Highly Correlated Chaotic Emission From Bidirectionally Coupled Semiconductor Lasers

Optically coupled semiconductor lasers (SLs) are known to exhibit chaotic properties in their emitted signals. Depending on the number of SLs and the coupling topology, their emissions can potentially show stable, synchronized behavior. The level of synchrony depends on numerous parameters and is the key factor to design secure communication systems based on synchronized chaotic signals. In this work we investigate a bidirectional coupling topology, with two or more SLs coupled with a common hub SL, which leads to an unprecedented level of synchronization. Cross-correlation (CC) values as high as 0.9961 are reported between SLs, when the latter operate at a fully chaotic regime and with spectral emission profiles that show minimized periodicities. Such conditions promote the proposed topology for cryptographic applications.