Effects of a transition layer on slab polaritons

Dispersion relations are derived for polaritons in a dielectric slab, coated with a transition layer (thickness 20 to 150 Å), on a substrate. If \documentclass{article}\pagestyle{empty}\begin{document}$ \[{\tilde \varepsilon }\] $\end{document} 1(ω) is the dielectric function of the transition layer a splitting of the dispersion curves occurs for resonances of the form \documentclass{article}\pagestyle{empty}\begin{document}$ \[{\tilde \varepsilon }\] $\end{document} (ω ⟂) = ∞ and \documentclass{article}\pagestyle{empty}\begin{document}$ \[{\tilde \varepsilon }\] $\end{document} (ω∥) = 0 in the case of p‐polarized polaritons. In the case of s‐polarized polaritons the splitting is obtained only for resonances of the form \documentclass{article}\pagestyle{empty}\begin{document}$ \[{\tilde \varepsilon }\] $\end{document} (ω ⟂) = ∞.