Aperiodic Quasi-Phase-Matching as a Method to Reduce Switching Intensity in Devices Based on Second Order Cascading

The combination of two novel techniques second order cascading [1] and quasi phase matching [2] (QPM) can yield to solutions for construction small, low power operated, all-optical switching devices. Important parameters in this devices are the switching intensities Iπ/2 and Iπ necessary for obtaining nonlinear phase shift (NPS) with amount of π or π/2, correspondingly. Here we show that one way to reduce the parameters Iπ/2and Iπ is to use aperiodic quasi-phase matched structure. We investigated the NPS obtained by the fundamental beam involved in the process of second harmonic generation in second order material for which the normalized phase mismatch satisfy where ki=2πni/λi (i=ω,2ω), p is a coefficient and Kgrat(z) = 2π/Λgrat(z) with Λgrat being the grating period.