JPS59128225A - Manufacture of base material for optical fibre - Google Patents

Abstract

PURPOSE:To synthesize a base material for an optical fiber at a high speed by mixing fine particles such as SiO2, GeO2 in gaseous starting materials for glass contg. SiCl4, GeCl4 or the like and synthesizing fine glass particles from the mixed gaseous starting materials to prevent the lowering of reaction efficiency caused by the quantity of starting materials to be supplied. CONSTITUTION:Fine particles such as SiO2 transported by gaseous Ar from a supply apparatus 1 of fine particles are mixed with gaseous starting materials for glass such as SiCl4, GeCl4 transported by the gaseous Ar from a supply apparatus 2 of gaseous starting materials and supplied into a synthetic torch 3. The mixture 4 supplied into the torch 3 is hydrolyzed by flame in a flame stream 6 blown out from the torch 3 and synthesized to glass fine particles 6. In this case, the fine particles 6 play a role to lower the activation energy of the synthetic reaction of glass fine particles. As the result, it makes possible to lower the reaction temp. and to improve the reaction velocity compared with the case of the synthesis of glass fine particles by supplying conventional gaseous starting materials. Then, the fine particles 6 are adhered to the direction of an axis and deposited to form an objective porous base material 7.

Description

Detailed Description of the Invention: VAD that synthesizes glass particles in a flame, adheres and deposits them in the axial direction of a starting material to form a porous base material, and then sinters at a high temperature to produce a transparent base material. Conventionally, in the law, SICe4
Only a frit gas such as T GeCl+ was supplied to a synthesis torch, and glass particles were synthesized within a flame reaction zone.

However, when glass particles are synthesized using this conventional method, if the raw material gas supply amount is increased to improve the production speed of the base material, the reaction efficiency for synthesizing the glass particles decreases, and the speed of base material synthesis is increased. The problem was that it became difficult.

The present invention eliminates this drawback by using SICe4 1Ge
In the frit gas containing c 13 4 etc., Sin2
, Ge02 1Ae O , Tie□, B20
8. Glass particles with a small amount of P2O (both types of 8 or more) are mixed and glass particles are synthesized from the mixed raw material gas.The purpose is to increase the reaction efficiency as the amount of raw material supplied increases. The objective is to prevent the deterioration and enable high-speed synthesis of the base material by the VAD method.

FIG. 1 is a diagram showing an embodiment of the present invention, in which 1 is a microparticle supply device, 2 is a frit gas and flame gas supply device, 8 is a synthesis torch, and 4 is a mixture of frit gas and microparticles. , 5 is a flame stream, 6 is a synthesized glass particle, ? is a porous matrix.

transported by Ar gas from the microparticle supply device 1,
For example, 5in2 microparticles are 5iCV4GeCe4 transported by Ar gas from the raw material gas supply device 2.
It is mixed with frit gases such as and supplied into the synthesis torch 3. 4 is the supplied mixture. This mixture 4
is flame-hydrolyzed in the flame stream 6 blown out from the synthesis torch 8 to synthesize glass fine particles 6, but at this time, the fine particles serve to lower the activation energy of the glass fine particle synthesis reaction. . As a result, the temperature required for the reaction is lowered and the reaction rate is improved compared to the conventional case where glass particles are synthesized by supplying only the raw material gas. This generally corresponds to the phenomenon that activation energy decreases when a surface reaction is used, and it is thought that the surface of the microparticle acts as a surface for the glass microparticle synthesis reaction. The glass fine particles 6 synthesized in this way are adhered and deposited in the axial direction to form a porous base material 7.
is formed. This porous base material 7
'A transparent base material can be obtained by GK heating and sintering.

Now, in the above embodiment of the present invention, high-purity 5i02 particles (about 0.1 μm in diameter) are used as the microparticles, and are transported by Ar gas at a rate of 1 g per minute from the supply device 1, while from the supply device 2. Glass raw material moth/((5ICe+
: 9 Q MoAy%, oece4: 10 Mo#%
) is transported at a rate of 50 g/min, mixed with the SiO□ particles, and then supplied to the synthesis torch 3 to produce a porous base material, a porous base material can be obtained at a synthesis rate of 12 g/min. Ta.

The reaction efficiency in this case reached over 70%. Under the same conditions, when the 5in2 fine particles were not mixed as in the conventional method, the reaction efficiency was extremely low to 20%.

FIG. 2 shows the relationship between the relative amount of mixed fine particles (relative amount: amount of fine particles/amount of raw material gas) and reaction efficiency when the raw material gas supply rate is 50 g/min.

In FIG. 2, the hand stamp indicates the case where there is no mixing of fine particles.

As shown in Figure 2, 1/1 of the glass raw material gas supply amount
The effect is seen at a fine particle mixing amount of ooo -''/loo, and a constant value of about 80% at an amount of '/io or more.

, When the porous matrix was manufactured by increasing the amount of glass raw material supplied and transporting it at a rate of 100 V, the reaction efficiency was 80% with Nobuoki's mixed particulate bone and 50% with the mixed amount of '/l O. was secured. In this case, the reaction efficiency was 10% or less when the base material was produced under the same conditions as the conventional method with the amount of fine particles mixed at zero.

The reaction efficiency improvement method shown in this application is not limited to the VAD method.
The external method can be applied to other optical fiber base material manufacturing methods that are based on synthesizing glass fine particles using flame, such as the external method, and can also be applied to fine particle synthesis in an electric furnace.

In addition to the 5102 particles shown in the above example, the fine particles to be mixed into the raw material gas include ()eos+l he
Particles containing one or more of 208° Tie, B2O3, and P2O5 can be used.

As explained above, according to the method for producing an optical fiber preform of the present invention, it is possible to prevent a decrease in reaction efficiency when the raw material gas supply amount is increased. In addition, it also enables high-speed synthesis and improved efficiency at the same time, which has the advantage of significantly reducing the manufacturing cost of the optical fiber base material.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the present invention, and FIG. 2 is a diagram showing the relationship between the relative amount of mixed fine particles and reaction efficiency. l... Microparticle supply device, 2... Frit gas and flame gas supply device, 8... Synthesis torch, 4...
・Mixture of frit gas and fine particles, 5...Flame flow, 6...Synthesized glass particles, ? ...Porous base material. Patent Applicant: Nippon Telegraph and Telephone Public Corporation No. 2, 1, 1, 131

Claims (1)

[Claims] L After adhering and depositing glass particles synthesized by flame in the axial direction of the starting material to form a round rod-shaped porous base material,
In a method for manufacturing an optical fiber base material, which obtains an optical fiber and a base material by heating and sintering at a high temperature, Sl"4, CkeC
5in2t Ge in frit gas containing e4e etc.
m2r A4208. Tie,. It is characterized by mixing fine particles of at least one of B2O3 and P2O5, synthesizing glass fine particles from the mixed raw material gas to form a porous base material, and producing a transparent base material by high-temperature sintering. A method for manufacturing an optical fiber base material.