Fiber optic cables with multiple stacks of optical fiber ribbons

• US 6,317,542 B1
• Filed: 09/15/1999
• Issued: 11/13/2001
• Est. Priority Date: 09/15/1999
• Status: Expired due to Fees

• Current Assignee: Fitel USA Corporation (Furukawa Electric Company Limited)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Weimann, Peter A., Jackson, Kenneth Wade, Small, Richard Dalton Jr., Norris, Richard Hartford, Sheu, Jim Jenqtsong, Hardwick, Nathan E. III, Lever, Clyde Jefferson, Taylor, Carl Raymond
• Primary Examiner(s): Schuberg, Darren
• Assistant Examiner(s): BOUTSIKARIS, LEONIDAS
• Application Number:
  US09/396,305
• Time in Patent Office: 790 Days
• Field of Search: 385/110, 385/111, 385/112, 385/113, 385/105, 385/106, 385/114, 385/109
• US Class Current: 385/114
• CPC Class Codes: G02B 6/4411 Matrix structure
• CPC Class Codes: G02B 6/4413 Helical structure
• CPC Class Codes: G02B 6/4433 Double reinforcement laying in straight line with optical transmission element
• 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 multiple differently sized stacks of optical fiber ribbons. The stacks include a central stack that is approximately centrally located in a jacket passage and peripheral stacks positioned radially around the central stack. A difference exists between the dimensions of the central stack and the dimensions of one or more of the peripheral stacks. Another fiber optic cable has multiple longitudinally extending stacks of optical fiber ribbons that are within a jacket passage. The stacks include a central stack that is approximately centrally located in the jacket passage, and peripheral stacks positioned radially around the central stack. Buffer encasements that respectively contain the peripheral stacks are longitudinally stranded around the central stack. Each buffer encasement includes a longitudinally extending interior surface that extends around and defines a longitudinally extending passage that contains the respective peripheral stack, and each interior surface closely bounds and engages a substantial portion of the periphery of the respective peripheral stack. Another fiber optic cable includes multiple optical modules within a longitudinally extending jacket and longitudinally stranded around a central member. Each optical module includes a stack of optical fiber ribbons enclosed in a buffer encasement. Each buffer encasement includes a longitudinally extending interior surface that extends around and defines a longitudinally extending passage that contains the respective stack, and the interior surface closely bounds and engages a substantial portion of the periphery of the respective stack.

Claims

1. A fiber optic cable with efficiently packaged optical fibers, comprising:

a jacket extending in a longitudinal direction and defining a longitudinally extending jacket passage; and

a plurality of longitudinally extending stacks of optical fiber ribbons, wherein each stack is within the jacket passage, each optical fiber ribbon comprises a laterally extending array of longitudinally extending optical fibers that are bonded together as a unit, each optical fiber ribbon comprises a pair of longitudinally extending opposite edges and a pair of opposite lateral surfaces that extend laterally between the edges, the plurality of stacks comprises a central stack that is approximately centrally located in the jacket passage and peripheral stacks positioned radially around the central stack in an end elevation view of the fiber optic cable, in the end elevation view thereof the periphery of each stack defines a first cross-dimension between a first pair of opposite sides that are defined by edges of the optical fiber ribbons of the stack, in the end elevation view thereof each stack further defines a second cross-dimension between a second pair of sides that are defined by one of the lateral surfaces of one of the optical fiber ribbons of the stack and one of the lateral surfaces of another of the optical fiber ribbons of the stack, and a difference exists between the central stack and all of the peripheral stacks of the fiber optic cable, wherein the difference is selected from the group consisting of;

the first cross-dimension of the central stack is larger than the first cross-dimensions of all of the peripheral stacks of the fiber optic cable, and

the second cross-dimensions of the central stack is larger than the second cross-dimensions of all of the peripheral stacks of the fiber optic cable.

2. A fiber optic cable according to claim 1, further comprising a plurality of buffer encasements respectively containing the peripheral stacks, wherein each buffer encasement comprises longitudinally extending interior surface, each interior surface extends around and defines a longitudinally extending passage that contains the respective peripheral stack, and each interior surface closely bounds and engages the periphery of the respective peripheral stack.

3. A fiber optic cable according to claim 1, wherein the first and second cross-dimensions of the central stack are larger than the first and second dimensions of the peripheral stacks.

4. A fiber optic cable according to claim 1, wherein in the end elevation view thereof, the periphery of each stack defines a generally parallelogram-like shape.

5. A fiber optic cable according to claim 1, wherein for each stack the first cross-dimension thereof is approximately equal to the second cross-dimension thereof.

6. A fiber optic cable according to claim 5, wherein the first and second cross-dimensions of the central stack are larger than the first and second dimensions of the peripheral stacks.

