Systems and methods for reducing splice loss in optical fibers

• US 20040086243A1
• Filed: 11/04/2002
• Published: 05/06/2004
• Est. Priority Date: 11/04/2002
• Status: Active Grant

• Current Assignee: Furukawa Electric North America Incorporated (Furukawa Electric Company Limited)
• Original Assignee: Fitel USA Corporation
• Inventors: Holmblad, Peter Mikal, Yablon, Andrew D., DiGiovanni, David John, Veng, Torben E.
• Granted Patent: US 6,826,341 B2
• Time in Patent Office: Days
• US Class Current: 385/123
• CPC Class Codes: C03B 2201/10 doped with boron C03B2201/14 takes precedence
• CPC Class Codes: C03B 2201/28 doped with phosphorus
• CPC Class Codes: C03B 2203/22 Radial profile of refractive index, composition or softening point
• CPC Class Codes: C03B 2203/222 Mismatching viscosities or softening points of glass layers
• CPC Class Codes: C03B 2203/36 Dispersion modified fibres, e.g. wavelength or polarisation shifted, flattened or compensating fibres (DSF, DFF, DCF)
• CPC Class Codes: C03B 2205/40 Monitoring or regulating the draw tension or draw rate
• CPC Class Codes: C03B 37/01413 Reactant delivery systems C03B37/01807 takes precedence; devices therefor in general B01D1/00, B01J4/00
• CPC Class Codes: C03B 37/01807 Reactant delivery systems, e.g. reactant deposition burners
• CPC Class Codes: C03B 37/027 Fibres composed of different sorts of glass, e.g. glass optical fibresC03B37/0253, C03B37/028 take precedence
• CPC Class Codes: G02B 6/03644 arranged - + -
• CPC Class Codes: G02B 6/03666 arranged - + - +
• CPC Class Codes: G02B 6/03694 Multiple layers differing in properties other than the refractive index, e.g. attenuation, diffusion, stress properties
• CPC Class Codes: G02B 6/2551 using thermal methods, e.g. fusion welding by arc discharge, laser beam, plasma torch

Abstract

Optical fibers are described that exhibit reduced splice loss. Further described are techniques for fabricating optical fibers exhibiting reduced splice loss. One described fiber includes a plurality of regions, one region having a higher viscosity and the other region having a lower viscosity, such that when the fiber is drawn under tension, a strain is frozen into the higher viscosity region. A lower viscosity buffer layer is sandwiched between the higher viscosity region and the lower viscosity region. The buffer layer isolates the lower viscosity region from changes in refractive index in the higher viscosity region arising from a change in the strain frozen into the higher viscosity region.

Claims

1. An optical fiber, comprising:

at least two regions,

one region having a higher viscosity and the other region having a lower viscosity, such that when the fiber is drawn under tension, a strain is frozen into the higher viscosity region; and

a lower viscosity buffer layer sandwiched between the higher viscosity region and the lower viscosity region,

the buffer layer isolating the lower viscosity region from changes in refractive index in the higher viscosity region arising from a change in the strain frozen into the higher viscosity region.

2. The optical fiber of claim 1, wherein the lower viscosity region comprises a core structure, and wherein the higher viscosity region comprises a cladding.

3. The optical fiber of claim 2, wherein the core structure includes a core and at least one layer surrounding the core.

4. The optical fiber of claim 3, wherein the core structure includes a core, a trench layer surrounding the core, and a ring layer surrounding the trench layer.

5. The optical fiber of claim 1, wherein the buffer layer has a refractive index that matches the refractive index of the cladding in the optical fiber after it is drawn from a preform.

6. An optical fiber preform, comprising:

at least two regions,

one region having a higher viscosity and the other region having a lower viscosity, such that when the fiber is drawn under tension from the preform, a strain is frozen into the higher viscosity region; and

a lower viscosity buffer layer sandwiched between the higher viscosity region and the lower viscosity region,

the buffer layer isolating the lower viscosity region from changes in refractive index in the higher viscosity region arising from a change in the strain frozen into the higher viscosity region.

7. The optical fiber preform of claim 6, wherein the lower viscosity region comprises a core structure, and wherein the higher viscosity region comprises a cladding.

8. The optical fiber of claim 7, wherein the core structure includes a core and at least one layer surrounding the core.

9. The optical fiber of claim 8, wherein the core structure includes a core, a trench layer surrounding the core, and a ring layer surrounding the trench layer.

10. The optical fiber of claim 6, wherein the buffer layer has a refractive index that matches the refractive index of the cladding in the optical fiber after it is drawn from a preform.

11. A method for fabricating an optical fiber, comprising:

(a) fabricating a preform, comprising at least two regions, one region having a higher viscosity and the other region having a lower viscosity, such that when an optical fiber is drawn under tension from the preform, a strain is frozen into the higher viscosity region;

(b) sandwiching a lower viscosity buffer layer between the higher viscosity region and the lower viscosity region, such that the lower viscosity region is isolated from changes in refractive index in the higher viscosity region arising from a change in the strain frozen into the higher viscosity region; and

(c) drawing the preform into an optical fiber.

12. The method of claim 11, wherein in step (a) the lower viscosity region comprises a core structure, and wherein the higher viscosity region comprises a cladding.

13. The method of claim 12, wherein in step (a) the core structure includes a core and at least one layer surrounding the core.

14. The method of claim 13, wherein in step (a) the core structure includes a core, a trench layer surrounding the core, and a ring layer surrounding the trench layer.

15. The method of claim 11, wherein the buffer layer has a refractive index that matches the refractive index of the cladding in the optical fiber after it is drawn from a preform.

16. A method for fabricating an optical fiber preform, comprising:

(a) fabricating at least two regions, one region having a higher viscosity and the other region having a lower viscosity, such that when the fiber is drawn under tension from the preform, a strain is frozen into the higher viscosity region; and

(b) sandwiching a lower viscosity buffer layer between the higher viscosity region and the lower viscosity region, the buffer layer isolating the lower viscosity region from changes in refractive index in the higher viscosity region arising from a change in the strain frozen into the higher viscosity region.

17. The method of claim 16, wherein in step (a) the lower viscosity region comprises a core structure, and wherein the higher viscosity region comprises a cladding.

18. The method of claim 17, wherein in step (a) the core structure includes a core and at least one layer surrounding the core.

19. The method of claim 18, wherein in step (a) the core structure includes a core, a trench layer surrounding the core, and a ring layer surrounding the trench layer.

20. The method of claim 16, wherein in step (a) the buffer layer has a refractive index that matches the refractive index of the cladding in the optical fiber after it is drawn from a preform.