Consecutive three-wave interactions in nonlinear optics of periodically inhomogeneous media

A brief review of recent advances in the studies of two coupled three-wave nonlinear optical processes with multiple frequencies, which possess a numb er of special properties compared to conventional three-wave processes, is presented. The consecutive interactions of co-propagating and counter-propa gating light waves in a LiNbO3 crystal with a regular domain structure are considered. The energy exchange upon consecutive interactions of the waves with frequencies omega, 2 omega and 3 omega is analysed. The prospects of u sing consecutive nonlinear optical processes in quantum electronics and non linear optics are discussed.