At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

At&t Technologies, Inc.

Charles H Gartside

Andrew J Panuska

Parbhubhai D Patel

Carl Raymond Taylor

Manuel R Santana

Alvin C Levy

Bernard Raymond Eichenbaum

Bob J Overton

An optical fiber cable (20) includes a core (21) comprising a plurality of optical fibers (24--24) without intended stranding. The plurality of optical fibers are enclosed in a common tube (34) which provides a predetermined packing density and which is substantially parallel to the longitudinal axis of the cable. In one embodiment, a waterblocking material (36) is disposed within the tube to fill the interstices between the optical fibers and between the fibers and the tube. The waterblocking material is such that its critical yield stress does not exceed about 70 Pa at 20.degree. C. and such that it has a shear modulus of less than about 13 KPa at 20.degree. C. The common tube is enclosed with non-metallic or metallic strength members and a plastic inner jacket and by another layer of strength members and by a plastic outer jacket. This arrangement is such that the cable may be manufactured and installed with optical fibers capable of moving within the cable structure to prevent undue stresses being imparted thereto which would cause unwanted microbending losses.

Optical fiber cable

An optical fiber cable (20) includes a core (21) comprising a units a unit (22). The unit is formed by a plurality of optical fibers (24-24) which are assembled together without intended standing. The unit is enclosed in a tube (34) which provides a predetermined packing density and which is substantially parallel to the longitudinal axis of the cable. In one embodiment, a waterblocking material (36) is disposed within the tube to fill the interstices between the optical fibers and between the unit and the tube. The waterblocking material is such that its critical yield does not exceed about 70 Pa at 20.degree. C. and such that it has a shear modulus of less than about 13 KPa at 20.degree. C. The tube is enclosed with non-metallic or metallic strength members and a plastic inner jacket and by another layer of strength members and by a plastic outer jacket. This arrangement is such that the cable may be manufactured and installed with the optical fibers capable of moving within the cable structure to prevent undue stresses being imparted thereto which would cause unwanted microbending losses.

Optical fiber cable and methods of making

An optical fiber cable (20) includes a core (21) comprising a plurality of units (22--22). Each unit is formed by a plurality of optical fibers (24--24) which are assembled together without intended stranding. The plurality of units are enclosed in a common tube (34) which provides a predetermined packing density and which is substantially parallel to the longitudinal axis of the cable. In one embodiment, a waterblocking material (36) is disposed within the tube to fill the interstices between the optical fibers and between the units. The waterblocking material is such that its critical yield stress does not exceed about 70 Pa at 20.degree. C. and such that it has a shear modulus of less than about 13 KPa at 20.degree. C. The common tube is enclosed with non-metallic or metallic strength members and a plastic inner jacket and by another layer of strength members and by a plastic outer jacket. This arrangement is such that the cable may be manufactured and installed with the optical fibers capable of moving within the cable structure to prevent undue stresses being imparted thereto which would cause unwanted microbending losses.

Optical fiber cable including a plurality of multifiber units within a

A single mode optical fiber ribbon cable is disclosed. In preferred embodiments, the cable comprises a filling compound having a critical yield stress less than about 70 Pa at 20.degree. C. and/or fibers having a coating that comrises a low modulus (less than about 1.5.multidot.10.sup.6 Pa at 20.degree. C.) inner coating and a high modulus (more than 10.sup.8 Pa at 20.degree. C.) outer coating. Communication cable according to the invention can have low cabling loss, is adapted for array joining, can have high fiber density, and can advantageously be used in short-haul applications such as for metropolitan trunk lines or loop, as well as for long-haul applications.

Single mode optical fiber ribbon cable

A grease composition comprising oil, colloidal particle filler, and, optionally, a bleed inhibitor is disclosed. The grease typically has a critical yield stress below 140 Pa at 20.degree. C., preferably below 70 or 35 Pa. The grease can advantageously be used as a cable filling material, especially for optical fiber cable. In the latter case it can result in cable having substantially no cabling loss. Preferred compositions comprise 77 to 95% b.w. of ASTM type 103, 104A, or 104B paraffinic or naphthenic oil, or polybutene oil; 2 to 15% b.w. of hydrophobic or hydrophilic fused silica; and optionally, up to 15% b.w. of styrene-rubber or styrene-rubber-styrene block copolymer, or semiliquid rubber.

Thixotropic grease composition and cable comprising same

An optical fiber cable comprises one or more 'units' surrounded by a sheath. Each unit comprises a dielectric central strength member, a smooth cushion layer thereon, and one or more optical fibers helically wrapped thereon. A tube surrounds this structure, with the space therebetween optionally filled with a waterproofing gel that has a low modulus over a wide temperature range. The tube is made of a material (typically PVC) that obtains a low modulus during cooling after extrusion so that substantially no compressive stresses are transmitted to the optical fibers. In an alternate embodiment, the optical fibers do no lay directly on the cushion layer but 'float' in the waterproofing gel. In another embodiment, a spacer fiber of larger diameter than the optical fibers provides for clearance between the tube and the optical fibers. The resulting structure provides for ease of manufacture and low microbending losses for the optical fibers over a wide temperature range.

Growing community of inventors

Lilburn, GA, United States of America

Charles H Gartside