JPS6232405A - Leading-in part structure of optical fiber - Google Patents

Abstract

PURPOSE:To prevent the microbend loss even if a water pressure is applied to the inside of a joint chamber, by fixing an optical fiber core and an optical fiber to a core bar apart from each other by adhesion. CONSTITUTION:Two jaws 20 and 22 provided with longitudinal grooves to which the optical fiber should be inserted in the axial direction are provided on a core bar 9 projected to the joint chamber side. The coating part of an optical fiber core 7 and an exposed optical fiber 7A are fixed apart from each other in positions of jaws 22 and 20 respectively by an adhesive. Even if a water pressure is applied to the inside of the joint chamber to press the optical fiber 7A and the optical fiber core 7 in the axial direction of the core bar 9, shearing stress is not caused in the optical fiber 7A and the microbend loss is not generated.

Description

[Detailed Description of the Invention] [Summary] In an optical fiber whose outer periphery of a core metal is sealed with a low melting point metal in order to airtightly penetrate an end plate separating a joint chamber and a repeater circuit section. By dividing the optical fiber core part and the optical fiber part into two stages and fixing them to the core metal with an adhesive, an increase in optical loss due to water pressure is prevented when the joint chamber is flooded with water.

[Industrial application field]

The present invention relates to an optical submarine repeater, and particularly to an improvement in the structure of an optical fiber introduction section.

FIG. 3 is a side sectional view of an optical submarine repeater, in which the repeater circuit section 1 is housed in a cylindrical pressure-resistant container 3, and an end plate 4 is placed inside the pipe of the pressure-resistant container 3 as a partition wall from the joint chamber 2. is inserted, and the outer peripheral surface of the end plate 4 is hermetically welded to the inner wall of the pressure vessel 3.

The optical cable 5 is introduced into the rejoint chamber 2 from the end of the joint chamber 2, and the outer periphery of the optical cable 5 and the end face of the joint chamber 2 are hermetically sealed by, for example, welding or molding. . Therefore, seawater flows from the outer peripheral surface of the optical cable 5 into the joint chamber 2.
There is no intrusion inside.

The outer sheath of the optical cable 5 is removed in the joint chamber 2, and a plurality of optical fiber core wires (the optical fiber whose outer periphery is coated with a cladding is called an optical fiber core wire) 6 are exposed.

Reference numeral 7 denotes an optical fiber core wire that hermetically passes through the end plate 4 and is introduced into the repeater circuit section 1, and is connected to each optical fiber core wire 6 within the joint chamber 2.

Since the introduction part of the optical cable of the optical submarine repeater is configured as described above, if a crack or the like occurs in the outer sheath of the optical cable 5, seawater will leak into the joint chamber 2 through the axial hole of the optical cable 5. to invade.

When the seawater flows into the joint chamber 2 in this way, the pressure inside the joint chamber 2 becomes equal to the depth at which the optical submarine repeater is installed.

The optical fiber core wire 7 passing through the end plate 4 in this state
If the airtightness around the optical submarine repeater is broken, seawater will enter the repeater circuit section 1, making it impossible to function as an optical submarine repeater. Therefore, this part needs to have a sufficiently pressure-resistant structure.

Furthermore, if unreasonable stress is applied to the optical fiber by seawater that has entered into the joint chamber 2, optical transmission loss will increase. Therefore, a structure that does not cause such a problem is desirable.

[Conventional technology]

FIG. 4 is a side cross-sectional view of a main part showing the conventional structure of an optical fiber introduction part, (a) of FIG. It is a side sectional view showing details of.

4 and 5, an insertion hole is provided almost at the center of the end plate 4, and a sleeve 8 made of, for example, beryllium copper is airtightly inserted into the axial hole of the sleeve 8. It has a structure in which a long rod-shaped core metal 9 made of, for example, phosphor bronze is inserted.

The coating of the optical fiber core wire 7 is peeled off by approximately the same length as the length of the core bar 9 to expose the optical fiber 7A, and the exposed portion of the optical fiber 7A is metallized by vapor depositing gold or the like, as will be described later. This is to improve the adhesion of the low melting point metal 10.

