Chaotic Communications in Semiconductor Lasers

Abstract

Chaotic data encoding or scrambling is a technology for overcoming the difficulties of the digital methods in secure communications. Using chaotic lasers as light sources, high-speed and broadband secure communications can be established. In this chapter, we discuss cryptographic applications of chaos in semiconductor lasers. The technique we treat in this chapter is an analog chaotic encryption and decryption. Messages to be sent are encoded into chaotic time series generated from a chaotic semiconductor laser and decoded by a chaotic laser with the same characteristics. The key for chaos communications is chaos synchronization, which we discussed in the previous chapter. In chaotic communications, a small message is embedded into a chaotic laser carrier and the total signal is sent to the receiver. Only the chaotic oscillation is reproduced based on chaos synchronization and a chaos-pass filtering effect in the receiver laser. By subtracting the receiver output from the transmission signal, the message is successfully decoded. Message Encryption in a Chaotic Carrier and Its Decryption Chaotic CommunicationsThe development of efficient technologies for high-speed and massive data transmissions is an urgent subject in the rapidly growing information-oriented society. One of the important issues of information and communication networks is the security problem. In secure data transmissions, a message to be sent is usually encoded by computer software and the security of encoding is guaranteed by the complexity of the calculations necessary to decode the original message. However, the development of digital computer technology is so fast that the standard code for scrambling data in secure communication systems can be soon decoded by a fast computer. On the other hand, the enhancement of the complexity of calculations for encoding and decoding messages may lose real-time processing of data transmissions. In the meantime, J. Ohtsubo, Semiconductor Lasers, Springer Series in Optical Sciences 111,