Exact stable pulses in asymmetric linearly coupled Ginzburg-Landau equations

We put forward the first physical model based on coupled Ginzburg-Landau equations that supports exact stable pulse solutions. The model describes a doped twin-core optical fiber with dispersive losses, dispersion, and cubic nonlinearity in one component, and pure losses in the other. The exact stable pulses are found for the cases of the anomalous, normal, and zero dispersion. Necessary conditions for stability of the pulses are obtained analytically, and a full stability analysis is performed numerically. We find nontrivial stability borders on the model's phase planes that do not follow from elementary theorems of the bifurcation theory. (C) 1998 Elsevier Science B.V.