JPS6155615A - Manufacture of light branching and coupling section - Google Patents

Abstract

PURPOSE:To enable form a light branching and coupling section that does not cause disconnection by forming a light branching and coupling section by fusing plural optical fibers and then selecting a coupling section having sufficient strength after making a specified strength test. CONSTITUTION:Two optical fibers 11, 12 are held by conductor clamps 15, 16 on moving stages 13, 14, and voltage is applied to a pair of discharge electrodes 23, 24 to heat and melt the optical fibers 11, 12 and a coupling section is manufactured. Then, the fibers 11, 12 are held by a strand clamp 18 and a clamp 19 to which a tensile load measuring device 20 is attached. When the moving stage 14 is moved to the left under this condition, the branching and coupling section is subjected to tensile load. When the stage 14 is moved until an output of the measuring device 20 arrives at a specified value, disconnection is caused when strength is insufficient. As products having sufficient strength are selected in the stage of manufacture, a branching and coupling section free from disconnection can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a method of manufacturing an optical branching and coupling section of an optical fiber used in the optical communications sector.

[Prior art and its problems]

Conventionally, as shown in Fig. 3, a method for performing this type of optical branching and coupling involves arranging a plurality of optical fibers 1.2 parallel to each other and contacting each other (Fig. 3a), and exposing this contact portion to electric discharge. The optical branching/coupling section 3 is formed by heating and fusing, and the optical branching/coupling section is cut in the middle and the cut surface is attached to the end face of another optical fiber 4 to be optically branched/coupled. In some cases, the optical branching and coupling portion 5 is obtained by butting and fusion splicing (FIG. 3C). In the case of the optical branching/coupling unit manufactured in this way, the tensile strength of the υ optical fiber decreases due to heat fusion.

On the other hand, the experimental results shown in FIG. 4 were obtained regarding the relationship between the tensile load and disconnection probability of the completed optical branching and coupling part.

Further, the optical fiber source branch coupling part is, for example, as shown in FIG. 5, taking the example of FIG. 3, as shown in FIG. It is fixed by the fixing resin 8 filled between the two. In the use state after fixing, the optical branching and coupling section 6 includes a fixing member 7,
A tensile load due to internal stress is applied due to the difference in thermal expansion and elastic strain between the fixing resin 8 and the optical branching/coupling section 6.

To explain this in detail, since the elongation of each part is the sum of the elongation due to thermal expansion and the elongation due to internal stress and is constant, the following equation holds true.

・・・・・・(1) However, the cross-sectional area of the optical branching/coupling section 6 is constant.

Here, α is the total length of the fixing member, ΔT is the temperature difference that occurs during use, ε is the coefficient of linear expansion, E is Young's modulus, S is the cross-sectional area, P is the load due to internal stress, and the subscript f is the optical branching coupling part. 6, g
1 indicates the fixing member 7, and e indicates the fixing resin.

Furthermore, since the sum of internal stresses is 0, the following equation holds true.

Pf + Pg + Pe ” O... (2) Now, if we calculate the load Pf due to the internal stress applied to the optical branching and coupling part 6 from equations (1) and (2), we get: Now, each part is expressed as Ef= 7.5 x 103ky/m2)'4=4X1
0-7deg-', 5f=2.5 cut O-2-1Eg=0
-2-1E to 7゜”s gg-=9×10-'cle
g-', Sg=4. I x 10-cost, E6 = 3.
5 x 103kf/mm2) εe = 5 x 10
−0−5de”, 5e=7.lX1O−−2)ΔT=8
When it is 0deg1, Pf=125g. According to Figure 2, at this load, approximately 30%
The optical branching/coupling section will be disconnected.

Therefore, it is necessary to provide an optical branching/coupling section that can withstand at least this load.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical branching/coupling part that is free from breakage when fixed to a fixing member by selecting and removing optical branching/coupling parts whose strength is significantly reduced during the manufacturing process.

[Key points of the invention]

According to the present invention, this object is to manufacture an optical branching/coupling part by arranging a plurality of optical fibers in parallel with each other and contacting each other, and fusing this contact part with a heating fusing means, in which a predetermined position is formed after fusing. This can be achieved by conducting a strength test by applying a tensile load of the magnitude of , and selecting optical branching connections with sufficient strength.

[Embodiments of the invention]

Next, the present invention will be explained in detail based on the embodiments shown in FIGS. 1 and 2.

