Abstract

When exciting surface plasmon waves along thin metal films by means of a light beam, the procedure often used is to adjust the incidence parameters to minimize the reflected field. Such incidence conditions are assumed to maximize the power coupled into the plasmon field, but they imply that the incoming flux is matched to a complex zero of the reflectance function. However, maximum intensity is achieved for the plasmon field if the incident flux is matched to a complex pole of the reflectance function rather than to a complex zero. This general conclusion agrees with recently reported results¹ for plasmons in iron films. We found that the difference between the incidence angles for the two (zero or pole) situations can be substantial; this difference is strongly dependent on the configuration used to support the plasmon wave, and, in each geometry, it is generally larger for metals with greater damping loss.

© 1987 Optical Society of America