GROWTH AND CHARACTERIZATION OF PHOTOREFRACTIVE BI12TIO20 SINGLE-CRYSTALS

Photorefractive Bi12TiO20 single crystals of high optical quality were grown in a resistive heating furnace from high temperature nonstoichiometric (10:1) solutions of Bi2O3 and TiO2 at pulling rates 0.3-0.8 mm/h at rotation 20-30 rpm along the [001] and [011] 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) Angstrom. The chemical composition of the crystals can be written down as Bi12.1+/-0.2Ti0.96+/-0.09O20.1. Natural optical activity, rho of BTO crystals is 6.3 +/- 0.2 deg/mm at lambda = 0.633 mu m and 11.9 +/- O.2 deg/mm at lambda = 0.5145 mu m, optical absorption coefficient alpha = 0.42 +/- 0.04 cm(-1) at lambda = 0.633 mu m and linear electro-optic coefficient gamma 41 = gamma 52 = gamma 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 lambda = 0.633 mu m for 2 x 3 mW input light power.