Temperature dependence and fixing study of volume gratings in the photorefractive barium titanate

Photorefractive materials have received a great deal of attention because of their potential applications in optical information processing and volume hologram storage. The large electro-optic coefficient of the photorefractive barium titanate makes it of great interest in optical computing for storage and amplification. It has been reported that its relatively slow response time can be improved by increasing the temperature of the crystal, and that some degree of hologram fixing may be possible. But in the standard model for photorefractive effect, Kukhtarev's Band Transport Model, there is no explicit expression for temperature dependence, and a well-understood model for temperature effects is not yet available. In trying to better understand the temperature dependence theoretically and experimentally, we have made measurements of temperature dependencies. These are based on non-degenerate four-wave mixing and self-pumped phase conjugation experiments, and changes in response times and decay times and diffraction efficiency, as a function of temperatures ranging from room temperature to about 100{dollar}spcirc{dollar}C. These results are presented and discussed. A possible fixing method is also presented following these discussions.