Optical Activity Parameters Research Articles

New type of surface electromagnetic wave caused by the optical activity of boundary materials

This paper theoretically predicts surface electromagnetic waves on the planar interfaces of media distinguished by gyration pseudotensors that describe natural optical activity. A twinned optically active crystal of one of the planal classes 3m, 4mm, or 6mm is discussed whose halves have rotational symmetry axes that coincide in the interface but differ in the signs of the gyration pseudotensors. It is shown that a weakly localized surface wave can propagate perpendicular to the crystal’s symmetry axis. Its dispersion equation is derived, and it is established how the characteristic penetration depth depends on the optical-activity parameter.

Surface electromagnetic waves in 1D optically active photonic crystals

Surface electromagnetic waves at the interface of a semi-infinite isotropic medium and aone-dimensional photonic crystal consisting of alternating optically active layers of a planar3m,4mm, or6mm symmetry class are considered. The layers differ only in the sign of the antisymmetricmagnetoelectric pseudotensor that describes the optical activity, and their rotationsymmetry axes are perpendicular to the layer boundaries. It is shown that the surfacewaves are either TE (transverse electrically) or TM (transverse magnetically) polarized andcan be excited in the photonic crystal with arbitrarily small activity of the layers. Thedispersion equations for surface TE and TM modes are obtained in closed form. The phasevelocities of the surface electromagnetic waves are numerically calculated for thecase where one of the crystal lattice parameters (crystal period, optical activityparameter, or relative layer thickness) is varied. Depending on the sign of the activityparameter, in photonic crystals with the layers of the same thickness only oneof the polarization types (either TE or TM) is allowed for the surface modes.

Optically active surface polaritons

A new wave-vector-space method of finding electromagnetic wave propagation in bounded media without use of boundary conditions is applied to finding surface polaritons on an optically active anaxial crystal. Because a proper constitutive derivation of the optical-activity tensor shows that the quadrupolar interaction plays an important role, the continuity of the tangential component of the H field is no longer a valid boundary condition. In its absence the use of the wave-vector-space method that uses no boundary conditions is essential. Another unique aspect of the wave-vector-space method is that it derives a surface-nonlocality tensor that accounts for the altered nonlocal interaction of optical activity near the surface. The dispersion relation of the surface polariton is found to be independent of both the bulk optical-activity parameter and the surface-nonlocality parameters. The electric field profile is dependent on the bulk optical-activity parameter to first order. This dependence causes the surface polariton to lose the TM-mode character that it has in a nonoptically active crystal. Surprisingly, the surface-nonlocality parameters also disappear from the field profile to first order. This complete disappearance to first order of the nonlocality parameters is a surprising and physically unexplained result because it does not happen in the transmission and reflection problem or in the optically active waveguide problem.