JPH0616447A - Production of optical fiber base material - Google Patents

Abstract

PURPOSE:To provide the process for production of the optical fiber base material which obviates the failure of glass particulate layers during production. CONSTITUTION:This process for production of the optical fiber base material consists in depositing the glass particulate 2 for constituting a clad on a glass rod 1 for a core having at least a part to constitute the core by using an oxyhydrogen burner 3 along its axial direction while rotating the glass rod around its axis. The deposition thickness by one time of traversing of the burner 3 is specified to 1.0 to 2.0mm, more preferably to 1.5+ or -0.2mm in the above- mentioned process, the deposition thickness is specified in the prescribed region, by which the failure of the base material at the time of production is obviated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a glass fiber preform for optical communication, and is intended to prevent damage to the preform during production.

[0002]

2. Description of the Related Art As a method for producing an optical fiber preform, a glass fine particle layer to be a clad is formed around a silica glass rod having a core portion prepared in advance by an external method, and then this glass fine particle layer is formed. There is a method of dehydrating and forming transparent glass into a predetermined optical fiber preform. In the external attachment, one or more oxyhydrogen burners are traversed along the axial direction of the glass rod to deposit glass fine particles obtained by the flame hydrolysis method around the rod to a predetermined thickness.

[0003]

However, the glass fine particle layer sometimes breaks during the production of the base material by this method. When the inventors of the present invention examined the cause of the damage, it was found that the burner had a deep relationship with the deposition thickness of each traverse, and it was found that the frequency of the damage sharply increases when the thickness exceeds a predetermined value. did. The reason for this is that if the burner is manufactured thickly with one traverse, the bulk density of the glass fine particles becomes uneven in the radial direction, and relatively soft and hard parts are formed, which are damaged by the strain generated at the boundary. It is supposed to be that.

[0004]

The present invention has been made from the above viewpoint, and the invention according to claim 1 is characterized in that a silica-based glass rod including at least a core portion is provided with When at least one burner is traversed along the axial direction while rotating around the glass rod to deposit the glass fine particles to be the cladding around the glass rod, the glass fine particles are deposited by the traversing once by the burner. It is to manufacture while controlling the thickness within a predetermined range. Further, the invention according to claim 2 characterized in that the deposition thickness of the glass fine particles by one traverse of the burner is 1.0 to 2.0 mm, preferably 1.
5 ± 0.2 mm.

[0005]

Since the thickness of the silica glass fine particle layer for clad by one traverse using the oxyhydrogen burner is set to 2.0 mm or less, a small bulk density is provided between the inside and the outside of the glass fine particle layer. Since there is no difference and no distortion occurs, there is no damage during manufacturing. In addition, the deposition thickness of the silica glass fine particle layer per traverse of the burner was 1.0 mm.
The reason for the above is that the manufacturing efficiency is remarkably low below that.

[0006]

Embodiment 1 FIG. 1 is a schematic explanatory view showing the method of the present invention. In the figure, reference numeral 1 is a core rod made of silica glass such as GeO ₂ —SiO ₂ or pure quartz, which is rotated around its axis. Reference numeral _{2 is} a glass fine particle layer made of SiO ₂ or fluorine-doped SiO ₂ which becomes a clad deposited on the core rod 1, and 3 is a concentric multi-tube burner or a multi-burner for producing the glass fine particles. Although only shown, a plurality of glass rods are usually prepared to increase the deposition efficiency of the glass particles and traversed along the axis of the core rod 1. When the burner is a concentric quadruple burner, for example, SiCl ₄ or SiF ₄ + SiCl _{4 as} a cladding material gas is supplied to the center of the burner, a seal gas such as Ar is supplied to the second layer, and hydrogen is supplied to the third layer. Oxygen gas is sequentially supplied to the fourth layer. Reference numeral 4 is a camera for measuring the thickness of the deposited glass particles, which measures the thickness of each burner before and after passing, and it is 1.0 to 2.
It should be in the range of 0 mm. Specifically, the measurement result of the thickness is fed back to the supply amount of the raw material gas so that the thickness falls within the above range. One of each burner
When the deposition thickness by the single traverse was set within the allowable range of 1.5 ± 0.2 mm, the glass fine particle layer could be produced without any damage.

[0007]

According to the method of manufacturing an optical fiber preform according to the present invention, when the glass particles for cladding are deposited by the external attachment method, the deposition thickness by one traverse of the burner is 1.0 to 2.0 mm, Preferably 1.5 ± 0.2 mm
Therefore, it can be manufactured without damaging the glass fine particle layer during manufacturing.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an optical fiber preform according to the method of the present invention.

[Explanation of symbols]

 1 Quartz glass rod for core 2 Quartz glass particle layer for clad 3 Hydrogen oxyburner 4 Camera

Claims (2)

[Claims] 1. A quartz glass rod including at least a core portion is rotated around its axis, and at least one burner is traversed along its axial direction to form a cladding around the glass rod. The method for producing an optical fiber preform, characterized in that, when depositing the glass particles, the glass fiber is produced while controlling the deposition thickness of the glass particles by one traverse of the burner within a predetermined range. 2. The optical fiber according to claim 1, wherein the deposition thickness of the glass particles by one traverse of the burner is 1.0 to 2.0 mm, preferably 1.5 ± 0.2 mm. Base material manufacturing method.