Chiral waves in a metamaterial medium

Résumé

The conventional metamaterials require both negative permittivity (ε) and negative permeability (μ), to achieve negative refraction. Chiral metamaterial is a new class of metamaterials offering a simpler route to negative refraction. In this paper, we review the history of metamaterials and the developments on chiral metamaterials. We study the wave propagation properties in chiral metamaterials and show that negative refraction can be realized in chiral metamaterials with a strong chirality, with neither permittivity (ε) nor permeability (μ) negative required. We have developed a retrieval procedure, adopting a uniaxial bi-isotropic model to calculate the effective parameters such as of the chiral metamaterials. In this paper we study the anomalous refraction at the boundary of a metamaterial medium with strong chirality. The fact that for a time-harmonic monochromatic plane wave the direction of the Poynting vector is antiparallel with the direction of phase velocity, leads to exciting features that can be advantageous in the design of novel devices and components at microwaves frequencies. This work is concerned with the propagation of electromagnetic waves in isotropic chiral media and with the effects produced by a plane boundary between two such media. In analogy with the phenomena of reflection and refraction of plane electromagnetic waves in ordinary dielectrics, the kinematical and dynamical aspects of these phenomena are studied, in situations such as the intensity of the various wave components and the change in the polarization of the wave, as it crosses the boundary. This research might be applied to the design of very high frequency microwaves and non symmetrical transmission lines. In our work, the design, numerical calculations and experimental measurements of chiral metamaterials is introduced. Strong chiral behaviours such as optical activity and circular dichroism are observed and negative refraction is obtained for circularly polarized waves in these chiral metamaterials. We show that 3D isotropic chiral metamaterials can eventually be realized. © 2010 SPIE.