Optical absorption of Co2+-doped silica gel-derived glasses

Abstract Monolithic samples of silica and Co-doped silica gels were obtained by the sol–gel method and heat-treated at temperatures from 40 to 1000 °C. The colors of Co-doped silica samples depended on heat-treatment temperature. Ultraviolet, visible and near-infrared (NIR) absorption spectra of the samples heated at different temperatures were recorded and compared with those of undoped silica samples. Results showed that 0.4 wt.% Co-doped silica samples heated at temperatures ranging 750–1000 °C exhibited broad absorption band in the range of 1200–1600 nm, and the intensity of the absorption band increased with heat-treatment temperatures. Co-doped silica glass is potential to be used as a kind of laser passive Q-switching material in NIR range.