Effects of message encoding and decoding on synchronized chaotic optical communications

Chaotic optical communication at 2.5 Gb/s is experimentally investigated using three major encoding and decoding schemes, namely chaos shift keying (CSK), chaos masking (CMS), and additive chaos modulation (ACM). The effects of message encoding and decoding on the chaotic dynamics, the chaos synchronization, and the chaotic communication performance are compared among the three schemes. In the schemes of CSK and ACM, it is found that a small amount of message injected into the chaotic dynamics can increase the complexity of the chaotic state dramatically. In the CMS scheme, the chaotic dynamics is found not to be influenced by the encoded message. The synchronization quality deteriorates dramatically with an increase in the message strength in CSK and CMS. The ACM scheme is found to have the best synchronization quality among the three schemes when there is an encoded message. Message recovery is demonstrated for each of the three schemes. The ACM scheme is found to have the best communication performance.