Synthesis of β-BaB2O4 thin films from a metallorganic precursor

β-BaB 2 O 4 (β-BBO) thin films have been successfully synthesized by the sol–gel method from a BBO precursor solution. A stable BBO precursor solution was prepared from barium metal and boron triethoxide in a mixed solvent of ethanol and 2-ethoxyethanol. The precursor films crystallized into β-BBO on glass (Corning 7059) and fused silica substrates at 550 °C. BBO films on glass (Corning 7059) and fused silica substrates showed a highly (006) preferred orientation. The absorption edge of β-BBO films on fused silica substrates was at <190 nm. The β-BBO films on glass (7059) and fused silica substrates showed second harmonic generation (SHG) of 532 nm light upon irradiation with 1064 nm Nd:YAG laser light. The SH power from the BBO films has been correlated with the fundamental power through the square-law proportionality based on theory.