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

Patent metadata

Field	Value
Publication number	US-9841349-B2
Application number	US-201615382671-A
Country	US
Kind code	B2
Filing date	Dec 18, 2016
Priority date	Aug 3, 2016
Publication date	Dec 12, 2017
Grant date	Dec 12, 2017

Abstract

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 M x (N) of the equation set; continually updating M A values for iteration, so as to obtain the distribution of polarization transmission matrices of the optical fiber.

First claim

What is claimed is:

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 M 3N-2 , M 3N-1 and M 3N , wherein due to slow changes of principle polarization axes of the optical fiber, M 3N-2 =M 3N-1 =M 3N =M x (N), so that M x (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:

{

S
B
0

⁡

(

3
⁢
N

-
2

)

=

M
A

·

M
x
2

⁡

(
N
)

·

M
A

·

S

i
⁢

⁢
n

S
B
0

⁡

(

3
⁢
N

-
1

)

=

M
A

·

M
x
4

⁡

(
N
)

·

M
A

·

S

i
⁢

⁢
n

S
B
0

⁡

(

3
⁢
N

)

=

M
A

·

M
x
6

⁡

(
N
)

·

M
A

·

S

i
⁢

⁢
n

wherein in the equation set:
M A =M 3N-3 ·M 3N-4 . . . M 2 ·M 1 =M x 3 ( N− 1) . . . M x 3   (1);

s in is a polarization state of an input lightwave;
S B 0 (3N−2) is a polarization state backscattered from a point (3N−2) Δz and received at the point 0;
S B 0 (3N−1) is a polarization state backscattered from a point (3N−1) Δz and received at the point 0;
S B 0 (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 M x (N) of the equation set; continually updating M A values

Assignees

• Univ Electronic Sci & Tech China

Inventors

• Wang Zinan
• Fu Yun
• Rao Yunjiang

Classifications

• G01M11/3181 Primary

  Reflectometers dealing with polarisation · CPC title