Synchronization via clustering in a small semiconductor laser network

The first experimental observation of synchronization is presented via clustering, in an array of three semiconductor lasers coupled with varying strengths and delay times. Simulation based on a simple model that is an extension of the Lang-Kobayashi equations is performed (assuming identical single-mode lasers and neglecting multiple reflections) and found that the cluster is a robust mechanism towards synchronization, i.e., it appears in a wide region of parameter space. It is also studied in detail the cluster dynamics in the time and frequency domains.