UV-assisted crystallisation of tellurite and germanate-based glasses

Glass ceramics, which are of significant interest for the production of new optoelectronic devices, are usually obtained by heat treatment of a glass at the crystallisation temperature. We show in this paper that partition of Er3+ ions into crystal nanophase can also be achieved by irradiating tellurite or germanate-based glasses with a cw UV laser during annealing treatment performed at a temperature lower than the crystallisation temperature. Thermal differential analysis is used to measure the crystallisation temperatures of these two kinds of glasses. Sharp fluorescence peaks characteristic of a crystal-like structure reveal the successful crystallisation of the glass after UV exposure. The intensity of the red emission, due to the 4F9/2 → 4I15/2 transition of the Er3+ ions, is used to prove that UV exposure leads to a higher fraction of active ions into crystals than in case of pure thermal annealing.