Manufacturing method and manufacturing apparatus of optical fiber
AssigneeFujikura Ltd.
InventorKenji OKADA
Life of this patent
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Abstract
A manufacturing method of an optical fiber includes: heating and melting an optical fiber preform; drawing a bare optical fiber from a heated and melted portion of the optical fiber preform; cooling the bare optical fiber drawn from the optical fiber preform; forming a coating layer on a surface of the cooled bare optical fiber; obtaining an optical fiber by curing the coating layer; adding torsion to the optical fiber by transmitting the torsion up to the heated and melted portion through the bare optical fiber from the optical fiber so that spin is applied to the bare optical fiber; and winding the optical fiber.
Claims13
A manufacturing method of an optical fiber, comprising:
- heating and melting an optical fiber preform;
- drawing a bare optical fiber from a heated and melted portion of the optical fiber preform;
- cooling the bare optical fiber drawn from the optical fiber preform;
- forming a coating layer on a surface of the cooled bare optical fiber;
- obtaining an optical fiber by curing the coating layer;
- adding torsion to the optical fiber by transmitting the torsion up to the heated and melted portion through the bare optical fiber from the optical fiber so that spin is applied to the bare optical fiber;
- and
- winding the optical fiber, wherein
- when the bare optical fiber is drawn from the heated and melted portion, generating a non-circularity of a core in a range of 0.3% to 1% in the bare optical fiber is performed,
- when the torsion is added to the optical fiber, applying the spin to the bare optical fiber is performed so that torsion in a first direction and torsion in a second direction, which is opposite to the first direction, are alternately present around a longitudinal direction of the bare optical fiber, and
- when the torsion is added to the optical fiber, applying the spin to the bare optical fiber is performed so that a unidirectional torsion length in the spin becomes equal to or less than a beat length converted from birefringence generated due to a non-circular core and an amplitude of the spin indicating a degree of unidirectional torsion in the spin reaches 30 rad or more.
A manufacturing apparatus of an optical fiber, comprising:
- a heating furnace that heats and melts an optical fiber preform;
- a cooling device that cools a bare optical fiber drawn from a heated and melted portion of the optical fiber preform;
- a coating device that provides a coating layer to a surface of the cooled bare optical fiber;
- a curing device that cures the coating layer;
- a torsion application device that adds torsion to an optical fiber obtained by curing the coating layer so that spin is applied to the bare optical fiber by transmitting torsion up to the heated and melted portion from the optical fiber through the bare optical fiber;
- and
- a winding device that winds the optical fiber to which the torsion has been added, wherein
- the heating furnace is constituted so that a non-circularity of a core in a range of 0.3% to 1% is generated in the bare optical fiber when the bare optical fiber is drawn from the optical fiber preform,
- the torsion application device is constituted so that the spin is applied to the bare optical fiber so that torsion in a first direction and torsion in a second direction, which is opposite to the first direction, are alternately present around a longitudinal direction of the bare optical fiber, and
- the torsion application device applies the spin to the bare optical fiber so that a unidirectional torsion length in the spin becomes equal to or less than a beat length converted from birefringence generated due to the non-circular core and a spin amplitude indicating a degree of unidirectional torsion in the spin reaches 30 rad or more.
Dependencies are inferred from the claim text.