Preferential growth orientation of laser-patterned LiNbO3 crystals in lithium niobium silicate glass

Dots and lines consisting of LiNbO3 crystals are patterned on the surface of 1CuO–40Li2O–32Nb2O5–28SiO2 (mole ratio) glass by irradiations of continuous-wave Nd:YAG laser (wavelength: λ=1064 nm), diode laser (λ=795 nm), and Yb:YVO4 fiber laser (λ=1080 nm), and the feature of laser-patterned LiNbO3 crystal growth is examined from linearly polarized micro-Raman scattering spectrum measurements. LiNbO3 crystals with the c-axis orientation are formed at the edge parts of the surface and cross-section of dots. The growth direction of an LiNbO3 along the laser scanning direction is the c-axis. It is proposed that the profile of the temperature distribution in the laser-irradiated region and its change along laser scanning would be one of the most important conditions for the patterning of crystals with a preferential growth orientation. Laser irradiation giving a narrow width is also proposed to be one of the important factors for the patterning of LiNbO3 crystal lines with homogeneous surface morphologies.