Abstract

The linear optical properties of metal-dielectric composites have been the subject of extensive study,¹ in particular, for solar energy applications.² Free-electron metal-dielectric composites are seen to have a strong resonant absorption at the reduced small-particle plasma frequency. Greatly enhanced Raman scattering and second harmonic generation signals from rough free-electron metal surfaces have also been observed.³ Recently,⁴ Ricard et al, used the resonant enhancement to observe large four-wave mixing signals in an analogous system, gold colloids. We report here on what is, to our knowledge, the first use of second harmonic generation to study the nonlinear properties of gold particles. The particles, of the order of 100 Ả in diameter, are supported by an amorphous alumina matrix, a configuration which allows access to higher volume fractions of gold than are accessible in colloid form.

© 1987 Optical Society of America