Crystal growth behavior in CuO-doped lithium disilicate glasses by continuous-wave fiber laser irradiation

Crystal growth behaviors in CuO-doped Li2O-2SiO2 glasses by continuous-wave (cw) Ytterbium doped fiber laser (wavelength: 1080 nm) irradiations are examined. The lines (width: ~5 μm) consisting of highly oriented nonlinear optical lithium disilicate (Li2Si2O5) crystals are patterned in various laser powers (1.2-2.4 W) and scanning speeds (2-42 μm/s), and it is found that the crystal growth having the rates of 1 to 32 μm/s gives crystal lines with smooth surface morphologies. The critical (maximum) growth rates of Li2Si2O5 crystals in cw fiber laser irradiations are compared with the crystal growth kinetics (the reference data) in the Li2O-2SiO2 glass system determined by a conventional crystallization method in electric furnaces. It is proposed that the temperature of the fiber laser irradiated region for the Li2Si2O5 crystal growth would be 650-850°C. It is of importance to avoid crystal nucleation during laser irradiations for the patterning of homogeneous crystal lines.