STRETCHABLE FIBER OPTIC CABLE

• US 20150153531A1
• Filed: 06/25/2014
• Published: 06/04/2015
• Est. Priority Date: 09/24/2013
• Status: Active Grant

• Current Assignee: Coming Optical Communications LLC
• Original Assignee: Coming Optical Communications LLC
• Inventors: McAlpine, Warren Welborn, Seddon, David Alan
• Granted Patent: US 9,075,212 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02B 6/4413 Helical structure
• CPC Class Codes: G02B 6/4429 Means specially adapted for strengthening or protecting the cables
• CPC Class Codes: G02B 6/443 Protective covering
• CPC Class Codes: G02B 6/4432 with fibre reinforcements
• CPC Class Codes: G02B 6/4433 Double reinforcement laying in straight line with optical transmission element
• CPC Class Codes: G02B 6/4434 Central member to take up tensile loads
• CPC Class Codes: G02B 6/44384 the means comprising water blocking or hydrophobic materials G02B6/4439, G02B6/4479 take precedence

Abstract

A fiber optic cable includes a strength member, tubes coupled to the strength member, and optical fibers. The strength member provides tensile and anti-buckling strength. The tubes have a cavity into which the optical fibers are packed. The cable is stretchable in that the optical fibers experience less than 0.5 dB/km of increased average attenuation at 1310 nanometers wavelength when the cable experiences strain of up to 2×10⁻³.

Claims

1. A fiber optic cable, comprising:

a strength member configured to provide tensile strength as well as anti-buckling strength, wherein the strength member is a rod;

tubes, each tube having a cavity, wherein the strength member provides reinforcement to the tubes, wherein the rod is a central strength member and wherein the tubes are wound around the rod in a pattern of reverse-oscillatory winding, wherein the tubes are generally round in cross-section and have an average outer diameter of 3 millimeters or less, wherein the tubes have an average inner diameter of 2 millimeters or less; and

a binder sleeve for constraining the tubes, wherein the binder sleeve is primarily formed from an extruded polymer material;

a jacket extruded around the binder sleeve; and

optical fibers packed into the cavity of each tube such that the optical fibers bend therein, having excess optical fiber length providing a strain window such that the optical fibers experience less than 0.5 dB/km of increased average attenuation at 1310 nanometers wavelength when the cable experiences strain of up to 1% compared to when unstrained.

2. The cable of claim 1, wherein the tubes each contain at least twelve optical fibers, the optical fibers comprising a glass core, a glass cladding, and a polymeric coating, and wherein the optical fibers have an outer diameter of at least 200 micrometers.

3. The cable of claim 1, wherein the extruded polymer of the binder sleeve is continuous lengthwise along a 10 meter long section of the cable and continuous peripherally around the tubes to form a closed loop.

4. The cable of claim 3, wherein the binder sleeve has an average thickness that is less than a fifth that of the jacket.

5. The cable of claim 4, wherein the binder sleeve is bonded to the jacket.

6. A fiber optic cable, comprising:

a strength member configured to provide tensile strength as well as anti-buckling strength, wherein the strength member is a rod;

tubes formed from polymer, each tube having a cavity, wherein the strength member provides reinforcement to the tubes, wherein the rod is a central strength member and wherein the tubes are wound around the rod in a pattern of reverse-oscillatory winding, wherein the tubes are generally round in cross-section and have an average outer diameter of 3 millimeters or less, and wherein the tubes have an average inner diameter of 2 millimeters or less;

a binder sleeve for constraining the tubes, wherein the binder sleeve is primarily formed from an extruded polymer material;

a jacket extruded around the binder sleeve; and

optical fibers packed into the cavity of each tube such that the optical fibers bend therein, wherein the optical fibers have a greater length than the length of the respective tube in which the optical fibers are packed, thereby providing a strain window for the cable and correspondingly increasing the stretch-ability of the cable.

7. The cable of claim 6, wherein the tubes each contain at least twelve optical fibers, the optical fibers comprising a glass core, a glass cladding, and a polymeric coating, and wherein the optical fibers have an outer diameter of at least 200 micrometers.

8. The cable of claim 6, wherein the average distance between reversals in the pattern of reverse-oscillatory winding is at least 10 centimeters along the length of the cable and is less than 5 meters along the length of the cable, whereby the tubes have stored torsion motivating separation between the tubes and the central strength member, which the binder sleeve mitigates by providing a relatively uniform distributed load along the tubes to hold the tubes to the central strength member.

9. The cable of claim 6, wherein the binder sleeve is primarily formed from polyethylene.

10. The cable of claim 9, wherein the binder sleeve is continuous lengthwise and peripherally around the tubes, forming a closed loop for a length of at least 10 meters along the cable, thereby limiting localized stressing of the tubes.

11. The cable of claim 9, wherein the jacket is formed from a polymer that defines the outermost surface of the cable, wherein the binder sleeve is bonded to the jacket.

12. The cable of claim 11, wherein the jacket comprises polyethylene.

13. The cable of claim 11, wherein the binder sleeve has an average thickness of 0.5 millimeters or less, which is less than a fifth the thickness of the jacket on average.

14. A fiber optic cable, comprising:

a strength member configured to provide tensile strength as well as anti-buckling strength, wherein the strength member is a rod;

tubes formed from polymer, each tube having a cavity, wherein the strength member provides reinforcement to the tubes, wherein the rod is a central strength member and wherein the tubes are wound around the rod in a pattern of reverse-oscillatory winding, wherein the tubes are generally round in cross-section and have an average outer diameter of 3 millimeters or less, and wherein the tubes have an average inner diameter of 2 millimeters or less;

a binder sleeve, wherein the binder sleeve is continuous lengthwise and peripherally around the tubes, forming a closed loop for a length of at least 10 meters along the cable; and

optical fibers packed into the cavity of each tube such that the optical fibers bend therein, wherein the optical fibers have a greater length than the length of the respective tube in which the optical fibers are packed, thereby providing a strain window for the cable and correspondingly increasing the stretch-ability of the cable.

15. The cable of claim 14, wherein the tubes each contain at least twelve optical fibers, the optical fibers comprising a glass core, a glass cladding, and a polymeric coating, and wherein the optical fibers have an outer diameter of at least 200 micrometers.

16. The cable of claim 14, wherein the average distance between reversals in the pattern of reverse-oscillatory winding is at least 10 centimeters along the length of the cable and is less than 5 meters along the length of the cable, whereby the tubes have stored torsion motivating separation between the tubes and the central strength member, which the binder sleeve mitigates by providing a relatively uniform distributed load along the tubes to hold the tubes to the central strength member.

17. The cable of claim 14, wherein the binder sleeve is primarily formed from a polymer.

18. The cable of claim 17, further comprising a jacket formed from a polymer that defines the outermost surface of the cable, wherein the binder sleeve is bonded to the jacket.

19. The cable of claim 18, wherein the binder sleeve comprises polyethylene and the jacket comprises polyethylene.

20. The cable of claim 18, wherein the binder sleeve has an average thickness of 0.5 millimeters or less, which is less than a fifth the thickness of the jacket on average.