Monitoring et caractérisation des effets de polarisation de deux liaisons optiques cohérentes

Abstract

States of polarization (SOP) changes of polarization-division-multiplexed optical signals are a potential source of performance degradation in coherent optical links which require further study. This research project aims at monitoring and characterization of polarization effects and performance parameters of two coherent optical links, a predominantly direct buried 230-km link of the CANARIE network and a 900-km optical ground wire (OPGW) link of Verizon’s network. The thesis describes the methodology and tools that have been developed for processing performance (bit error ratio (BER) and signal-to-noise ratio (SNR)) and polarization (polarization mode dispersion (PMD), polarization dependant loss (PDL), SOP fluctuations) measurements made during two measurement periods of several weeks each by using a 40-Gb/s DP-QPSK coherent transponder and a polarimeter in coherent optical links carrying live traffic, as well as an analysis of observed polarization effects. In the project, indexed data structures have been developed for managing large amounts of collected data (64 days spread over 24 months). Data analysis tools designed in Matlab® environment have been applied to the indexed data structures to characterize the temporal fluctuations, as well as to perform a statistical analysis of polarization effects including the calculation of autocorrelation and probability density functions. The results have allowed for a better understanding of the characteristics of SOP fluctuations in coherent optical links by providing the following findings: the temporal characteristics of PMD and PDL fluctuations and other transient polarization effects depending on the type of physical installation (aerial or buried link). The calculation and fitting of the probability density function of polarization rotation rates by a double probability density function obtained by the convolution of Rayleigh and exponential density functions has revealed the presence of two physical phenomena at the origin of SOP fluctuations measured on the OPGW link.

Date	19 Sept 2014
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Christine Tremblay (Supervisor)