Non-Linear Optical Response of Metallic and Emiconducting Nanocrystals in Fused Silica

The linear and nonlinear optical properties of Ge-implanted fused-silica were examined and compared with Au- and Si-implanted samples. Samples as-implanted with 1.0 MeV Ge ions to a fluence of 3x1017 Ge.cm-2 exhibited relatively large non-linearities, |n2| ≤5x10-12 cm2/W, and fast relaxation times, ∼lps. In contrast, samples implanted with comparable fluences of Au ions exhibited smaller non-linearities, |n2| ∼1x10-13 cm2/W, and slower response times, ≥ 10ps. The non-linearity for Ge was much larger than that for samples as-implanted with Si.