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 analogue 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 chaospass filtering effect in the receiver laser. By subtracting the receiver output from the transmission signal, the message is successfully decoded.