JPH0763924A - Method for laying optical cable and optical cable used in the same - Google Patents

Abstract

PURPOSE:To provide a method capable of efficiently measuring line loss at the time of laying optical fibers and an optical cable used in this method. CONSTITUTION:This optical cable 11 is formed by integrating the plural optical fibers 12 and exposing both ends thereof. All the optical fibers 12 are turned back and connected by one pair each at both ends of the optical cable 11 and the optical fibers are eventually made into a series by at least one of the turned back connections. Both ends 14a, 14b thereof constitute the turned back and connected fibers 14 existing at one end of the optical cable 11. The optical cable 11 constituted in such a manner is laid in each of the respective sections and the optical fibers 12 are connected to each other by disconnecting the turned back connections 13 between the respective sections.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical cable laying method capable of efficiently measuring line loss when laying an optical cable, and an optical cable used therefor.

[0002]

2. Description of the Related Art As a conventional optical cable, for example, FIG.
As shown in FIG. 2, a log-shaped optical cable 2 is known in which the intermediate portions of a plurality of optical fiber core wires 1 are integrally assembled, and the optical fiber core wires 1 are exposed only at both ends thereof. Also,
An optical cable with an optical connector in which an optical connector is provided at the end of the optical cable is also known. In these conventional optical cables, as shown in FIG. 9, the optical cable 2 is laid in each section, and after the optical fiber core wires 1 are connected to each other, the connection loss and the transmission loss are measured. It was In the figure,
Reference numeral 3 indicates a fusion splicing point, and 4 indicates a connector connection point.

[0003]

As a method of measuring the connection loss and the transmission loss of the optical cable 2 thus laid, a light source 5 is connected to one side of the laid section and an optical signal is incident on each channel. There is a method of measuring the output optical power with the optical power meter 6 connected to the other side. But,
This method has the problem that measurements must be taken on both sides of the installed section.

There is also a measuring method using an optical pulse tester as shown in FIG. FIG. 10A shows a measurement example in which the optical pulse tester 7 is connected to the laid optical cable 2, and FIG. 10B shows an example of the measurement result. In the figure, a to e indicate connection positions between the sections. However, with this measurement method, especially when measuring a single mode optical fiber, the refractive index of the optical fiber here,
There is a problem that the measurement result depends on the direction due to the difference in the structural parameters such as the mode field diameter or the refractive index distribution, and the connection loss cannot be accurately measured by the measurement from only one side.

In view of such circumstances, it is an object of the present invention to provide a method capable of efficiently measuring line loss when laying an optical fiber and an optical cable used in this method.

[0006]

The present invention for achieving the above object is an optical cable in which a plurality of optical fibers are integrated and both ends thereof are exposed, and at least one end of the optical cable is substantially provided. All optical fibers are folded back and connected one by one, whereby at least one turn back is connected in series and both ends thereof are present at the other end of the optical cable, and an optical cable constituting a turn back connection fiber is provided for each section. In the optical cable laying method, the laying is performed, and the folded connection is released between the respective sections to connect the optical fibers to each other.

Further, in an optical cable in which a plurality of optical fibers are integrated and both ends thereof are exposed, substantially all the optical fibers are folded and connected in pairs at least at one end of the optical cable. An optical cable is characterized in that at least one folded connection forms a series, and both ends thereof constitute a folded connection fiber present at the other end of the optical cable.

[0008]

In the present invention, an optical cable having a folded connection is used to connect the optical cables while disconnecting the folded connection at the time of connecting each section. At this time, the optical cable ends at both ends of the laid section are connected. There are still folded connections. Therefore, it is possible to measure the connection loss of a series of folded connection fibers using an optical pulse tester or the like at one end of the optical cable in the section where the installation has been completed. In addition, it is possible to connect in both directions with an optical communication device or the like by using the folded connection fiber of the optical cable in the section where the installation is completed.

[0009]

EXAMPLES The present invention will be described below based on examples.

FIG. 1 shows the basic structure of an optical cable according to an embodiment of the present invention. As shown in FIG. 1, the optical cable 11 is formed by integrating the intermediate parts of a plurality of optical fibers 12 and forming a plurality of folded connection parts 13 connecting a pair of optical fibers 12 at both ends thereof. In this way, a series of folded connection fibers 14 are constructed.

Here, the folding connection portion 13 is shown in FIG.
It is formed as shown in (A) and (B). Figure 2 (A)
As shown in FIG. 3, the fusion splicing 13A for fusing the ends of the optical fiber 12 may be used, or the connector splicing 13B for connecting with the optical connector may be used.

