Coupling between finite electromagnetic beam and long-range surface-plasmon mode

Abstract

In this paper, we consider a layered structure consisting of dielectric, metal, and dielectric media and compute the fields produced in the structure by a finite width beam of incident radiation which couples to a long-range surface-plasmon mode in the metallic layer. The analysis allows for complex dielectric constants in all media and focuses on optical radiation. Curves are presented which show the profiles of the reflected field intensity for different values of the propagation length of the mode relative to the width of the incident beam. We discuss the conditions in which the field reradiated from the long-range surface mode can interfere with the specularly reflected radiation so as to produce an interference zero in the reflected profile. In these conditions our analysis allows for a determination of the separate loss coefficients of the mode associated with energy reradiation and dissipation, respectively