# US 10,501,362 B2 · Fabrication method and fabrication apparatus for porous glass base material for optical fiber

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- Number: US 10,501,362 B2
- Document ID: US10501362B2
- Status: Granted
- Kind: B2
- Application number: 16/150,277
- Filed: 2018-10-03
- Published: 2019-04-18
- Granted: 2019-12-10
- Earliest claimed: 2017-10-13
- Assignees: Shin-Etsu Chemical Co., Ltd.
- Applicants: Shin-Etsu Chemical Co., Ltd.
- Inventors: Tetsuya Otosaka
- Web page: https://patentgrep.com/patent/US10501362B2

## CPC

- C03B 37/01815: {Reactant deposition burners or deposition heating means}
- C03B 37/0142: {Reactant deposition burners}
- C03B 37/01486: {Means for supporting, rotating or translating the preforms being formed, e.g. lathes (C03B37/01884 takes precedence)}
- C03B 37/01884: {Means for supporting, rotating and translating tubes or rods being formed, e.g. lathes}
- C03B 2207/50: Multiple burner arrangements
- C03B 2207/62: Distance
- C03B 2207/64: Angle
- C03B 2207/66: Relative motion
- C03B 2207/70: Control measures
- C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES

## 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.

## Claims

### Claim 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 2)

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.

### Claim 4 (depends on 3)

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.

### Claim 5 (depends on 1)

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.

### Claim 6 (depends on 1)

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.