Effectiveness of noncoplanar Raman–Nath self-diffraction in resonant media

A theoretical analysis is made of noncoplanar four-beam Raman–Nath self-diffraction in media with saturable absorption. The mechanisms responsible for the generation of the first- and second-order diffracted beams are identified. The intensities of the diffracted beams not lying in the planes of convergence of the exciting beams can, for certain phase relationships, be considerably higher (by a factor of ~ 10²) than the intensities of the beams in these planes. The reason for the dependence of the effectiveness of self-diffraction on phase relationships between the excited beams is interference between elementary diffraction processes in various light-induced gratings.