Two Dyakonov-Voigt surface waves guided by a biaxial-isotropic dielectric interface.

Electromagnetic surface waves guided by the planar interface of an orthorhombic dielectric material and an isotropic dielectric material were analyzed theoretically and numerically. Both naturally occurring minerals (crocoite, tellurite, and cerussite) and engineered materials were considered as the orthorhombic partnering material. In addition to conventional Dyakonov surface waves, the analysis revealed that as many as two Dyakonov-Voigt surface waves can propagate in each quadrant of the interface plane, depending upon the birefringence of the orthorhombic partnering material. The coexistence of two Dyakonov-Voigt surface waves marks a fundamental departure from the corresponding case involving the planar interface of a uniaxial dielectric material and an isotropic dielectric material for which only one Dyakonov-Voigt surface wave is possible. The two Dyakonov-Voigt surface waves propagate in different directions in each quadrant of the interface plane, with different relative phase speeds and different penetration depths. Furthermore, the localization characteristics of the two Dyakonov-Voigt surface waves at the planar interface are quite different: the Dyakonov-Voigt surface wave with the higher relative phase speed is much less tightly localized at the interface in the isotropic dielectric partnering material.

Dyakonov-Voigt surface waves.

Electromagnetic surface waves guided by the planar interface of an isotropic dielectric medium and a uniaxial dielectric medium, both non-dissipative, were considered, the optic axis of the uniaxial medium lying in the interface plane. Whereas this interface is known to support the propagation of Dyakonov surface waves when certain constraints are satisfied by the constitutive parameters of the two partnering mediums, we identified a different set of constraints that allow the propagation of surface waves of a new type. The fields of the new surface waves, named Dyakonov-Voigt (DV) surface waves, decay as the product of a linear and an exponential function of the distance from the interface in the anisotropic medium, whereas the fields of the Dyakonov surface waves decay only exponentially in the anisotropic medium. In contrast to Dyakonov surface waves, the wavenumber of a DV surface wave can be found analytically. Also, unlike Dyakonov surface waves, DV surface waves propagate only in one direction in each quadrant of the interface plane.