An MCF having a structure excellent in mass productivity and suppressing increases in splicing cost and loss are provided. The MCF includes 12 or 16 cores, a cladding, and a coating. The cores are arranged at positions of line symmetry while no adjacent relationship is established between the cores having an adjacent relationship with any core. A coating diameter is 235-265 μm, a cladding diameter CD is from CD.sub.nominal−1 μm to CD.sub.nominal+1 μm with a nominal value CD.sub.nominal of 195 μm or less, an MFD at 1310 nm is from MFD-reference-value−0.4 μm to the MCF-reference-value+0.4 μm with the MFD-reference-value of 8.2-9.2 μm, and a 22 m-cable-cutoff wavelength λ.sub.cc is 1260-1360 nm. A core's zero-dispersion wavelength is a wavelength-reference-value−12 nm to the wavelength-reference-value+12 nm with the wavelength-reference-value of 1312-1340 nm, and a dispersion slope at the wavelength is 0.092 ps/(nm.sup.2.Math.km) or less. A shortest distance from a cover-cladding interface to each core center, a structure, and optical characteristics satisfy predetermined conditions.

An MCF having a structure excellent in mass productivity and suppressing increases in splicing cost and loss are provided. The MCF includes 12 or 16 cores, a cladding, and a coating. The cores are arranged at positions of line symmetry while no adjacent relationship is established between the cores having an adjacent relationship with any core. A coating diameter is 235-265 μm, a cladding diameter CD is from CD.sub.nominal−1 μm to CD.sub.nominal+1 μm with a nominal value CD.sub.nominal of 195 μm or less, an MFD at 1310 nm is from MFD-reference-value−0.4 μm to the MCF-reference-value+0.4 μm with the MFD-reference-value of 8.2-9.2 μm, and a 22 m-cable-cutoff wavelength λ.sub.cc is 1260-1360 nm. A core's zero-dispersion wavelength is a wavelength-reference-value−12 nm to the wavelength-reference-value+12 nm with the wavelength-reference-value of 1312-1340 nm, and a dispersion slope at the wavelength is 0.092 ps/(nm.sup.2.Math.km) or less. A shortest distance from a cover-cladding interface to each core center, a structure, and optical characteristics satisfy predetermined conditions.

A multicore fiber optic cable comprising of a central fiber having a central fiber outer diameter, a central fiber coating surrounding the central fiber outer diameter of the central fiber, the central fiber coating having a continuous spiraled groove around the central fiber outer diameter, a dual core optical fiber having a dual core optical fiber geometry, the dual core optical fiber spiraled around the central fiber coating and disposed within the spiraled groove such that the dual core optical fiber is wound around the central fiber coating in a spiral pattern and the central fiber core geometry and the dual core optical fiber geometry are oriented longitudinally to negate link path length difference; and an outer sheath surrounding the central fiber coating and the dual core optical fiber.

A fiber optic cable assembly includes an elongate housing, a plurality of fiber optic cables placed inside the housing and extending longitudinally, and acoustic isolating material placed inside the housing and extending longitudinally. The acoustic isolating material includes a plurality of outwardly radially extending arms extending from a center of the housing towards a circumference of the housing. The plurality of arms divides a space inside the housing into a plurality of acoustically isolated sections. Each acoustically isolated section extends longitudinally. Each acoustically isolated section includes at least one of the plurality of fiber optic cables. Each acoustically isolated section is acoustically insulated from remaining sections of the plurality of acoustically isolated sections. A surface of the acoustic isolating material of each acoustically isolated section is covered by acoustic reflective material.

The present disclosure includes: an optical fiber ribbon including a plurality of optical fibers having an outer diameter of 0.2 mm or less and a ribbon resin that integrates the plurality of optical fibers in a parallel state; and a coating resin that covers the optical fiber ribbon. The optical fiber ribbon is in an assembled form in which the plurality of optical fibers are assembled so that a length in an arrangement direction is shorter than that of a case where the optical fibers are arranged in a row, and the optical fiber ribbon is covered with the coating resin in the assembled form.

Provided is a polyethylene resin for use in a spacer for an optical fiber cable, the polyethylene resin having a density of 0.952 g/cm.sup.3 or more, containing a polyethylene having a molecular weight of 10,000 or less in a weight fraction of 22% or more, and containing a polyethylene having a molecular weight of 300,000 or more in a weight fraction of 12% or more.

A signal and power cable is provided with a plurality of twisted pair conductor elements, at least one of which is configured for power transmission and at least one of which is configured for signal transmission. At least one cable filler element is configured to at least partially separate one of the plurality of twisted pairs from another, the at least one cable filler element having at least one hollow opening. At least one optical fiber, the at least on optical fiber positioned within the at least one hollow opening of the at least one cable filler element.

An optical fiber cable having a slot core which includes a plurality of ribs formed along a cable longitudinal direction and in which slot grooves for housing optical fibers are formed between the ribs. The optical fiber cable includes: subunits each of which is formed by bundling a plurality of intermittent-connection-type optical fiber ribbons in which a connection part where adjacent optical fibers are connected to each other and a non-connection part where adjacent optical fibers are not connected to each other are intermittently provided in the longitudinal direction among some or all of optical fibers; and a thin-skin-shaped tube having Young's modulus lower than Young's modulus of a material forming the slot core. The subunits are housed in the slot grooves, and among the subunits in the slot grooves, at least a subunit located at an outer peripheral part of the slot grooves is covered with the tube.

An optical fiber cable having a slot core which includes a plurality of ribs formed along a cable longitudinal direction and in which slot grooves for housing optical fibers are formed between the ribs. The optical fiber cable includes: subunits each of which is formed by bundling a plurality of intermittent-connection-type optical fiber ribbons in which a connection part where adjacent optical fibers are connected to each other and a non-connection part where adjacent optical fibers are not connected to each other are intermittently provided in the longitudinal direction among some or all of optical fibers; and a thin-skin-shaped tube having Young's modulus lower than Young's modulus of a material forming the slot core. The subunits are housed in the slot grooves, and among the subunits in the slot grooves, at least a subunit located at an outer peripheral part of the slot grooves is covered with the tube.

Provided is a polyethylene resin for use in a spacer for an optical fiber cable, the polyethylene resin having a density of 0.952 g/cm.sup.3 or more, containing a polyethylene having a molecular weight of 10,000 or less in a weight fraction of 22% or more, and containing a polyethylene having a molecular weight of 300,000 or more in a weight fraction of 12% or more.