures are demonstrated by finite element numerical simulations

High-Q Fano resonances via direct excitation of an antisymmetric dark mode

International audienc

Directive metamaterial-based subwavelength resonant cavity antennas – Applications for beam steering

International audienceThis article presents the use of composite resonant metamaterials for the design of highly directive subwavelength cavity antennas. These metamaterials, composed of planar metallic patterns periodically organized on dielectric substrates, exhibit frequency dispersive phase characteristics. Different models of metamaterial-based surfaces (metasurfaces), introducing a zero degree reflection phase shift to incident waves, are firstly studied where the bandwidth and operation frequency are predicted. These surfaces are then applied in a resonant Fabry-Perot type cavity and a ray optics analysis is used to design different models of ultra-compact high-gain microstrip printed antennas. Another surface presenting a variable reflection phase by the use of a non-periodic metamaterial-based metallic strips array is designed for a passive low-profile steering beam antenna application. Finally, the incorporation of active electronic components on the metasurfaces, allowing an electronic control of the phase responses, is applied to an operation frequency reconfigurable cavity and a beam steering cavity. All these cavity antennas operate on subwavelength modes, the smallest cavity thickness being of the order of lambda/60. To cite this article: A. Outir et al., C R. Physique 10 (2009). (C) 2009 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved