Hyperchaotic dynamics and synchronization of external-cavity semiconductor lasers

Two unidirectionally coupled external cavity semiconductor lasers showing chaotic intensity fluctuations are studied by numerically solving the Lang-Kobayashi model equations [IEEE J. Quantum Electron. QE-16, 347 (1980)]. The systems are shown to synchronize when operating in the regime of low-frequency fluctuations, which is characterized by a very high-dimensional $\mathrm{}(d>\mathrm{}150\mathrm{})\mathrm{}$ attractor. The influence of parameter differences between the two lasers on the synchronization quality is investigated.