Fabrication method and fabrication apparatus for porous glass base material for optical fiber

Patent metadata

Field	Value
Publication number	US-10501362-B2
Application number	US-201816150277-A
Country	US
Kind code	B2
Filing date	Oct 3, 2018
Priority date	Oct 13, 2017
Publication date	Dec 10, 2019
Grant date	Dec 10, 2019

Abstract

According to a fabrication method for fabricating a porous glass base material for optical fiber, the orientation of a clad forming burner used to form the outermost layer of a clad-corresponding portion is changed further upward while glass fine particles are deposited during the period between a first timing and a second timing. At the first timing, the outer diameter of the porous glass base material for optical fiber has not reached a target outer diameter. The second timing is later than the first timing, and either a timing at which the outer diameter of the porous glass base material for optical fiber reaches the target outer diameter for the first time, or a timing prior to this timing.

First claim

What is claimed is:

1. A fabrication method for fabricating a porous glass base material for optical fiber, in which a core-corresponding portion corresponding to a core of optical fiber is formed by depositing glass fine particles onto a hanging seed rod, and at least a portion of a clad-corresponding portion corresponding to a clad of the optical fiber is formed by depositing glass fine particles onto the core-corresponding portion, wherein
the fabrication method includes a period during which, while glass fine particles are being deposited, a gradient of a clad forming burner used to form an outermost layer of the clad-corresponding portion is changed toward a predetermined gradient relative to the porous glass base material for optical fiber from a downward gradient compared with the predetermined gradient.

2. The fabrication method for fabricating a porous glass base material for optical fiber as set forth in claim 1 , wherein
at a start of the deposition of the glass fine particles, the clad forming burner faces downward relative to a horizontal plane.

3. The fabrication method for fabricating a porous glass base material for optical fiber as set forth in claim 2 , wherein
the predetermined gradient is an upward gradient.

4. The fabrication method for fabricating a porous glass base material for optical fiber as set forth in claim 3 , wherein
the gradient of the clad forming burner goes beyond the horizontal plane before an outer diameter of the porous glass base material reaches a target outer diameter of the porous glass base material.

5. The fabrication method for fabricating a porous glass base material for optical fiber as set forth in claim 1 , wherein
the predetermined gradient is determined in advance based on a target outer diameter of the porous glass base material for optical fiber to be fabricated.

6. The fabrication method for fabricating a porous glass base material for optical fiber as set forth in claim 1 , wherein
an orientation of the clad forming burner is changed within such a range that a flame ejected from the clad forming burner is continuous with a flame of a different forming burner that is adjacent to the clad forming burner.

Assignees

• Shinetsu Chemical Co

Inventors

• Otosaka Tetsuya

Classifications

• C03B2207/62

  Distance · CPC title

• C03B37/01486

  Means for supporting, rotating or translating the preforms being formed, e.g. lathes (C03B37/01884 takes precedence) · CPC title

• C03B37/0142 Primary

  Reactant deposition burners · CPC title

• C03B2207/66

  Relative motion · CPC title

• C03B2207/50

  Multiple burner arrangements · CPC title