Writing of crystalline dots and lines in Sm₂O₃ doped borate and tellurite glasses by YAG laser irradiation and their optical properties

Crystalline dots and lines such as Sm₂Te₆O ₁₅ and β-BaB₂O₄ were written in Sm ₂O₃ containing glasses by irradiation from a continuous Nd: YAG laser operating at a wavelength of 1064 nm, and their morphologies and nonlinear optical properties were examined. It was found that the crystalline phases formed by YAG laser irradiations were the same as those in crystallised glasses obtained by heat treatment in an electric furnace. Crystalline dots with corn-like shapes were formed, and their size depended on laser power, laser irradiation time and Sm₂O₃ content in glass. A close relation between dot size/length(depth) and cube root of laser irradiation time t¹¹³ was found, suggesting that the growth of crystalline dots is controlled by diffusion of ions. Crystal lines of β-BaB₂O ₄ were written by scanning YAG laser, and it was demonstrated from second harmonic generation measurements that the lines are β-BaB ₂O₄ single crystals with the c-axis orientation along the laser scanning direction. The present study proposes that Nd: YAG laser irradiations of Sm₂O₃ containing glasses has a great potential for spatially selected crystallisation.