Method for distributedly measuring polarization transmission matrices of optical fiber and system thereof

摘要

A method for distributedly measuring polarization transmission matrices of an optical fiber includes steps of: inputting a fully polarized pulse into the optical fiber with linear birefringence only; and demodulating polarization states of Rayleigh backscattered light at different points on the optical fiber from a pulse input end; after demodulating, dividing the polarization states of the Rayleigh backscattered light into Q groups in sequence, wherein every three polarization states are divided into one group; calculating a transmission matrix of Group N; and solving the equation set using a numerical analysis method for obtaining multiple solutions, and screening the multiple solutions according to characteristics of the polarization transmission matrix, wherein each time of screening provides a unique solution Mx(N) of the equation set; continually updating MA values for iteration, so as to obtain the distribution of polarization transmission matrices of the optical fiber.

主权项

1. A method for distributedly measuring polarization transmission matrices of an optical fiber, comprising steps of:
inputting a fully polarized pulse into the optical fiber with linear birefringence only; and demodulating polarization states of Rayleigh backscattered light at different points on the optical fiber from a pulse input end; after demodulating, dividing the polarization states of the Rayleigh backscattered light into Q groups in sequence, wherein every three polarization states are divided into one group; calculating the transmission matrix of Group N, defining polarization transmission matrices corresponding to a segment from (3N−3)Δz to (3N−2)Δz, a segment from (3N−2)Δz to (3N−1)Δz, and a segment from (3N−1)Δz to (3N)Δz as M3N-2, M3N-1 and M3N, wherein due to slow changes of principle polarization axes of the optical fiber, M3N-2=M3N-1=M3N=Mx(N), so that Mx(N) is the transmission matrix of the Group N; wherein, Δz is a pulse width, N is a positive integer from 1 to Q; and listing an equation set:{SB0(3N-2)=MA·Mx2(N)·MA·SinSB0(3N-1)=MA·Mx4(N)·MA·SinSB0(3N)=MA·Mx6(N)·MA·Sin  wherein in the equation set:
MA=M3N-3·M3N-4 . . . M2·M1=Mx3(N−1) . . . Mx3  (1); Sin is a polarization state of an input lightwave; SB0(3N−2) is a polarization state backscattered from a point (3N−2) Δz and received at the point 0; SB0(3N−1) is a polarization state backscattered from a point (3N−1) Δz and received at the point 0; SB0(3N) is a polarization state backscattered from a point (3N) Δz and received at the point 0; and solving the equation set using a numerical analysis method in order to obtain multiple solutions, and screening the multiple solutions according to the characteristics of the polarization transmission matrix, wherein each time of screening provides a unique solution Mx(N) of the equation set; continually updating MA values for iteration, so as to obtain the distribution of polarization transmission matrices of the optical fiber, which is a series of polarization transmission matrices corresponding to each pulse width of the optical fiber.