Surface electromagnetic waves with damping. I. Isotropic media

Abstract

Surface-electromagnetic-wave dispersion curves are usually calculated using a simple equation derived from Maxwell's equations and boundary conditions. When complex dielectric functions are used for the two media, the component of the propagation vector along the surface, ${k}_{x}$, becomes infinite as the frequency approaches the surface polariton frequency ${\ensuremath{\omega}}_{s}$ if $\ensuremath{\omega}$ is considered complex and ${k}_{x}$ is real. On the other hand, if ${k}_{x}$ is considered complex and $\ensuremath{\omega}$ real, the dispersion curves bend back toward smaller ${k}_{x}$ as $\ensuremath{\omega}$ approaches ${\ensuremath{\omega}}_{s}$. We have previously demonstrated that both types of behavior can be obtained from attenuated-total-reflection measurements of silver. We now extend this result to other materials and show that dispersion curves alone present an inadequate summary of the data.