JPS6041626B2 - Manufacturing method of fiber base material for optical communication - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a fiber preform for optical communications by an external attachment method, and is particularly characterized by a method of processing a starting member.

The first method for manufacturing fiber base material for optical communication using the external attachment method is
As shown in the figure, 1 fine glass powder 12 is placed on the starting member 11.
Step 2 of depositing the starting member 11; Step 3 of removing the starting member 11; and Step 3 of converting the fine glass powder 12 into transparent vitrification.

If the starting material removal step 2 is performed after the transparent vitrification step 3, the fine glass powder 12 is removed with the starting material 11 still attached.
Since the glass is made into transparent glass, the transparent glass comes into close contact with the starting member 11.

Stress cracks often occur due to the difference in thermal expansion coefficient between the starting member 11 and the starting member 11. Furthermore, if it is attempted to remove the starting member 11 before transparent vitrification, the work is difficult because the glass fine powder 12 has not yet solidified.

An object of the present invention is to provide a starting member 1 without having any adverse effect on the glass fine powder 12 or its transparent vitrified product.
The purpose of the present invention is to provide a method in which 1 is made into a glassy state, a portion of the material is volatilized, and the remaining portion is removed by etching with hydrofluoric acid if necessary.

An overview of the present invention will be described.

J As the material of the starting member 11, for example, B or B-S
i, B-P) Alloys such as B-Ge, or compounds thereof such as BN, B, and Co, which become glass-like when burned and oxidized at a temperature close to the temperature at which fine glass powder becomes transparent vitrification. use

This can also be used in the form of a vibrator. Then, a glass fine powder body 12 is formed thereon in a conventional manner. When vitrifying the starting member, it is heated while flowing 02 gas inside it to oxidize and vitrify it. This glass is removed by evaporation or etching with hydrofluoric acid. For example, B. ．．
BN,. B4C3 and the like are oxidized in 02 gas at 1200°C to form oxide glasses such as B2O3 and evaporate.

Usually, the transparent vitrification of the glass fine powder body 12 is about 1300
Do it at around ℃.

Therefore, the vitrification and evaporation of the substrate 11 can also be carried out simultaneously during the transparent vitrification step. Next, a more detailed explanation will be given with reference to FIG.

First, let's talk about the equipment.

21 is a base material made of a vibrator made of BN, for example, and has an outer diameter of 20Tm1n1 and a wall thickness of 2? Use something like that.

22 is a glass fine powder body deposited on the outside by a conventionally known method.

A support vibe 23 made of quartz and having an appropriate length is connected to the upper end of the glass fine powder body 22 by, for example, a screw. Support vibe 2
An input 24 for 02 gas is provided in the middle of 3. Support vibe 2
The upper end of 3 is held between a rotating chuck 25 of a known lifting device and suspended in a heating furnace 27.

28 is a heater.

Next, we will discuss the effect.

The transparent vitrification temperature of the glass fine powder body 22 is controlled by the heater 28 (
1300° C.), and while 02 gas is introduced from the inlet 24 and flows through the inside of the support vibe 23 and the base material 21, the support vibe 23 is gradually lowered using the temperature raising device 26. Then, the glass fine powder body 22 becomes transparent glass 29 sequentially from the lower end. At the same time, the base material 21 burns and becomes glass.
The saw part begins to evaporate in O3. When the entire glass fine powder 22 becomes transparent glass 29 in this way, the starting member 21 completely disappears or remains as glass.

The transparent glass 29 is not subjected to any stress from the starting member 21. This remaining glass that does not evaporate can be removed later with hydrofluoric acid. Examples are shown below.

Outer diameter 12 as a starting material? φ, inner diameter 10TWLφ, length 20h using a BN vibrator, and a length 180mm on top of it.
Over P2O5 (10%) - SiO2 (83%)
-CeO2 (7%) glass fine powder sintered body 22 for the core has a thickness of 8.5T1n, and on top of that is SiO2 (82%).
-B, O3 (18%) glass fine powder sintered body 22 for cladding (ratio is weight%) to a thickness of 8. -The total outer diameter is 44T! r! It was set as n.

This is connected to the lower end of the 1WL support vibe 24, suspended in the heating furnace 27, heated to 1280°C, and at the same time the 02
Flow at a rate of Umin, and at the same time turn the glass fine powder 22 into transparent glass 29, the base material 21 is burned and vitrified, and the transparent glass 29 with an inner diameter of 9W$L1, an outer diameter of 13 types, and a length of 120 gourds is not damaged in any way. I was able to get it without any problems.
After this, clean the inner surface of the vibrator with HF, and
3 glasses were removed. The effects of this invention will be described.

(1) The base material 21 can be removed at the same time as the glass fine powder body 22 becomes transparent vitrified.

(2) Stress cracking will not occur when the glass fine powder body 22 becomes transparent vitrified.

(3) Since the base material 20 is in the shape of a vibrator, the contact area for the 02 gas is large, and the reaction gas can easily flow out.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a conventional manufacturing process in the middle, and FIG. 2 is an explanatory diagram schematically showing a state in the middle of the manufacturing method of the present invention. 21: Starting member, 22: Fine glass powder, 3: Support vibe, 24: Inlet, 25: Chuck, 26: Lifting device, 2
7: Heating furnace, 28: Heater, 29: Transparent glass.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a fiber preform for optical communication, which includes the steps of depositing fine glass powder on a starting member and converting the pile of fine glass powder into transparent vitrification, which comprises: A pipe-shaped material that undergoes combustion oxidation to become glass at a temperature close to the temperature at which it becomes transparent vitrification is used as the starting member, and is heated while flowing O_2 inside it to oxidize, vitrify, and volatilize it. A method for manufacturing a fiber base material for optical communication. 2. Claim 2, characterized in that the starting member is a material consisting mainly of metal B, which becomes glass that easily evaporates, and an alloy doped with P, Ge, and Si, or their carbides or nitrides. 2. A method for manufacturing a fiber preform for optical communication according to item 1.