Modulational Instability of a Plane Wave in the Presence of Localized Perturbations: Experiments in Nonlinear Fiber Optics

Abstract

Modulational instability (MI) is a ubiquitous phenomenon in focusing nonlinear media, and consists in the instability of a constant background to long-wavelength perturbations [1,2]. The linear stage of MI is characterized by an exponential growth of all the perturbations falling in the long-wavelength region of the Fourier spectrum [1]. This simple picture ceases however to be valid when the amplitude of the perturbation becomes comparable to the background, i.e. in the nonlinear stage of MI.