JPS595841Y2 - optical fiber submarine cable - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a cable structure of a submarine cable system using an optical fiber in the field of optical communication using a low-loss optical fiber as a transmission medium.

Optical fiber has features such as low loss, wide bandwidth, and light weight, so it is seen as a promising future transmission medium to follow the conventionally used coaxial submarine cables.

Submarine cables are laid in deep seas up to 10,000 m deep, so they are exposed to high water pressure of up to 1,000 atmospheres on the ocean floor.

When such a high voltage is applied to an optical fiber cable, a slight bend is applied to the optical fiber due to the non-uniformity of the surface of the material covering the optical fiber, which significantly deteriorates the transmission characteristics.

Furthermore, since the optical fiber is made of low-loss quartz glass or optical glass, the material is brittle, and the optical fiber may break when subjected to large bends.

Since the material of the optical fiber is glass, if it is immersed in seawater for a long period of time, its mechanical properties and transmission properties will deteriorate.

For this reason, it has already been proposed to house optical fibers for submarine cables in high-pressure resistant pipes (Japanese Patent Laid-Open No. 5
1-99032).

Since the wall thickness of a high-pressure pipe increases as the inner radius of the pipe increases for the same external pressure, it is necessary to make the pipe diameter as small as possible in manufacturing the pressure-resistant pipe.

However, when inserting a single optical fiber into a pipe, it is possible to reduce the diameter of the pipe, but when it is necessary to insert multiple optical fibers into a pipe, a pressure-resistant pipe can be used for power supply, etc. It becomes difficult to reduce the diameter of the pipe when the pipe is made to have the same function as the pipe.

In the optical submarine cable system, not only can a large amount of information be transmitted due to the broadband nature of the optical fiber itself, but also the economic efficiency of the optical submarine cable system can be improved by using the thin diameter of the fiber to create multiple pairs. It is necessary to increase it.

A possible method is to protect each optical fiber core with a pipe and create multiple pairs, but in this case, splitting loss occurs during pipe manufacturing.

For these reasons, it is desirable to accommodate multiple optical fibers in a single pressure-resistant pipe, but in conventional technology, as the inner diameter of the pipe increases, the pipe wall thickness increases, so it is difficult to insert the optical fibers into the center of the pipe. The disadvantage is that it is difficult to manufacture thick-walled pipes.

The present invention aims to improve these drawbacks by inserting a structure into the relatively thin cylindrical pressure-resistant layer to improve the pressure resistance of the pressure-resistant layer. The company provides fiber submarine cables.

The present invention will be explained in detail below.

An embodiment according to the present invention is shown in FIG.

In this method, the cylindrical pressure-resistant layer and the structure within the pressure-resistant layer are manufactured at the same time by shaping a single plate-like tape made of a material such as copper or aluminum, which is extremely easy to manufacture.

In FIG. 1, 1 indicates an optical fiber, 3 a structure for increasing the strength of the pressure-resistant layer, 2 the pressure-resistant layer, and 4 welding or adhesive.

Figure 2 shows an intermediate manufacturing process for forming the pressure-resistant layer shown in Figure 1.
At this time, the required number of optical fibers 1 are inserted.

Thereafter, it is shaped as shown by the arrow and fixed by welding or the like as shown by 4 in FIG.

According to this method, the structure-containing pressure layer can be manufactured very easily.

Furthermore, by providing unevenness at the seam indicated by 11 in FIG. 3, the purpose is to lengthen the path of the joint and improve airtightness.

In FIG. 1, the structure has three legs, but it goes without saying that any number of legs can be manufactured using this method.

In any case, due to the connection between the thin cylindrical pressure-resistant layer 2 and the structure 2, the deformation of the space into which the fiber coated wire 1 is inserted under high water pressure is within a minute range, and the optical fiber coated wire 1 Although the thin cylindrical pressure-resistant layer 2 does not come into contact with the space, the optical fiber core 1 is accommodated in such a way that its characteristics do not deteriorate within the space even under the high pressure.

