Optical cable

An optical cable comprising:

• a central tensile wire;
• a plurality of optical fiber bundles formed by gathering a plurality of rollable optical fiber ribbons including a plurality of optical fibers;
• a plurality of tubular members arranged around the central tensile wire and accommodating the plurality of optical fiber bundles therein;
• and
• a jacket covering the plurality of tubular members,
• wherein a ratio (ε) of an excess group length of the rollable optical fiber ribbons of the optical fiber bundles to a length of the tubular members satisfies the following formula:
• 0
• ≤
• ε
• ≤
• 2
• ⁢
• R
• 2
• ⁢
• R
• -
• H
• -
• 1
• ,
• wherein R denotes a lossless bending radius of the optical fibers, and
• H denotes a diameter based on a cross-sectional area of the optical cable with a spiral trajectory of a center point on the optical fiber bundle modeled as having a circular cross-section,
• wherein the plurality of optical fibers of the optical fiber bundle comprise at least one rollable optical fiber ribbon and optical fibers constituting the at least one rollable optical fiber ribbon comprise at least one of G.652.D optical fibers, G.657.A1 optical fibers, G.657.A2 optical fiber, or G.657.B3 optical fibers,
• wherein R is 40 millimeters (mm) when the type of the optical cable including the rollable optical fiber ribbons is G.652.D, is 30 mm when the type of the optical cable is G.657.A1, is 25 mm when the type of the optical cable is G.657.A2, and is 20 mm when the type of the optical cable is G.657.B3.

A manufacturing method of a multi-core optical cable, comprising:

• forming an optical fiber bundle by gathering a plurality of rollable optical fiber ribbons;
• forming a tubular member by a first extrusion molding device to surround the optical fiber bundle;
• forming an optical unit assembly by gathering a plurality of tubular members by a gathering device while repeatedly twisting the plurality of tubular members around a central tensile wire in an sz-direction, and binding the plurality of tubular members by a binding member;
• and
• forming a jacket by a second extrusion molding device to cover the optical unit assembly,
• wherein, when in the forming of the tubular member, an insertion rate of the optical fiber bundle is V1 and an extrusion rate of the tubular member is V2, the following formula is satisfied:
• 1
• ≤
• V
• ⁢
• 1
• V
• ⁢
• 2
• ≤
• 2
• ⁢
• H
• 2
• ⁢
• R
• -
• H
• ,
• wherein R denotes a lossless bending radius of the optical fibers, and
• H denotes a diameter based on a cross-sectional area of the optical cable with a spiral trajectory of a center point on the optical fiber bundle modeled as having a circular cross section.