Synchronization and secure communication in time delayed semiconductor laser systems

We investigate the synchronization in coupled time delayed semiconductor laser models without and under the influence of external noise sources. The synchronization and its robustness are observed by mean synchronization error and the effect of parameter mismatch respectively. A communication scheme is introduced based on symmetrical encryption and decryption method in the frame of coupled synchronized lasers with optical feedback. The scheme is effective irrespective of the nature and dynamics of the transmitted signal. The security of the scheme is verified by the effect of relative parameter mismatch, key sensitivity frequency and cross correlation analysis. Numerical results support the proposed analysis.