PROCESS FOR PRODUCING OPTICAL FIBER PREFORM - SUMITOMO ELECTRIC INDUSTRIES

Title:

PROCESS FOR PRODUCING OPTICAL FIBER PREFORM

Document Type and Number:

WIPO Patent Application WO/2006/046458

Kind Code:

A1

Abstract:

A process for producing an optical fiber preform, in which while reducing unsintered portions and foams, glass synthesis and deposition can be performed at a high rate in accordance with an internal CVD using a plasma burner as a heat source. The process comprises the step of by means of a plasma burner which travels while feeding a gas containing glass raw materials into a starting pipe of d (mm) wall thickness, heating the pipe and depositing a glass film on the inside wall of the pipe. In the first mode, heating temperature is controlled so that at every point of the pipe, the temperature does not exceed (1800+100×d)°C and so that the time of temperature ≥ (1100+100×d)°C continues for ≥ 20 sec. In the second mode, the plasma burner has at least two gas inlets and has an inside diameter of ≥ 80 mm (sectional area S) at site of plasma generation. In the deposition step, when Q represents the total flow rate of gas introduced in the burner, there is satisfied the relationship: 150 mm/sec < Q/S < 600 mm/sec.

Inventors:

NAKANISHI TETSUYA
HIRANO MASAAKI

Application Number:

PCT/JP2005/019279

Publication Date:

May 04, 2006

Filing Date:

October 20, 2005

Export Citation:

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Assignee:

SUMITOMO ELECTRIC INDUSTRIES (JP)
NAKANISHI TETSUYA
HIRANO MASAAKI

International Classes:

C03B37/018

Foreign References:

JP2004284944A	2004-10-14
JPH07196326A	1995-08-01
JPH0195295A	1989-04-13
JPH07307199A	1995-11-21

Other References: