Transition From Short-to-Long Cavity and From Self-Mixing to Chaos in a Delayed Optical Feedback Laser

We analyze the regime of strong perturbation in a laser diode subjected to delayed optical feedback (DOF) from an external reflector, and study the intermediate region between short and long cavities, using Lang and Kobayashi equations to follow the dynamic regimes of the DOF system. We find that well-known regimes of unperturbed oscillations, period one, multi-periodic, and chaos are dictated by interplay of coupling factor K, distance L, and phaseΦ ( mod.2π)of the external reflector, and linewidth enhancement factorα. We plot the boundaries of different regimes in theK-Φplane for several values of L andα, and characterize them in the transition from very short cavity( L<0.01~ L_ fr)with negligible high-level effects, to long cavity( L=0.5~ L_ fr)where theK-Φplane is almost completely filled with chaos. We show that chaos and periodicity regimes are only found atC>1, though forC<1the DOF system is also subject to self-mixing perturbations. Self-mixing induced FM and AM of the optical signal are found in all regions of stable oscillations, and forC>1frequency switching occurs at a certainΦfor any K and L. Chaos develops at increased K and L in correspondence to loci of frequency switching.