JPH05330831A - Production of rare-earth-element-doped quartz glass - Google Patents

Abstract

PURPOSE:To produce a rare-earth-element-doped quartz glass capable of forming an optical fiber exhibiting an excellent property as an use for a light amplifier. CONSTITUTION:In this method for producing the rare-earth-element-doped quartz glass, gaseous hydrogen and gaseous oxygen are supplied into a concentric multiple tube burner to form oxyhydrogen flame, a glass forming raw material gas composed of a halide of silicon, a halide containing an element to be a dopant and a sublimable organic rare earth element compound are supplied into the flame and the porous silica base material obtained by depositing a silica glass particulates produced by flame hydrolyzing is sintered at high temp. and transparently vitrified. In this way, gaseous hydrogen for forming oxyhydrogen flame is used as a carrier gas of the organic rare earth element compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing rare earth element-doped quartz glass, and more particularly to a method for producing functional rare earth element-doped quartz glass used in optical fiber lasers and the like.

[0002]

2. Description of the Related Art Since rare earth element-doped quartz glass has an optical function, an optical fiber laser, an optical amplifier,
It is used as a sensor element. However, the method of manufacturing the quartz glass of this kind by the MCVD method has been conventionally known (see Japanese Patent Publication No. 63-501711).
This is because the rare earth element oxide is heated to a high temperature to be vaporized and supplied to the reaction system. Therefore, it is difficult to control the supply amount and it is difficult to obtain a large base material.

On the other hand, in the production of this rare earth element-doped quartz glass, a silicon compound as a glass forming raw material is fed into an oxyhydrogen flame, and silica glass fine particles produced by the flame hydrolysis are deposited to form porous silica. Making the base material,
The porous silica base material is immersed in a solution of a rare earth element compound to impregnate the porous silica base material with the rare earth element compound,
Then, a method has been proposed in which it is sintered at a high temperature to form a transparent glass (see Japanese Patent Publication No. 58-3980), in which the amount of dope can be controlled by the concentration of the solution and the compound with a low vapor pressure is used. However, when the solvent migrates to the surface of the porous silica matrix by capillary action when the porous silica matrix is dipped in the solution of the rare earth element compound and dried, Since the solute also moves at the same time and accumulates near the surface, the obtained glass has a dopant concentration distribution,
In an extreme case, there is a problem that it is cracked due to the difference in coefficient of thermal expansion between the surface and the inside, and this also causes a part of the rare earth element compound to volatilize during sintering and vitrification, There is also a drawback in that a desired amount of doping cannot be obtained.

In addition, it has been proposed to add a step of oxidizing the dope raw material in the porous silica matrix in an oxidizing atmosphere maintained at a temperature below the melting point of the dope raw material (Japanese Patent Publication No. 63-63-63). However, it is difficult to oxidize rare earth chlorides completely to convert them to oxides, and a considerable amount of rare earth chlorides remains even after heat treatment in an oxidizing atmosphere. Even if it is taken into the glass without doing so, it cannot enter the glass network in the chloride state and separates as minute crystals, causing the glass to become cloudy and causing optical transmission loss. However, there is a disadvantage that the laser oscillation efficiency is low.

[0005]

Therefore, as a method of producing this rare earth element-doped quartz glass, a method of supplying a halogen-free glass forming raw material gas and a sublimable organic rare earth element compound in a gas phase has also been proposed. (See Japanese Patent Application No. 3-89741), which provides the advantage that the supply amount can be easily controlled because the organic rare earth element compound can be vaporized at a low temperature. However, even if this organic rare earth element compound is an acetylacetonite complex, it decomposes rapidly in an atmosphere containing water or a halide, and this reacts in the middle of the pipe, inside the burner, or at the tip of the nozzle to cause solidification. There is a risk that it will form an object, and this will block the path, so this is done with a single nozzle with a silicon halo. Supplying down products and dopant consisting of germanium and aluminum halides, it has been solved by feeding in a gas phase sublimable organic rare-earth compounds to a different one nozzle.

As the carrier gas for supplying the organic rare earth element compound to the gas phase, it is conceivable to use the same argon gas as the carrier gas of the glass forming raw material gas or the dopant raw material gas. Elemental compounds have a small vapor pressure and are decomposed when heated to a high temperature in order to increase the vapor pressure. Therefore, it is necessary to use a large amount of carrier gas in order to sufficiently dope the rare earth element. However, when a large amount of argon gas is flown as this carrier gas, it becomes difficult to manufacture the base material,
In an extreme case, there is a problem that production becomes impossible, and when oxygen is used as the carrier gas, there is a problem that oxidative decomposition of the organic rare earth element compound is promoted in the container or the transfer tube.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a rare earth element-doped quartz glass, which solves the above disadvantages and problems, by supplying hydrogen gas and oxygen gas to a concentric multi-tube burner. Form an oxyhydrogen flame,
In this flame, a glass-forming raw material gas consisting of a silicon halide, a halide containing an element serving as a dopant, and a sublimable organic rare earth element compound were supplied to obtain silica glass fine particles produced by flame hydrolysis. In a method for producing a rare earth element-doped quartz glass in which a porous silica base material is sintered at a high temperature to form a transparent glass, a hydrogen gas for forming an oxyhydrogen flame is used as a carrier gas for the organic rare earth element compound, To do.

