Physically enhanced secure wavelength division multiplexing chaos communication using multimode semiconductor lasers

A physically enhanced secure wavelength division multiplexing chaos communication scheme in virtue of the chaos synchronization of two multimode semiconductor lasers (MSLs) is introduced. In this scheme, two communicating MSLs are subjected to identical optical injections from a chaotic external-cavity MSL, and each mode of the communicating MSLs is used as a chaotic carrier. The messages are divided into a set of blocks, and these blocks are transmitted by different modes in different time slots, according to a pre-negotiated pattern. The numerical results indicate that high-quality chaos synchronization with a wide operation region and relatively strong frequency detuning tolerance can be achieved between the communicating MSL modes, which can afford multiple simultaneous bidirectional message transmissions. Moreover, because of the carrier-consumption competition in the MSL cavity, the peak average power ratios of the chaotic carriers are much larger and more widely distributed with respect to selected single-mode injection or feedback cases, which can obviously enhance the link security against the attack of linear filtering. Also, the carrier-consumption competition induces a cross talk between the transmission messages, which can greatly improve the link security when eavesdroppers adopt the synchronization utilization method to attack the public link. Furthermore, with the non-fixed wavelength transmission technology, the system security can also be further improved greatly. The proposed scheme provides a new way to implement high-speed multichannel chaos communication with high physically enhanced security.