High photorefractive sensitivity in an n-type 45°-cut BaTiO_3 crystal

We report the beam-coupling properties of a cobalt-doped oxygen-reduced n-type barium titanate crystal in the 0° and 45° crystallographic orientations. Oxygen reduction improved the response time of the 0°-cut crystal by a factor of ~4.5 without diminishing the beam-coupling gain. The 45°-cut crystal has a peak gain of ~38.7 cm−1, a response time of ~21 ms, and a photorefractive sensitivity of 3.44 cm3/kJ. We infer from response time measurements an equivalent percentage change in the dc dielectric constant and the mobility with respect to crystallographic orientation.