Dark solitons in dispersive quadratic media.

We analyze dark solitons supported by second-order parametric interactions between the fundamental and second harmonics in the presence of dispersion and group-velocity mismatch. We reveal various types of solitary waves, including a family of two-wave dark solitons propagating on a modulationally stable background, dark solitons with nonmonotonic tails, and bound states of dark solitons.

Spatial optical solitons governed by quadratic nonlinearity.

We demonstrate that a dielectric medium with purely quadratic nonlinearity [the so-called chi((2)) material] can display self-focusing phenomena through a new type of modulational instability of the interacting fundamental and second-harmonic field components and therefore can support propagation of (two-wave) optical solitons. We prove the existence of a family of such solitons, which are found numerically and, in some particular cases, also analytically. The two-wave solitons are stable in the whole parameter region in which they exist.

Is two-photon absorption a limitation to dark soliton switching?

It is shown that two-photon absorption does not always place a fundamental limitation on soliton devices: The steering angle, the key characteristic of switching devices based on the propagation of dark spatial solitons, is almost preserved as the intensity of the background wave decays in the presence of weak two-photon absorption.

Gordon-Haus effect on dark solitons.

The theory of the Gordon-Haus effect with application to dark solitons is presented. It is proved analytically that a random frequency shift of a fundamental dark soliton results in a time jitter radical2 times lower than that for bright solitons.