Phase-matching for Nonlinear Optical Parametric Processes with Multistep Cascading

We present a brief overview of different methods for simultaneous phase-matching of several parametric optical processes (the so-called multistep cascading) in engineered structures with the modulated second-order nonlinear susceptibility. In particular, we discuss the possibility of double phase-matching in both uniform and non-uniform quasi-phase-matched (QPM) periodic optical superlattices and also in the recently fabricated two-dimensional nonlinear photonic crystals. We include also some original results demonstrating the possibility to achieve double-phase-matching with phase-reversed and periodically chirped QPM structures and also with uniform QPM structures in non-collinear geometry.