PRODUCTION METHOD OF OPTICAL FlBER PREFORM AND PRODUCTION METHOD OF OPTICAL FIBER

Patent metadata

Field	Value
Publication number	US-2016304387-A1
Application number	US-201615192590-A
Country	US
Kind code	A1
Filing date	Jun 24, 2016
Priority date	Jan 7, 2014
Publication date	Oct 20, 2016
Grant date	—

Abstract

A production method of an optical fiber preform includes: forming a porous preform by depositing silica particles at an outer periphery of a core rod; and vitrifying the porous preform by conducting thermal treatment steps. At a first thermal treatment step that is an initial thermal treatment step of the thermal treatment steps, the porous preform is heated so that internal temperatures at two end portions in a longitudinal direction of the porous preform increase before an internal temperature of a center portion in the longitudinal direction increases.

First claim

What is claimed is:

1 . A production method of an optical fiber preform, comprising:
forming a porous preform by depositing silica particles at an outer periphery of a core rod; and vitrifying the porous preform by conducting thermal treatment steps, wherein at a first thermal treatment step that is an initial thermal treatment step of the thermal treatment steps, the porous preform is heated so that internal temperatures at two end portions in a longitudinal direction of the porous preform increase before an internal temperature of a center portion in the longitudinal direction increases.

2 . The production method of an optical fiber preform according to claim 1 , wherein
the first thermal treatment step is conducted by a device including heaters arranged in the longitudinal direction of the porous preform, and outputs of the heaters heating the two end portions in the longitudinal direction increase before an output of the heater heating the center portion in the longitudinal direction increases.

3 . The production method of an optical fiber preform according to claim 1 , wherein
the first thermal treatment step is conducted by a device including a heater configured to heat a partial section in the longitudinal direction of the porous preform, and a position of the heater relative to the porous preform in the longitudinal direction repeatedly moves back and forth at a predetermined cycle.

4 . The production method of an optical fiber preform according to claim 1 , wherein the porous preform is heated so that a temperature difference between the internal temperatures in the longitudinal direction of the porous preform is not higher than 800° C.

5 . The production method of an optical fiber preform according to claim 1 , wherein, at the first thermal treatment step, a temperature-rising rate of internal temperatures at the two end portions in the longitudinal direction of the porous preform is not higher than 6000° C. per hour.

6 . The production method of an optical fiber preform according to claim 1 , wherein, at the first thermal treatment step, the porous preform is subjected to a thermal treatment in an atmosphere containing inert gas and halogen gas at a temperature lower than 1400° C.

7 . The production method of an optical fiber preform according to claim 1 , wherein, at a final thermal treatment step of the thermal treatment steps, the porous preform is subjected to a thermal treatment in an atmosphere containing inert gas at a temperature higher than 1400° C.

8 . The production method of the optical fiber preform according to claim 1 , wherein at the thermal treatment steps other than a final thermal treatment step, the porous preform is heated so that the internal temperatures of the two end portions in the longitudinal direction of the porous preform increase before the internal temperature of the center portion in the longitudinal direction increases.

9 . A production method of an optical fiber, comprising:
drawing an optical fiber preform produced by a production method of an optical fiber preform including:
forming a porous preform by depositing silica particles at an outer periphery of a core rod; and
vitrifying the porous preform by conducting thermal treatment steps, wherein
at a first thermal treatment step that is an initial thermal treatment step of the thermal treatment steps, the porous preform is heated so that internal temperatures at two end portions in a longitudinal direction of the porous preform increase before an internal temperature of a center portion in the longitudinal direction increases.

10 . The production method of an optical fiber according to claim 9 , wherein
the first thermal treatment step is conducted by a device including heaters arranged in the longitudinal direction of the porous preform, and outputs of the heaters heating the two end portions in the longitudinal direction increase before an output of the heater heating the center portion in the longitudinal direction increases.

11 . The production method of an optical fiber according to claim 9 , wherein
the first thermal treatment step is conducted by a device including a heater configured to heat a partial section in the longitudinal direction of the porous preform, and a position of the heater relative to the porous preform in the longitudinal direction repeatedly moves back and forth at a predetermined cycle.

12 . The production method of an optical fiber according to claim 9 , wherein the porous preform is heated so that a temperature difference between the internal temperatures in the longitudinal direction of the porous preform is not higher than 800° C.

13 . The production method of an optical fiber according to claim 9 , wherein, at the first thermal treatment step, a temperature-rising rate of internal temperatures at the two end portions in the longitudinal direction of the porous preform is not higher than 6000° C. per hour.

14 . The production method of an optical fiber according to claim 9 , wherein, at the first thermal treatment step, the porous preform is subjected to a thermal treatment in an atmosphere containing inert gas and halogen gas at a temperature lower than 1400° C.

15 . The production method of an optical fiber according to claim 9 , wherein, at a final thermal treatment step of the thermal treatment steps, the porous preform is subjected to a thermal treatment in an atmosphere containing inert gas at a temperature higher than 1400° C.

16 . The production method of an optical fiber according to claim 9 , wherein at the thermal treatment steps other than a final thermal treatment step, the porous preform is heated so that the internal temperatures of the two end portions in the longitudinal direction of the porous preform increase before the internal temperature of the center portion in the longitudinal direction increases.

Assignees

• Furukawa Electric Co Ltd

Inventors

• Shinada Seiichi

Classifications

• C03B37/01446 Primary

  Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering (C03B37/01853 takes precedence) · CPC title

• C03B37/01453

  for doping the preform with flourine · CPC title

• C03B2201/12

  doped with fluorine (C03B2201/14 takes precedence) · CPC title