Applying the data fusion method to evaluation of the performance of two control signals in monitoring polarization mode dispersion effects in fiber optic links

M Dashtbani Moghari,P Rezaei,A Habibalahi

doi:10.2971/jeos.2015.15008

Abstract

With increasing distance and bit rate in fiber optic links the effects of polarization mode dispersion (PMD) have been highlighted. Since PMD has a statistical nature, using a control signal that can provide accurate information to dynamically tune a PMD compensator is of great importance. In this paper, we apply the data fusion method with the aim of introducing a method that can be used to evaluate more accurately the performance of control signals before applying them in a PMD compensation system. Firstly, the minimum and average degree of polarization (DOPmin and DOPave respectively) as control signals in monitoring differential group delay (DGD) for a system including all-order PMD are calculated. Then, features including the amounts of sensitivity and ambiguity in DGD monitoring are calculated for NRZ data format as DGD to bit time (DGD/T) varies. It is shown that each of the control signals mentioned has both positive and negative features for efficient DGD monitoring. Therefore, in order to evaluate features concurrently and increase reliability, we employ data fusion to fuse features of each control signal, which makes evaluating and predicting the performance of control signals possible, before applying them in a real PMD compensation system. Finally, the reliability of the results obtained from data fusion is tested in a typical PMD compensator.

Highlights

Increasing bit rate and distance in fiber optic links have made polarization mode dispersion (PMD) a serious problem in high-speed transmission at 40 Gb/s or beyond
Since PMD has a statistical nature and it causes a delay known as differential group delay (DGD) between the two principle states of polarization (PSP), the instantaneous DGD should be monitored in a PMD compensation (PMDC) system in order to evaluate dynamically the quality of signals affected by PMD and provide PMDC with a control signal
It can be interpreted that using DOP ave as a control signal in a PMDC system leads to achieving better results in lowering outage probability, as compared with using DOP min since a PMDC system with DOP ave as a control signal can track DGD variations more effectively

Summary

Introduction

Increasing bit rate and distance in fiber optic links have made polarization mode dispersion (PMD) a serious problem in high-speed transmission at 40 Gb/s or beyond. PMD is a statistically arbitrary pulse distortion that arises from the random birefringence in optical fibers and limits pulse width and linearity. It is studied in a Taylor series expansion framework in terms of the first-order PMD, second-order PMD, etc. Since PMD has a statistical nature and it causes a delay known as differential group delay (DGD) between the two principle states of polarization (PSP), the instantaneous DGD should be monitored in a PMDC system in order to evaluate dynamically the quality of signals affected by PMD and provide PMDC with a control signal. There are some advantages to using the DOP as monitoring signal, as it is simple, bit-rate independent and does not require high-speed electronics [8]

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Conclusion