16. A fiber optic cable according to claim 2, wherein each buffer encasement is a one-piece buffer encasement and for each of the optical fiber ribbons the interior surface of the respective buffer encasement engages each of the edges of the optical fiber ribbon.

7. A fiber optic cable, comprising:

a plurality of optical modules, wherein each optical module comprises;

a stack of optical fiber ribbons extending in a longitudinal direction, wherein each optical fiber ribbon comprises a laterally extending array of longitudinally extending optical fibers bonded together as a unit and a pair of opposite edges that extend in the longitudinal direction, and

a one-piece buffer encasement comprising longitudinally extending interior and exterior surfaces, wherein the interior surface extends around and defines a longitudinally extending passage that contains the stack, with the interior surface closely bounding and engaging a substantial portion of the periphery of the stack so that for each optical fiber ribbon the interior surface of the buffer encasement engages each of the edges of the optical fiber ribbon;

a central member around which the optical modules are longitudinally stranded; and

a longitudinally extending jacket defining a longitudinally extending jacket passage through which the central member and the optical modules extend,

wherein for each optical module the stack is in a longitudinally twisted configuration and the buffer encasement is a sheath that is thin such that the exterior surface of the sheath defines ridges that correspond to the twist of the stack, and the ridges are at comers of the sheath that are respectively positioned at comers of the stack that is enveloped by the sheath.

8. A fiber optic cable according to claim 7, wherein for each optical module:

each optical fiber ribbon comprises a pair of longitudinally extending opposite edges and a pair of longitudinally extending opposite surfaces that extend laterally between the edges, and each optical fiber ribbon has a thickness defined between its opposite surfaces; and

the buffer encasement is a relatively thin sheath, in an end elevation view of the sheath at least a majority of the sheath has a thickness defined between the interior and exterior surfaces that is not substantially greater than the thickness of each of the optical fiber ribbons.

9. A fiber optic cable according to claim 7, wherein for each optical module:

in an end elevation view of the stack the periphery of the stack defines a shape; and

in the end elevation view of the buffer encasement the interior surface of the buffer encasement defines a shape that is substantially similar to the shape defined by the periphery of the stack in the end elevation view of the stack.

10. A fiber optic cable according to claim 9, wherein for each optical module, in the end elevation view of the buffer encasement, the exterior surface of the buffer encasement defines a shape that is substantially similar to the shape defined by the periphery of the stack in the end elevation view of the stack.

11. A fiber optic cable according to claim 7, wherein for each optical module, the interior surface of the buffer encasement is unadhered to the stack and the stack is capable of moving longitudinally relative to the stack.

12. A fiber optic cable with efficiently packaged optical fibers, comprising:

a jacket extending in a longitudinal direction and defining a longitudinally extending jacket passage;

a plurality of longitudinally extending stacks of optical fiber ribbons, wherein each optical fiber ribbon comprises a laterally extending array of longitudinally extending optical fibers that are bonded together as a unit and a pair of opposite edges that extend in the longitudinal direction, each stack is within the jacket passage, and the plurality of stacks comprises;

a central stack that is approximately centrally located in the jacket passage, and

peripheral stacks positioned radially around the central stack in an end elevation view of the fiber optic cable;

a plurality of one-piece buffer encasements respectively containing the peripheral stacks and longitudinally stranded around the central stack, wherein each buffer encasement comprises a longitudinally extending interior surface, each interior surface extends around and defines a longitudinally extending passage that contains the respective peripheral stack, and each interior surface closely bounds and engages a substantial portion of the periphery of the respective peripheral stack so that for each optical fiber ribbon the interior surface of the respective buffer encasement engages each of the edges of the optical fiber ribbon; and

a longitudinally extending central member defining a longitudinally extending central passage, wherein the central stack is within the central passage, and the buffer encasements are longitudinally stranded around the central member, and wherein the central member has a longitudinally extending exterior surface and in an end elevation view of the central member the exterior surface defines a generally polygon-like shape, and the polygon-like shape has a number of sides that corresponds to the number of peripheral stacks.

13. A fiber optic cable according to claim 12, wherein:

the central stack that is approximately centrally located in the jacket passage, and

a radial distance is defined between the center of the central stack and the center of each of the peripheral stacks, and the radial distances defined between the center of the central stack and the center of each of the peripheral stacks is approximately equal.

14. A fiber optic cable according to claim 12, wherein each of the peripheral stacks is longitudinally twisted within its buffer encasement to define a lay length.

15. A fiber optic cable according to claim 12, wherein:

the central member has a longitudinally extending exterior surface that defines a lay length; and

the longitudinally stranded peripheral stacks define a lay length that is equal to the lay length defined by the exterior surface of the central member.