Time-delayed coupled chaotic semiconductor lasers show new types of   synchronization: Experiment and theory
  Topologies of two, three and four time-delay-coupled chaotic semiconductor lasers are experimentally and theoretically found to show new types of synchronization. Shifted zero-lag synchronization is observed for two lasers separated by long distances even when their self-feedback delays are not equal. Shifted sub-lattice synchronization is observed for quadrilateral geometries while the equilateral triangle is zero-lag synchronized. Generalized zero-lag synchronization, without the limitation of precisely matched delays, opens possibilities for advanced multi-user communication protocols. 
Y. Aviad, I. Reidler, M. Zigzag, M. Rosenbluh and I. Kanter
nlin.CD physics.optics