Growth and characterization of photorefractive Bi12TiO20 single crystals

Photorefractive Bi 12 TiO 20 single crystals of high optical quality were grown in a resistive heating furnace from high temperature nonstoichiometric (10: 1) solutions of Bi 2 O 3 and TiO 2 at pulling rates 0.3-0.8 mm/h at rotation 20-30 rpm along the and axis. Powder X-ray analysis, Laue method, and electron-probe microanalysis were used for characterization. BTO crystals have the bcc structure of sillenite type with a 0 = 10.178(8) A. The chemical composition of the crystals can be written down as Bi 12.1±0.2 Ti 0.96±0.09 O 20.1 . Natural optical activity ρ of BTO crystals is 6.3 ± 0.2 deg/mm at λ = 0.633 μm and 11.9 ± 0.2 deg/mm at λ = 0.5145 μm, optical absorption coefficient α = 0.42 ± 0.04 cm −1 at λ = 0.633 μm and linear electro-optic coefficient r 41 = r 52 = r 63 = 5.3 pm/V. Fanning effect in the «fiber-like» BTO sample was studied and double phase conjugation with conversion efficiency up to 8% was observed in a wide range of incidence angles of the pump at λ = 0.633 μm for 2 × 3 mW input light power