Abstract

We show that manipulation and selection of optical patterns is possible by a frequency detuning of the pump beams. We account for both pump and sideband frequency detunings, and derive an analytical threshold condition for the general case of a complex coupling constant considering both mirror and open boundary conditions. Our theoretical predictions are compared with experiments using a photorefractive potassium niobate crystal. We report first experimental and theoretical evidence for transverse modulational instability of two counter-propagating external beams. For the feedback mirror case, we show that a controlled pump frequency detuning allows us to switch between different patterns.

© 2001 Optical Society of America