  Dynamics of coupled semiconductor lasers is investigated by numerical
simulations. A realistic laser simulation engine is used to study the
synchronization and dynamical regime in two mutually coupled Fabry-Perot and/or
DFB lasers. Both, single- and multi-mode operation regimes are studied with
emphasis on the role of the multiple laser-cavity modes. Our findings indicate
that the two laser synchronize within each laser-cavity mode, while the
synchronization across different cavity modes is significantly weaker.
