JPH0442819A - Production of rare earth doped glass - Google Patents

Abstract

PURPOSE:To obtain a rare earth doped glass enabling uniform dope of rare earth element and capable of simplifying production process by heating an aggregate of glass fine grains in a rare earth element compound gas atmosphere formed in a specific manner. CONSTITUTION:An atomized article of a rare earth element compound solution S is jetted from a nebulizer 13 and sprayed onto the surface of soot 11 rotating and simultaneously reciprocating in the vertical direction. Then the atomized article of the rare earth element compound is uniformly attached onto the surface of soot 11 by several reciprocations of the soot 11. The soot is dried in dried nitrogen stream, etc., to remove water content of soot. Then the soot 11 to which the rare earth element compound is attached is housed in a heating furnace 14 in which temperature gradient distribution in a closed state is formed, and then the heated rare earth element compound is sublimed. Thereby the inside of a heating furnace 14 is kept to the gaseous atmosphere of the rare earth element compound and simultaneously soot 11 is sintered. According to this production method of glass, it is not required to previously dehydrate the rare earth element compound and most water is removed in the drying process after attaching of the rare earth element compound solution onto the soot and removed also in sublimation thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION C. Industrial Application Field The present invention relates to a method for manufacturing rare earth element-doped glass used for optical amplification and the like.

[Conventional technology]

One of the methods for manufacturing quartz glass doped with rare earth elements such as erbium is the VAD method, MCVD method, O
The glass particle aggregate obtained by the VD method is hereinafter abbreviated as soot. ) is heated and sintered in a gas atmosphere containing a rare earth element compound such as erbium chloride, and the glass is doped with erbium ions.

In this method, as a means for forming a rare earth element compound gas atmosphere, as shown in FIG. A method is adopted in which a rare earth element compound A such as the following is heated with a heater 5 to make it rise, thereby creating a rare earth element compound gas atmosphere in the furnace 2.

However, this method has the following problems.

That is, it is necessary to keep the gas concentration of the rare earth element compound in the atmosphere constant, but this requires keeping the amount of sublimation of the rare earth element compound constant. In order to keep the amount of sublimation constant, it is necessary to precisely control the amount of heat per unit time from the heater 5 to the rare earth element compound A according to the remaining amount of the rare earth element compound A, but this control is extremely difficult. be.

Furthermore, as the amount of rare earth element compound A decreases, the heating efficiency also decreases. Due to these factors, there is a difference in the amount of sublimation between the start and end of sublimation, resulting in the inconvenience that the dope amount changes in the longitudinal direction of the resulting glass-metal glass, as shown in Figure 6. arise.

Furthermore, since rare earth element compounds such as erbium chloride generally contain water of crystallization, it is necessary to use the rare earth element compound A to be placed in the raw material container 4 from which this water of crystallization has been removed in advance. For this reason, there is a drawback that a dehydration process must be provided separately from dehydration of the soot itself.

[Problem to be solved by the invention]

Therefore, an object of this invention is to make it possible to keep the supply amount of the rare earth element compound gas constant when sintering soot in an atmosphere of the rare earth element compound gas, and to make it possible to uniformly dope the rare earth element. The object of the present invention is to provide a method that can also simplify the manufacturing process.

[Means to solve the problem]

This problem is solved by forming the rare earth compound gas atmosphere by gradual sublimation of the rare earth compound deposited on the soot to be sintered.

The present invention will be explained in detail below.

In the manufacturing method of this invention, a rare earth element compound is first attached to soot. FIG. 1 shows an example of a device used for this purpose, and reference numeral 11 in the figure indicates a suit. This soot 11 is a rod-shaped member formed at one end of a rod-shaped base material 12 by a well-known VAD method. The bulk density of the soot 11 may be in the range of 0.2 to 0.7 g/cz', and a slightly lower bulk density is preferable because the gas of the rare earth element compound described later will penetrate better. This suit
The other end of the rod-shaped base material 12 is attached to a traverser device (not shown), so that the suture 11 is rotated and reciprocated in the vertical direction. On the other hand, the reference numeral 13 in the figure is a nebulizer (atomizer). This nebulizer 1
3 is a carrier gas introduction pipe 13a for atomizing the rare earth element compound solution to form a mist and spraying this mist onto the surface of the soot 11, and for introducing a gas such as argon, nitrogen, helium, etc. , a main body 13b that stores the rare earth element compound solution S, and an ejector f ejector 13c that ejects a mist accompanied by a carrier gas. As the rare earth element compound forming the rare earth element compound solution S, salts such as chlorides and nitrates of erbium, neodymium, europium, etc. are used,
These salts are dissolved in water, an aqueous acid solution such as hydrochloric acid or nitric acid, or alcohol to form a solution.

