An optical cable includes one or more tension members, optical fibers disposed around an outer periphery of the one or more tension members, and an outer sheath housing the one or more tension members and the optical fibers. A boundary elongation of the one or more tension members is smaller than a boundary elongation of the optical fibers. The boundary elongation of the one or more tension members and the boundary elongation of the optical fibers is a cable elongation corresponding to a boundary between an initial elongation region and an elastic region.

The present disclosure relates to an optical unit including a tubular member, which accommodates a plurality of optical fibers and whose shape is variable to achieve an optimal space factor, to minimizes optical loss or the deterioration of optical properties when the optical cable is bent or compressed or external impact is applied, secure waterproof performance, and minimize an outer diameter, and an optical cable including the same.

An image-conducting optical fiber bundle extends along a central bundle axis between image input and image output ends. The bundle is twisted along a portion of its length such that an image inputted into the image input end is angularly displaced about the central bundle axis before being outputted through the image output end. Each constituent optical fiber includes a cladding with a cladding diameter corresponding with the fiber diameter of that fiber and a core with a core diameter. The ratio of the core diameter to the cladding diameter defines a core-to-clad diameter ratio relative to each fiber. In various embodiments, at least one of fiber diameter and core-to-clad diameter ratio varies as a function of a fiber's radial displacement from the central bundle axis.

A flame-retardant fiber optic cable includes core elements, a film surrounding the core elements, and a jacket surrounding the film. The core elements include one or more optical fibers and at least one tube surrounding the one or more optical fibers. The material composition of the film differs from the jacket and the film is relatively thin.

A fiber laser apparatus includes a pumping light source which launches pumping light, an amplifying optical fiber which includes a core and a noncircular cladding, and absorbs the pumping light to launch laser light, an amplifying coil which has a configuration around which the amplifying optical fiber is wound, a first reflector which is provided on an input side of the amplifying coil and is configured to reflect the laser light toward the amplifying coil, and a second reflector which is provided on a launching side of the amplifying coil, has a lower reflectance than a reflectance of the first reflector, and is configured to reflect the laser light toward the amplifying coil.

[Problem] The thickness on a ripcord in a circular optical cable is reduced, to improve workability.

[Solution] An optical cable of the present invention includes: an optical fiber unit including optical fibers; a sheath, having a circular external form, configured to house the optical fiber unit in a housing portion; and two strength members embedded in the sheath; and two rip cords, wherein when a direction of connecting the two strength members sandwiching the housing portion is a first direction and a direction intersecting the first direction is a second direction, in a cross section of the optical cable, a cross-sectional shape of the housing portion has a dimension in the second direction greater than that in the first direction, and the two rip cords is disposed to sandwich the optical fiber unit such that a direction of connecting the two rip cords is in the second direction, in the cross section of the optical cable.

An optical fiber cable includes: a plurality of optical fibers; a cable sheath covering the plurality of optical fibers; and a plurality of tension member groups embedded in the cable sheath. Each of the plurality of tension member groups includes at least one tension member. In a cross section of the optical fiber cable perpendicular to a longitudinal direction of the optical fiber cable, roundness of the cable sheath is 85% or more.

A method for producing an optical fiber unit by winding at least two bundling members on the outer circumference of an optical fiber bundle formed by bundling a plurality of optical fibers, including: feeding the optical fiber bundle from a fiber passage member; feeding the bundling members while forming intersection points between two of the bundling members on the outer circumference of the optical fiber bundle by feeding at least one of the bundling members from a bundling member passage part of a rotating member arranged to the outer circumference of the fiber passage member, while causing the rotating member to oscillate, with the feeding direction serving as the axis; and fusion-bonding the bundling members at their intersection points.

An optical cable comprises a strength member element and a plurality of buffer tubes, wherein each of the buffer tubes encapsulates at least one optical fiber. The buffer tubes are stranded around the strength member element with subsequent different directions of lay. In order to fix the stranded buffer tubes and to prevent any unwinding of the stranded buffer tubes an adhesive component is disposed in at least one fixing area of the optical cable, the at least one fixing area being a regional area of the optical cable, where sections of the buffer tubes having a different direction of lay adjoin to each other.

A fiber optic cable includes a cable core of core elements and a protective sheath surrounding the core elements, an armor surrounding the cable core, the armor comprising a single overlap portion when the fiber optic cable is viewed in cross-section, and a jacket surrounding the armor, the jacket having at least two longitudinal discontinuities extruded therein. A method of accessing the cable core without the use of ripcords includes removing a portion of the armor in an access section by pulling the minor away from the cable core so that an overlap portion separates around the cable core as it is being pulled past the cable core. A protective sheath protects the core elements as the armor is being pulled around the cable core.