Stable propagation of dark solitons in dispersion maps of either sign of path-average dispersion

In fibres with alternating dispersion, dark solitons are shown to propagate stably as far as can be told from numerical simulation. This holds even in the case of a dispersion map with average anomalous dispersion, i.e. in the regime which for homogeneous fibres is the `forbidden´ regime for dark solitons. We have shown that the pulse shape is characteristically modified in the dispersion-managed fibre, and we see indications of a modified soliton power. These results demonstrate an appealing symmetry with earlier corresponding finding that bright solitons are modified in shape and power, and can extend their existence into their `forbidden´ regime