JPS58213645A - Piling of oxide powder by vapor-phase axial deposition - Google Patents

Abstract

PURPOSE:To prevent insufficiently reacted oxide powder from attaching to a powder layer for core and a powder layer for clad, by setting a sealing means at the boundary between a spray zone for a device to prepare powder for core and a spray zone for a device to prepare powder foc clad. CONSTITUTION:The reaction container 1 is divided into the reaction chamber 2 having the device 4 to prepare powder for core and the reaction chamber 3 having the device 5 to prepare powder for clad by the sealing means 12 consisting of the partitioning plates 13 and 14 with the through holes 17 and 18. The powder piling device 8 set in the container 1 is rotated on the shaft line, moved in the shaft direction, simultaneously a sealing gas is sent from the feed system 16 to the sealing chamber 15 divided by the partitioning plates 13 and 14, and leaked through the through holes 17 and 18 into the reaction chambers 2 and 3. Glass-based oxide powder is sprayed from the device 4 to the piling face of the piling device 8, so that the bar powder layer 19 for core is formed, and glass- based oxide powder from the device 6 is sprayed to it to form the powder layer 20 for clad.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method of depositing oxide powder in a vapor deposition method.

In the gas-phase axial method, which is adopted as a method for manufacturing base materials for optical fibers, a multi-tube burner for flame hydrolysis is used as a powder generator, and the glass-based oxide powder produced by the powder generator is is deposited on the deposition surface of a powder depositor that moves in the axial direction while rotating in the circumferential direction, and the rod-shaped powder layer thus formed is vitrified by heat treatment.

□Normally, when making an optical fiber base material in this way, a powder layer for the core and a powder layer for the cladding on the outer periphery are deposited at the same time. Two powder generators are used, and both powder generators are placed in a predetermined position with an appropriate distance between them, and the spray angle relative to the powder depositor is also set.

By the way, the composition of an optical fiber consisting of a core with a high refractive index and a cladding with a lower refractive index is adjusted in the base material manufacturing process as described above. Oxide powder for the core (e.g. 5
i02-Ge'02-''P20g) and cladding oxide powder (e.g. 8 i02, S i02-P2
051. S 102Pt Oi Bt On ) are different in composition from each other, but when the core powder layer and the cladding powder layer are simultaneously formed using the two powder generators in the above, the powder injection by the core-powder generator If the area and the powder injection area from the cladding powder generator partially overlap, or if the flames of both devices (oxyhydrogen flame) affect each other, or if powder is insufficiently reacted and flies out of the flame. The above-mentioned conventional method, which does not have a countermeasure against this problem, causes problems such as disturbance of the refractive index distribution between the core and the resin and formation of bubbles.

The present invention is a method for preparing powder for the core in the gas-phase shafting method.
□This method solves the problems of the conventional method described above by providing a sealing means at the boundaries of both injection areas of powder for rad, and the specific method will be explained below with reference to an example shown in the figure. is the lower reaction chamber (2)
and an upper reaction chamber (3), and one reaction chamber (2) contains a core powder generator (4) and its exhaust system (
5], and the other reaction chamber (3) is equipped with a cladding powder generator (6) and its exhaust system (7).

Furthermore, a powder depositor (8) that rotates around the axis Y in FIG. 1 and moves along the axis Y in the reaction vessel (11) is provided.
), and the powder depositor (8) is located at one end (
The lower end in the figure is the deposition surface (9).

Of course, both powder generators +4) (61 maintains a predetermined angle intersecting the axis Y of the powder depositor (8).) Also, both powder generators +41 (61 are multi-pipe tubes) It consists of a structured burner that can simultaneously inject vapor phase glass raw material, vapor phase dopant, carrier gas, oxygen, hydrogen, etc.

In the present invention, a predetermined gas phase axis method, which will be described later, is carried out using the apparatus shown in FIG. (
6), these two areas (IQ
(A sealing means a is provided to partition lυ.

This sealing means az has two partition plates (1:l (141
Seal chamber Q! 9 and a sealing gas supply system aQ connected to the sealing chamber a9, and the plate surface of the cut plate aaQ of both companies has through holes aI) (g) through which the core powder layer described later can pass. Each is drilled.

In addition, between the hole diameter of both through holes (to) and the outer diameter of the core powder layer described later, the through hole a1)Ql is larger, and the through hole (1) is larger.
From 71011, the seal gas in the seal chamber ae leaks in a predetermined direction.

