Alcatel

Draka Comteq B.v.

Nicholas V Nechitailo

Michael T Rossi

Brian G Risch

Dean J Rattazzi

Christopher L Johnson

Matthew Soltis

Igor V Khudyakov

Raymond G Lovie

Mike Rossi

Thierry Auvray

The present invention introduces a concept of 'smart' ribbons, which use functionally tensioned optical fibers during the manufacture of fiber optic ribbons to create fiber ribbons with controlled geometrical configuration, optimized strain distribution and reduced attenuation. The ribbons may have flat or bowed cross section and be straight along the length or curved in its plane, or twisted unidirectionally, or periodically. These shapes and residual stress-strain state are induced and controlled by using tension functions instead of traditional constant-value tension per fiber during the ribbon manufacture. Further, the present invention reduces signal loss and/or attenuation in ribbon fibers caused by an increase in the strain variation from tensile strain to compressive strain along the length of the individual fibers when ribbons are manufactured, stacked, stranded around a strength member or twisted and bent during cable installation. In a first embodiment of the present invention, either a symmetric or non-symmetric load distribution is applied across the fibers being placed or drawn into a ribbon structure to eliminate or control residual twist in a completed fiber ribbon. Additionally, in the present invention, the load distribution on the fibers of a ribbon can be varied (e.g. periodically changed) along the length of the ribbon to provide a ribbon with the required design characteristics for any particular application. In a second embodiment of the invention, a fiber optic ribbon is made up of a plurality of sub-unit ribbons arranged in substantially the same plane. Each sub-unit ribbon includes a plurality of optical fibers coated by sub-unit matrices.

Functionally strained optical fibers

A fiber optic buffer tube containing fiber optic ribbons centrally located within the buffer tube and a gel compound surrounding the fiber optic ribbons. Disposed within the gel compound, between the walls of the buffer tube and the fiber optic ribbons are gel swellable yarns and/or particles. The gel swellable yarns/particles volumetrically expand when in contact with the gel compound causing greater force to hold the gel compound in place, especially when the fiber optic buffer is heated. The gel swellable yarns/particles also provide greater surface area and help to prevent the fiber optic ribbons from coming into contact with the walls of the buffer tube, thereby preventing signal attenuation problems.

Gel-swellable particles and yarns in gel-filled buffer tubes

The present invention adds a gel-swellable layer in fiber optic cables to aid in protecting the fibers within the cable. The gel-swellable layer can be placed on the fibers, individual ribbons, stacks of ribbons and on the inner surface of tubes by various methods, such as co-extrusion, and can be cured by either heat curing or UV curing. The gel-swellable layers of this invention can be either smooth or textured. When the fibers are placed into the tubes and the tubes are filled with the water resistant gel, the gel-swellable layer absorbs some of the gel causing it to 'swell'. As a result of the 'swelling' a certain volume of gel is absorbed by the layer, thus reducing the capability of the gel to flow at elevated temperatures.

Gel-swellable layers on fibers, fiber ribbons and buffer tubes

The present invention provides a method for reducing and/or controlling the variations of excess fiber length along the length of reeled fiber optic buffer tubes during the manufacture of the buffer tubes. The present invention varies any number, or combination, of parameters during the manufacture of buffer tubes to achieve a substantially uniform excess fiber length along a reeled buffer tube. One embodiment of the inventive method uses monotonically decaying draw or take-up tension of the buffer tubes during winding, combined with a stiffness-compliant pad placed on the reel core to aid in providing a substantially uniform excess fiber length in the tube, while another embodiment uses a monotonically increasing angular speed of the reel in combination with the stiffness-compliant pad on the reel core. In yet another embodiment a pad is placed either periodically or continuously in the windings of the buffer tube to provide an absorbing layer for the residual stresses existing in the buffer tube as it is reeled and after the reeling is complete, combined with re-reeling the buffer tube onto a second reel after the buffer tube has cooled (after manufacture), where the pad is removed during the re-reeling process. Additionally, the present invention can have the layers of buffer tube separated with rigid, cylindrical panels separating the layers. The present inventive method also combines any, or all, of the above steps to aid in achieving a substantially uniform excess fiber length along the length of the reeled buffer tube.

Method and apparatus to reduce variation of excess fiber length in buffer tubes of fiber optic cables

A fiber optic cable having a plurality of buffer tubes and filler rods or filler tubes disposed between the inner surface of the outer jacket of the fiber optic cable and the buffer tubes. The buffer tubes contain a plurality of optical fibers. The filler rods have a non-round core surrounded by a superabsorbant water swellable coating to provide protection for the optical fibers against the penetration of water within the cable. The filler rods and filler tubes are made of a solid or porous or foam-type material expanding in the presence of water.

