JPS61256938A - Production of glass optical fiber - Google Patents

Abstract

PURPOSE:To enable the production of a glass optical fiber having the characteristic which is not suitable for spinning method requiring high-temp. heating by making a liquid which contains a glass raw material and can gel in a fine pipe to gel then drying and sintering the same. CONSTITUTION:The tip of a slender and long needle 2 of an injection cylinder 3 is put into a sol liquid 1 which is prepd. by mixing alkoxide of Si with ethanol and water and can gel and a syringe 4 of the cylinder 3 is pulled up to put the sol liquid 1 into the cylinder 3 in the stage of producing the optical fiber of the glass having the characteristic with which the heating of the base material to a high temp. is not possible as in the case of forming the fiber by an ordinary spinning method in the stage of producing the glass optical fiber. The top end of the needle 2 is then put into a melt 5 mixed with ethanol so as to have the density slightly smaller than the density of the gel and the sol liquid 1 in the needle 2 part is made to gel. Said liquid is extruded each slightly into the liquid 5 by a fine wire 6. The liquid 5 is removed upon the end of the extrusion and the gel is dried and sintered. The production of the optical glass fiber is thus enabled without a spinning stage.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a novel glass optical fiber, and particularly relates to a method for manufacturing a glass optical fiber, which is not desirable to be exposed to high temperatures such as drawing temperature. The present invention relates to a method of manufacturing a glass optical fiber containing additives that are undesirable to be exposed to.

(Prior art) The development of optical fibers in recent years has been remarkable, and the manufacturing methods include VAD method, MOVD method, plasma OVD method, etc.
Various methods are known, such as the sol-gel method, the double crucible method, and the double crucible method. However, in most of these conventional methods, glass is heated above its softening temperature and drawn into fiber.

Until now, there have been almost no attempts to manufacture optical fibers at temperatures lower than the temperature at which glass softens. However, this method is extremely difficult and is not practical as a method for manufacturing optical fibers.

(Problems to be Solved by the Invention) Recently, requirements for optical fibers have become more diverse, and in some cases, optical fibers containing particularly large numbers of additives or those doped with various elements are desired.

In such a case, the length of the optical fiber is
It does not necessarily have to be long; for example, in the case of a fiber with a nonlinear effect, it may be possible to use a length of several centimeters.

However, glass containing many 1 cm OH groups and G
There have been cases in which fibers cannot be made using conventional techniques, such as those containing a large amount of eOj may foam when heated to high temperatures, those containing a small amount of Os may crystallize, and so on.

It is an object of the present invention to provide a method for producing optical fibers with good characteristics without heating glasses to such high temperatures that it is undesirable to heat them to such high temperatures.

(Means for Solving the Problems) The present invention is characterized in that a gelatable liquid containing a glass raw material is gelled into a fiber shape in a thin pipe, and the gel is dried and sintered. The above object is achieved by a method of manufacturing a glass optical fiber.

That is, if a thin gel is sintered and made into a fiber as it is, it becomes possible to manufacture a high-silica optical fiber that is not exposed to temperatures of 1100° C. or higher, for example.

An example of the steps of the method of the invention is shown in FIG.

First, the gel referred to in the present invention will be explained.

Generally speaking, when it comes to gel, the particle size of the constituent particles is 11.5μ.
It refers to the following, but in the present invention, gel refers to a substance that can be gelled even if it contains larger particles.

Examples of the gelable liquid in the present invention include Sl
A silica sol solution prepared by mixing an alkoxide with ethanol or water, a mixture of the sol solution and glass raw material powder such as silica, or a mixture of these with additives are used. The case in FIG. 1 is an example that does not contain additives.

In the method of the present invention, by gelling the above-mentioned gelatable liquid to form a gel with a small diameter, the fiber can be made into a fiber as it is after sintering, without requiring high-temperature heating as in conventional methods for drawing.

In the conventional method, a gel with a diameter of about 10 IIm was sintered and drawn, but in the present invention, the gel diameter is α3■ or more 2
It is preferably less than fi.

Q. Gels with a diameter of less than 5wx have low strength and are easy to break, and are also difficult to extrude from a pipe after gelation. Moreover, if the diameter exceeds 2 mm, it is difficult to make the diameter sufficiently thin so that it is flexible after vitrification. Although the method of the present invention can be applied to gels exceeding 2 m in length, in this case, the resulting gels have a large diameter, resulting in reduced flexibility and a rond shape.

Therefore, the diameter of the gel is preferably 2 tm or less so that the final product to which the cladding or coating is applied does not lose its 7 Lexiperity.

