Dispersion anomalies of surface plasmons on corrugated metal-insulator interfaces

Abstract

Experiments on the anomalies in surface-plasmon dispersion on periodically modulated single- and multilayered structures are analyzed. These anomalies arise if the dispersion curves intersect in the reduced Brillouin zone. Experiments on different types of gratings and for different excitation methods, e.g., excitation by light or by electrons are discussed. It is shown that the type of anomaly depends strongly on the periodicity, depth, and profile of the surface corrugations and also on the excitation mechanism and the method of detection. Three types of anomalies were found: a momentum gap which does not depend on the type of the excitation and detection, an energy gap showing the same features, and a situation in which, depending on the applied method of detection, both momentum and energy gaps were found.