JPS59190232A - Preparation of parent material of optical fiber - Google Patents

Abstract

PURPOSE:To prepare a parent material of optical fiber free from foams, by spraying fine particles of glass from a burner upon a bar substrate while making a gas charged in a piling chamber flow in the longitudinal direction of the substrate. CONSTITUTION:As the bar substrate 12 such as glass rod, etc. is rotated, the substrate 12 or the burner 14 is reciprocated in the longitudinal direction of the substrate 12. The given raw material A is fed to the burner 14 and suction force is simultaneously made to act on the exhaust vent 16. The gas B such as air, etc. is made to flow from the gas inlets 10 through the filter 18 into the piling chamber 11, the gas B is put in the interior of the cylinder 13 from both sides of it, made to flow in the longitudinal direction of the piling layer 17 of fine particles of glass, and discharged from the exhaust vent 6. In the operation, the gas B carries unpiled fine particles of glass and flows out from the exhaust vent 6. Consequently, no foaming occurs during calcination of the piled layer 17.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an optical fiber base material for r'i optical communications.

One of the methods for manufacturing a silica glass optical fiber base material is the so-called external CVD method.

In this method, four large rods called baits are placed around the outer periphery of a !1°C body while rotating the base body and a supply burner. Fine glass particles are sprayed to form a deposited layer of glass particles around the outer periphery of the substrate.

In the CVD method, the step of depositing glass particles is performed in a clean atmosphere in order to prevent impurities from entering from the outside.

FIG. 1 shows the conventional CVD method, in which a deposition chamber 3 having a gas intake 01.1 and an exhaust port 2.2 provided opposite to these is placed in a deposition chamber 3. In this case, a rod-shaped base 4 such as bait is rotatably installed (the base 4 here
A burner 5 for supplying a glass thick phase is installed facing the same direction.

When depositing the glass end, the base body 4 is rotated and either the base body 4 or the burner 5 is moved in the longitudinal direction of the base body 4.

However, such conventional methods (this way, it is not possible to obtain / this!
There is a problem that bubbles often occur in JAJ.

In this way, no matter how small the bubbles are from the foamed matrix, optical fibers with large transmission losses are produced!1 etc.]1.
If /(') is large, it will not be made into a fiber. Substrate 4 that is not touched
It is estimated that the fine glass particles that have adhered to the surface of the glass may become discolored during the sintering process.

/i\Invention tqt The idea is to provide the exhaust port at a position opposite to the burner and to flow the gas in the longitudinal direction of the glass fine particle deposit layer (thus solving the above problem,
This can be explained by referring to the figure 9 shown in Figure 1ni, and as shown in Figure 2 (gas intake D
A rod-shaped base body 12 of a bait tongue is rotatably installed in a deposition chamber 11 having a
A cylindrical body 13 is installed at a predetermined interval from 2.

This cylindrical body 13 is provided with a flame 15 which allows the flame from the burner 14 installed facing it to be drawn out for the first time, and a position opposite to the flame port 15.
The cylindrical body 13 is in communication with the outside of the cylinder 11 (an exhaust port 16 is provided at the center of the cylinder 13, and the cylinder 13 is connected to the cylinder 13 through the 1st air 16). (This is happening.

The outer periphery of the base 12 (blow glass fine particles)
When forming the glass fine particle deposition layer 17 (copper, substrate 12
(The four bases 12 are rotated in their longitudinal direction.)
The burner 14 can be reciprocated along the longitudinal direction of the base body 12.

When moving the burner 14, the cylindrical body 13 is also moved in conjunction with the burner 14.

In order to manufacture a base material using such an apparatus, the base body 14 or the burner 12 is reciprocated in the longitudinal direction of the base body 14 while the base body 12 is rotated.

When a predetermined raw material A is supplied to the burner 12 (and when a suction force is applied to the exhaust port 16, the gas intakes 1110, 10
A gas 13 of η flows into the deposition chamber 11 through the filter 18, and the flowed scum 3 enters the inside of the cylinder 130 from both ends and flows along the longitudinal direction of the crow fine particle deposition layer 17. It flows out from 4J1 air port 6.

At this time, the gas B+ flows out from the exhaust port 16, accompanied by the undeposited glass particles.

In addition, when bait is used as the substrate 12 as described in "-" (
This is to pull out the bait after the glass particles are deposited.
However, instead of the bait, a glass rod for the core or for the core and cladding may be used; in this case, the glass rod will be used as part of the 4υ material.

Here, a more specific example will be described. [Specific Example 1] Burner 14 (02, H2, and 5iCt, 1) is supplied, and the degree of depressurization of the 1-1 air port 16 is adjusted to take in gas 1-11.
The debris that entered from 0 and 10 was allowed to flow along the 1111 layer of glass fine particles (top layer) to form an appropriate deposited layer of glass fine particles (support). When processed into an optical fiber with core diameter 5 Q l1m z outer diameter] 25 μm, the loss was 2.4 at a wavelength of 085 μm.
A low value of dB/Km was obtained. [Example 2] In order to form a glass fine particle deposit layer to become the core and cladding on the outer periphery of a tapered alumina hat with a diameter of approximately 5 m, a bar 14 Raw material for core 5iCA4,G
eCl4 and BBr3, raw materials for cladding SiC/:4 and ■3Br3, and 1-I2 and 02 are supplied, and the degree of pressure reduction of the air inlet 16 is adjusted to supply the gas to the glass particle deposition ha'riNl. After forming a layer of fine glass particle deposits while flowing the glass, the bait was pulled out and the deposited layer was heated to about 1500° C. in a helium scum atmosphere to make it transparent vitrified. No bubbles were observed at all.

As described above, an exhaust port is provided at a position opposite to the Cζ burner, and glass fine particles are blown from the burner to the base while flowing the scum along the longitudinal direction of the base. The glass particles ejected from the fc JA body and not deposited on the body will be entrained by the Ganube and flow out from the 4th vent, so that the glass particles ejected from the fuselage will be absorbed by the amount of jXli of the base body that has not been hit by the flame. 1υi 2) There is no foaming during sintering, and no bubbles can be seen during sintering.
be obtained.

Simple 11'IfL explanation of 41 songs in one piece Figure 1 is an explanatory diagram showing a conventional method, and Figure 2 is an explanatory diagram of a method according to an uninvented method.

10... Gas intake port 1 1... Gasai JIi chamber 12...
Substrate 14...Burner 16...4'' 1 Air port 17...Glass fine particle deposit layer 1 person (substitute) Patent attorney Makoto Izu

Claims (2)

[Claims] (1) A gas intake port and an air bleed port are rotatably installed in a deposition chamber, and glass particles are deposited on the outer periphery of a rod-shaped base such as a glass fist. In the method for manufacturing a fiber base material (depositing a layer), the above exhaust port is provided at a location facing the phase 7J and the space 7J is placed in the blue chamber. A former fiber matrix is characterized in that the above-mentioned rod-shaped substrate is sprayed with fine particles from a blower while flowing the gas along one direction along the length of the substrate. manufacturing method. (2) Waste f: From both ends of the substrate to the center (patent characterized by flowing in the opposite direction%'? + water conversion 1jl' + first apex -
A method of manufacturing a certain original fiber motherboard 44.