Analyzes the model proposed for the diffusion of copper, hydrogen and titanium through potassium lithium tantalate niobate crystals. Occupation of potassium/lithium vacant sites by copper and hydrogen ions; Effect of titanium on the ability of hydrogen ions to stay at the sites; Reduction in the hydrogen ion concentration.

We present experimental evidence indicating the formation of dipolar holographic gratings in potassium lithium tantalate niobate at the paraelectric phase slightly above the phase transition, These gratings are formed in the dark, following the writing of space-charge-based photorefractive gratings, under an external electric field. The dipolar gratings create a spatial modulation of the low-frequency dielectric constant, and the latter induces a spatially correlated modulation of the polarization, which is transformed into birefringence gratings through the quadratic electro-optic effect. (C) 1997 Optical Society of America.

Examines the formation of Barkhausen spikes in volume phase holograms of potassium lithium tantalate niobate crystals. Effect of ferroelectric domain reversal induced by photorefractive space charge fields; Measurement of displacement currents; Changes in diffraction efficiency during a single macrodomain switching.

We predict spatial solitons in photorefractive centrosymmetric media driven by the dc Kerr effect.