Research On The Method And System For Measuring Polarization Mode Dispersion In Optical Fiber

With the continuous growth of communication business and the demand for communication capacity and communication speed,optical fiber communication system has been developing towards high speed,large capacity and long distance.This leads to the more obvious restriction of polarization mode dispersion(PMD)to the performance of optical fiber communication system.The generation mechanism,measurement scheme and compensation method of PMD have important guiding significance for new optical fiber manufacturing and old-fashioned optical fiber transmission network.At present,the theoretical system of PMD has been perfected.The PMD measurement methods are mainly divided into two types,the time-domain method and the frequency domain method.Among them,the fixed analyzer method is convenient,efficient and low cost,thus it is a widely used PMD measurement method.Aiming at the problem of PMD measurement,various measuring methods are studied and analyzed.A set of PMD measurement system based on fixed analyzer is designed and implemented.A de noising scheme based on wavelet threshold de noising and Butterworth filtering is proposed,which realizes PMD precise measurement.The main contents and results of the paper are as follows:1.We studied the theoretical basis of PMD measurement technology,and analyzed and compared various PMD measurement methods.such as interferometric fixed analyzer,Poincare sphere method and Jones matrix method.The fixed analyzer method was selected as the measurement method of this subject.2.A PMD measurement system is designed based on the fixed analyzer method.The light source module,polarizer,polarization controller,optical fiber,analyzer and output signal receiver module are used to set up the measurement system.3.The output signal characteristics of the measurement system based on the fixed analyzer method are analyzed.Two data processing methods,extreme value counting method and Fourier transform method,are studied,and the extreme value counting method is chosen as data processing method.4.Analysis of the nature of the noise measurement system,studied several denoising methods,puts forward two kinds of denoising scheme and algorithm denoising method and Butterworth filtering method based on wavelet threshold,in the weak coupling situation and random mode coupling situation,to measure and analyze the error and accuracy of noise schemes,has differential group delay error is less than 2%,to achieve accurate measurement.