Abstract

Semiconductor lasers are fast dynamical systems that can operate in time scales on the order of picoseconds. Recently there has been much interest in situations where two such lasers are coupled optically via injection of their emitted light into each other, both for fundamental and technological purposes. In this case, and when the distances separating the lasers are larger than tens of centimeters, the coupling signals take longer than nanoseconds to reach the receiver laser, which implies that delays in the coupling become non-negligible with respect to the intrinsic dynamics of the lasers. It is well known that such delay-coupled lasers exhibit different kinds of lag synchronization [1], where one of the lasers advances the dynamics of the other, while both the sign and amount of the lag depends on the details of the coupling architecture that links the lasers. Moreover, in the case of mutual injection, coupling is known to destabilize the otherwise stable lasers, and if the laser frequencies are close enough to each other, the resulting dynamics exhibits a special type of lag synchronization in which the leader and laggard roles of the dynamics alternates irregularly between the two lasers [2].

© 2009 IEEE