Abstract

Experiments show that irradiating photorefractive BaTiO₃ with γ-rays can increase the photorefractive efficiency of some crystals. We measured the two-beam coupling gain as a function of grating period for two crystals, irradiated both crystals with γ-rays from a ⁶⁰Co source, and repeated the two-beam coupling gain measurements. This sequence was repeated for irradiation doses totaling 10⁵, 10⁶, 10⁷, and 10⁸ rad (water). Results of the measurements showed no change in one crystal. The second crystal showed a marked improvement in photorefractivity; however, this increase saturated at an irradiation of 10⁷ rad. All of our results are explained by a model that assumes dual photoactive species in BaTiO₃, only one of which is affected by the γ-irradiaion.

© 1992 Optical Society of America