JPS5845132A - Method and apparatus for manufacturing base material for optical fiber by vad method - Google Patents

Abstract

PURPOSE:To enhance the efficiency of manufacturing a base material for an optical fiber by a VAD method by blowing a heated gas into a muffle furnace used in the manufacture to accelerate the hydrolysis of a gaseous starting material and to prevent the scattering of a dopant. CONSTITUTION:A quartz rod 1 is put in a muffle furnace 4 as a reactor, and while rotating the rod 1, H2 and O2 for forming an oxyhydrogen flame, SiCl4 as a starting material for glass and GeCl4 or the like as a dopant are blown from an oxyhydrogen burner 2. The cheorides are hydrolyzed by the intense heat of an oxyhydrogen flame formed with the burner 2 and produced H2O to form a glass layer 3 with a specified refractive index on the tip target of the rod 1 as a base material for an optical fiber. At this time, by blowing N2, CO2, air or the like into the furnace 4 from a suction hole 7 after heating with a heater 8, the internal temp. of the furnace 4 is raised and the heat of the flame is chiefly applied to the hydrolysis of the starting material, thereby preventing a reduction in the efficiency of manufacturing the base material 3 due to the scattering of GeO2 as the dopant.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides optical fibers using the V-muk method (Vaporphas method).
...Relates to an improved method for manufacturing by axial deposition (vapor phase axial growth method).

To explain the WAD method 1 in detail with reference to FIG. 1, H, 0,, 810 no.
, Ge04, Pool@, BBrl, etc., and caused hydrolysis in an oxyhydrogen flame to produce 8101.
, GeO2, p=O, % n5os, or the like. An example of this reaction is expressed as follows.

81ot, + 211 0-+810 mushroom + 4
HC! jGfhO14+ 2H10-+G@01 +
4107 As a result of this oxide fine particle being sprayed onto the target, soot body 3 grows in the length direction. These 1.
2. Part or all of 3 is surrounded by Matsuful 4,
Reference numeral 58 denotes an exhaust hole attached to the muffler 4, and in order to prevent fine oxide particles from adhering to the inner surface of the muffler 4, nitrogen and gas are flowed into the muffler #4 from the intake hole 6.

The above is an outline of the conventional WAD method and device.

In this method, the burner is activated by the reaction of oxygen and hydrogen gases, which are simultaneously discharged from the burner.
BiCl2, G13C14 by increasing the temperature of gas such as Ge04 and H and O generated by oxyhydrogen reaction.
It performs two functions: to perform hydrolysis into equal gases.

However, the conventional method had the disadvantage that the production efficiency of the soot body was somewhat low and that the formation of the soot was not stable, which caused GeO2 to diffuse. The present invention aims to eliminate such drawbacks in the WAD method, and to
A heated gas such as N2 gas, CO, gas, or air is injected into the new tank to raise the temperature of the gas in the oxyhydrogen burner or to suppress the dissipation of thermal energy from the flame formed by the oxyhydrogen burner. , the raw skin function of the oxyhydrogen burner is concentrated on hydrolysis, which reduces the burden on the temperature rise of the discharged gas, enables stable # during soot production, increases the soot synthesis rate, and improves the gas of GeO gas. This is to prevent the spread.

In addition, when GeO2 is included as a dopant during the production of soot bodies, when heated to 700°C or higher, G as a dopant is
002 Control becomes unstable. That is, if 011oz comes into contact with N1 gas in an oxyhydrogen burner during soot production, GeO2+ H! →GeO+ Since this GeO has a boiling point of 710° C., evaporation occurs and the controllability of the amount of Geoz becomes poor. Furthermore, if the temperature of the cissus body rises to around 7 DrJ° C. after heating gas is blown in, the amount of new soot deposited is reduced because the soot often settles in areas lower than the flame temperature. Therefore, in the present invention, the temperature at which the soot body and its surroundings are heated by blowing heated gas is as follows:
It is necessary to set an upper limit within the range to prevent the above-mentioned adverse effects.

GeO, Fi is generally the main dopant for optical fibers, but other dopants include B503, which has a boiling point of 1500°C or higher (F), GeO2
There is no problem if the upper limit temperature in this case is set to 700°C or less. P2os is also used as a dopant, but it sublimes easily and sublimes at 560°C, so the yield is very poor at around 700°C. However, 810! Adsorbs to 9P,
Since it can be used in the form of Bye.

In the present invention, as shown in FIG. 2, an intake hole 7 is attached to the muffler 4 shown in FIG. Note that 9 is pulp for adjusting the amount of blowing, p, 10t.
fN2 gas, CO! It is a cylinder of gas, air, etc. Note that when the heating gas is N2, the N2 gas intake hole 6 and the heating gas blowing hole 7 can also be used.

In the present invention, the temperature inside Matsufuru 4 is raised as a whole due to the injection of heated gas, and in such a state, the oxyhydrogen burner burns the raw material gas (840t4, G60j4, BB
r3, H required for the hydrolysis of POCl2.

Emphasis can be placed on selecting the amount of gas for work 02.

On the other hand, if the temperature rise is insufficient, adjust the temperature of the blown gas.
This maintains balance.

In other words, the control can be stabilized, and the soot body production efficiency can be increased by increasing the ratio of the raw material gas amount to N2 and 03 of the burner.

[Brief explanation of the drawing]

The accompanying drawings are schematic diagrams 69 for explaining the vAD method and its apparatus, with FIG. 1 relating to the conventional method and FIG. 2 relating to the method of the present invention. Agents 1) Akira’s agent Ryo Hagiwara −

Claims (1)

[Scope of Claims] 1. When producing a soot body to be used as a base material for party fibers using vApg, heating gas is blown into a container containing at least the flame of an oxyhydrogen burner and a part of the soot body. Features: A manufacturing method for optical fiber base material. 2 The container is equipped with an oxyhydrogen burner, Ms gas intake hole, heating gas intake hole, and exhaust hole, and holds the starting material in the space in such a way that it is pulled upward while rotating once. This is an optical fiber base material manufacturing device using the WAD method.