Strong ultraviolet induced absorption and absorption gratings in BaTiO3

Efficient optical pumping of impurity levels in BaTiO3 is achieved using low intensity ultraviolet (UV) exposure. The resulting large photoinduced absorption in the visible is assessed in the context of interband charge transfer. An induced absorption of up to 12 cm−1 is observed at 633 nm. The effect, which takes place close to the UV‐exposed crystal surface, occurs on a millisecond time scale.