Isotropic Permittivity Research Articles

On the treatment of the propagation of electromagnetic waves in an isotropic inhomogeneous dielectric medium as waves in a medium with effective anisotropy described by the permeability tensor

We show that plane E and H waves in a smoothly inhomogeneous isotropic plane-stratified medium (plasma) can be considered as normal waves in a uniaxial medium with isotropic permittivity and effective-permeability tensor.

Coupled phonon-photon excitations in semiconductor superlattices

Coupled phonon-photon excitation field structure and dispersion in binary semiconductor superlattices are studied using a local theory with retardation. The material layers are characterized by the frequency-dependent isotropic dielectric permittivities. Numerical calculations have been carried out for GaAs/AlAs superlattices with the layer thickness ratio d 1/ d 2 < 1 and d 1/ d 2 > 1 in the case of in-plane propagation of p-polarized electromagnetic waves. Seven main dispersion branches and two series of additional ones related to confined modes are obtained. The latter are found to exist just below the transverse optical phonon frequencies of constituent materials. The branches characterized by different types of filed symmetry are found to intersect in the absence of damping. The conditions of the crossing points existance are estimated.

Microscopic treatment of substrate effects on linear optical properties of model Langmuir–Blodgett films

An algebraic treatment is developed for the effect of a plane substrate with isotropic relative permittivity on the linear optical response of layers of molecules treated as sets of point submolecules so as to incorporate molecular elongation and orientation. Results are modified from those for free-standing films by planewise sums describing the field at a dipole due to its image in the substrate. Numerical calculations of refractive indices are performed for a monolayer of molecules initially packed in a tetragonal structure normal to the substrate and then tilted to yield monoclinic structures. The head-group polarizability is varied relative to that of the other submolecules, as is the spacing between the layer and the substrate. Substrate effects are largest when a very polarizable head group of a tilted molecule is adjacent and very close to the substrate; in extreme cases the refractive indices diverge. The results support the idea that first-layer effects on optical properties could be dielectric as well as structural in origin.

Plane‐wave propagation in an anisotropic chiral medium with isotropic permittivity and permeability

AbstractPlane‐wave propagation in an anisotropic chiral medium with isotropic permittivity and permeability and symmetric chirality dyadic is considered. The eigenvalue equation is formed and the wave numbers and the corresponding eigenpolarizations are given. The results make possible the construction of a polarization transformer in which one can also choose the handedness. © 1994 John Wiley &amp; Sons, Inc.

Green dyadic and dipole fields for a medium with anisotropic chirality

A closed-form expression is derived for the Green dyadic corresponding to a reciprocal bianisotropic medium with isotropic permittivity and permeability and arbitrary anisotropic chirality. Such a medium can be approximated, for example, by inserting in an isotropic host medium an equal number of similar right- and left-handed metal helices with suitable orientations. The solution is applied to determine the electric field of an electric dipole embedded in such a medium. Evaluation of its far-field shows that the wave is split into two plane waves with different wave-normal directions.