Transmission of Light Through Thin Silver Films Via Surface Plasmon-polaritons

We report results of measurements and calculations that help to clarify the role of surface plasmon-polariton modes in the transmission of light through thin continuous films of silver. Our experimental data show that there is an optimum silver film thickness for which transmission is maximal. We offer an explanation of this phenomenon in terms of competition between increasing absorption in the metal and increasing optical field-enhancement due to surface plasmon-polariton excitation as the metal film thickness is increased. We find no need to invoke the regeneration of evanescent waves as has recently been suggested.