Abstract

The non-linear Schrodinger equation (NLS) predicts an existence of stable solutions (e.g. solutions conserving amplitude and phase under propagation) for both positive and negative Group Velocity Dispersion (GVD) regions. The solution existing in the positive GVD region consist of a rapid dip in a CW background and is called a "dark soliton" analogously to a "bright soliton" for the negative GVD region [1,2]. The fundamental dark soliton is an anti- symmetric function of time, with an abrupt π phase shift and zero intensity at its center. Although the existence of dark optical solitons in fibers was first predicted in the early 1970-s, experimental verification was reported not long ago [3]. In all the experiments known to date a dip of a dark pulse existed in the intensity of a broad pulse. Another possibility of forming of dark solitons from a periodically modulated CW signal in a fiber with amplification was reported recently [4].

© 1993 Optical Society of America