Rare-earth doped transparent glass-ceramics with high cross-sections

Erbium doped oxy-fluoride glass-ceramics (50GeO2,[50−x]PbO,xPbF2) have been prepared by thermal treatments of as-melted glass. The optical absorption and emission cross-sections were measured. The controlled crystallisation of the fluoride compounds by nucleation and growth in the oxide matrix produced crystallites ∼10 nm in size and a filling factor of 10−2. The phase separation process was investigated using thermal and structural analysis. Changes were observed in the optical properties of the glass after reheating (10 h at 360°C). The inhomogeneous linewidth of the 4I15/2↔4S3/2 transition was reduced by 50% by incorporating most of the Er ions in the crystalline phase. An increase of the maximum absorption cross-section, up to 100%, was obtained at room temperature.