A fibre optic cable (500, 700, 1420) comprises one or more fibre units (502, 1302). Each fibre unit comprises two or more optical fibres (506, 1306) embedded in a solid resin material (520, 1320) to form a coated fibre bundle and an extruded polymer sheath (524, 1324). The sheath (524, 1324) of each fibre unit is primarily polybutylene terephthalate (PBT), with a friction reducing additive such as polydimethylsiloxane (PDMS). The additive may be polythene based and/or polyacrylate based. The fibre unit may be applied in a pullback cable (500, 800, 1100), as a cable for pulling or pushing or as a blown fibre cable (502, 1302).

A method is disclosed of making a coated optical fiber. The method may involve drawing a preform through a furnace to create a fiber having a desired diameter and cross sectional shape. The fiber is then drawn through a slurry, wherein the slurry includes elements including at least one of metallic elements, alloy elements or dielectric elements, and the slurry wets an outer surface of the fiber. As the fiber is drawn through the slurry, it is then drawn through a forming die to impart a wet coating having a desired thickness on an outer surface of the fiber. The wet fiber is then drawn through an oven or ovens configured to heat the wet coating sufficiently to produce a consolidated surface coating on the fiber as the fiber exits the oven or ovens.

A method is disclosed of making a coated optical fiber. The method may involve drawing a preform through a furnace to create a fiber having a desired diameter and cross sectional shape. The fiber is then drawn through a slurry, wherein the slurry includes elements including at least one of metallic elements, alloy elements or dielectric elements, and the slurry wets an outer surface of the fiber. As the fiber is drawn through the slurry, it is then drawn through a forming die to impart a wet coating having a desired thickness on an outer surface of the fiber. The wet fiber is then drawn through an oven or ovens configured to heat the wet coating sufficiently to produce a consolidated surface coating on the fiber as the fiber exits the oven or ovens.

An optical fiber coating apparatus that provides increased gyre stability and reduced gyre strength, thereby providing a more reliable coating application process during fiber drawing includes a cone-only coating die having a conical entrance portion with a tapered wall angled at a half angle α, wherein 2°≤α≤25°, and a cone height L.sub.1 less than 2.2 mm, and a cylindrical portion having an inner diameter of d.sub.2, wherein 0.1 mm≤d.sub.2≤0.5 mm and a cylindrical height of L.sub.2, wherein 0.05 mm≤L.sub.2≤1.25 mm; a guide die having an optical fiber exit, the guide die disposed adjacent the cone-only coating die such that a wetted length (L.sub.5) between the optical fiber exit of the guide die and the entrance of the cone-only coating die is from 1 mm to 5 mm; and a holder for holding the cone-only coating die and the guide die in a fixed relationship defining a coating chamber between the guide die and the cone-only coating die, the coating chamber having an inner radius L.sub.6 from the optical fiber axis to an inner wall of the holder that is from 3 mm to 10 mm.

An optical fiber coating apparatus that provides increased gyre stability and reduced gyre strength, thereby providing a more reliable coating application process during fiber drawing includes a cone-only coating die having a conical entrance portion with a tapered wall angled at a half angle α, wherein 2°≤α≤25°, and a cone height L.sub.1 less than 2.2 mm, and a cylindrical portion having an inner diameter of d.sub.2, wherein 0.1 mm≤d.sub.2≤0.5 mm and a cylindrical height of L.sub.2, wherein 0.05 mm≤L.sub.2≤1.25 mm; a guide die having an optical fiber exit, the guide die disposed adjacent the cone-only coating die such that a wetted length (L.sub.5) between the optical fiber exit of the guide die and the entrance of the cone-only coating die is from 1 mm to 5 mm; and a holder for holding the cone-only coating die and the guide die in a fixed relationship defining a coating chamber between the guide die and the cone-only coating die, the coating chamber having an inner radius L.sub.6 from the optical fiber axis to an inner wall of the holder that is from 3 mm to 10 mm.

An optical fiber coating apparatus that provides increased gyre stability and reduced gyre strength, thereby providing a more reliable coating application process during fiber drawing includes a cone-only coating die having a conical entrance portion with a tapered wall angled at a half angle α, wherein 2°≤α≤25°, and a cone height L.sub.1 less than 2.2 mm, and a cylindrical portion having an inner diameter of d.sub.2, wherein 0.1 mm≤d.sub.2≤0.5 mm and a cylindrical height of L.sub.2, wherein 0.05 mm≤L.sub.2≤1.25 mm; a guide die having an optical fiber exit, the guide die disposed adjacent the cone-only coating die such that a wetted length (L.sub.5) between the optical fiber exit of the guide die and the entrance of the cone-only coating die is from 1 mm to 5 mm; and a holder for holding the cone-only coating die and the guide die in a fixed relationship defining a coating chamber between the guide die and the cone-only coating die, the coating chamber having an inner radius L.sub.6 from the optical fiber axis to an inner wall of the holder that is from 3 mm to 10 mm.

An optical fiber coating apparatus that provides increased gyre stability and reduced gyre strength, thereby providing a more reliable coating application process during fiber drawing includes a cone-only coating die having a conical entrance portion with a tapered wall angled at a half angle α, wherein 2°≤α≤25°, and a cone height L.sub.1 less than 2.2 mm, and a cylindrical portion having an inner diameter of d.sub.2, wherein 0.1 mm≤d.sub.2≤0.5 mm and a cylindrical height of L.sub.2, wherein 0.05 mm≤L.sub.2≤1.25 mm; a guide die having an optical fiber exit, the guide die disposed adjacent the cone-only coating die such that a wetted length (L.sub.5) between the optical fiber exit of the guide die and the entrance of the cone-only coating die is from 1 mm to 5 mm; and a holder for holding the cone-only coating die and the guide die in a fixed relationship defining a coating chamber between the guide die and the cone-only coating die, the coating chamber having an inner radius L.sub.6 from the optical fiber axis to an inner wall of the holder that is from 3 mm to 10 mm.

An optical communication cable includes a jacket having an interior surface that defines a cable jacket internal cross-sectional area and a plurality of optical fibers, wherein less than 60% of the cable jacket internal cross-sectional area is occupied by the cross-sectional area of the plurality of optical fibers. A scaffolding structure is provided adjacent to and supporting the jacket such that when the jacket is subjected to a burn and melts, the melted jacket material bonds to the scaffolding structure rather than sloughing off.

An optical communication cable includes a jacket having an interior surface that defines a cable jacket internal cross-sectional area and a plurality of optical fibers, wherein less than 60% of the cable jacket internal cross-sectional area is occupied by the cross-sectional area of the plurality of optical fibers. A scaffolding structure is provided adjacent to and supporting the jacket such that when the jacket is subjected to a burn and melts, the melted jacket material bonds to the scaffolding structure rather than sloughing off.

An optical fiber manufacturing method includes: coating an outer periphery of a bare optical fiber with a resin before curing by a coating device; and curing the resin with a coating curing device. The following equations are satisfied: t×sin θ>T1× tan θ and θ=tan.sup.−1 (d/L), where T1 is a tension in the upstream of the coating device, t is the shear force applied to the bare optical fiber by the resin, d is the design maximum value of a deviation amount of an entry position of the bare optical fiber into the resin in the coating device with respect to the center axis of the die hole of the coating device, and L is the contact length between the resin and the bare optical fiber in the coating device along the center axis.