Mismatch and synchronization: Influence of asymmetries in systems of two delay-coupled lasers

We study the synchronization properties of the delay dynamics of two identical semiconductor lasers coupled
through a semitransparent mirror. Via an analytical and numerical approach, we investigate the influence of
asymmetries, in particular mismatches of self- and cross-coupling strength and differences in self- and crosscoupling
delay. We show that the former mismatch affects the stability of the zero-lag state but not the dynamics
within the synchronization manifold, while the latter mismatch does not affect the quality of synchronization but
alters the dynamics significantly. Our results are extended to different unidirectional coupling schemes. This is
highly relevant for communication schemes utilizing chaotic dynamics. Finally, the influence of nonlinear gain
saturation on the dynamics and stability of synchronization is discussed.