Abstract

Over the last decade modulational instability (MI) in optical fibers has attracted much attention for both its fundamental and applied interests [1]. MI in fibers can be interpreted as a stimulated four-wave-mixing process that is naturally phase-matched by the balance between chromatic dispersion and Kerr nonlinearity. In self-focusing Kerr media, such as silica optical fibers, anomalous dispersion is required in order for this phase matching process to occur. In the presence of normal dispersion, phase matching can be achieved with the help of an extra degree of freedom that is provided by the coupling with an additional intense carrier wave of different polarization [2] or wavelength [3]. In 1992 Haelterman et al. suggested in a theoretical work that this extra coupling mechanism is not necessary to obtain an extension of MI to the normal dispersion regime [4]. It was shown that when nonlinear dispersive waves are subject to cavity boundary conditions, the underlying four-wave mixing processes are altered so as to make possible MI with normal dispersion.

© 1998 Optical Society of America