Dispersive waves and radiation trapping in optical fibers with a zero-nonlinearity wavelength

Abstract

The formation of dispersive waves and radiation trapping are two most relevant phenomena in supercontinuum generation. In spite the fact that the nonlinear coefficient of many waveguides depends strongly on wavelength and even changes sign, the influence of a frequency-dependent nonlinearity on these phenomena have seldom been studied. The goal of this work is to fill this gap in the literature by thoroughly studying the behavior of dispersive waves and radiation trapping in the presence of a zero-nonlinearity wavelength (ZNW). Although the generalized nonlinear Schrödinger equation (GNLSE) is widely used to model optical pulse propagation in waveguides, it has been shown that the GNLSE may lead to unphysical results in the case of frequency-dependent nonlinearities. For this reason, we perform our analysis by resorting to the newly introduced photon-conserving generalized nonlinear Schrödinger equation (pcGNLSE). Further, we discuss results obtained with both equations and put in evidence the inadequacy of the GNLSE to appropriately account for radiation trapping.