Dyakonov hybrid surface waves at the isotropic-biaxial media interface

Dyakonov surface waves (DSWs) at the interface of an isotropic dielectric material and a biaxial dielectric crystal were considered in the case in which two principal axes of the biaxial crystal lie in the plane of the interface. Both x-cut and y-cut biaxial crystals were considered, and all permittivity scalars were assumed to be real and positive. A rather simple expression to relate the components of the wave vector of a DSW was derived, and analytical expressions for the limit angles at which the DSWs can propagate and the Poynting vector components of the DSWs were obtained. These expressions were numerically investigated for several biaxial materials. Different conditions for the relative permittivity scalars at which the DSWs can exist were identified. As an example, DSWs can exist not only for the positive, but also for the negative y-cut biaxial crystals.