Low frequency fluctuations in a multimode semiconductor laser with opticalfeedback

We study a multimode semiconductor laser subject to a moderate optical feed back. The steady state is destabilized by either a simple Hopf bifurcation leading to in phase dynamics or by a degenerate Hopf bifurcation leading to antiphase dynamics. The degenerate bifurcation is also a source of multipl e coexisting attractors. We show that a simple interpretation of the low fr equency fluctuations in the multimode regime is provided by a chaotic itine rancy among the many coexisting unstable attractors produced by the degener ate Hopf bifurcation.