Resonant light reflection in quadratic waveguide arrays

In this work, we suggest employing the arrays of weakly coupled nonlinear quadratic waveguides for the study of novel effects in the resonant light scattering. We assume that only one or several neighboring waveguides have periodic poling and, therefore, possess a quadratic nonlinear response. When the phase-matching conditions are satisfied, the fundamental-frequency (FF) mode can generate parametrically the second-harmonic (SH) wave, so that such a structure may behave as a nonlinear defect with localized quadratic nonlinearity. In addition, we have performed the numerical simulation of the Gaussian beam propagation in this structure. We believe that the quadratic waveguide arrays may be employed for the first experimental observation of the Fano resonance in nonlinear optics.