Synchronization and communication based on semiconductor lasers with phase-conjugate feedback

Chaotic synchronization characteristics of external cavity semiconductor lasers with phase-conjugate feedback and its application to optical cryptograph communication are investigated numerically. The results indicate that the range of feedback coefficient making the system well synchronized is related to the bias current of the semiconductor laser. The robustness of the synchronization scheme is sensible to the internal parameter mismatch between the transmitter and the receiver. Encoding message with high bit rate can be recovered easily without any filter.