Formation of LiNbO3 crystals at the surface of TeO2 -based glass by YAG laser-induced crystallization

Lithium niobate LiNbO3 crystals were formed at the surface of CuO (1 mol%)-doped 25Li2O–25Nb2O5–50TeO2 glass (mol%) by heat-assisted (150 ∘C) continuous-wave Nd:YAG laser irradiations with a wavelength of λ=1064 nm. Nd:YAG laser energies absorbed by Cu2+ ions (d–d transitions) were converted to the lattice vibrations of surrounding Cu2+ ions (nonradiative relaxations), giving the increase in the temperature of the laser irradiated local region. The formation of LiNbO3 crystals was confirmed from micro-Raman scattering spectra. For the line patterned by a laser scanning with a power of 0.59 W and a speed of 6 μm/s, the possibility of a cc-axis orientation of LiNbO3 crystals along the laser scanning direction was proposed. The present study demonstrates that the combination of Cu2+ and Nd:YAG laser with λ=1064 nm, i.e. transition metal atom heat processing, is effective in inducting LiNbO3 crystals in TeO2-based glasses.