Rayleigh Backscattering Impact on Fiber Optic Transmission SystemsPing Wan (supervisor: Dr. Jan Conradi)
Ph.D. Thesis, Department of Electrical & Computer Engineering, University of Alberta, September 1996
By modeling the Rayleigh scattering coefficient along the fiber as a circular complex Gaussian random variable, this dissertation derives a general and accurate expression which describes the intrinsic noise generated by Rayleigh backscattering. The expression is so general that it can be applied to systems with an arbitrary magnitude of source coherence. After experimental verification, this expression has been applied to directly and externally modulated cable television systems, which use Amplitude Modulated-Subcarrier Multiplexed (AM-SCM) format. In doing this the system performance in relation to fiber length, source coherence and number of optical amplifiers has been analyzed.
To avoid the amplified noise generated by Rayleigh backscattering in optically amplified Intensity Modulated-Direct Detection (IM-DD) digital systems, isolators can be placed in front and after the in-line amplifiers. However, isolators in the transmission link will restrict the direction to be one-way and therefore, it may not be the most cost-effective method to use in bi-directional transmission systems. This dissertation discusses various kinds of optically amplified bi-directional transmission configurations. In particular, a series of bi-directional transmission experiments have demonstrated that systems with a single link and no isolators show the greatest potential in minimizing the number of components in providing long distance bi-directional transmission.
Furthermore, a derivation of the power penalty expression due to both the effects of Rayleigh backscattering of the Amplified Spontaeous Emission (ASE) and the signal in optically amplified IM-DD digital systems, as well as its experimental verification, have been included. Using this expression a theoretical study of systems with a single link and no isolators has been performed. Finally, the theoretical study is extended to include systems utilizing high scattering fiber amplifiers, such as the Praseodymium-Doped Fluoride Fiber Amplifiers (PDFFAs) or distributed Erbium-Doped Fiber Amplifiers (EDFAs).
CONTACTS: Ping Wan, Jan Conradi
SUBJECTS: Photonic Networks
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