Saffman, MarkMcCarthy, GlennKrolikowski, Wieslaw2015-12-131464-4266http://hdl.handle.net/1885/87244We study theoretically and experimentally the modulational instability of broad optical beams in photorefractive nonlinear media. The angular dependence of the growth rate of periodic perturbations is calculated. Our findings are confirmed by experimental measurements on a strontium barium niobate photorefractive crystal.Keywords: Approximation theory; Laser beams; Light modulation; Light propagation; Nonlinear equations; Nonlinear optics; Perturbation techniques; Strontium compounds; Photorefractive media; Self-focusing; Photorefractive materials Instabilities; Photorefractive nonlinear optics; Self-focusing200410.1088/1464-4266/6/5/0302015-12-12