Observation of Stimulated Emission in Short Wavelength Band from Silica-Based Superstructure Films

We report Ultraviolet (UV)-induced visible light luminescence in artificial-lattice thin films of ion-doped silica glass (silica superstructure thin films). The film was composed of periodic nanometer layers of germanium-doped silica (Ge: SiO2), titanium-doped silica (Ti: SiO2), and tin-doped silica (Sn: SiO2). The thickness of each layer was between 10 and 30nm. Despite the small thickness of the film (few microns), a relatively bright luminescence of white light was observed, along with cathode-ray luminescence in the superstructure film. In addition, irradiation of the superstructure film with UV light led to light amplification by stimulated emission at 405nm. The experimental results suggest the potential application of silica superstructure thin films as optical amplifiers.