Optical image encryption and transmission with semiconductor lasers

Optical chaos has great advantages in image encryption and optical message secure transmission, hence a novel image encryption and transmission system based on optical chaos is proposed. In this paper, we introduce optical chaos generated by the semiconductor laser in the encryption process. For increasing the chaotic complexity of slave lasers (SL1 and SL2), the master laser (ML) is subjected to the optical feedback and the external optical injection from the driven laser (DL). Then the SL1 and SL2 can generate the optical chaotic signal simultaneously, which can be used as chaotic carrier and the key for better security. The secret key and a new chaos sequence for the permutation can be structured by selecting randomly numbers from the optical chaos signal generated by the SL1 (or SL2). Furthermore, the result of color image encryption based on the Hilbert curve (HC) can be improved by introducing the optical chaos, after employing logistic chaotic map, the pixel positions and values of plain image are changed disorderly. The security analysis and simulation results can demonstrate the feasibility of proposed algorithms. Moreover, under the condition of chaos synchronization between the SL1 and SL2, the encrypted image can be modulated by using the chaos masking (CMS) technique and transmitted in 10 km single mode fiber (SMF) channel from the SL1 to SL2. The bit error rate (BER) can be for less than 4.22 x 10(-20) and high quality factor (Q-factor) can be also for more than 9.