Method and apparatus for manufacturing optical fiber

• US 9,389,361 B2
• Filed: 05/28/2013
• Issued: 07/12/2016
• Est. Priority Date: 08/12/2011
• Status: Active Grant

• Current Assignee: Fujikura Limited
• Original Assignee: Fujikura Limited
• Inventors: Matsushita, Shingo
• Primary Examiner(s): HERRING, LISA L
• Application Number:
  US13/903,542
• Publication Number:
  US 20130255323A1
• Time in Patent Office: 1,141 Days
• US Class Current: 1/1
• CPC Class Codes: C03B 2203/24 Single mode [SM or monomode]
• CPC Class Codes: C03B 37/02718 Thermal treatment of the fibre during the drawing process, e.g. cooling coating C03C25/10
• CPC Class Codes: C03B 37/02727 Annealing or re-heating
• CPC Class Codes: G02B 6/02395 Glass optical fibre with a protective coating, e.g. two layer polymer coating deposited directly on a silica cladding surface during fibre manufacture G02B6/02052, G02B6/02057, G02B6/024, G02B6/032, G02B6/105, G02B6/14 take precedence; coating on fibre gratings G02B6/02104; multilayer core or cladding G02B6/036; reinforcing splice joints G02B6/2558; optical cables, i.e. comprising protective structures external to the protective coating such as a jacket or plural coated optical fibres G02B6/44; coating of glass to obtain optical fibres C03C25/104

Abstract

Provided is a method for manufacturing an optical fiber. The method includes the steps of: heating and melting a silica-based optical fiber preform in a drawing furnace; drawing the melted preform into a linear shape from the drawing furnace, continuously cooling and solidifying the preform to form a bare optical fiber; coating the bare optical fiber with a resin to form an optical fiber; and continuously taking up the optical fiber while applying a tensile force, wherein, when a surface temperature of the cooled and solidified bare optical fiber reached down to 100° C. or lower, a surface of the bare optical fiber is reheated while applying a tensile force so as to remelt only a surface layer of the bare optical fiber, and the surface layer of the bare optical fiber is re-solidified, the bare optical fiber is coated with a resin, and the tensile force is released afterward.

Claims

1. A method for manufacturing an optical fiber comprising:

heating and melting a silica-based optical fiber preform in a drawing furnace;

drawing the melted preform into a linear shape from the drawing furnace at a speed of approximately 5 m/min to 100 m/min, continuously cooling and solidifying the linear shape through cooling in an atmosphere to form a bare optical fiber;

coating the bare optical fiber with a resin to form an optical fiber; and

continuously taking up the optical fiber while applying a tensile force using a take-up machine,

wherein, when a surface temperature of the cooled and solidified bare optical fiber reached down to 100°

C. or lower, a surface of the bare optical fiber is reheated while applying a tensile force so as to remelt only a surface layer of the bare optical fiber,

a time period from when the melted preform is drawn from the drawing furnace to when the reheating begins is set to 2 seconds or more; and

the surface layer of the bare optical fiber that has been remelted is re-solidified, then, the bare optical fiber is coated with a resin, and the tensile force is released afterward, thereby obtaining an optical fiber having a residual compressive stress imparted to the surface layer in the bare optical fiber.

2. A method for manufacturing an optical fiber comprising:

heating and melting a silica-based optical fiber preform in a drawing furnace;

drawing the melted preform into a linear shape from the drawing furnace at a speed of approximately 100 m/min to 1000 m/min, continuously cooling and solidifying the linear shape through a cooling device to form a bare optical fiber;

coating the bare optical fiber with a resin to form an optical fiber; and

continuously taking up the optical fiber while applying a tensile force using a take-up machine,

wherein, when a surface temperature of the cooled and solidified bare optical fiber drawn from the cooling device reached down to 100°

C. or lower, a surface of the bare optical fiber is reheated while applying a tensile force so as to remelt only a surface layer of the bare optical fiber, and

the surface layer of the bare optical fiber that has been remelted is re-solidified, then, the bare optical fiber is coated with a resin, and the tensile force is released afterward, thereby obtaining an optical fiber having a residual compressive stress imparted to the surface layer in the bare optical fiber.

3. The method for manufacturing an optical fiber according to claim 2, the method further comprising:

measuring the surface temperature of the cooled and solidified bare optical fiber using a surface temperature detection device; and

controlling the cooling device using a cooling control device depending on the surface temperature detected by the surface temperature detection device.