Manufacturing method of glass base material for optical fiber

Patent metadata

Field	Value
Publication number	US-12565442-B2
Application number	US-202318374763-A
Country	US
Kind code	B2
Filing date	Sep 29, 2023
Priority date	Oct 28, 2022
Publication date	Mar 3, 2026
Grant date	Mar 3, 2026

Abstract

A manufacturing method of glass base material for optical fiber in which occurrence of opaque glass portion and elongation can be suppressed is provided. A preparation step of porous base material for optical fiber in which a porous glass layer is formed around the periphery of a core rod; a sintering preparation step, in which the porous base material for optical fiber is hung in a furnace core tube of a sintering apparatus; and a sintering step in which a mixture of halogen-containing gas and inert gas is flowing into the furnace core tube and the porous base material for optical fiber is made into transparent glass by heating the porous base material for optical fiber while moving the heater relative to the porous base material for optical fiber from one end of the core rod to the other end, to obtain glass base material for optical fiber, are performed.

First claim

What is claimed is:

1 . A manufacturing method of glass base material for optical fiber performing:
preparation of a porous base material for optical fiber in which a porous glass layer is formed around the periphery of a core rod; sintering preparation, in which the porous base material for optical fiber is hung in a furnace core tube of a sintering apparatus; and sintering in which a mixture of halogen-containing gas and inert gas is constantly flowing into the furnace core tube, and the porous base material for optical fiber is made into transparent glass by heating the porous base material for optical fiber while moving a heater relative to the porous base material for optical fiber from one end of the core rod to an other end, to obtain the glass base material for optical fiber, wherein, in the process of moving the heater relative to the porous base material for optical fiber in the sintering, the concentration of halogen-containing gas in the mixed gas is reduced, and wherein a concentration of the halogen-containing gas at a start of an execution of the sintering is C 0 and a concentration of the halogen-containing gas at a time when the other end of the core rod passes a vertical midpoint of the heater is C 1 , and a relationship between C 0 and C 1 is 0.25×C 0 ≤C 1 ≤0.5×C 0 .

2 . The method of manufacturing glass base material for optical fiber according to claim 1 , wherein a length of the core rod is L, and a distance from the other end of the core rod to a position on the core rod where the concentration of the halogen-containing gas begins to decrease is H, and a relationship between L and His 0.05×L≤H≤0.30 L.

3 . The method of manufacturing glass base material for optical fiber according to claim 1 , wherein the one end of the core rod is a lower end of the core rod and the other end is an upper end of the core rod at a time the porous base material for optical fiber is hung.

4 . The method of manufacturing glass base material for optical fiber according to claim 1 , wherein the heating temperature by the heater is 1400 to 1650° C.

5 . The method of manufacturing glass base material for optical fiber according to claim 1 , wherein the halogen-containing gas is chlorine or silicon tetrachloride.

6 . The method of manufacturing glass base material for optical fiber according to claim 1 , wherein the inert gas is helium, nitrogen or argon.

Assignees

• Shinetsu Chemical Co

Inventors

• Kashiwagi Yusuke

Classifications

• C03B2201/20

  doped with non-metals other than boron or fluorine · CPC title

• G02B6/04

  formed by bundles of fibres (G02B6/24 takes precedence) · CPC title

• C03B37/01208

  for making preforms of microstructured, photonic crystal or holey optical fibres · CPC title

• C03B37/029

  Furnaces therefor · CPC title

• C03B2205/63

  Ohmic resistance heaters, e.g. carbon or graphite resistance heaters · CPC title