Space-selective enhancement of blue photoluminescence in gallium germanosilicate glass through laser-induced nanostructuring

Crystalline gallium oxide is known to possess UV-excited blue photoluminescence together with one of the widest band gaps among transparent conducting oxides, with a transmittance range extending from the visible to the near-UV range, thus making it a promising material for efficient solar-blind UV-to-visible converters. In the present paper, we report for the first time laser-induced space-selective precipitation of γ-Ga2O3 nanosized crystals in alkali gallium germanosilicate glass using a sum frequency beam (271 nm) of a copper vapor laser. At the glass surface, the laser writing process generates transparent nanostructured channels which emit broadband blue photoluminescence (centered at about 460 nm) under UV exposure, with excitation efficiency peaked at about 260 nm. Only much weaker blue photoluminescence can instead be observed in the starting non-irradiated glass from the precursor stage of the nanocrystallization. Spectral properties of light emission in the nanocrystallized regions are similar to those of earlier studied bulk nanostructured material produced from the same composition by heat treatment. Laser-written photoluminescent patterns in the studied glass provide advanced opportunities for developing novel solar-blind UV detectors.