Method of producing optical fiber preform and optical fiber

Patent metadata

Field	Value
Publication number	US-11795097-B2
Application number	US-202016869076-A
Country	US
Kind code	B2
Filing date	May 7, 2020
Priority date	Aug 6, 2014
Publication date	Oct 24, 2023
Grant date	Oct 24, 2023

Abstract

A method of producing an optical fiber preform includes a silica glass body forming step of forming a silica glass body to be at least a portion of a core portion. The method includes an alkali-metal-doped silica glass body forming step of forming an alkali-metal-doped silica glass body doped with an alkali metal around the silica glass body such that the alkali-metal-doped silica glass body contacts the silica glass body. The method further includes 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:
a silica glass body forming step of forming a silica glass body to be at least a portion of a core portion;
an alkali-metal-doped silica glass body forming step of forming an alkali-metal-doped silica glass body doped with an alkali metal around the silica glass body such that the alkali-metal-doped silica glass body contacts the silica glass body, wherein the alkali-metal-doped silica glass body is formed by:
synthesizing an alkali-metal-doped silica soot doped with the alkali metal by using an outside vapor deposition (OVD) method, and
a step of vitrifying the alkali-metal-doped silica soot such that a dehydration step in a chlorine-based gas atmosphere is not performed in the vitrification step, but only a sintering step as heat treatment in a non-chlorine-based atmosphere is performed;

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; and
after the diffusing, a grinding and removing step of removing the alkali-metal-doped silica glass body by grinding, wherein:
the silica glass body forming step comprises forming a silica glass rod having a first outer diameter,
the alkali-metal-doped silica glass body forming step comprises forming an alkali-metal-doped silica glass body having a second outer diameter, and
the grinding and removing step comprises removing the entire alkali-metal-doped silica glass body and an outer portion of the silica glass rod such that a remaining portion of the silica glass rod has a third outer diameter which is less than the first outer diameter.

2. The method of claim 1 , wherein the first outer diameter is 20 mm, the second outer diameter is 36 mm and the third outer diameter is 18 mm.

3. 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:
a silica glass body forming step of forming a silica glass body to be at least a portion of a core portion;
an alkali-metal-doped silica glass body forming step of forming an alkali-metal-doped silica glass body doped with an alkali metal around the silica glass body such that the alkali-metal-doped silica glass body contacts the silica glass body, wherein the alkali-metal-doped silica glass body is formed by:
synthesizing an alkali-metal-doped silica soot doped with the alkali metal by using the outside vapor deposition (OVD) method, and
a step of vitrifying the alkali-metal-doped silica soot such that a dehydration step in a chlorine-based gas atmosphere is not performed in the vitrification step, but only a sintering step as heat treatment in a non-chlorine-based atmosphere is performed;

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 and
after the diffusing, a grinding and removing step of removing the alkali-metal-doped silica glass body by grinding, wherein:
the silica glass body forming step comprises forming a silica glass rod having a first outer diameter,
the alkali-metal-doped silica glass body forming step comprises forming an alkali-metal-doped silica glass body having a second outer diameter, and
the grinding and removing step comprises removing the entire alkali-metal-doped silica glass body and an outer portion of the silica glass rod such that a remaining portion of the silica glass rod has a third outer diameter which is less than the first outer diameter.

4. The method of claim 3 , wherein the first outer diameter is 20 mm, the second outer diameter is 36 mm and the third outer diameter is 18 mm.

Assignees

• Furukawa Electric Co Ltd

Inventors

• Aiso Keiichi
• Gonda Tomohiro

Classifications

• C03B37/01446 Primary

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

• C03B37/014

  made entirely or partially by chemical means {, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD] (C03C17/02 takes precedence)} · CPC title

• C03B37/018

  by glass deposition on a glass substrate, e.g. by {inside-, modified-, plasma- or plasma modified-} chemical vapour deposition {[ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod} (C03B37/016 takes precedence; surface treatment of glass by coating with glass C03C17/02) · CPC title

• C03B37/01228

  Removal of preform material (C03B37/01251 takes precedence) · CPC title

• C03B37/01231

  to form a longitudinal hole, e.g. by drilling · CPC title