In the present invention, the vapor phase axis method is carried out using the apparatus shown in FIG. The atmosphere is replaced with an inert gas, and the deposition surface (9) of the powder depositor (8) is initially positioned at point a of the reaction chamber (2).

Thereafter, the core glass raw material is flame-hydrolyzed through the core powder generator (4), and the reaction product, glass-based oxide powder, is transferred to the deposition surface of the rotating powder depositor (8). The powder is deposited continuously, and the powder depositor (8) is moved in the axial direction (upward in the figure) according to the deposition rate of the powder, thereby forming the powder layer 4 for the rod-shaped core. be done.

On the other hand, in the reaction chamber (3), the glass raw material for cladding is subjected to flame hydrolysis via the cladding powder generator (6), and the core powder layer a field formed as described above is used for the reaction. When point b IN of the chamber (3) is reached, the glass-based oxide powder for cladding from the powder generator (6) is blown onto the outer periphery of the core powder layer C11 to form a cladding powder layer (up to). is deposited and formed.

In the present invention, the powder layer Q for 17 and the powder layer for cladding on its outer periphery are formed as described above, but at this time, the sealing means for partitioning both the injection areas Ql (11) is tightly closed and the sealing chamber ( Inert gas (Ars Hes
Nz, etc.) or chlorine gas (C4) is supplied to form a sealing gas layer.

When the sealing gas layer is formed in this way, the oxide powder from the core powder generator (4) is sprayed into the cladding injection area a0.
Of course, the oxide powder from the cladding powder generator (6) will not be mixed into the core injection region Ql side, and therefore, the oxide powder obtained as described above will not be mixed into the core injection region Ql side. When the oxide powder pellets (powder layer for the core and powder layer for the cladding) are made into transparent glass by heat treatment and used as a base material for an optical fiber, and this base material is further processed into an optical fiber, the core and cladding A proper refractive index distribution without any disturbance can be obtained.

Furthermore, the sealing means (12) is one of the injection regions (II
The through hole (171Q19) which is formed as a specific means for this does not prevent the transfer of the core powder layer α9 from one injection area to the other injection area Qυ. Since a part of the sealing gas in the sealing chamber QQ will leak toward Therefore, since the above-mentioned transfer of the core powder layer Ql is made possible, the two oxide powders do not mix together.

Furthermore, the sealing gas leaked from each through-hole punch (G), the insufficiently reacted oxide powder which escaped to the outside of the oxyhydrogen flame in each injection region QCj (11) forms the core powder layer α and the cladding powder layer α. (a) This prevents any adhesion of the powder, and therefore, during vitrification after a predetermined deposition, there will of course be no foaming phenomenon caused by the incorporation of insufficiently reacted powder.

Next, specific examples of the present invention will be explained.

Specific Example 1 In this specific example, a base material for a gray, dead-index optical fiber was manufactured, and the main conditions were determined as follows.

First, in the core powder generator (4), 8
Introducing i C24'', GaCl2, POCA3,
S i 02- after flame hydrolysis reaction of these
G e 02 P 20H-based oxide powder was deposited along the front legs, and the powder layer Q for the core with an outer diameter of 60 mm was removed.

Furthermore, in the cladding powder generator (6), 5iC24 is introduced into the oxyhydrogen flame to undergo a flame hydrolysis reaction, and the resulting 8i0□-based oxide powder is placed on the outer periphery of the core powder layer CI. A fixed amount of powder was deposited to form a powder layer for cladding.

At this time, Ar is used as the seal gas, and this is 107
/mm into the sealing chamber as, and both injection regions Ql(lυ) were partitioned off by such a sealing means α2-.

The diameter of the partition plate (through hole aη (g) of 14α) was 65cm.

What can be said about the sealing means α4 in the above is that the through hole (1
7) The strength of the seal gas flow leaking from (g) to each injection area α It is possible to prevent the cladding powder layer CIL from being deposited on the cladding powder layer (a).

Of course, each through hole aηα has a hole diameter of 65 for the core powder layer Ql with an outer diameter of 60 mm, and the sealing gas supply amount is lO4/l.
! iIR satisfied the above-mentioned problems.

He and C1
It was heated in an electric furnace in an atmosphere of 0 to make it transparent and vitrified, and used as a base material for optical fiber.

At this base material stage, no foaming was observed on the surface, and a material in good condition was obtained.

Furthermore, when the above-mentioned base material was spun into an optical fiber by heating and drawing, the refractive index distribution shown by the solid line in FIG. 2 was confirmed.

