JPS604138B2 - Burner for manufacturing optical fiber base material - Google Patents

Description

[Detailed description of the invention] The present invention relates to a burner for producing an optical fiber preform.

A well-known method for producing an optical fiber preform is to deposit glass soot on a starting member in a reaction vessel and heat and sinter it to obtain a transparent optical fiber preform.

In this method, in order to obtain a uniform optical fiber preform, the pressure and temperature inside the reaction vessel, the distance between the raw material supply burner and the deposition soot, etc. are precisely controlled.

However, the properties of the resulting product were not sufficiently stable, and there was still a gap between the best properties (top data) and the average properties.

As a result of experiments, the present inventors discovered that one of the causes of this variation is the raw material supply burner.

Conventionally, the raw material supply burner is a D multiple burner as shown in FIG.
IC14, GeC14, POC13, etc. are flowed, and reaction materials such as 02 and Hi2 are flowed in the peripheral area 3. These react near the exit of the burner to form glass soot, which is deposited. At this time, there is a possibility that glass soot may adhere to the tip of the burner, and when soot adheres, the flow of raw materials changes, causing variations in the properties of the base material. In the concentric multiplex burner, although the soot adhesion is made less likely to occur by flowing ~ through the intermediate layer 2, it has not been possible to completely eliminate this soot adhesion.

In view of this situation, the present invention aims to provide a burner for producing an optical fiber preform that can stably obtain an optical fiber preform with excellent characteristics.

The configuration of the present invention will be specifically explained with reference to FIG. 2 showing one embodiment.

In FIG. 2, the burner has a semicircular cross section extending 20', and is partitioned so that two of them are combined to form a concentric multi-tube as a whole.

Raw material gas is flowed through the semicircular center 21, and opposite material gas is flowed through the peripheral portion 23, apparently acting like an Oka0 multiple burner.

22 is an intermediate layer, which is used when flowing Ar or the like.

The burner of the present invention as described above provides the following remarkable effects. '1} Since it is a set of multiple burners, even if soot adheres to one semicircular burner, there is no problem with the other burners, so the soot deposited on the rotating starting member is hardly disturbed. An optical fiber base material with stable characteristics can be obtained.

[2' Since the structure as a whole is like the same D multiple burner, the refractive index distribution can be controlled easily and accurately, unlike the case where a large number of independent burners are used.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional burner for manufacturing an optical fiber base material, and FIG. 2 is a sectional view showing an embodiment of the present invention. 20: Semi-circular burner 21: Center, 23: Periphery.

Claims (1)

[Claims] 1. A raw material supply burner used in a method for producing an optical fiber preform by depositing glass soot on a rotating starting member in a reaction vessel and later sintering it, the burner comprising two semicircular cross-section burners. A burner for producing an optical fiber preform, characterized in that the burner is composed of a set of concentric tubes and is partitioned into a concentric multi-tubular shape, and the raw material is flowed in the center of the semicircle, and the reactive material is flowed in the periphery of the semicircle. .