Abstract

Long-range surface plasmon (LRSP) modes have been observed on very thin metal films sandwiched between two dielectrics¹ that can be excited using frustrated total internal reflection.² The intensity profile of the light in the reflected beam contains a structure caused by interference between the light reflected from the prism base and the light being reradiated by the mode. It is possible to determine the loss coefficient of the LRSP mode from this intensity profile, and if there is an interference zero in this profile, loss coefficients caused by dissipation and reradiation can also be determined.³ A computer-controlled system that locates the plasmon resonance angle and also measures the reflectance vs angle and the intensity profile from a charge-coupled-device array was used for the data acquisition. We have measured the decay constants of several thin silver films based on the intensity profile. The results are compared with the decay constant obtained from the angular width of the plasmon resonance.

© 1985 Optical Society of America