Comparison of two types of synchronization of unidirectionally coupled external-cavity semiconductor lasers

摘要

We study numerically the synchronization regimes of optical-feedback-induced chaos in unidirectionally coupled semiconductor lasers. Depending on the operating conditions, the receiver laser intensity, I_R(t), synchronizes with the intensity of the optically injected field, I_T(t-τ_c), where τ_c is the flight time from the transmitter laser to the receiver laser, or synchronizes with I_T(t-τ_c+τ), where τ is the is the external-cavity round-trip time. In the latter case, the intensity produced by the receiver anticipates the injected intensity I_T(t-τ_c) by an anticipation time equal to τ. We find that synchronization with a lag time τ_c-τ is much more sensitive to frequency detuning and noise than synchronization with a lag time τ_c. Moreover, we also find that though synchronization with a lag time τ_c can be obtained using either an external-cavity or an open-loop receiver, the synchronization quality is always better when an external-cavity receiver is used.