EE Seminar: Nonlinear Interference in Fiber-Optic Communications

~~Speaker: Ronen Dar
PhD student under the supervision of Prof. Meir Feder and Prof. Mark Shtaif

Wednesday, June 3rd, 2015 at 15:00
Room 011, Kitot Bldg., Faculty of Engineering

Nonlinear Interference in Fiber-Optic Communications

Abstract
The nonlinearity of optical fibers is arguably the most significant factor limiting the capacity of modern wavelength division multiplexed (WDM) communications systems. The Kerr nonlinear effect of the fiber introduces complex distortions into the transmitted optical waveforms, generating nonlinear interference noise (NLIN) between the various WDM channels; this diminishes the receiver's capability of decoding the transmitted data and limits the reach of the system and the achievable data-rates. The modeling of NLIN and the understanding of its impact on system performance are therefore key components in the efficient design of fiber-optic communication systems and in the evaluation of their ultimate reach and capacity.
We formulate a discrete-time channel model for an arbitrarily link and use it to study the statistical nature of NLIN. We examine the accurate extraction of the NLIN variance, its dependence on modulation format, the role of nonlinear phase-noise and polarization rotation, and the existence of temporal correlations. We propose new practical schemes for nonlinear interference mitigation that exploit the temporal correlations and further derive new bounds on the channel capacity. In addition, we present a pulse-collision theory that provides qualitative and quantitative insight into
the build-up of NLIN, offering a simple and intuitive explanation to many of the reported and previously unexplained phenomena.