A method for producing the narrow-diameter gel of the present invention can be, for example, by placing the above-mentioned gelatable liquid in a thin pipe, gelling the vaginal fluid in the pipe, and then expelling it after gelation. Gels can be obtained in longer lengths by using long pipes or by continuous production. To do this, for example, as shown in FIGS. 2(a) to (1), the syringe 4 of the syringe barrel 3 equipped with the long needle 2 with a thin diameter is pulled up, and a gelatinable liquid such as a sol solution is inserted into the syringe 4. into the syringe barrel 3 [Figure 2 (a)), and then dip the tip of the needle 2 into liquid 5, such as gel, in hot water mixed with ethanol so that the density is slightly lower. A method in which a certain sol solution in the needle 2 inside is turned into a gel, and the gel 1' is pushed out little by little into the liquid 5 using a thin wire 6 [see Fig. 2], and then it is returned one after another. can be used.

After extrusion of the gel is completed, the liquid 5 is removed and the gel is dried. The obtained gel is sintered using known conditions and methods. Of course, sintering may be performed after calcination at a low temperature. After sintering, it is made into a fiber without any drawing process.

As mentioned above, for example, Ge
, P, Os, I'b, B, Ti, A/, Yb, Nd, F
It is also possible to add additives containing, etc.

Further, the additive may be included in the raw material, doped after gelling, or added during sintering.

If the additive is OH, it is included in the raw material, so there is no need to add it. F, Oj, etc. are preferably included in the raw materials or added during sintering. Also, if the additive is metal or
If it is a metalloid oxide, it is easy to include it in the raw material in the form of an alkoxide or salt, or to soak it into a gel as a solution of an alkoxide or salt. However, this is a generalization, and it may of course be added by other methods. Furthermore, the additives are not limited to those mentioned above.

By the way, an optical fiber requires a core and a cladding.

The fiber produced by the above-described method may use air as the cladding, or may be coated with a transparent resin or the like, and the resulting resin layer may be used as the cladding.

It is also possible to apply a sol containing a glass raw material with a low refractive index to the surface of the fiber, gel it, and sinter it to form a cladding. Furthermore, the core-cladding structure can also be created by adding additives to the gel state of the fiber before sintering so that the refractive index of the central part is higher than that of the peripheral part. For example, after uniformly infiltrating the gel with an OeN% aqueous solution, the gel is soaked in water and the surrounding area of CaNO3 is
A method can be used in which the concentration is lowered, the material is oxidized, and then sintered.

According to the present invention, it is possible to add substances such as OH groups and F to G, which tends to foam during drawing when contained in large amounts, which cannot be added using conventional methods. It is advantageous for manufacturing fibers with

(Example) The method of the present invention will be specifically explained below with reference to Examples.

Example 1 E? 1 (00Ha), 9.5 f and ethanol 11
．． Mix 5 f with a magnetic stirrer, and add 1 c
Water with one drop of 13% ammonia water9. Of was added and further mixed. After degassing the liquid at a pressure of about 60 Torr, it was poured into a glass pipe with an inner diameter αSWZ and a length of 40°C, and after the gel was made into a blister, the gel was pushed out into water with a thin wire, and the water was discarded and the gel was dried. This gel was calcined in air at 500°C and then sintered in He at 131)0°C to a diameter of approximately 300μ and a length of 10cm.
! n glass fibers were obtained.

It was confirmed by the infrared absorption spectrum that this fiber contained an extremely large number of OBs. When this fiber was exposed to an oxyhydrogen flame, it foamed. In other words, it can be seen that glass containing a large amount of OH groups will foam if heated to a high temperature.

Example 2 A thin gel was obtained in the same manner as in Example 1, except that one drop of 13% aqueous ammonia was not added.

After calcining this in air at 500°C, it was heated to 110°C in He.
It was possible to obtain a glass fiber by sintering at 0°C.

(Effects of the invention) The method of the present invention can be used to make fibers even for glasses that do not require high-temperature heating as in the conventional wire-drawing process, and can also be used to make fibers for glasses that have been added with substances that could not be added because high-temperature heating was not suitable. This is an excellent method for manufacturing glass optical fibers with nonlinear effects that can be short in length without heating at high temperatures.

[Brief explanation of the drawing]

Figure 1 is a process diagram of an embodiment of the present invention, Figure 2 (2) and Φ) are diagrams specifically explaining the method of obtaining gel in the method of the present invention, and Figure 3 is a process diagram of a conventional method. shows.

Claims (1)

[Claims] 1. A method for manufacturing a glass optical fiber, which comprises gelling a gelatable liquid containing a glass raw material into a fiber shape in a thin pipe, and drying and sintering the gel.