Combination of anticipated and isochronous synchronization in coupled semiconductor lasers system

Combination of two basic types of synchronization, anticipated and isochronous synchronization, is investigated numerically in coupled semiconductor lasers. Due to the combination, a synchronization of good quality can be obtained. We study the dependence of the lag time between two lasers and the synchronization quality on the converse coupling retardation time $\tau_{c21}$. When $\tau_{c21}$ is close to the difference of external cavity round trip time $\tau$ and coupling retardation time $\tau_{c12}$, the combination of anticipated and isochronous synchronization may produce a better synchronization, with a lag time proportional to $\tau_{c21}$. When $\tau_{c21}$ is largely different from $\tau-\tau_{c12}$, the combination is noneffective and even negative in some cases, with a lag time independent of $\tau_{c21}$.