Optical cable

An optical cable comprising:

• a central tensile member;
• a plurality of optical fiber bundles formed by gathering a plurality of optical fibers;
• a plurality of tubular members arranged around the central tensile member 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 rollable optical fiber ribbons of the plurality of optical fiber bundles to a length of the plurality of tubular members of the optical cable satisfies the following formula:
• 0
• ≤
• ε
• ≤
• 2
• ⁢
• R
• 2
• ⁢
• R
• -
• H
• -
• 1
• ,
• wherein R denotes a lossless bending radius of the plurality of 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 plurality of optical fiber bundles modeled as having a circular cross section.

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

• forming an optical fiber bundle by gathering a plurality of optical fibers;
• 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 twisting the plurality of tubular members, 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 forming 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
• ⁢
• R
• 2
• ⁢
• R
• -
• H
• ,
• wherein R denotes a lossless bending radius of the plurality of optical fibers, and
• H denotes a diameter based on a cross-sectional area of the multi-fiber optical cable with a spiral trajectory of a center point on the optical fiber bundle modeled as having a circular cross section.