Intrinsic modes in a wedge-shaped taper above an anisotropic substrate

Intrinsic modes yield exact solutions away from the tip in a wedge-shaped taper with penetrable boundaries. Unlike adiabatic modes, they are uncoupled and pass smoothly through the cutoff transition. This model has been generalized to accommodate stratified multiwave substrates and weakly range-dependent environments. Here, a wedge-shaped taper above an anisotropic substrate is considered. In the spectral representation of intrinsic modes, the plane wave reflection coefficient from the substrate depends on the orientation of the optic axis, which, in turn, affects the cutoff condition and the direction of the leakage field in the substrate. Since the phase propagation vector and average power flow vector are usually nonparallel in anisotropic media, the field in the substrate is substantially different from that in isotropic cases