Zero-lag chaos synchronization properties in a hierarchical tree-type network consisting of mutually coupled semiconductor lasers.

Chaos synchronization properties in a novel hierarchical tree-type optical network consisting of semiconductor lasers (SLs) are investigated numerically. In such network, each child node is asymmetrically mutually coupled with the parent node. Zero-lag synchronization is found among the nodes belonging to the same layer, while the nodes belonging to different layers are not synchronized, which is denoted as hierarchical chaos synchronization (HCS). The effects of injection strength, asymmetrical injection parameters, bias currents and frequency detuning on the performance of HCS and chaotic complexity are studied in detail. Our results show that high-quality HCS can be obtained under moderate parameters. The stability of the network is also investigated systematically. Further, we explore the robustness of HCS by considering an asymmetrical network. Finally, output bit streams are generated from each SL at a tunable rate of up to about 10 Gbps with verified randomness. These results are enlightening to the multi-user chaotic communication and the synchronization mechanism in biological neuronal networks. [ABSTRACT FROM AUTHOR]