Space-selective precipitation of silver nanoparticles in Ag2O doped silicate glass by irradiation of femtosecond laser

We report on the observation of space-selective precipitation of silver nanoparticles in the Ag2O doped silicate glass in a method of irradiation with an 800nm femtosecond laser and then heat-treatment. The irradiated portion of the glass first became gray in color after irradiation of the femtosecond laser and then turned into yellow after further heat-treatment at around 400 degreesC. An absorption peak at 402 nm observed in the absorption spectra of the irradiated and heat-treated glass indicates that silver nanoparticles have precipitated in the irradiated region of the glass. A possible mechanism has been suggested that the Ag+ ions in the region irradiated are first reduced to Ag atoms by femtosecond laser through multiphoton absorption and then accumulate to form silver nanoparticles when glass sample was heat-treated. The observed phenomenon should have potential applications in fabrication of ultrafast all-optical switch.