Abstract

Degenerate four-wave mixing measurements on gold particles with sizes ranging from 5 to 30 nm are presented. Conjugate reflectivities were found to be independent of particle size in contrast to theoretical predictions based on quantum size effects which predicts χ⁽³⁾ is proprtional to 1/r³. Time response measurements reveal a fast and a slow component. The fast component was shorter than the pulse duration (30 ps) while the slow component was size dependent. A possible mechanism for the fast response is "Fermi smearing"¹ and for the slower response a thermooptic mechanism based on lattice heating.

© 1989 Optical Society of America