A flange 13 is provided at the tip of the core bar 9, the outer periphery of the flange 13 is divided into equal parts, a plurality of vertical grooves 14 are provided parallel to the axis, and the optical fiber core wire 7 is inserted into each of the vertical grooves 14. The coated portion of the optical fiber core wire 7 and the exposed portion of the optical fiber 7A are fixed to the core bar 9 with an adhesive 11.

Then, the optical fiber 7A is passed through the axial hole of the sleeve 8 with the optical fiber 7A running parallel to the periphery of the core metal 9.

Then, the core bar 9 portion that passes through the end surface of the sleeve 8 is
It is fused and hermetically sealed with a low melting point metal 10 (for example, solder).

Also adhesive 11. The area from the tip of the core bar 9 to the end face of the sleeve 8, including the low melting point metal 10, is covered with a synthetic resin 12 to protect the exposed portion of the optical fiber 7A.

As described above, by sealing and fixing the optical fiber 7A with the low melting point metal 10 after fixing the optical fiber 7A with the adhesive 11, the optical fiber 7A is aligned and the sealing work is easy.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional optical fiber introduction structure, the coating of the optical fiber core 7 is inserted into the vertical groove 14, and the boundary between the coating of the optical fiber 7 and the optical fiber 7A with the coating removed is inserted into the vertical groove 14. It has a structure in which it is fixed with an adhesive 11.

Therefore, when seawater enters the joint chamber 2 and water pressure is applied, the compressive strain of the sheathing material of the optical fiber core wire 7 is greater than the compressive strain of the adhesive 11, which causes the sheathing to peel off. Optical fiber 7A before and after the boundary
There is a problem in that shear stress is generated in the optical fiber 7A, causing microbending loss in the optical fiber 7A, and increasing optical transmission loss.

[Means for solving problems]

In order to solve the above-mentioned conventional problems, the present invention, as shown in FIG.
and a core metal 9 that passes through the axial hole of the sleeve 8, and optical fibers 7A are arranged around the core metal 9 along the axial direction,
In an optical submarine repeater in which the end surface of the sleeve 8 is hermetically sealed with a low melting point metal 10, a vertical groove into which an optical fiber is inserted along the axial direction is arranged in the core bar 9 that protrudes toward the joint chamber side. Two tV20.22 were installed, the coating was peeled off at the part of the collar 20 near the sleeve 8, and the exposed optical fiber 7A was fixed with an adhesive, and the optical fiber core wire 7 covered with the other part of the collar 22 was fixed. It is fixed with adhesive.

[Effect]

According to the above means of the present invention, the covering portion of the optical fiber core wire 7 is the collar 22, and the exposed optical fibers 7A are fixed at separate locations at the collar 20 with an adhesive. Therefore, water pressure is applied inside the joint chamber, and the optical fiber 7^
Even when the optical fiber core wire 7 is pressed in the axial direction of the core metal 9, no shear stress horns occur in the optical fiber 7A, and no microbend loss occurs.

〔Example〕

The present invention will be specifically explained below with reference to illustrated examples. Note that the same reference numerals indicate the same objects throughout the figures.

FIG. 1 is a side cross-section of the main part of one embodiment of the present invention, and FIG.
) and (b) correspond to the dashed lines X and -Xf shown in Figure 1, respectively.
It is a sectional view of the t1vAxz-xt portion.

In FIGS. 1 and 2, an insertion hole is provided almost at the center of the end plate 4, a sleeve 8 is airtightly inserted into the insertion hole, and a rod-like shape longer than the sleeve 8 is inserted into the axial hole of the sleeve 8. The core bar 9 is inserted.

The coating of the optical fiber core wire 7 is peeled off by approximately the same length as the length of the metal core 9 to expose the optical fiber 7A, and the exposed portion n of the optical fiber is metallized, for example, by vapor depositing gold or the like.

A flange 22 is provided at the tip of the core bar 9, and the outer periphery of the flange 22 is equally divided into a plurality of vertical grooves 23 into which the coated portion of the optical fiber core 7 is inserted parallel to the axis. The optical fiber core 7 is inserted into the groove 23, and the coated portion of the optical fiber core 7 is fixed to the vertical groove 23 with an adhesive 11.