Non-round filler rods and tubes with superabsorbent water swellable material for large cables

A coated optical fiber includes a fiber coating having an unblended primary portion on the optical fiber, an unblended secondary portion, and a blended portion intermediate the unblended primary and secondary portions. The thickness of the blended portion is greater than or equal to about 10% but less than 100% of the thickness of the fiber coating. An optical fiber ribbon includes a ribbon matrix similarly having an unblended primary portion, an unblended secondary portion, and a blended portion between the unblended primary portion and unblended secondary portion. A method for fabricating a coated optical fiber or optical fiber ribbon includes applying a primary portion material to the optical fiber or plurality of coated optical fibers, and applying a secondary portion material in a manner selected to provide a blend of the primary portion material and the secondary portion material. An applicator apparatus includes means for performing the described steps.

Coated optical fiber and optical fiber ribbon and method for the fabrication thereof

A fiber optic buffer tube containing fiber optic ribbons centrally located within the buffer tube and a gel compound surrounding the fiber optic ribbons. Disposed within the gel compound, between the walls of the buffer tube and the fiber optic ribbons are yarns. The yarns provide greater surface area which helps to hold the gel compound in place when the gel compound is heated. Also, the yarns provide a cushion which helps prevent the fiber optic ribbons from coming into contact with the walls of the buffer tube, thereby preventing signal attenuation problems.

Use of yarns with whiskers to improve gel compound flow performance of fiber optic cables

The present invention includes an optical fiber cable configuration comprising fibers that are grouped into buffer tubes or buffer cells, containing fiber bundles or ribbon stacks, using a lightweight fabric-type composite tape material to serve as a light-weight strength member and protective low-thermal-expansion sheath. A plurality of the buffer tubes or buffer cells of various shapes are then positioned upon another piece of composite tape material. Gel or foamy glue is placed on the tape and is used to secure the buffer tubes to the tape. A triangular or trapezoidal stack is then formed by rolling the tape to enclose the buffer tubes and excess gel serves to fill in gaps. Multiple stacks may then be stranded to form a larger super-cable structure that uses a piece of composite tape material along with the rolling process, as described above, to support the individual stacks.

Tape based high fiber count cable

An optical fiber cable includes an optical fiber ribbon stack having a plurality of optical fibers, and at least one cushion member disposed on outer side surfaces of the optical fiber ribbon stack. The cushion member functions as a spacer and strain energy absorbing member for protecting corner fibers of the optical fiber ribbon stack from bending and contact stresses due to contact with a buffer tube or other surrounding elements. The cushion member may have material characteristics, such as contact hardness and Young's modulus, which are similar to those of the ribbon stack, or which gradually change from a soft inner layer at the side of the cushion member which contacts the ribbon stack to a stiff outer layer at the side of the cushion member which may contact a buffer tube or other surrounding elements. An elastic membrane surrounds the optical fiber ribbon stack and attached cushion member, and a filler material, such as bubbled foam or foamed gel, is disposed in the space between the ribbon stack and the elastic membrane and the space between the elastic membrane and the buffer tube.

Optical fiber cable with cushion members protecting optical fiber ribbon stack

A buffer tube and fiber optic cable having an optimized ribbon stack packaging configuration, minimized attenuation problems and a reduced overall cable diameter and weight is provided. Specifically, a packaging configuration utilizing parallel lying and perpendicular lying fiber ribbons is configured into a ribbon stack having a square shape or cross-type configuration. Cushions may be placed between the high-fiber count ribbon stack and buffer tube walls thus enabling the ribbon stack to center itself within the tube thereby decreasing attenuation problems.

Buffer tube having a high fiber count ribbon stack packaging configuration and corner cushions

An optical fiber cable including a buffer tube wherein the optical unit is maintained in an axial center location of the buffer tube and protected from contact with an inner wall of the buffer tube. At least first and second gel layers are interposed between the buffer tube and the optical unit, wherein the first gel layer surrounds the optical unit, the second gel layer surrounds the first gel layer, and the first and second gel layers have different rheological properties. The inner gel layer may have a yield stress and a viscosity which are lower than a yield stress and a viscosity of the outer gel layer. The lower yield stress and viscosity of the inner gel layer serves to maintain the optical unit in an axial center position within the buffer tube and facilitates easy re-positioning of the optical unit to the axial center position when the buffer tube is flexed or bent. As a result, the optical unit may be maintained in a low stress state and stress-induced attenuation may be prevented.

Optical cable housing an optical unit surrounded by a plurality of gel layers

An optical fiber cable configuration having a central strength member. The central strength member includes a hollow tube. One or more strength rods are disposed along or within the tube. To avoid water penetration, the tube is filled with a gel or water-absorbing powder, which provides a water barrier.

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Conover, NC, United States of America

Nicholas V Nechitailo