Bistable dark solitary wave solutions of the generalized nonlinear Schrodinger equation and their stability

Bistable dark solitary wave solutions (bistable holes) to the generalized nonlinear Schrodinger equation are shown to exist in the normal dispersion regime for nonlinearities which are Kerr-like at low intensities I, rise sufficiently rapidly at intermediate I , and become Kerr-like again or approach a constant value at large I. The origin of the gaps in the energy surface reported by the authors in a recent publication (Opt. Lett., vol.14, p.509-11, 1989) is discussed. The collisional stability of the holes is also numerically examined and correlated with previous optical switching results