JPS61106434A - Preparation of stress affording parent material for optical fiber - Google Patents

Abstract

PURPOSE:To provide a stress affording parent material for optical fiber having high quality with small numbers of prepd. stage and with high efficiency by using a vessel provided with specified partitions and utilizing sol-gel process. CONSTITUTION:Sol for forming a core part, stress affording part, and a clad part is prepd. respectively by hydrolyzing a metal alkoxide wherein the sol for forming the stress affording part and the clad part are prepd. to have a compsn. giving a same refractive index after calcination. Then, a vessel 3 with sections 2a, 2b, 2c, and 2d separated by partitions 1a, 1b, and 1c is prepd. and the sol for the clad is contained in the section 2a, the sol for the stress affording part is contained in the section 2b and 2c, and the sol for clad part is contained in the section 2d, and each sol is allowed to stand. Immediately before the sol is coagulated by gelling, each partition 1a, 1b, and 1c is removed and the boundary is combined to form one body. Obtd. gel is then dried, melted and vitrified.

Description

[Detailed Description of the Invention] "Industrial Application Field" ``This invention relates to a method of manufacturing an optical fiber base material, so for more details, please refer to The present invention relates to a method for manufacturing a base material of a stress-applying optical fiber in which a stress-applying portion is formed in a cladding portion.

"Prior Art" Conventionally, stress-applied optical fibers have been manufactured by the following two methods. That is, in the first method, a 3 m long rod consisting of a single mode optical fiber base material with a thin cladding part, a rod serving as a stress applying part, and a rod serving as an intermediate cladding part was prepared in advance by a vapor phase method or the like. In this method, each of these rods is inserted and arranged in a quartz pipe serving as an outer cladding portion, this is used as a base material, and this base material is heated and melt-spun to obtain a stress-applied optical fiber. In the second method, a single-mode optical fiber base material with a large cladding part and a rod serving as a stress-applying part are made by a vapor phase method, and one is made using a stress-applying part in the cladding part of the ripple-mode optical fiber base material. This is a method in which a corresponding hole is bored, the rod is inserted, the whole base material is made into a base material, and this base material is heated and melt-spun to obtain a stress-applied optical fiber.

``Invention'' ゛Problems to be Solved'' According to the method for manufacturing the optical fiber base material described above, the core part, the cladding part, the stress-applying part? Since they must be formed separately and then drilled in order to combine them into one, the number of man-hours increases and high-volume, high-speed production is not possible. (9) In the base material, there are gaps between the core part, crat part, and stress-applying part).
There is a problem in that the bubbles are easily trapped, and the bubbles remain even during spinning, resulting in defects in the optical fiber.

This invention was made in view of the above circumstances, and requires fewer manufacturing steps, allowing mass and high-speed production.
It is an object of the present invention to provide a method for manufacturing a stress-applied optical fiber preform without introducing air bubbles during melt spinning.

"Means for Solving the Problems Between Droplets" The method for manufacturing a stress-applying optical fiber preform according to the present invention includes forming metal alkoxides constituting the core portion, stress-applying portion, and cladding portion in each of the above-mentioned portions. Based on the proportions, each solution was made into a five-aqueous solution, and each solution was injected into each compartment of the container, which was divided into corresponding compartments such as a core part, a stress-applying part, and a cladding part. Immediately before converting, remove the partitions) to assimilate the boundaries of each part,
Dry the formed gel and obtain a dry gel? The optical fiber preform is obtained by heating and vitrifying it.

"Action of the Invention" According to the above method, after the solution is prepared and poured into a container, - pages can be processed continuously, so the number of man-hours can be reduced, and high-volume, high-speed production can be carried out. Immediately before gelation, the boundaries of each part are assimilated, and then the gel is integrated, so that there is no possibility of air bubbles being mixed in during subsequent melting, which will cause problems.

This invention will be explained in detail below using actual examples.

"Example" Metal alkoxide is 51COC2H5)4, G8r
Q02H514, At(QC3H,)3, Zr (OC
3H7) 4, etc., and these are hydrolyzed to create a solution. At this time, in addition to water, a small amount of HC/, ,, N
H4OH1CH30H etc. may be added as a hydrolysis catalyst. These solutions are used to prepare solutions for each part at appropriate mixing ratios for creating the core part, cladding part, and stress applying part. Generally, the core is made of quartz glass KQe? Doped composition, stress applying part is quartz glass KB+At+B+P
Refraction 1 by mixing +Zr? The composition should match that of the cladding part. Each of these solutions is left at room temperature. Next, as shown in FIG. 1, each section 2a is formed into a core section, a stress applying section, and a cladding section by one partition l'q IJ 1cK.

