On Dyakonov-Voigt surface waves guided by the planar interface of dissipative materials

Dyakonov-Voigt (DV) surface waves guided by the planar interface of (i) material $A$ which is a uniaxial dielectric material specified by a relative permittivity dyadic with eigenvalues $\epsilon^s_A$ and $\epsilon^t_A$, and (ii) material $B$ which is an isotropic dielectric material with relative permittivity $\epsilon_B$, were numerically investigated by solving the corresponding canonical boundary-value problem. The two partnering materials are generally dissipative, with the optic axis of material $A$ being inclined at the angle $\chi \in [ 0^\circ, 90^\circ ]$ relative to the interface plane. No solutions of the dispersion equation for DV surface waves exist when $\chi=90^\circ$. Also, no solutions exist for $\chi \in ( 0^\circ, 90^\circ )$, when both partnering materials are nondissipative. For $\chi \in [ 0 ^\circ, 90^\circ )$, the degree of dissipation of material $A$ has a profound effect on the phase speeds, propagation lengths, and penetration depths of the DV surface waves. For mid-range values of $\chi$, DV surface waves with negative phase velocities were found. For fixed values of $\epsilon^s_A$ and $\epsilon^t_A$ in the upper-half-complex plane, DV surface-wave propagation is only possible for large values of $\chi$ when $| \epsilon_B|$ is very small.