Abstract

The electromagnetic origin of surface enhanced Raman scattering (SERS) may involve local or delocalized surface plasmons (SP). We consider here grating excited delocalized SP. It is known that these SP may be resonantly excited leading in this way to enhanced Raman scattering. It has been even predicted that there exists an optimum groove depth of the grating for which the Raman efficiency is the greatest [1]. To the best of our knowledge, this effect has only been observed in the case of a prism coupler in the Kretschmann configuration where an optimum Ag-thickness has been found[2]. In this Communication, we report on optimized SERS at a coated grating of variable groove depth. We also show that, when optimization is achieved and SP resonance occurs, the Raman process is no longer a spontaneous one but becomes stimulated.

© 1995 Optical Society of America