Two-Dimensional Mapping of Er3+ Photoluminescence in CaF2 Crystal Lines Patterned by Lasers in Oxyfluoride Glass

The laser‐induced crystallization method is applied to an oxyfluoride glass with the composition of 41.5SiO2–21.3Al2O3–4.8CaO–12.6NaF–16.4CaF2–2.9NiO–0.5ErF3 (mol%), and the lines consisting of CaF2 nanocrystals (diameter: ∼20 nm) are patterned on the glass surface. It is found from micro‐photoluminescence (PL) spectra of Er3+ ions that Er3+ ions are incorporated into CaF2 nanocrystals formed by laser (continuous‐wave Yb:YVO4 fiber laser with a wavelength of 1080 nm) irradiations. Two‐dimensional mappings of the PL intensity for the 4S3/2→4I15/2 transition of Er3+ ions are measured for the surface and cross section of the patterned lines. It is found that two phases giving different PL intensities are formed in the laser‐irradiated region, suggesting that the center part of the laser‐irradiated region consists of Er3+‐doped CaF2 nanocrystals and the surrounding of the center part gives the fluoride ion rich coordination state for Er3+ ions. The formation mechanism of Er3+‐doped CaF2 nanocrystals is related to the temperature distribution of the laser‐irradiated region.