Formation of copper and silver nanometer dimension clusters in silica by sol-gel process

Ag and Cu ~pure and/or mixture! nanoclusters doped silica films were prepared by the sol-gel process. In the case of Ag and Cu codoped silica films, Cu/Ag molar ratio was 1, 2, and 3 at constant ~Ag1Cu!/SiO2 molar ratio of 0.175. Separated Ag and Cu nanoclusters are formed in the silica matrix. The size of the clusters and their distribution are dependent on the film composition. Optical absorption was measured from 185 to 800 nm. Intensity-dependent nonlinear refractive index was measured for pure Cu and Ag–Cu ~1:1 molar ratio! samples using z-scan technique in the wavelength range from 570 to 596 nm. The measured nonlinear refractive index is of the order of 10213 m2/W at a pulse repetition rate of 15.2 MHz