Next, the atomized material of the rare earth element compound solution S is ejected from the nebulizer 13 as shown in the figure, and is sprayed onto the surface of the soot 11 which is rotating and reciprocating in the vertical direction. By reciprocating the soot 11 several times, the atomized material of the rare earth compound is uniformly deposited on the surface of the soot 11. Thereafter, the soot is dried, such as in a stream of dry nitrogen, to remove moisture.

The attachment of the rare earth element compound to the soot in this invention is not limited to the method of spraying a mist using the above-mentioned nebulizer 13. A method of quantitatively dropping minute droplets of rare earth element compound solution onto
If the bulk density of is 0.4g/c++S or more, soot l
A method such as immersing the entire portion in a rare earth element compound solution for a short time can be adopted. Also, as suit 11, VAD
The soot is not limited to one obtained by the method, but may be one obtained by the OVD method (external method) or the soot obtained by the MCVD method.

Next, as shown in FIG. 2, the soot 11 to which the rare earth element compound has adhered is housed in the heating furnace 14 in which a temperature gradient distribution is formed in a closed state, and heated. The soot 11 is sintered while creating an atmosphere of rare earth element compound gas inside.

In the heating furnace 14, as shown in FIG. 2, a temperature distribution is formed by the heater 14a that continuously changes such that the lower end side is low temperature and the upper end side is high temperature. When using erbium, the temperature at the lower end is 850°C, which is the sublimation temperature of erbium chloride.
The temperature on the upper end side is about 1500°C, which is higher than the melting temperature of the silica glass particles forming the quartz glass particles.

Further, the soot 11 is attached to a traverser device (not shown) as an initial position so that one end where the rod-shaped base material 12 is located is located on the low temperature side of the heating furnace 14, and is gradually moved upward at a constant speed while rotating. It is supposed to be done. Furthermore, an inert gas such as argon or helium is introduced into the heating furnace 14, so that the pressure inside the furnace is slightly higher than atmospheric pressure, and the furnace is in a substantially sealed state.

In this state, when the soot 11 is rotated from the initial position and gradually moved above the heating furnace 14, the upper end of the soot 11 enters the sublimation temperature range where the low temperature rare earth element compound of the heating furnace 14 sublimates. Here, the rare earth element compound adhering to the surface of the soot 11 sublimates, and this sublimated gas fills the heating furnace 14, so that the soot 11 is placed in a gas atmosphere of the rare earth element compound. and,
This sublimated gas penetrates into the voids of the soot 11 and penetrates into the interior of the glass particles.

As soot 11 gradually moves upwards.

The remaining portion of the heating furnace 11 gradually enters the sublimation temperature range, and the attached rare earth element compound is sublimated one after another, and the inside of the heating furnace 14 is maintained in a gas atmosphere of the rare earth element compound.

When the upper end of the soot 11 enters the high-temperature sintering temperature range of the upper part of the heating furnace 14, sintering of the soot 11 in the gas atmosphere of the rare earth element compound starts, and the rare earth element compound is sequentially added to the soot 11 from the upper end of the soot 11. is doped and turned into transparent glass. In this way, when the lower end of the soot 11 enters the sintering temperature range, the entire soot 11 is transparently vitrified in a state doped with the rare earth element, and a rare earth element-doped glass rod is obtained.

If the soot is obtained by the OVD method, the operation can be performed in exactly the same way as described above, and even if the soot is obtained by the MCVD method, the same procedure can be used to turn the soot into transparent glass. After that, all you have to do is heat it up and turn it into a cobras.

In such a manufacturing method, if the amount of the rare earth element compound attached to the surface of the soot 11 per unit area is uniform throughout the soot 11, then when the upward movement speed of the soot 11 is constant, The amount of rare earth compound supplied to the sublimation temperature range per unit time is constant, and if the temperature in the sublimation temperature range is kept constant and a sufficient amount of heating heat is given, the amount of sublimation of the rare earth compound will be constant, and the amount of sublimation in the heating furnace 14 will be constant. The sublimation gas concentration in the atmosphere easily becomes constant. Therefore, suit 1
The amount of rare earth element doped in the entire structure can be made uniform very easily.

