الفهرس 
Cover EnglishOnly 14 pages are availabe for public view
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Abstract
Security is a crucial issue in optical communication systems. Chaotic communication, in which the encryption is held at the physical layer, provides a high security level. It requires a pair of synchronized chaotic laser diodes that can be used as a transmitter-receiver pair. Our main purpose, in this work, is to study the chaotic behavior of semiconductor laser diodes and the different synchronization schemes. Some methods used to generate chaos using a laser diode, such as optical feedback, external optical injection and optoelectronic feedback, are first discussed in detail. To adequately describe the temporal behavior (dynamics) of a chaotic laser diode, the amplitude and phase of the laser electric field together with the density of charge carriers inside the laser cavity must be obtained. Thus we developed a numerical algorithm to simulate these dynamics, which depend on the method of chaos generation. The type of the route to chaos when a laser diode is subjected to optical feedback depends on the feedback parameters (strength and delay) as well as the injection current. A detailed study of these different routes to chaos was carried out resulting in a 3D phase diagram. The effects of external optical injection and optoelectronic feedback on the dynamics of the laser diode were then overviewed. To study the synchronization process between two similar chaotic laser diodes, we extended the algorithm to describe a transmitter-receiver pair. According to the method of chaos generation and coupling parameters (which include frequency detuning and injection strength), the different synchronization schemes were presented. The synchronization quality strongly depends on the parameter mismatch between the transmitter-receiver pair. Using a synchronized chaotic laser diode pair, a message can be embedded in the chaotic carrier and recovered at the receiver end using different encryption techniques. With the purpose of maintaining robust synchronization between the transmitter and receiver laser diodes, we developed a scheme that reduces the effect of parameter mismatch. Then, we studied the synchronization recovery time after desynchronization burst that can occur in a communication link and its dependence on the parameter mismatch and the intrinsic parameters of the laser diode pairs.