Physical Electronics Dept.

***** Seminar *****

Alon Nafta

(M.Sc. student under supervision of Prof. Mark Shtaif, School of EE, Dept. of Physical Electronics)

POLARIZATION MULTIPLEXED FIBER-OPTIC SYSTEMS:

PERFORMANCE ANALYSIS AND METHODS FOR BLIND EQUALIZATION

Modern optical transmission schemes employ coherent detection, often using high-order modulation and deploy advanced signal processing techniques in order to maximize the exploitation of available fiber bandwidth. The potential of the various schemes is determined by the various physical impairments that are unique to fiber-optic transmission. These include nonlinear propagation, dispersion and polarization related effects.

In this work we concentrate on linear optical channels, where the challenge of realizing efficient and reliable communications, are due primarily to polarization distorting effects – namely polarization mode dispersion (PMD) and polarization dependent loss (PDL). The work contains two distinct parts. In the first, we study the capacity of a fiber-optic channel and how it is affected by the presence of polarization effects. In the second part, we study blind equalization methods and propose an algorithm for blind equalization and phase recovery based on independent component analysis (ICA). ICA is a blind signal separation technique which has been originally proposed for scenarios where extraction of statistically independent components from measured mixtures is needed. It has been shown to be useful in various technological areas, such as biomedical informatics, image and signal processing, wireless communications and others. Yet, its beneficial use in optical communications has received very limited attention so far. In our study, we extend the use of ICA to accommodate for equalization and blind phase recovery and propose a multi-tap ICA algorithm.