JPS58167440A - Production of parent material for optical fiber - Google Patents

Abstract

PURPOSE:A raw material gas prepared by mixing a silane or the like with the compound glass raw material is blown from the synthesis torch to form a porous parent material, thus dissipating the unreacting layer formed in the synthesis flame of glass fine particles to increase the glass formation speed. CONSTITUTION:In the production of an optical fiber parent material by the VAD method, H2, O2, Ar and others are fed from the feeder 21 to the synthesis torch 24. The halide glass raw material consisting of SiCl4, GeCl4 and others is fed from the feeder 22 and another glass raw material consisting of SiH4 and SiHCl3 is fed from the feeder 23, then they are mixed and fed to the synthesis nozzle 24 to form glass fine particles 29 and form the porous parent material 210. This process forms no unreacting layer in the glass fine particles 29 and gives the porous parent material 210 at a high synthetic speed. The reduction in glass deposition efficiency is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a method of manufacturing an optical fiber preform using VmuIIK.

Conventionally, in the VAD method, as a raw material for forming glass.

Silicon tetrachloride (810/), germanium tetrachloride (
Goo/,), one of the wire mesh halides such as boron tribromide (BBr-), or a multi-tank mixed gas was used. (1), (1)K by flame hydrolysis.

Oxidation - To generate glass particles, 5lot + mHo/ →SiO+ 4HO1
(1) Cloudy 1G@Ct
+ 1HOj -* G@O+ 4HO1 (戈)4
11060-ILOO
A reaction temperature of C or higher is required.

The reaction of the heavy front flame hydrolysis freeze reaction [reaction customer (1), reconnaissance)] cannot be said to be fast (Reference ``71ber.

0ptios J, i Bun! low @s pl
Published by @nuy press, see) 0 Figure 1 (a) is a diagram showing the state of the glass fine particle synthesis flame in conventional VD removal, and Figure 1 (b) is a cross section at Moom' of the 1st WJ (1). It's a gang. In No. 149, l is a synthesis torch, ! 1 is a flame gas outlet, 1 is a glass raw material gas outlet, 4 is a flame flow, 1 is a glass particle flow, 6 is an unreacted layer T: Therefore, in order to increase the glass formation rate, % of the halide is added. When the number of glass raw material supply binaries is increased, glass particles as shown in the m1 diagram (tortoise) K are not generated in the glass mold particle synthesis flame stream, and the glass particles flow out in the state of 11 halides. In other words, the proportion of the unreacted layer 6 in the flame flow increases as the amount of frit gas supplied increases, so the glass deposition efficiency decreases and the amount of t or porous matrix increases. This has the disadvantage that it becomes difficult to form a glass, making it even more difficult to improve the glass formation rate during V-D removal.

In order to eliminate these drawbacks, the present invention uses silane (81H
6), ) A glass-forming raw material gas containing one or both of silylsilane (SillO/, ) is blown out from a synthesis torch to form a porous base material, and its purpose is to form a glass-forming particle synthesis flame. To eliminate the unreacted layer that occurs in the VLD method and improve the glass formation rate in the VLD method. Figure S is a block diagram of an embodiment of the present invention.

ill is a flame gas supply device, Tomi S is a halogenated glass raw material (810j, G@O/,) gas supply device, 18 is a silane gas supply device, 34 is a synthesis torch, 16 is a flame gas outlet, and s6 is a glass Raw material gas blowout 0.
1? is the flame flow, s8 is the unreacted part, s9 is the glass particle flow, m1 (I is the porous base material).
- A mixed gas of O14 and 81H6 supplied from the silane gas supply system S is transported into the synthesis torch s4, and glass particles are synthesized within the flame RsII. In this case, even if the glass raw material supply amount is increased, an unreacted area as shown in s8 is observed, but within the glass fine particles mII, an unreacted area (see Fig. 111) as seen in the conventional VmuD method is observed. 6) shown in Fig. 6) does not occur, and flame [1?] does not occur. All of the frit gas blown out into the chamber was turned into oxide glass fine particles by a flame hydrolysis reaction.

