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Waves Seminar Series

Wednesday, November 15, 2006, 4:00 pm (special time)

Cullimore 611

New Jersey Institute of Technology

Large deviation principles in optical communication systems: Theoretical
and experimental study

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Maxim Shkarayev
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Program in Applied Mathematics

The University of Arizona

**Abstract**

Using methods of large deviation theory from statistical physics, we carry out analytical and experimental study of error statistics in optical communication systems in the presence of additive and multiplicative noise. In the slowly varying envelope approximation light propagation through optical fiber is described by Schroedinger's equation. Signal transmission is impeded by the spacial disorder (birefringence) of the optical fibers as well as short correlated noise from the optical amplifiers. This results in signal distortion that may lead to erroneous interpretation of the signal. System performance is characterized by the probability of error occurrence. Fluctuation of spacial disorder due to changing external factors (temperature, vibrations, etc) leads to fluctuations of error rates. Commonly the distribution of error rates is assumed to be Gaussian. Using optimal fluctuation method we show that this distribution is in fact lognormal. Such distribution has "fat" tails implying that the likelihood of system outages is much higher than it would be in the Gaussian approximation. Our theory provides excellent agreement with experiment.