Improvement of the photorefractive efficiency of BaTiO₃ by γ irradiation

We report that the photorefractive response of as‐grown BaTiO₃ crystals can be improved by γ irradiation from a Co⁶⁰ source. An increase in photorefractive response was observed with irradiation doses exceeding 10⁶ rad, with a maximum observed increase in two‐beam coupling gain of ∼15%. We interpret our results within the context of a well‐known model of photorefractivity in BaTiO₃ and conclude that γ irradiation increases the effective trap density and possibly also increases the normalized conductivity in samples where both holes and electrons contribute to photorefractivity.