Extending a range of an optical fiber distributed sensing system

Patent metadata

Field	Value
Publication number	US-10386247-B2
Application number	US-201715460286-A
Country	US
Kind code	B2
Filing date	Mar 16, 2017
Priority date	Sep 29, 2016
Publication date	Aug 20, 2019
Grant date	Aug 20, 2019

Abstract

Embodiments are directed to a distributed temperature sensing system. The system includes a first fiber optic cable and a second fiber optic cable. A first coupler is coupled to the first fiber optic cable. A second coupler is coupled to the second fiber optic cable. An optical isolator coupled between the first coupler and the second coupler to remove a Stokes signal in order to increase the range of the distributed temperature sensing system.

First claim

What is claimed is:

1. A system for measuring temperature via distributed temperature sensing comprising:
a first fiber optic cable;
a second fiber optic cable;
a first coupler coupled to the first fiber optic cable;
a second coupler coupled to the second fiber optic cable;
an optical isolator disposed between the first coupler and the second coupler and in optical communication with the first coupler and the second coupler;
a light source configured to send a light through the first and second fiber optic cable;
a photodetector configured to convert received light into electrical signals; and
a computing unit configured to calculate a ratio between and anti-Stokes band in the received light and a Stokes band in the received light to determine a temperature along a length of the first or second fiber optic cable.

2. The system of claim 1 , wherein the first coupler is a first wavelength division multiplexer.

3. The system of claim 2 , wherein the first wavelength division multiplexer is configured to separate a light signal from the first fiber optic cable into a pump signal and a Stokes signal.

4. The system of claim 3 , wherein the second coupler is a second wavelength division multiplexer.

5. The system of claim 4 , wherein, the optical isolator is configured to filter a Stokes signal traveling from the first fiber optic cable to the second fiber optic cable.

6. The system of claim 5 , wherein the optical isolator is further configured to allow a backscattered signal to travel from the second fiber optic cable to the first fiber optic cable.

7. The system of claim 1 , further comprising:
a third fiber optic cable;
a third coupler coupled to the second fiber optic cable;
a fourth coupler coupled to the third fiber optic cable; and
a second optical isolator coupled between the third coupler and the fourth coupler.

8. A system for measuring temperature via distributed temperature sensing comprising:
a first fiber optic cable;
a first coupling system coupled to the first fiber optic cable; and
a second fiber optic cable; wherein the first coupling system comprises:
a first coupler coupled to the first fiber optic cable;
a second coupler coupled to the second fiber optic cable;
a first optical isolator coupled between the first coupler and the second coupler;
a light source configured to send a light through the first and second fiber optic cable;
a photodetector configured to convert received light into electrical signals; and
a computing unit configured to calculate a ratio between an anti-Stokes band in the received light and a Stokes band in the received light to determine a temperature along a length of the first or second fiber optic cable.

9. The system of claim 8 , further comprising:
a third fiber optic cable; and
a second coupling system coupled between the second fiber optic cable and the third fiber optic cable; wherein,
the second coupling system comprises:
a third coupler coupled to the second fiber optic cable;
a fourth coupler coupled to the third fiber optic cable; and
a second optical isolator coupled between the first coupler and the second coupler.

10. The system of claim 9 , wherein:
a length of the first fiber optic cable is not equal to a length of the second fiber optic cable.

11. The system of claim 10 , wherein:
the length of the first fiber optic cable is at least 6 kilometers; and
the length of the second fiber optic cable is at least 15 kilometers.

12. A method for measuring temperature via distributed temperature sensing comprising:
transmitting light through a first fiber optic cable, wherein the first fiber optic cable is coupled to a second fiber optic cable;
detecting backscattered light, wherein the backscattered light comprises an anti-Stokes band and a Stokes band in the first fiber optic cable;
calculating a ratio between an intensity of the anti-Stokes band and an intensity of the Stokes band; and
using the calculated ratio to determine a temperature being sensed in the first fiber optic cable or the second fiber optic cable; wherein:
the first fiber optic cable is coupled to the second fiber optic cable via a first coupler coupled to the first fiber optic cable, a second coupler coupled to the second fiber optic cable, and an optical isolator coupled between the first coupler and the second coupler; and
wherein the optical isolator is configured to remove a Stokes signal traveling from the first fiber optic cable to the second fiber optic cable.

13. The method of claim 12 , wherein the first coupler is a first wavelength division multiplexer.

14. The method of claim 12 , wherein the first wavelength division multiplexer is configured to separate a light signal from the first fiber optic cable into a pump signal and the Stokes band.

15. The method of claim 14 , wherein the second coupler is a second wavelength division multiplexer.

16. The method of claim 15 , wherein the optical isolator is further configured to allow a backscattered signal to travel from the second fiber optic cable to the first fiber optic cable.

Assignees

• Ofs Fitel Llc

Inventors

• Sun Xiaoguang

Classifications

• G02B6/264

  with optical elements between opposed fibre ends which perform a function other than beam splitting (having lens focusing means G02B6/32; utilising prism or grating G02B6/34) · CPC title

• G02B6/2938

  for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM · CPC title

• G01K11/32 Primary

  using changes in transmittance, scattering or luminescence in optical fibres · CPC title

• G01K2011/324

  Physics · mapped topic

• G01K11/324

  using Raman scattering · CPC title