Novel wave effects on anisotropic and ferrite planar slab waveguides in connection with singularity theory

The characteristic interactions of discrete modes supported by planar isotropic and anisotropic dielectric and ferrite slab waveguides are analyzed using singularity and critical point theory, leading to a rigorous and complete explanation of all modal interactions. For an anisotropic planar waveguide having an arbitrarily-orientated optical axis, it is shown that mode coupling is controlled by the presence of an isolated Morse critical point accompanied by a pair of complex-conjugate frequency-plane branch points. The interaction of space-wave leaky modes on a grounded anisotropic slab is studied by investigating the evolution of complex frequency-plane branch point singularities as the orientation of the optical axis varies. Space-wave leaky modes of a biased grounded ferrite slab waveguide are studied in connection with different types of branch-point singularities, resulting in the observation of novel wave effects on ferrite slabs. The general theory is presented, and numerical results are provided for some specific waveguides.