Abstract
Island silver films (nanoclusters, quantum dots) embedded in silica are prepared on silicon wafers and glasses by sputtering. Atomic force microscope is used to characterize the morphology and distribution of silver nanoclusters, the size of nanoclusters varies from several ten to several hundred nanometers. Linear optical absorption spectra of annealed samples have a blue-shift compare to that of as- prepared samples, it suggests thermal treatment decomposes large clusters to small clusters. Z-scan technique is applied to study the third-order non-linear optical properties. It is found that the embedded silver nanoclusters present remarkable third order nonlinear effect even if the size of silver nanoclusters are as large as several tens to several hundreds nanometers. Thermal treatment leads to a slight reduction in NRIC, indicating annealing also dissolve tiny nanoclusters. The size distribution of silver nanoclusters therefore becomes centralized after thermal treatment.