Photorefractive effect in hydrogen-reduced BaTiO₃

Optical and photorefractive properties of hydrogen-reduced BaTiO₃ are investigated. Hydrogen-reduction induced a broad optical absorption around 620 nm. From two beam coupling, the electrooptic gain is highly dependent on intensity, with electrons being the major carriers. When the annealing temperature increases, the electrooptic gain decreases, though the trap density increases. From light-induced erasure decay measurement, the response time has a little change with intensity at low intensity, though it is much faster than that of the as-grown sample. These properties can be attributed to high dark conductivity of the reduced sample. The dark conductivity increases about three orders after hydrogen-reduction. It is about 6.6 × 10^-11 1/(cm Ω) for the reduced sample, compared with 2.3 × 10-14 1/(cm Ω) for the as-grown.