The present invention (solid line) in Fig. 2 has a predetermined and appropriate refractive index distribution (exhibits a predetermined and appropriate refractive index distribution) compared to the conventional example (dotted line in the figure). In this specific example, a base material of a single mode optical fiber is manufactured. The main conditions were determined as follows. In other words, the powder layer for the core Q1 and the powder layer for the cladding (A)
A similar product was made with the same composition as in Example 1, but
Regarding these outer diameters, the core powder layer Ql is 12++o.
A predetermined amount of powder layer for cladding was deposited on the outer periphery as n.

In addition, the diameter of the through hole αη (e) is -15wn, and the sealing chamber a9 is filled with N2 as a sealing gas.
It was supplied at a flow rate of /-.

Thereafter, the oxide powder rod thus obtained was made into transparent glass by the same means as in Example 1, and the base material thus obtained was processed into an optical fiber.

Of course, even in this specific example, no foaming was observed at the base material stage.
Further, the refractive index distribution was as shown by the solid line in FIG. 3, and there was no disturbance in the refractive index distribution as in the conventional example (dotted line in the same figure).

As explained above, the method of the present invention allows for free movement in the axial direction,
The core powder generator and the cladding powder generator are placed apart from each other by maintaining a predetermined angle intersecting the axis of the powder depositor that can freely rotate in the circumferential direction, and while rotating in the circumferential direction, The deposition surface of the powder depositor that can be moved in the axial direction includes:
Glass-based oxide powder from a core powder generator is sprayed to form a rod-shaped core powder layer on the deposited surface, and glass-based oxide powder from a cladding powder generator is sprayed on the outer periphery of the core powder layer. In the vapor phase deposition method, in which a cladding powder layer is deposited and deposited on the outer circumferential surface of the cladding powder layer by spraying a material powder onto the boundary between the injection area by the core powder generator and the cladding powder generator. is characterized by providing a sealing means that allows the passage of the core powder layer and partitioning the two injection regions from each other by the sealing means, so that the refractive index distribution is disturbed due to the partitioning effect through the sealing means. This means that glass products for optical communication that are free from bubbles and do not cause foaming etc. can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram schematically showing one embodiment of the method of the present invention together with its apparatus, and FIGS. 2 and 3 are refractive index distribution diagrams comparing the optical fiber according to the present invention and its conventional example. 0 (4) ... Core powder generator (6) ...
...Powder generator for cladding (8) ...Powder depositor (9) ...Deposition surface Ql (lυ...Injection area 0 ...Sealing means (13α) ...Partition plate O [with] ...Seal chamber αQ ...Seal gas supply system Qη (g) ...Through hole (lil) ...Powder layer for core Powder bed patent applicant for cladding Patent attorney Makoto Ito Continued from page 1 0 Inventor Yasubumi Furui 0 Applicant Furukawa Electric Co., Ltd. 2-6 Marunouchi, Chiyoda-ku, Tokyo No. 1

Claims (4)

[Claims] (1) The core powder generator and the two core powder generators are placed apart from each other by maintaining a predetermined angle intersecting the axis of the powder depositor, which is movable in the axial direction and rotatable in the circumferential direction. Then, glass-based oxide powder from the core powder generator is sprayed onto the deposition surface of the powder depositor, which can rotate in the circumferential direction and move in the axial direction. In the vapor phase axial method, in which a layer is deposited and a cladding powder layer is deposited and formed on the outer periphery of the core powder layer by spraying glass-based oxide powder from a cladding powder generator onto the outer periphery of the core powder layer. At the boundary between the injection area by the core powder generator and the injection area by the cladding powder generator, sealing means is provided to allow passage of the core powder layer, and the sealing means allows the core powder layer to pass through. A method for depositing oxide powder in a vapor phase deposition method characterized by partitioning the injection areas from each other. (2) A method for depositing oxide powder in a vapor phase deposition method according to claim 11, wherein a sealing gas layer is formed between both injection regions as a sealing means. (3) As a sealing means, two wall surfaces intersecting the moving direction of the core powder layer are supplied between the two injection regions to form a sealing gas layer between the two injection regions, and each of the sealing chambers is 3. A method for depositing oxide powder in a vapor phase deposition method according to claim 1 or 2, wherein a gas flow is generated from the through hole toward each injection region. (4) Seal gas layer with inert gas 1. A method for depositing oxide powder in a vapor phase deposition method according to claim 2 or 3, wherein the oxide powder is formed using chlorine gas or the like.