JPS60142303A - Multicore fiber for optical transmission and its manufacture - Google Patents

Abstract

PURPOSE:To improve the array quality of plural optical glass fiber consisting of a core and a clad and the uniformity of the distance between adjacent fibers by arranging plural glass fibers on a glass body in parallel, and welding part of the clads of the glass fibers to the glass body. CONSTITUTION:All optical fibers 1 are welded to the common glass body 8 at part 7 of their circumferences. Namely, the optical fibers 1 and glass body 8 are united lengthwise in terms of structure. This structure allows the individual optical fibers to be discriminated. For the purpose, plural preforms 12 are arrayed closely and supplied to heating furnaces 15 which function individually and then heated in the heating furnace 15. The glass body 13, on the other hand, is supplied to the heating furnaces 14 and also heated in the heating furnace 14. Those are heated individually and the both are assembled in the state where the surface of the glass body 13 is parallel to the array surface of the plural optical fibers when they are fused, thereby welding the respective optical fibers onto the glass body.

Description

[Detailed Description of the Invention] [Object of the Invention] The present invention provides a practical multi-core optical transmission fiber that improves the identification of fibers including each core, the alignment of each fiber, and the distance between adjacent cores. The present invention aims to provide an optical fiber with improved uniformity and a method for manufacturing the same.

[Prior art and its problems]

A multi-core optical fiber is composed of an optical fiber consisting of a plurality of cores and claddings, and the claddings are welded together and mechanically integrated.

This is intended to make it possible to connect multiple cores at once by keeping the distance between adjacent cores constant, but for this reason, even if a slight stress is applied at the time of connection, the arrangement of the multiple cores will not change. The core and cladding must be made of glass that has approximately the same physical properties. FIG. 1 shows a cross section of a conventional parallel multi-core glass fiber. It has a shape in which a plurality of optical fibers 1 are closely bundled in parallel, and the outer periphery thereof has a uniform groove 2 in the axial direction. Since the multi-core optical fiber of this structure has a symmetrical configuration with respect to the left and right sides, there is a drawback that individual multi-core optical fibers cannot be easily identified. Identifying each optical fiber in an optical cable is
This is an essential matter when constructing optical cable transmission lines.

In addition, when manufacturing the product shown in Figure 1, usually multiple preforms (base materials) are closely arranged in parallel, each preform is bonded to each other, and then heated to a high temperature and melted to create a wire. A method is adopted in which the material is drawn and finished to a predetermined narrow diameter. According to this method, as shown in FIG. 2, during welding, the inner optical fiber 4 is pulled by the optical fibers 3 on both sides.
This causes problems such as the optical fibers becoming flat or the degree of alignment of the optical fibers deteriorating.

[Disclosure of the invention]

The present invention aims to solve the problems of conventional parallel multi-core fibers, and involves arranging a plurality of glass fibers consisting of a core and a cladding in parallel to a glass body. The invention relates to an optical transmission fiber in which a part of the cladding is welded to a glass body, and also to a method for manufacturing the optical transmission fiber.

〔Example〕

3(a'L(b), (c), and (d) are cross-sectional views of an embodiment of the present invention. 5 and 6 are the core and cladding of an optical fiber made of, for example, quartz glass.

In FIG. 3(a), all the optical fibers 1 are welded to a common glass body 8 at a portion 7 of their circumference.

Part of the circumference of the cladding 6 of the adjacent optical core ino is 9
It may be welded at.

The optical fiber 1 and the glass body 8 are structurally integrated in the longitudinal direction. According to this structure, it becomes possible to identify individual optical fibers. For example, as shown in the figure, A, B, C, D, E based on the glass body 8.
optical fibers can be identified.

FIGS. 3(b) and 3(c) show core 5. It has a structure in which a plurality of optical fibers made of cladding 6 are sandwiched between glass bodies 8 and 1o from both sides, and in FIG. 3(b), a colored glass body 10 is used, and C
), the dimensions of the glass body 11, such as width and thickness, are different from those of the glass body 8, so that each optical fiber can be identified and specified.

Further, in FIG. 3(d), one side of the glass body 8 is bent, and is used as a reference for identification as an asymmetric shape.

Next, the manufacturing method will be explained.

