Chaos-synchronization in Semiconductor Laser Systems: an Optical Phase Dependent Scenario

Synchronization of chaotic oscillators is of high current interest in various areas of science. Semiconductor laser systems offer a great potential for experimental studies of synchronization phenomena, because of well-controllable parameters, wellstudied nonlinear dynamical behavior and their broad spectrum of applications. We investigate chaos-synchronization of two unidirectionally coupled semiconductor lasers with delayed optical feedback. We present a characteristic synchronization scenario in dependence of the relative optical cavity phase of the subsystems. For adjusted phase, we find excellent synchronization of the intensity dynamics in combination with coherence among the emitted fields of the lasers, despite of the fast chaotic wavelengthfluctuations. Variation of the phase leads to conspicuous changes in the intensitydynamics associated with drastically reduced correlation and loss of coherence among the lasers. Our results provide insight into the consequences of vectorial coupling for the synchronization scenario and open the perspective for innovative concepts for encrypted GHz data communication.