In the optical branching/coupling unit manufacturing apparatus according to the present invention shown in FIG. The strands of the optical fibers 11 and 12 are guided by a fixed stage 17 so as to be able to move while maintaining contact with each other as the optical fiber moving stages 13 and 14 move. The strands of the optical fibers 11, 12 can be further held by a strand clamp 18 on the optical fiber moving stage 14 and a strand clamp 19 for measuring tensile load. This wire clamp 19 is attached to the tensile load measuring device mark. -21 and n are drive motors that move the optical fiber moving stages 13 and 14 left and right, respectively. A pair of discharge electrodes 24 are disposed at the center of the fixed stage 17 to heat and fuse the mutually contacting portions of the strands of the optical fibers 11 and 12 by electric discharge. These electrodes A and B are connected to a discharge power source 5. The control circuit 26 is connected to the moving stage drive motor 21,n, the discharge power source 5, the tensile load measuring device 20, and the input/output circuit 27. According to the data manually inputted from the input/output circuit 27, the optical fiber moving stages 13, 14 and the group 1!
The discharge power supply for the electrodes n and 24 is controlled by the moving speed and moving distance πt of the optical fiber moving stage 13 and 14.
, direction of movement, release 'j knee i! jW start time, discharge current, and discharge time are controlled to obtain an optical branching/coupling section with desired branching characteristics (see Figure 3).

After forming the optical branching and coupling portion 3, the optical fiber 11.1 is connected to the left and right wire clamps 18.19 based on the present invention.
When the optical fiber moving stage 14 is moved to the left while holding the strands of the optical fibers 2 and 3, a tensile load is applied to the optical branching/coupling section 3.

When the optical fiber moving stage 14 is moved by the control circuit 26 until the output of the tensile load measuring device 20 reaches a predetermined value, those whose strength has significantly decreased during heat fusion will break during this strength test. , those that are found to be unusable and have not been disconnected can be determined to be usable.

The tensile load applied to the optical branching and coupling part is selected to be slightly larger than the tensile load (P4) due to the internal stress generated in the optical branching and coupling part, for example, when the optical branching and coupling part is fixed.

On the other hand, in the case of the embodiment shown in FIG. 2, the tensile load measurement Masuda is omitted and the strand clamp 19' is placed on the optical fiber moving stage 13 on the right side. In this case, the tensile load applied to the optical branching/coupling unit 3 is determined by the relative movement distance of the optical fiber moving stage 13, 14 and the optical fiber 1.
1.12, the tensile load can be controlled by controlling the relative travel distance of the fiber optic translation stage 13.14.

In the above-described embodiment, an example was explained in which two optical fibers are heat-fused, but it is of course possible to use three or more optical fibers, and the heat-fusion means may be a laser, a gas torch, or the like in addition to electric discharge.

〔Effect of the invention〕

According to the present invention, a tensile strength test is performed on the optical branching and coupling parts at the manufacturing stage of the optical branching and coupling parts, and those whose strength has significantly decreased are removed, and only those with sufficient strength can be used. Since the wire is supplied as a wire, there will be no disconnection accidents when it is fixed or used.

[Brief explanation of drawings]

1 and 2 are structural layout diagrams of different embodiments of the apparatus for carrying out the method of the present invention, FIG. 3 is an explanatory diagram showing the manufacturing process of the optical branching and coupling section, and FIG. 4 is an illustration of the formed light beam. FIG. 5, which is a diagram showing the relationship between the tensile load of the branching coupling part and the disconnection probability, is a sectional view showing an example of the fixing structure of the optical branching coupling part. 1.2... Optical fiber, 3... Optical branching/coupling unit, 5...
... Optical branching and coupling part, 6... Optical fiber, 7... Fixing member, 8... Fixing resin, 11.12... Optical fiber, 13.14... Optical fiber moving stage ,1
5.1G... Optical fiber clamp, 17...
・Fixed stage, 18.19.19791. Optical fiber strand clamp, 20... tensile load measuring device, 21.2
2... Drive motor, n124... Discharge electrode, 5...
-Discharge power supply, 26...control circuit, 27...input/output circuit. Tail figure 3 [0-) Do (b) Figure 4 section $l*l (9)

Claims (1)

[Claims] 1) A plurality of optical fibers are arranged parallel to each other and brought into contact with each other, and the contact portions are fused using a heat fusion means to produce an optical branching/coupling portion. 1. A method for manufacturing an optical branching coupling part, which comprises carrying out a strength test by applying a tensile load of 100 mL to select an optical branching coupling part with sufficient strength. 2) In the method according to claim 1, the tensile load of a predetermined magnitude is a load that is slightly larger than the load due to internal stress generated in the optical branching coupling part when the optical branching coupling part is fixed. A method for manufacturing an optical branching/coupling unit, characterized in that: 3) The method according to claim 1 or 2, wherein the predetermined tensile load is applied by a means for moving the optical fiber during the optical fiber heating and fusing process. A method of manufacturing a branch joint.