A new scheme for spontaneous formation of hexagonal optical patterns in photorefractive crystals with dominant reflection gratings and a single pump wave is proposed and realized experimentally. It is shown theoretically that spontaneous hexagon formation results from random small-angle scattering of the pump wave inside the crystal. The threshold of spontaneous hexagon formation is found.
© 1999 Optical Society of America
P. M. Lushnikov and A. V. Mamaev, "Spontaneous hexagon formation in photorefractive crystal with a single pump wave," Opt. Lett. 24, 1511-1513 (1999)