Optical excitation of both the symmetric and antisymmetric surface plasma waves (SPW) of a plasma layer has been observed in the p-polarized attenuated total reflection (ATR) angular spectra of a three film system (cryolite–Ag–cryolite) evaporated onto the base of a glass prism. The relative strengths of the two SPW reflectance resonances depend on the thicknesses of the cryolite films. In addition the ATR spectra of both p- and s-polarizations contain resonances due to excitation of guided light modes localized in the second dielectric layer, and the progression of the guided mode resonances is studied in transmittance as well as reflectance. Detailed calculations of the Poynting vector field help in understanding discrepancies between theory and experiment thought to be due largely to optical inhomogeneities of the cryolite films. A simple model of thin cermet layers at the metal–dielectric interfaces accounts qualitatively for the observed discrepancies in position and intensity of the resonances.
Optical excitation of surface plasma waves without grating structures