Examples of optical fiber submarine cables using pressure-resistant layers for protecting such optical fibers from high water pressure are shown in FIGS. 4, 5, and 6.

Figure 4 shows an optical fiber 10 with a pressure-resistant layer in the center of the submarine cable.
The structure of the voltage-resistant layer and/or the cylinder are made of materials such as copper or aluminum, and serve as both the voltage-resistant layer and the power supply line, and the insulation layer 5 is placed on the outside of the voltage-resistant layer. For example, it is a submarine cable having a structure in which it is covered with a material such as polyethylene, and a tension member 6 and a protective jacket 7 are arranged on the outside thereof.

Figure 5 shows a tension member 6 and a power supply tape 8 at the center of the cable, similar to a conventional unarmored coaxial cable.
and an insulating material such as polyethylene is placed on the outside thereof, and the optical fibers 10 with a pressure-resistant layer are placed inside this insulating material so that no local pressure is applied to each other so that they do not come into contact with each other. be.

In Figure 6, an optical fiber with a pressure-resistant layer is arranged in the center of the cable, at least the cylindrical part of the voltage-resistant layer is made of a material with good conductivity, such as copper or aluminum, and a conductor 9 is arranged concentrically with this cylinder. An insulator such as polyethylene is added between the layers and the cylinder to provide the functionality of a coaxial cable.

6 in FIG. 6 is an exterior wire and is a tension member, and 7 is a protective jacket.

The embodiment shown in FIG. 6 has the potential to be used as a submarine cable for information transmission and control of various submarine facilities, taking advantage of the broadband properties of optical fibers and the simplicity of the electric circuit of coaxial cables.

As explained above, the present invention has a structure in which a structure is inserted into the pressure-resistant layer that can withstand high tree pressure, making it possible to use a thin-walled cylinder and realizing a pressure-resistant layer that is easy to manufacture. .

Moreover, this pressure-resistant layer can be manufactured from a single piece of tape.

As described above, with this invention, it is possible to manufacture optical fibers by aligning them with the structure for reinforcing the cylindrical pressure-resistant layer, making it possible to maintain the optical fibers in a straight line. It is also possible to suppress the increase in loss of the optical fiber.

By using a highly conductive material for such a structure, it is possible to realize an optical fiber submarine cable with a simple structure that can also be used as a power supply line and can withstand high water pressure.

[Brief explanation of drawings]

1 and 3 are cross-sectional views for explaining other embodiments of the present invention, FIG. 2 is a cross-sectional view for explaining the manufacturing process of the embodiment of FIG. 1, and FIGS. 4, 5, and 6. FIG. 1 is a cross-sectional view for explaining an embodiment of the present invention. 1... Optical fiber core wire, 2... Thin cylindrical cylinder, 3
...Structure, 4.Adhesive, 5.Insulating layer, 6.
...Tension member 7...Protective jacket, 8...
・Power supply tape, 9... Conductor, 10... Optical fiber with pressure-resistant layer, 11... Joint.

Claims (1)

[Scope of utility model registration request] A cylindrical outer covering part is drawn out from a single plate-shaped tape with both edges curved inward, and three pieces are arranged radially from the center at each position in the longitudinal direction within the outer covering part. A structure having a cross-sectional structure that divides the circular cross section of the pressure-resistant layer into a plurality of spaces within a thin cylindrical pressure-resistant layer by integrally forming a structure having a cross-section shaped by the above structural pieces. The structure is such that the joint into which the structure is inserted has a required pressure resistance and the deformation of the space under high water pressure is within a minute range, and the plurality of structure pieces are separated from each other by the three or more structure pieces. spaces are formed, and at least one low-loss optical fiber is inserted into the plurality of spaces so that even under the high water pressure, the thin cylindrical pressure-resistant layer does not come into contact with the thin cylindrical pressure layer and its characteristics deteriorate. Optical fiber submarine cable with a structure that prevents