A manufacturing method of an optical fiber includes forming an optical fiber by forming a plurality of resin-coating layers around a glass fiber including a core part and a cladding part, and forming a marking on an outermost layer, which is a colored layer having pigment, of the plurality of resin-coating layers by melting or scorching a surface of the outermost layer with a laser.

A resin composition for optical fiber coating contains a photopolymerizable compound and a photopolymerization initiator, in which the photopolymerizable compound contains epoxy di(meth)acrylate having a bisphenol skeleton and alkylene oxide-modified di(meth)acrylate having a bisphenol skeleton, and a mass ratio of a content of the alkylene oxide-modified di(meth)acrylate with respect to a content of the epoxy di(meth)acrylate is 0.3 or more and 8.0 or less.

A resin composition for optical fiber coating contains a photopolymerizable compound and a photopolymerization initiator, in which the photopolymerizable compound contains epoxy di(meth)acrylate having a bisphenol skeleton and alkylene oxide-modified di(meth)acrylate having a bisphenol skeleton, and a mass ratio of a content of the alkylene oxide-modified di(meth)acrylate with respect to a content of the epoxy di(meth)acrylate is 0.3 or more and 8.0 or less.

A resin composition for optical fiber coating according to the present disclosure is a resin composition containing a photopolymerizable compound, a photopolymerization initiator, and surface-treated titanium oxide particles, in which a content of the surface-treated titanium oxide particles is 0.6% by mass or more and less than 25% by mass based on the total amount of the resin composition.

A resin composition for optical fiber coating according to the present disclosure is a resin composition containing a photopolymerizable compound, a photopolymerization initiator, and surface-treated titanium oxide particles, in which a content of the surface-treated titanium oxide particles is 0.6% by mass or more and less than 25% by mass based on the total amount of the resin composition.

The present invention provides a two-layer structure colored optical fiber which includes a colored secondary coating layer improved in collectability and separability. The two-layer structure colored optical fiber in an embodiment of the present invention includes a glass optical fiber, a primary coating layer coating the glass optical fiber, and a colored secondary coating layer coating the primary coating layer. The secondary coating layer has such characteristics that a surface cure percentage is 99% or more at an infrared absorption peak of a wave number of 1407 cm.sup.1 and a surface kinetic friction force in Knot Test is less than 0.075 N.

An optical fiber comprises a glass fiber, and a coating resin layer with which the glass fiber is covered, the coating resin layer has a plurality of layers, the plurality of layers includes a first layer being in contact with the glass fiber, and a longest diameter at 40 C. of a void formed in the first layer is 100% or more and 300% or less of a longest diameter at 23 C. thereof, or a longest diameter at 40 C. of a void formed in the first layer is 100% or more and 600% or less of a longest diameter at 23 C. thereof, and a Young's modulus of the first layer is 0.3 MPa or less.

A resin composition for optical fiber coating contains a photopolymerizable compound, a photopolymerization initiator, and surface-treated copper phthalocyanine particles, in which a content of the surface-treated copper phthalocyanine particles is 0.1% by mass or more and 10% by mass or less based on the total amount of the resin composition.

A resin composition for optical fiber coating contains a photopolymerizable compound, a photopolymerization initiator, and surface-treated copper phthalocyanine particles, in which a content of the surface-treated copper phthalocyanine particles is 0.1% by mass or more and 10% by mass or less based on the total amount of the resin composition.

An optical fiber draw system that prints one or more fiber identifiers on optical fibers is described. In one example, the optical fiber draw system includes a draw furnace, a coating device, a marking device, and a lighting device. The draw furnace generates a glass fiber from a glass preform and the coating device is configured to apply a curable coating composition to the glass fiber. The lighting device applies an ultraviolet or other curing light to form a coating from the curable coating composition. The application and curing of a curable coating composition can be completed one or more times to form one or more coatings on the glass fiber. The marking device applies a tracer marking fluid to a curable coating composition or coating and can be placed at one or more positions along the process pathway.