This is a reaction that generates an oxide from silane (811m) mixed with a halogenated glass raw material gas, as shown in equation (1).
% Formula % (1) Because it is an exothermic reaction accompanied by separation of hydrogen gas.

This is thought to be due to the promotion of the reaction (1), equation (fi), which generates oxides from halides ($10/a, Gem/-).Moreover, this effect becomes even stronger when the mixing ratio of silane gas is increased. Therefore, even when the amount of glass raw materials supplied is increased to improve the glass formation rate, adjusting the mixing ratio of silane gas will prevent the glass deposition efficiency from increasing due to the increase in unreacted layer that occurs in the conventional WAD method. The difficulty of reduction and formation of porous matrix.

For example, in FIG. 2, hydrogen gas is supplied from the supply device fil to the synthesis torch s4 at 20/min, hydrogen gas at 110/min, and argon gas at 6j/min to the synthesis torch s4. Also, from the supply amount @ss, O5ioz, so mole, GsO/a1
When glass fine particles are synthesized by supplying glass raw material gas, which is a mixture of 0 mole of halide compound glass raw material and BIM from the supply amount @ms at a ratio of 6=1, to synthesis torch S4 at 81/min, glass No unreacted layer was observed in the particle flow 39, and a porous base material could be produced at a synthesis rate of 6 tons per minute. Also, the Gates*S efficiency in this case was approximately yes.
Met. By the way, if the glass raw material supply speed is kept the same,
Conventional Mumm D method (i.e. 811!, not mixed)
When a porous matrix is formed with 1 synthesis rate is s - s per minute
, i (efficiency: 36 to ■)), and the shape of the growth surface of the porous base material was unstable, making it difficult to obtain a uniform base material.

Even when trichlorosilane (Silo/- was replaced with silane, an effect of #11141 was obtained at a vi degree of about 100% as described above.) The loss of an optical fiber manufactured using a transparent base material as a core material is saB7*■ at a wavelength of 0.81# vortex.

Wavelength 1. It was as low as 1 dB/km in Japan, and could be used for optical communication systems in Japan.

As explained above, in method 4 of producing an optical fiber preform according to the present invention, a frit gas containing one or both of silane and trichlorosilane is blown out from a synthesis torch to form a porous preform. Even when the supply amount is increased, there is an advantage that the generation of an unreacted layer can be prevented and the glass formation rate can be improved. This method has the advantage that it is easy to reduce the cost of optical fibers due to rapid base material production.

[Brief explanation of drawings]

Figure 1 (, ) is a diagram showing the state of the glass fine particle synthetic flame flow in the conventional WAD method, and Figure 1 (b) is a diagram showing the state of the glass particle synthetic flame flow in the conventional WAD method.
)'s ^-A'Ks? The cross-sectional view shown in Figure S is \of the present invention.
V! It is a block diagram of an example of a vagina. l...Synthetic torch, 3...Flame gas outlet. 8... Frit gas outlet, 4... Flame flow. S...Glass particle flow, 6...Unreacted layer, ll...
-Flame gas supply device 1, Bjl...halogenated glass raw material gas supply device, 2! ... Silane gas supply device l
j, i4...synthetic torch, 15...flame gas outlet. S6...Glass Toryo gas blowout B, Ste...Flame R. SS...unreacted 111. i19...Glass particle flow. 11G... Porous base material. Figure 1 (a>

Claims (1)

[Claims] 1. Glass particles are synthesized in a flame stream. After this is adhered and deposited in the axial direction to form a porous base material, the porous base material is heated to room temperature and burned to obtain a transparent optical fiber base material. Shafted is in law. '/ Rough (8iH6), ) +71 o Luci 5
A method for producing an optical fiber preform, which involves blowing out a raw material gas for glass particle synthesis from a synthesis torch to form a porous preform, including one or both of (sIHOl, >)◇