Laser patterning and enhanced red photoluminescence of Er3+/Yb3+ co-doped CaF2 crystal dots and lines in oxyfluoride glasses

Abstract

The laser-induced crystallization method is applied to Er 3+ /Yb 3+ co-doped oxyfluoride glasses, and dots and lines consisting of CaF 2 crystals are patterned on the glass surface in order to clarify whether co-doping of different rare-earth ions (Er 3+ and Yb 3+ ) is possible even into laser-patterned fluoride crystals. The morphology (bump's height and width) of dots and lines formed by laser (continuous-wave Yb:YVO 4 fiber laser with a wavelength of 1080 nm) irradiations is examined from confocal scanning laser microscope observations. It is found that the intensity of photoluminescence peaks corresponding to the 4 F 9/2 → 4 I 15/2 transition (red) of Er 3+ ions in the laser-patterned CaF 2 crystals in Er 3+ /Yb 3+ co-doped glasses are enhanced largely compared with laser-patterned CaF 2 crystals in only Er 3+ -doped glasses, suggesting that both Er 3+ and Yb 3+ ions might be incorporated into CaF 2 crystals. The present study proposes that the laser irradiation technique is extremely effective in crystallizing rare-earth doped fluoride crystals in oxyfluoride glasses.