Optic fibres and fibre optic sensing

• US 9,677,956 B2
• Filed: 11/11/2010
• Issued: 06/13/2017
• Est. Priority Date: 11/13/2009
• Status: Active Grant

• Current Assignee: Optasense Holdings Limited (Luna Innovations, Inc.)
• Original Assignee: Optasense Holdings Limited (Luna Innovations, Inc.)
• Inventors: Crickmore, Roger Ian, Hill, David John, McEwen-King, Magnus
• Primary Examiner(s): Kianni, Kaveh C
• Application Number:
  US13/509,425
• Publication Number:
  US 20120222487A1
• Time in Patent Office: 2,406 Days
• Field of Search: 385123
• CPC Class Codes: G01D 5/3538 using a particular type of fiber, e.g. fibre with several cores, PANDA fiber, fiber with an elliptic core or the like
• CPC Class Codes: G01H 9/004 using fibre optic sensors light guides per se G02B6/00, acousto-optical devices specially adapted for gating or modulating in optical wave guides G02F1/125
• CPC Class Codes: G01L 1/243 using means for applying force perpendicular to the fibre axis
• CPC Class Codes: G01L 11/025 using a pressure-sensitive optical fibre
• CPC Class Codes: G01V 1/208 having a continuous structure detecting traffic G08G, transducers in general G10K
• CPC Class Codes: G01V 1/52 Structural details
• CPC Class Codes: G02B 2006/0325 Fluid core or cladding
• CPC Class Codes: G02B 6/02 Optical fibres with cladding with or without a coating
• CPC Class Codes: G02B 6/443 Protective covering

Abstract

Fiber optic cables with improved performance for use in distributed sensing, for instance in distributed acoustic sensors, are disclosed. In one embodiment a fiber optic cable (210) comprises a core (208) and cladding (206) disposed within a buffer material (202) and surrounded by a jacket (204) and arranged so that the core is offset from the center of the cable. By offsetting the core from the center of the jacket any bending effects on the core can be maximised compared with the core being located at the center of the cable.

Claims

1. An optical fibre comprising a core, a cladding surrounding the core and a jacket surrounding the cladding further comprising at least one buffer material filling a space between the cladding and jacket the optical fibre further comprising at least one stiffening member, the at least one stiffening member having a stiffness that is greater in a first transverse direction than a second transverse direction, such that the optical fibre readily flexes in the second direction and does not readily flex in the first direction, and wherein the core is offset from the center of the optical fibre in the second transverse direction.

2. An optical fibre as claimed in claim 1 wherein the core is located to one side of optical fibre.

3. An optical fibre as claimed in claim 1 wherein the centre of the optical fibre does not lie within the core.

4. An optical fibre as claimed in claim 3 wherein the centre of the optical fibre does not lie within the cladding.

5. An optical fibre as claimed in claim 1 comprising more than one buffer material.

6. An optical fibre as claimed in claim 1 comprising a gel buffer disposed in the centre of the optical fibre with the core and cladding to one side of the gel buffer.

7. An optical fibre as claimed in claim 1 wherein the core and cladding are disposed within a gel buffer material.

8. An optical fibre as claimed in claim 1 comprising a solid buffer material in the centre of the optical fibre, surrounded by a gel buffer, with the core and cladding being disposed in the gel buffer.

9. An optical fibre as claimed in claim 1 wherein the core is a helix along the length of the fibre.

10. A fibre optic cable comprising an optical fibre as claimed in claim 1.

11. A fibre optic cable as claimed in claim 10 comprising a plurality of optical fibres.

13. A distributed acoustic fibre optic sensor comprising an optical source coupled to an optical fibre as claimed in claim 1 to interrogate said first optical fibre with optical radiation and a detector coupled to said first optical fibre to detect radiation which is back-scattered from said first optical fibre.

12. An optical fibre comprising a core, a cladding surrounding the core and a jacket surrounding the cladding further comprising at least one buffer material filling a space between the cladding and jacket wherein at least some of the buffer material is a gel, the fibre further comprising at least one stiffening member, the at least one stiffening member having a stiffness that is greater in a first transverse direction than a second transverse direction, such that the optical fibre readily flexes in the second direction and does not readily flex in the first direction, and wherein the core is offset from the center of the optical fibre in the second transverse direction.