2b, 2c, 2dK separated container 3? Prepare and inject each of the above solutions into the corresponding sections 2am2b and 2cszaK.

Then, just before each solution solidifies into an agar-like gel, each partition 1 a e 1 b * 1 c is removed, the boundaries of each compartment are assimilated, and an agar-like gel is integrally formed. This gel is dried, and the dried gel obtained is then melted and vitrified to form a base material for a stress-applied optical fiber.

In the above-mentioned example, the container with the gel-molded shell is a container with K-sections so that cylindrical stress-applying parts can be formed on both sides of the central core part, as shown in Fig. 1. , for example, 1 as shown in Figures 2(a) and (b)K.
It is possible to use a container suitable for an optical fiber of a desired shape, such as a shape in which the stress-applying part partition J) 4a has an arbitrary shape, or a round shape in which two core part partitions 4h are provided as necessary. .

"Effects of the Invention" As explained above, 1. According to the present invention, the core part, the clad part, the stress applying part? After the metal alkoxide solution to be formed is created and injected into each compartment in the container, it can be processed continuously, reducing the total number of man-hours and enabling high-volume, high-speed production. Since the boundaries of each part are assimilated and then integrated as a gel, air bubbles will not be mixed in during subsequent melting, which will cause no inconvenience.

Finally, 1. Experimental examples conducted to quantitatively confirm the effects of this invention will be shown.

"Experimental example" st (QC2H,)4 and Go (QC2H514) are mixed in a molar ratio of 98:2, and this is hydrolyzed with 10 times the total amount of water and 1 times the amount of ethyl alcohol to form a core. A solution for forming a thin section was prepared.Similarly, a solution of Si(QC2H5)4:At(QCHI
: A solution containing B rOcH3)3 in a ratio of 88:8:4 was prepared, and Si (QC
2) A solution of only I5) was prepared. On the other hand, in a container VC having the structure shown in Fig. 1, it is made of quartz with an inner diameter of 125 iua and a height of 350 mm, and the inner diameter of the core partition is 8 y.
The inner diameter of the partition of each stress applying part was 2 ozm, and the distance between the centers of the core part and each side pit part was set to 25 NJILK. Each compartment of this container was injected with each of the corresponding solutions described above. This was left for 40 hours, then each partition was removed.

When it was left in this state for a while, it completely turned into a solid gel, and the boundaries of each part were well assimilated. When this solid gel was heated at 80° C. for 30 hours, it became a porous glass C dry gel). This dried gel was further heated at IC300"υ, and then heated at 900°C in a He-, C10 atmosphere to dehydrate it. Subsequently, this was heated to 1600°C.
A rod (stress-applied optical fiber base material) of 15UIφ×280111L was completed. This base material was melted and spun to form a fiber, and its properties were measured. The loss was 4 dB at 1.3 μm, and the extinction ratio was 45 dB at 100 mm.

[Brief explanation of the drawing]

Is Figure 1 an example of a container suitable for carrying out this invention? Are the perspective views shown, fJ/c2 diagram (a), and (1:+) other examples of the same container? FIG. 1a, lb, 1c, 4a, 4b, old...partition, 2a2
bs2c, 2d... compartment, container for 3....

Claims (1)

[Scope of Claims] A stress-applying optical fiber that creates an optical fiber preform by forming a stress-applying part in the cladding part that applies stress to the core part in order to preserve the desired plane of polarization in the optical fiber. In the method for manufacturing a fiber base material, metal alkoxides constituting the core portion, stress applying portion, and cladding portion are each made into an aqueous solution based on the composition ratio for each portion, and each of these metal alkoxide solutions is partitioned internally. The solution is injected into each compartment of a container divided into compartments corresponding to the core part, stress applying part, and cladding part, and immediately before each solution gels, the partitions are removed to assimilate the boundaries of each part, and the solution is formed. 1. A method for producing a stress-applying optical fiber preform, comprising: drying the gel, and heating and vitrifying the obtained dried gel to obtain an optical fiber preform having a stress-applying portion.