It is shown that spatial gratings in photorefractive crystals, induced by the standing interference pattern of two coherent waves and an external alternating electric field, may be unstable against the excitation of weakly damped eigenmodes. The dependence of the exponential rate of growth of the instability on experimental parameters and crystal characteristics is investigated. The instability influences the amplification of the photorefractive sensitivity by an ac field. A comparison is made between theoretical results and experimental data.
© 1992 Optical Society of America
Original Manuscript: July 8, 1992
Published: November 15, 1992
B. I. Sturman, M. Mann, and K. H. Ringhofer, "Instability of spatial gratings induced by ac fields in photorefractive crystals," Opt. Lett. 17, 1620-1622 (1992)