That is, the inventors of the present invention have made various studies on a method for producing a rare earth element-doped quartz glass which solves the above disadvantages and problems, and as a result, the production of this rare earth element-doped quartz glass is carried out by a known oxyhydrogen flame. By the method of supplying a sublimable organic rare earth element compound into the flame during the production of the porous silica matrix to cause flame hydrolysis, and by the method of sintering the porous silica matrix thus obtained to form a transparent glass. At this time, when the carrier gas for transporting the organic rare earth element compound was hydrogen gas during the formation of the oxyhydrogen flame, the organic rare earth element compound could be transported without any trouble, and a large amount of this was flowed. However, the production of the porous silica base material does not become difficult, and the organic rare earth element compound is not decomposed by this. It was found that an undoped quartz glass can be efficiently produced, and it was confirmed that the optical fiber produced from the rare earth element-doped quartz glass thus obtained exhibits excellent characteristics for an optical amplifier. Was completed. This will be described in more detail below.

[0009]

The present invention relates to a method for producing rare earth element-doped quartz glass, which comprises supplying an organic rare earth element compound into a flame during the production of a porous silica base material by an oxyhydrogen flame and subjecting it to flame hydrolysis to obtain In a method of sintering the obtained porous silica base material to make it a transparent glass, the organic rare earth element compound is characterized by being carried as a hydrogen gas for forming an oxyhydrogen flame as a carrier gas. However, this provides the advantage that the desired rare earth element-doped quartz glass can be efficiently manufactured.

In the method for producing a rare earth element-doped quartz glass according to the present invention, an oxyhydrogen flame is formed by supplying hydrogen gas and oxygen gas to an oxyhydrogen flame burner composed of the same multi-tube.
Into this flame, a raw material gas for forming a glass consisting of a halide of silicon, a halide such as germanium or aluminum as a dopant and a sublimable organic rare earth element compound are supplied, and silica glass produced by flame hydrolysis of these. A known method is to deposit fine particles to form a porous silica preform, and sinter this at high temperature to form vitrified glass. The method for producing this porous silica preform is the production of an optical fiber preform. VAD known as a method
Method or OVD method.

The organic rare earth element compound used here is an organic compound such as neodymium, erbium, europium or cerium. The organic rare earth element compound used for this is neodymium, europium,
General formula of rare earth elements such as cerium R-CO-CH =
CO-R ', wherein R and R'are an alkyl group, an allyl group, a fluorine-substituted alkyl group, a heterocyclic group, etc., for example, acetylacetonite, trifluoroacetylacetonite, hexafluoroacetylacetonite, dibenzoyl. Examples thereof include trifluoroacetonite, dibenzoylmethanato, dipivaloylmethanato, thenoyltolufluoroacetylacetonite, and furoyltrifluoroacetylacetonite. These may be housed in an evaporator, heated in an oil bath to be vaporized, and supplied to the reactor with a carrier gas. Rare earth element-doped quartz glass doped from more than one species may be produced.

In the present invention, the rare earth element compound is introduced into the oxyhydrogen flame by using the hydrogen gas for forming the oxyhydrogen flame as the carrier gas. When the organic rare earth element compound is carried by the hydrogen gas as the carrier gas, the hydrogen The amount of rare earth element contained in the porous silica matrix can be controlled according to the amount, and in this case, the hydrogen gas does not hinder the transport of the organic rare earth element compound, and a large amount of this can be flowed. However, there is no difficulty in producing the porous silica base material, and the hydrogen gas does not cause a chemical change in the organic rare earth element compound.

In this case, as the hydrogen gas, a part of the hydrogen gas for forming the oxyhydrogen flame may be used, and the organic rare earth element compound carried by the hydrogen gas may be used as a glass forming gas. The halide and the halide such as germanium and aluminum as the dopant are supplied to a nozzle different from the nozzle, but the remaining hydrogen gas for forming the oxyhydrogen flame may be supplied to the burner from another nozzle.

