Simulation of the random violation of the quasi-phase-matching condition in optical parametric process

The parametric interaction of light waves in a nonlinear photonic crystal (NPC) with the random violation of the quasi-phase-matching condition is considered. A model with correlated fluctuations of the width of adjacent domains is used which corresponds to NPCs fabricated, for example, by the repolarisation method. Both a numerical calculation algorithm and analytic stochastic approach taking into account the influence of fluctuations of the domain width are presented. The behaviour of the average intensity and dispersion of intensity fluctuations of parametrically interacting waves, including the strong energy exchange regime, is studied by the example of a LiNbO₃ NPC. The obtained results can be used to estimate the required accuracy of manufacturing the nonlinear structure of the crystal.