Refractive index change in Al+-ion-implanted silica glass

Abstract
Al+ ions have been implanted in silica glass at an acceleration energy of 200 eV and doses ranging from 1×1013 to 1×1017 ions cm−2. Infrared reflection spectra and ultraviolet, visible, and near‐infrared absorption spectra have been measured. It was found that refractive index of silica glass increased by 6%–10% after implantation of 1×1017 Al+ ions cm−2. It was deduced that this refractive index change is caused by the formation of Si—Si homobonds, but not by the decrease in Si—O—‐Si bond angle which leads to compaction.