Dynamic light beam deflection caused by space charge waves in photorefractive crystals

During holographic recording in photorefractive crystals (BSO, EGO, and BTO ) by an oscillating interference pattern we observe a strong dynamic deflec tion of the laser beams reflected from the crystal's surface. The theoretic al treatment shows that this new effect is associated with a nonlinear inte raction of space charge gratings resulting in a quasi-homogeneous oscillati ng space charge field which provides deformations of the crystal via the pi ezoelectric effect.