FIG. 4 schematically shows a method of manufacturing the multi-core optical transmission glass fiber shown in FIG. 3(a) according to the present invention.

In the figure, reference numerals 14 and 15 indicate heating furnaces that function independently, and a plurality of preforms 12 are supplied to the heating furnace +5 in a close arrangement and heated by the heating furnace 15.

On the other hand, the glass body 13 is supplied to the heating furnace I4, and
Heat at 4. These are heated separately, and when they are in a molten state 16, the surface of the glass body 13 and the arrangement surface of the plurality of optical fibers are parallel to each other,
Both are assembled and each optical fiber is welded onto the glass body.

In this case, by appropriately setting the temperature of the heating furnace so that the viscosity of the glass body 13 is higher than the viscosity of each optical fiber during welding, problems such as flattening of each optical fiber and disordered arrangement can be avoided. It will be resolved. In other words, even if a force is generated that tries to break the shape of the optical fiber after each optical fiber is welded to the glass body, due to the high viscosity of the glass body,
It can absorb that force and prevent deformation. After gathering both, they may be melted again in a heating furnace and drawn. Furthermore, in order to be able to heat, weld, and draw wire in a common heating furnace, a glass body may be used whose viscosity at the time of welding at the same heating temperature is about the same level or higher than that of the preform.

Furthermore, in the case shown in FIGS. 3(b) and 3(c), the glass body 8 is coated with a colored glass body 101 so that glass body openings having different widths or thicknesses are finally formed. , the glass body 13 is heated in advance in a heating furnace.
A glass body having a different shape and color tone is prepared, and a plurality of optical fibers are sandwiched together with the glass body 13, melted and bonded, and then drawn as is or while being reheated.

In this case, the melt viscosity of the glass body sandwiching the plurality of optical fibers together with the glass body 13 has already been determined.
The same concept as described in No. 3 regarding the melt viscosity during welding of a plurality of optical fibers is applied, and furthermore, it is extremely desirable that the melt viscosities of both glass bodies sandwiching the optical fibers be approximately equal.

〔effect〕

According to the present invention, conventional multi-core optical fibers can be
It becomes possible to easily identify and specify each optical fiber that has been used, and to overcome difficulties in connection.

On the other hand, in manufacturing, when manufacturing a multi-core optical fiber as shown in Figure 1, even if a large number of preforms are aligned and lined up in a line, there is a problem with the optical fibers on both sides when drawing. There was a problem in that the inner optical fibers were pulled by the force in the direction, causing them to become flat as shown in Figure 2, and the alignment was likely to collapse.However, according to the manufacturing method of the present invention, it is possible to Because the optical fibers are aligned and welded on a glass body that has a higher viscosity during welding, the glass body can absorb the force that disrupts the cross-sectional shape of each optical fiber, and the problems of the prior art described in 1-1 can be avoided. It will be resolved.

As a result, according to the present invention, the alignment of a plurality of optical fibers and the uniformity of the distance between adjacent fibers are very high.As mentioned above, since each optical fiber can be identified, it is possible to This makes it easier to connect the core optical fibers all at once.

[Brief explanation of the drawing]

FIG. 1 shows a cross section of an example of a conventional multi-core optical fiber. FIG. 2 is an explanatory diagram of distortion caused by manufacturing the multi-core optical fiber shown in FIG. Figures 3(a), (b), (c), and (d) respectively show cross sections of embodiments of the present invention. Figure 4 is a schematic diagram of the manufacturing method of the present invention. 1.3...・Optical fiber, 2...Groove, 4...Flattened optical fiber, 5...Core of optical fiber, 6...
- The same cladding, 8.10, 11... Glass body, I2 preform, 13... Glass body, 14.15... Heating furnace. ■Figure 3

Claims (2)

[Claims] (1) A multicore optical transmission fiber characterized in that a plurality of glass fibers each consisting of a core and a cladding are arranged in parallel on a glass body, and a part of the cladding is welded to the glass body. (2) A multi-core structure characterized by arranging a plurality of glass fibers consisting of a core and a clad in parallel on a glass body whose viscosity at the time of welding is higher than that of the glass fiber, and welding the 0 and 1 clads. A method for manufacturing core optical transmission fiber.