Optically induced changes in the refractive index of ferroelectric crystals and their use in reusable holographic memories (review)

The mechanisms of light-induced changes in the refractive index in ferroelectric materials are reviewed on the basis of the models proposed by Chen, Johnston, Amodei, and Glass. The differences between these models and similarities are demonstrated. Expressions are obtained for the dependence of the change in the refractive index Δn on the radiation power density and other phenomenological parameters. These expressions are in satisfactory agreement with the experimental results. Methodological problems in the measurement of Δn and the influence of dopants as well as of thermal and electrical treatments on the value of Δn are reviewed.