Further, there is no need to dehydrate the rare earth element compound in advance, and most of it is removed in the drying process after the rare earth element compound solution is attached to the soot, and is also removed during sublimation.

Also, prior to sublimation of the rare earth compound, soot! l
It is also possible to dehydrate the soot 11 by supplying halogen gas such as chlorine gas into the heating furnace 14 while heating the soot to 700 to 800°C. During this dehydration, moisture caused by attachment of rare earth element compounds can also be removed. can be removed at the same time.

Hereinafter, specific examples will be shown to clarify the effects.

(Example) (2) A material having an outer diameter of 52 x m, a length of 200 x m, and a bulk density of 0.22 g/cj' was prepared by the AD method. This soot was attached to a traverser device as shown in FIG. 1, and an ErCQs aqueous solution was sprayed onto its surface using a nebulizer. In the nebulizer, ErC
1! It was filled with an ErCQs aqueous solution consisting of 24.75 g of s.o., 5Hto, 5 cc of 35% hydrochloric acid, and 150 cc of water, and Ar was supplied as a carrier gas at a flow rate of 5 Q/min to form a mist. The entire soot was sprayed at a rotation speed of 6 Orpm and a reciprocating speed of 20 x 1 minute.

After the entire soot has been sprayed,
It was dried for 4 hours in a nitrogen stream at 0''C.

This soot was placed in a heating furnace as shown in Figure 2, and the whole was heated to 800°C and dehydrated by flowing chlorine gas.Then, a temperature distribution was created in the heating furnace, and the lower part of the furnace was heated with ErCQ. The upper part of the furnace was kept at the soot sintering temperature of 1500°C, and the soot was heated at 20 rpm.
while rotating at a speed of 10 x M/min. As a result, an Er-doped quartz glass rod having an outer diameter of 1711 and a length of 96zx was obtained.

When the amount of Er doped in this quartz glass rod was measured in the radial and axial directions, it was found that it was uniformly 500 ppp in the radial and axial directions, as shown in FIGS. 3 and 4.
It was found that m was doped with Er.

〔Effect of the invention〕

As explained above, the method for producing rare earth-doped glass of the present invention involves heating a glass particle aggregate in a rare-earth element compound gas atmosphere to obtain rare-earth element-doped glass. is formed by gradual sublimation of the rare earth element compound attached to the aggregate of glass fine particles to be sintered, so it is possible to obtain glass with a uniform amount of rare earth element doping by a simple operation. can.

[Brief explanation of drawings]

Figures 1 and 2 are both schematic diagrams of the equipment used in the manufacturing method of the present invention, with Figure 1 being for spraying a rare earth compound solution onto soot, and Figure 2 being for spraying a rare earth compound solution onto soot. Fig. 3 and Fig. 4 both show the distribution state of Er in the Er-doped glass rod obtained in the example of the present invention. FIG. 5 is a schematic configuration diagram showing an apparatus used for manufacturing conventional rare earth doped glass, and FIG. 6 is a graph showing the distribution state of rare earth elements in rare earth doped glass obtained by the conventional manufacturing method. 11... Soot, 13... Nepurizer (sprayer), S... Rare earth element compound solution, 14... Heating furnace.

Claims (2)

[Claims] (1) When heating a glass fine particle aggregate in an atmosphere of a rare earth compound gas to obtain glass doped with a rare earth element, the formation of the rare earth compound gas atmosphere causes the glass fine particle aggregate to be sintered to be heated. 1. A method for producing rare earth doped glass, characterized in that it is carried out by gradual sublimation of a rare earth element compound attached to a glass. (2) A mist of a rare earth element compound solution is sprayed onto the glass particle aggregate, and then the glass particle aggregate is gradually heated from the low temperature side to the high temperature side in a closed heating atmosphere where a temperature gradient distribution is formed. The glass fine particle aggregate is heated while being moved to gradually sublimate the rare earth element compound adhering to the glass fine particle aggregate, and the sealed heating atmosphere is made into a rare earth element compound gas atmosphere. A method for producing rare earth doped glass, which involves sintering.