Coherence and synchronization in diode-laser arrays with delayed global   coupling
  The dynamics of a semiconductor-laser array whose individual elements are coupled in a global way through an external mirror is numerically analysed. A coherent in-phase solution is seen to be preferred by the system at intermediate values of the feedback coupling strength. At low values of this parameter, a strong amplification of the spontaneous emission noise is observed. A tendency towards chaos synchronization is also observed at large values of the feedback strength. 
J. Garcia-Ojalvo, J. Casademont, C.R. Mirasso, M.C. Torrent and J.M.   Sancho