The glass forming gas, the dopant and the organic rare earth element compound supplied to the oxyhydrogen flame burner are flame-hydrolyzed in the oxyhydrogen flame from the burner, and silica glass fine particles containing the dopant and the rare earth element are carried. It is deposited on the body to form a porous silica matrix. The porous silica base material thus obtained is then heat treated in an electric furnace by a conventional method, and is made into a rare earth element-doped quartz glass by vitrification, but the atmosphere in this case is helium gas. For the purpose of dehydration, a small amount of halogen gas may be mixed, or a small amount of oxygen gas may be mixed in order to complete conversion to oxide.

[0015]

EXAMPLES Next, examples of the present invention will be given. Example A hydrogen gas of 4.2 liters / minute and an oxygen gas of 7 liters / minute were supplied to a quartz concentric multi-tube burner to form an oxyhydrogen flame, and silicon tetrachloride and germanium tetrachloride were respectively supplied to the central nozzles of the burner. Argon gas of 0.18 liters / minute was supplied as a carrier gas.
The aluminum trichloride gas generated by sublimation was blown into the evaporating dish containing aluminum trichloride heated to the same temperature to stir the same.

On the other hand, the oxyhydrogen flame burner blows 4.2 liters / minute of hydrogen gas for forming the oxyhydrogen flame into an evaporation dish containing triscyclopentagenenyl erbium which is heated to 150 ° C., where sublimation is performed. This triscyclopentaenyl erbium gas was carried by this hydrogen gas,
This gas was supplied to the oxyhydrogen flame burner through a nozzle different from the above-mentioned glass forming raw material gas and dopant gas.

Then, the mixed gas of the raw material gas for forming glass, the dopant gas and the organic rare earth element compound supplied to the oxyhydrogen flame burner is flame-hydrolyzed in this flame to contain the dopant and the rare earth element generated therein. By depositing the silica glass fine particles on the carrier for 8 hours, a porous silica matrix with an outer diameter of 45 mm, a length of 300 mm, a weight of 150 g, and an average bulk density of 0.314 g / cm ² was obtained. Therefore, when the rare earth element content of this substance was examined by ICP emission analysis, it was found that erbium oxide was 700
It was confirmed that it contained ppm.

Next, an optical fiber preform in which this rare earth element-doped quartz glass was used as a core and fluorine-doped quartz glass was clad, and the optical amplification characteristics of this were investigated. It was excited by a pump light of 10 mW of 1.48 μm. , 1.55 μm signal light showed an amplification gain of 28 dB.

[0019]

Industrial Applicability The present invention relates to a method for producing a rare earth element-doped quartz glass, which, as described above, flame-hydrolyzes a glass forming raw material gas, a dopant gas and an organic rare earth element compound in an oxyhydrogen flame burner. In the method for producing a porous silica matrix, the organic rare earth element compound is characterized in that it is carried by using hydrogen gas for forming an oxyhydrogen flame as a carrier gas. Rare earth element compounds can be transported without any hindrance, and even if added in large quantities, it does not make the production of porous silica base material difficult, so it is sufficient for the porous silica base material to be used in any desired amount. Given the advantage that it is possible to dope rare earth elements, optical fibers using rare earth element-doped quartz glass manufactured by this method are used for optical amplifiers. It exhibits a superior characteristic.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Minoru Taie 2-13-1, Isobe, Annaka-shi, Gunma Shin-Etsu Kagaku Kogyo Co., Ltd., Institute for Precision Materials (72) Inventor Kazuo Kamiya Yasushi Gunma 2-13-1, Isobe, Naka-shi Shin-Etsu Chemical Co., Ltd. Precision Materials Research Laboratory

Claims (3)

[Claims] 1. A hydrogen gas and an oxygen gas are supplied to a concentric multi-tube burner to form an oxyhydrogen flame, and a glass forming raw material gas made of a silicon halide and a halide containing an element serving as a dopant in the flame. Of rare earth element-doped quartz glass, which is obtained by supplying silica and sublimable organic rare earth compound and depositing silica glass fine particles generated by flame hydrolysis to sinter porous silica matrix at high temperature to form transparent glass In the method, a hydrogen gas for forming an oxyhydrogen flame is used as a carrier gas for the organic rare earth element compound, and a method for producing a rare earth element-doped quartz glass. 2. The rare earth element according to claim 1, wherein a part of the hydrogen gas for forming the oxyhydrogen flame is used as a carrier gas for the organic rare earth element compound, which is combined with the remaining hydrogen gas and supplied to the burner. Method for producing doped quartz glass. 3. The method according to claim 1, wherein a part of the hydrogen gas for forming the oxyhydrogen flame is used as a carrier gas for the organic rare earth element compound, and this is supplied to the burner by a nozzle different from the rest of the hydrogen gas. Manufacturing method of rare earth element-doped quartz glass.