On electromagnetics of an isotropic chiral medium moving at constant velocity

A medium which is an isotropic chiral medium from the perspective of a co-moving observer is a Faraday chiral medium (FCM) from the perspective of a non-co-moving observer. The Tellegen constitutive relations for this FCM are established. By an extension of the Beltrami field concept, these constitutive relations are exploited to show that planewave propagation is characterized by four generally independent wavenumbers. This FCM can support negative phase velocity at certain translational velocities and with certain wavevectors, even though the corresponding isotropic chiral medium does not. The constitutive relations and Beltrami--like fields are also used to develop a convenient spectral representation of the dyadic Green functions for the FCM

Plane waves with negative phase velocity in Faraday chiral mediums

The propagation of plane waves in a Faraday chiral medium is investigated. Conditions for the phase velocity to be directed opposite to the direction of power flow are derived for propagation in an arbitrary direction; simplified conditions which apply to propagation parallel to the distinguished axis are also established. These negative phase-velocity conditions are explored numerically using a representative Faraday chiral medium, arising from the homogenization of an isotropic chiral medium and a magnetically biased ferrite. It is demonstrated that the phase velocity may be directed opposite to power flow, provided that the gyrotropic parameter of the ferrite component medium is sufficiently large compared with the corresponding nongyrotropic permeability parameters.Comment: accepted for publication in Phys. Rev.

On the inverse homogenization problem of linear composite materials

The standard problem of homogenization consists of a derivation or estimation of the electromagnetic constitutive properties of a composite material. In that approach, the constitutive properties of the constituent materials (as specified by their respective permittivity, permeability, and magnetoelectric dyadics), their mixing ratios, and certain geometrical properties pertaining to the constituents are known. Here, the inverse problem is pursued: What information about the electromagnetic constitutive parameters of one of the constituent materials in a two-component mixture can be extracted from a knowledge of the constitutive properties of the homogenized composite medium and those of the other component material? This approach is called the inverse homogenization problem, and it is studied within the framework of linear homogenization through the Maxwell Garnett and the Bruggeman formalisms

Homogenization of biaxial composite materials: bianisotropic properties

We explore in detail the conceptualization of biaxial bianisotropic mediums through the process of homogenization. Biaxial bianisotropy is found to arise when (i) the component mediums undergoing homogenization present two non-collinear distinguished axes and (ii) the most basic form of magnetoelectric coupling in the form of isotropic chirality is present in at least one of the component mediums. Two possible sources of directionality in the component mediums are considered: (i) topological and (ii) electromagnetic. Examples of these are investigated by considering the homogenization of particulate components with (i) non-spherical topologies and isotropic electromagnetic properties and (ii) uniaxial bianisotropic electromagnetic properties and spherical topologies. A generalized biaxial bianisotropic structure, characterized by 45 real-valued parameters, is presented. Complex symmetries are found in the constitutive dyadics of the homogenized composite mediums which would not be anticipated from a familiarity with the dielectric or dielectric-magnetic case

Vector potentials and scalarization for nonhomogeneous isotropic mediums

We show that the electromagnetic field in an isotropic (dielectric–magnetic) medium that is arbitrarily nonhomogeneous can be represented in terms of two vector potentials that are solutions of a system of two second-order partial differential equations. Furthermore, we derive conditions that permit the reduction of the two vector potentials to a pair of collinear single components and we establish a connection to an alternative solution formalism in terms of scalar Hertz potentials. The reduction involves both the vector potentials and their sources

Homogenisation of isotropic, cubically nonlinear, composite mediums by the strong-permittivity-fluctuation theory: third-order considerations

The third-order strong–permittivity–fluctuation theory (SPFT) is presented for an isotropic, cubically nonlinear, composite medium, under the long-wavelength approximation. The effective permittivity of the homogenised composite medium is thereby estimated. Convergence of the SPFT at the second-order level is demonstrated with respect to both the linear and nonlinear contributions to the effective permittivity. The nonlinear SPFT is found to be relatively insensitive to the choice of covariance function. The manifestation of nonlinearity enhancement is considered up to the level of the third-order SPFT