Theoretical And Experimental Research On Multi Coupling Points Polarization Coupling

Polarization-maintaining fiber(PMF)is an important component in optical fiber sensing and optical fiber communication,thus it is very important to measure its parameters accurately.In the experimental environment,PMF single-coupling point polarization coupling test is usually used as measure parameters,But in the practical environment,multi-coupling points tend to exist in the fiber,so polarization coupling test of multi-coupling points is more suitable for practical application and thus it is important to do PMF multi-coupling points research.In this thesis,the theory of multi-coupling point is deeply studied,and the signal processing of PMF polarization-coupling in time-domain and frequency-domain is studied based on our previous work.The completed work is shown as follows:1 The intensity of interference signal is derived when there are N coupling points in PMF.The mutual influence of coupling points,the identification and elimination method of ghost coupling points are discussed,and the experiment of two coupling points in PMF is performed.2 We initially completed the building and debugging of all-fiber polarization-coupling test system.3 In the time-domain signal processing,we analyze the multi-peak splitting phenomenon caused by the overlapping of two close-coupled points,and deduce the linear relationship between the splitting frequency and distance,which agrees with the experimental result and greatly improves the interference envelope resolution.4 In the frequency domain signal processing,an automatic interference term extraction algorithm based on ensemble empirical mode and empirical mode decomposition(EEMD-EMD)is proposed,which avoids the manual selection of filters in Fourier transform method.The feasibility of the algorithm is verified by numerical simulation and experiments.The coupling intensity relative error of the extracted interference term is less than 2%.