On the anatomy of voigt plane waves

Voigt plane waves propagate along singular optic axes in certain dissipative (and active) anisotropic dielectric materials. Mathematically, the amplitude of a Voigt plane wave exhibits a linear-exponential dependency on propagation distance, whereas the dependency is purely exponential for plane waves that propagate along directions in the neighborhood of a singular optic axis. Numerical studies were undertaken to dissect the anatomy of Voigt plane waves in dissipative biaxial dielectric materials. In particular, the manifestation of the linear-exponential dependency on propagation distance was elucidated. Both propagation in an unbounded biaxial material and reflection/transmission for a slab of biaxial material were investigated. As the direction of plane wave propagation tends toward the direction of a singular optic axis, there is a smooth variation in the electric and magnetic field phasors, and in the time-averaged Poynting vector, regardless of the state of polarization. Furthermore, reflectances and transmittances for a biaxial dielectric slab exhibit smooth variations as the propagation direction varies within the neighborhood of a singular optic axis. Therefore, in terms of amplitude dependency on propagation distance, a Voigt plane wave propagating along a singular optic axis is practically indistinguishable from a plane wave propagating along directions in the immediate neighborhood of that singular optic axis.