A flange 20 is provided closer to the sleeve 8 than the flange 22 at the tip, and at a desired distance from the flange 22. Then, the outer periphery of the collar 20 is equally divided to provide a plurality of vertical grooves 21 parallel to the axis into which the optical fibers 7A with peeled coatings are inserted, and the optical fibers 7A are inserted into each of the vertical grooves 21. , is fixed to the vertical groove 21 with an adhesive 11.

Then, with the optical fiber 7A running parallel to the periphery of the core metal 9, the core metal 9 is passed through the axial center hole of the sleeve 8, and the portion of the core metal 9 that passes through the end surface of the sleeve 8 is inserted. It is fused and hermetically sealed with a low melting point metal 10 (for example, solder).

Although not shown, the adhesive 11. As in the prior art, the area from the tip of the core bar 9 to the end face of the sleeve 8, including the low melting point metal 10, is covered with synthetic resin to protect the exposed portion of the optical fiber 7A.

As mentioned above, the coating portion of the optical fiber core wire 7 is the collar 22,
The exposed optical fibers 7A are fixed with adhesive at separate locations at the tW20 portion. Therefore, even if water pressure is applied in the joint chamber 2 and the optical fiber 7A and optical fiber core wire 7 are pressed in the axial direction of the core metal 9, no shear stress is generated in the optical fiber 7A, and microbend loss is reduced. It never occurs.

In addition, the adhesive 11 is used to connect the optical fiber 7A and the optical fiber core wire 7.
Since the optical fibers 7A are fixed at separate and distant locations, the alignment of the optical fibers 7A is further improved, the sealing reliability is high, and the sealing work is easy.

〔Effect of the invention〕

As explained above, in the present invention, the optical fiber core wire and the optical fiber are adhesively fixed to the core metal at separate locations, and microbend loss occurs even if water pressure is applied inside the joint chamber. There is no increase in transmission loss, and the optical fiber alignment is better.
It has excellent practical effects such as reliable and easy sealing work.

[Brief explanation of drawings]

FIG. 1 is a side cross-section of the main part of one embodiment of the present invention, and FIG.
), (b) are the dashed lines L-xi shown in FIG. 1, respectively,
Figure 3 is a side sectional view of the optical submarine repeater; Figure 4 is a side sectional view of the main part showing the conventional structure of the optical fiber introduction section; Figure 5 (a) is A cross-sectional view perpendicular to the axis of the chain line M portion shown in FIG. 4, (bl is a side sectional view showing details of the chain line M portion. In the figure, 1 is a repeater circuit section, 2 is a joint chamber, and 3 is a pressure vessel. , 4 is an end plate, 5 is an optical cable, 6 is an optical fiber core wire, 7 is an optical fiber core wire, 7A is an optical fiber, 8 is a sleeve,
9 is a core metal, 10 is a low melting point metal, 11 is an adhesive, 13.20.2
2 indicates the tsuba, 14, 21.23 indicates the vertical groove. ne I4-ro month. 1 dera harm F5 I regular day Mffi ID 1st
Figure (a) (I) N Minato Hatsuroi Suppressed Cross-section Diagram 2 z 1 Diagram

Claims (1)

[Claims] An end plate (4) that isolates the joint chamber from the repeater circuit, a sleeve (8) that hermetically passes through the end plate (4), and an axis of the sleeve (8). A core bar (9) passing through the core hole is provided, optical fibers (7A) are arranged around the core bar (9) along the axial direction, and the end surface of the sleeve (8) is covered with a low melting point metal ( In the optical submarine repeater that is hermetically sealed in step 10), the core bar (9) protruding toward the joint chamber side has a
Two flanges (20) and (22) are provided with longitudinal grooves into which optical fibers are inserted along the axial direction, and the sleeve (8
) The optical fiber (7A) exposed by peeling off the coating at the part of the flange (20) near the flange (20) is fixed with adhesive, and then
An optical fiber introducing structure characterized in that a partially covered optical fiber core wire (7) is fixed with an adhesive.