Chaotic communication with erbium -doped fiber ring lasers

The field of chaotic communication is relatively new; the concept was first conceived in the early 1990s. Since that time, many techniques for communicating with chaos have been proposed, and many of these techniques have been demonstrated with electronic circuits. When the research presented in this thesis was begun, however, no demonstrations of chaotic communication using optical systems had been performed. The aim of this thesis was to investigate the possibility of using optical systems for chaotic communication.;Synchronization of chaotic systems is fundamentally related to communication with chaotic systems. Experiments demonstrating synchronization of chaotic Nd:YAG lasers are presented in this thesis. These experiments also reveal a beautiful experimental realization of generalized synchronization. A technique for communication using generalized synchronization is also presented.;Erbium-doped fiber ring lasers (EDFRLs) were chosen for the experimental investigation of optical chaotic communication. To develop appropriate chaotic communication techniques with EDFRLs, investigations were performed to understand the origins of their chaotic intensity and polarization dynamics. As part of these investigations, a delay-differential model for the dynamics of an EDFRL was developed. Refinements to the model were made to incorporate important effects of the fiber-optic host. A high-speed (125 MHz) fiber-optic polarization analyzer was constructed to experimentally measure the rapid polarization dynamics of an EDFRL. It was also used to observe a striking EDFRL instability that involves self-pulsing and simultaneous polarization switching. The polarization analyzer revealed information about this instability that could not have been obtained without a full measurement of the lightwave's polarization state.;Several chaotic communication techniques were developed to encode information in the chaotic intensity fluctuations output from the EDFRL. Good message recovery is demonstrated in each case. The communication privacy afforded by these systems varies, and in general, is limited. This is a consequence of the relatively slow (compared to the intensity fluctuations) dynamical evolution of the chaotic intensity fluctuations generated by EDFRLs. A method utilizing the chaotic polarization fluctuations of EDFRLs for communication, which may offer more significant communication privacy, was also proposed and experimentally demonstrated.