Method of producing optical fiber preform and optical fiber

Patent metadata

Field	Value
Publication number	US-10676387-B2
Application number	US-201715417732-A
Country	US
Kind code	B2
Filing date	Jan 27, 2017
Priority date	Aug 6, 2014
Publication date	Jun 9, 2020
Grant date	Jun 9, 2020

Abstract

A method of producing an optical fiber preform includes: an alkali-metal-doped silica glass body forming step of forming an alkali-metal-doped silica glass body doped with an alkali metal; a silica glass body forming step of forming a silica glass body to be at least a portion of a core portion around the alkali-metal-doped silica glass body such that the silica glass body contacts the alkali-metal-doped silica glass body; and a diffusing step of diffusing the alkali metal from the alkali-metal-doped silica glass body to the silica glass body by a heat treatment.

First claim

What is claimed is:

1. A method of producing an optical fiber preform, the method comprising:
forming an alkali-metal-doped silica glass body doped with an alkali metal;
forming a silica glass body to be at least a portion of a core portion around the alkali-metal-doped silica glass body such that the silica glass body contacts the alkali-metal-doped silica glass body;
diffusing the alkali metal from the alkali-metal-doped silica glass body to the silica glass body by a heat treatment; and
after the diffusing, removing the alkali-metal-doped silica glass body from the silica glass body by drilling such that only the silica glass body remains, leaving a hole inside the silica glass body, the hole extending a longitudinal direction of the silica glass body, wherein
the forming of the alkali-metal-doped silica glass body includes a heat treatment performed in a non-chlorine-based atmosphere with a partial pressure of chlorine of at most 1%.

2. The method of producing the optical fiber preform according to claim 1 , wherein forming the alkali-metal-doped silica glass body comprises:
forming an alkali-metal-doped silica soot by using a vapor-phase axial deposition (VAD) method or an outside vapor deposition (OVD) method; and
vitrifying the alkali-metal-doped silica soot.

3. The method of producing the optical fiber preform according to claim 1 , further comprising, collapsing the silica glass body that remains after the drilling and removing of the alkali-metal-doped silica glass body.

4. The method of producing the optical fiber preform according to claim 1 , further comprising, after removing the alkali-metal-doped silica glass body, supplying chlorine gas to the hole, thereby to perform a surface treatment on an inner surface of the hole.

5. The method of producing the optical fiber preform according to claim 1 , wherein an inner diameter of the hole is greater than a diameter of the alkali-metal-doped silica glass body.

6. The method of producing the optical fiber preform according to claim 1 , further comprising, after forming the silica glass body, which includes therewithin the alkali-metal-doped silica glass body, stretching the silica glass body.

7. A method of producing an optical fiber, the method comprising drawing an optical fiber preform produced by a method of producing an optical fiber preform, the method of producing an optical fiber preform including:
forming an alkali-metal-doped silica glass body doped with an alkali metal;
forming a silica glass body to be at least a portion of a core portion around the alkali-metal-doped silica glass body such that the silica glass body contacts the alkali-metal-doped silica glass body;
diffusing the alkali metal from the alkali-metal-doped silica glass body to the silica glass body by a heat treatment; and
after the diffusing, removing the alkali-metal-doped silica glass body from the silica glass body by drilling such that only the silica glass body remains, leaving a hole inside the silica glass body, the hole extending a longitudinal direction of the silica glass body, wherein
the forming of the alkali-metal-doped silica glass body includes a heat treatment performed in a non-chlorine-based atmosphere with a partial pressure of chlorine of at most 1%.

Assignees

• Furukawa Electric Co Ltd

Inventors

• Aiso Keiichi
• Gonda Tomohiro

Classifications

• C03B2201/075

  Hydroxyl ion (OH) · CPC title

• C03B37/01257

  Heating devices therefor · CPC title

• C03B37/025

  from reheated softened tubes, rods, fibres or filaments {, e.g. drawing fibres from preforms (draw-down of tubes, rods or preforms to reduced diameter preforms C03B37/0124)} · CPC title

• C03B37/01466

  Means for changing or stabilising the diameter or form of tubes or rods (C03B37/01861 takes precedence) · CPC title

• C03B37/01248

  by collapsing without drawing · CPC title