Fabrication method for porous glass base material for optical fiber

Patent metadata

Field	Value
Publication number	US-11518704-B2
Application number	US-202016785651-A
Country	US
Kind code	B2
Filing date	Feb 10, 2020
Priority date	Feb 12, 2019
Publication date	Dec 6, 2022
Grant date	Dec 6, 2022

Abstract

To provide a fabrication method for a porous glass base material for optical fiber, the method including performing deposition of glass fine particles generated by using a burner for glass fine particle synthesis to form a porous glass base material, and heating this porous glass base material to be transformed into transparent glass to obtain a glass base material hardly containing any air bubbles. Provided is a fabrication method for a porous glass base material for optical fiber by depositing glass fine particles, which is generated in flame formed by ejecting a glass raw material gas and a combustible gas from a burner, on a rotating starting material, in which the burner continuously ejects inert gas for at least a predetermined period immediately after the end of the deposition of the glass fine particles.

First claim

What is claimed is:

1. A fabrication method for a porous glass base material for optical fiber, comprising:
supplying a glass raw material gas to a burner via a mass flow controller;
generating glass fine particles in flame formed by ejecting the glass raw material gas and a combustible gas from the burner; and
depositing the glass fine particles on a rotating starting material,
wherein the burner continuously ejects inert gas having passed through the mass flow controller for at least a predetermined period immediately after an end of deposition of the glass fine particles,
wherein the inert gas at 10% or less of a maximum value of a mass flow rate range is caused to continuously flow into the mass flow controller for at least the predetermined period immediately after the end of the deposition of the glass fine particles, and
wherein an additional inert gas is introduced from downstream of the mass flow controller to control a linear speed of the inert gas at a burner outlet.

2. The fabrication method for the porous glass base material for optical fiber according to claim 1 , wherein the inert gas is continuously ejected from the burner for a period from the end of the deposition of the glass fine particles to a start of a subsequent deposition.

3. The fabrication method for the porous glass base material for optical fiber according to claim 1 , wherein a linear speed Ns of the inert gas ejected from the burner is more than 0.5 m/s and less than 25 m/s.

4. The fabrication method for the porous glass base material for optical fiber according to claim 3 , wherein the linear speed Ns of the inert gas ejected from the burner is equal to or more than 1.0 m/s and equal to or less than 15 m/s.

5. The fabrication method for the porous glass base material for optical fiber according to claim 1 , wherein the mass flow controller is fully opened to cause the inert gas to flow.

6. The fabrication method for the porous glass base material for optical fiber according to claim 1 , wherein the glass raw material is SiCl 4 or GeCl 4 .

7. The fabrication method for the porous glass base material for optical fiber according to claim 1 , wherein the burner is a multi-nozzle burner.

8. The fabrication method for the porous glass base material for optical fiber according to claim 1 , wherein the inert gas is at least any of helium, argon, and nitrogen.

9. The fabrication method for the porous glass base material for optical fiber according to claim 1 , further comprising:
before the supplying, heating the glass raw material gas to a retention temperature between 100° C. and 120° C., wherein
the glass raw material gas supplied to the burner has passed through the mass flow controller that is maintained at the retention temperature.

10. The fabrication method for the porous glass base material for optical fiber according to claim 1 , wherein the inert gas is introduced to the mass flow controller after being preheated to have a temperature higher than a boiling point of the glass raw material gas.

11. The fabrication method for the porous glass base material for optical fiber according to claim 1 , wherein the inert gas has a temperature equal to or lower than a retention temperature of the mass flow controller.

Assignees

• Shinetsu Chemical Co

Inventors

• Kojima Hiroki
• Matsunaga Yuichi

Classifications

• C03B37/0142 Primary

  Reactant deposition burners · CPC title

• C03B2207/06

  Concentric circular ports · CPC title

• C03B37/01202 Primary

  Means for storing or carrying optical fibre preforms, e.g. containers · CPC title

• C03B2207/20

  Specific substances in specified ports, e.g. all gas flows specified · CPC title

• C03B2207/12

  Nozzle or orifice plates · CPC title