A Novel Configuration for Phase-Matched Second-Harmonic Generation in LiNbO$_3$ Waveguides

We present a feasibility study of a novel technique for continuously phase-matched second-harmonic generation in proton-exchanged lithium niobate waveguides. We demonstrate that a periodic variation of the nonlinear coefficient along the transverse direction with respect to the propagation one permits for efficient conversions. Comparison with the conventional first-order quasi-phase-matching interactions are then presented in front of unavoidable imperfections of real devices whenever Czochralski off-center technique is exploited in the fabrication process