Abstract

According to the theory of two-beam coupling in a thick Kerr medium, which is based on the firstorder coupled-wave method,¹ the energy exchange between the two incident beams is forbidden because the phase shift between the intensity grating and refractive-index grating is zero in the Kerr media. The energy exchange must be achieved by artificially creating a phase shift, e.g., by moving the intensity grating with respect to the medium at a speed of the order of one fringe per response time of the medium.

© 1987 Optical Society of America