Further, in this embodiment, the folded back connection portion 13 is provided.
All the optical fibers 1 are provided by providing both ends of the optical cable 11.
2 is one folded connection fiber 14, and both ends 14a and 14b thereof are present on one end side of the optical cable 11. In this way, when all the optical fibers 12 are made into a series of the folded connection fibers 14, since the even numbered optical fibers 12 are usually integrated, both ends of the folded connection fibers 14 are connected to one end side of the optical cable 11. Will exist. When the number of integrated optical fibers is an odd number, one core is removed to form a folded connection fiber. That is, in the present invention, it is sufficient that substantially all the fibers constitute the return connection fiber 14.

When carrying out a construction work using the optical cable thus constructed, as shown in FIGS. 3 (A) and 3 (B), the construction is carried out sequentially for each section. For simplicity,
In FIGS. 3A and 3B, the optical cable has two cores.

For example, as shown in FIG. 3A, after laying one optical cable 11A, the next optical cable 11B is provided.
The optical cables 11A and 11 are installed at this time.
The folded connection at the connection end of B is released, and the corresponding optical fibers 12 are connected by fusion splicing or optical connector connection. However, the folded connection 13 at the other end of the optical cable 11B is left as it is. As a result, all the optical fibers 12 of the optical cables 11A and 11B are
It becomes one folded connection fiber 14A, and both ends 14a and 14b thereof are present at the start end where the installation is started. Therefore, in this state, by alternately connecting, for example, the optical pulse tester 15 to each of the end portions 14a and 14b, the transmission loss and the connection loss (line loss) of the return connection optical fiber 14A from both directions are performed. Can be measured. That is, in this case, the connection loss at the connection point a can be measured from both directions, and the accurate connection loss at the connection point a can be measured.

Further, as shown in FIG. 3B, an optical cable 11C is laid in the next section. At this time, the optical cable 1
The folded connection between 1B and 11C is released, and the corresponding optical fibers 12 are connected by fusion splicing or optical connector connection. However, the return connection 13 at the other end of the optical cable 11C is left as it is. As a result, all the optical fibers 12 of the optical cables 11A, 11B and 11C are turned into one folded connection fiber 14B.
And both end portions 14a and 14b thereof are present at the start end where the laying is started. Therefore, in this state, by alternately connecting the end portions 14a and 14b, for example, by connecting the optical pulse tester 15, it is possible to measure the line loss from both directions of the return connection fiber 14B. That is, in this case, the connection loss at the connection points a and b can be measured from both directions, and the accurate connection loss can be measured at the connection points a and b. Note that FIG.
3 shows an example of the measurement result of the line loss from the end portion 14a in the case of FIG. 3B, the connection loss at all connection points can be measured by one measurement in this way.

As described above, according to the method of the present invention, it is possible to inspect only the section where the laying is finished at the start end of the laying at the same time as the laying is finished, even if the laying of the entire section is not finished, which is efficient. Installation work can be done.

FIGS. 5A and 5B show the optical cable 1
1A and 11B are shown as four cores. In the case of FIG. 5A as well, as in the case of FIG. 4, all the optical fibers 12 can be used as a series of folded connection fibers 14C. Then, by performing the same measurement, FIG.
As shown in (B), it is possible to measure the connection loss at all the connection points of the return connection fiber 14C with one measurement.

In the embodiment described above, all the optical fibers are one folded connection fiber. However, if the length of this folded connection fiber is too long, the measurement accuracy is lowered, and therefore some folded fibers are used. The connecting optical fibers may be formed independently.

Further, although an example in which a single-core optical fiber core wire is integrated into an optical cable has been described so far, the present invention can be similarly applied to the case where a multi-core optical fiber core wire is integrated into an optical cable. . In this case, each optical fiber forming the multi-core optical fiber may be folded and connected as described above to form one or several folded connection fibers, or one multi-core optical fiber. It is also possible to construct some folded-back connection fibers by fusion splicing or optical connector connection of the fiber core wire with other multi-core optical fiber core wires.

FIG. 6 shows an example in which a folded connection fiber is formed for each multi-core optical fiber using the folded connection optical component. Note that FIG. 6A shows the structure of the optical cable, and FIGS. 6B and 6C show the structure of the optical component for folded connection. As shown in FIG. 6A, the optical cable 21 has four
Two multi-core optical fiber core wires 23 each having a core optical fiber 22 are integrated, and an optical connector 24 is connected to both ends of each multi-core optical fiber core wire 23. Then, the optical connector 24 on the one end side is provided with the first optical component 25 for connection for folding back, and the optical connector 24 on the other end side is also provided.
A second turn-back connection optical component 26 is connected to. Here, the first turn-back connection optical component 25 is shown in FIG.
As shown in (B), the optical connector 25a and the optical fiber 22 constituting the multi-core optical fiber core wire 23 are connected to the return connection portion 25b and the remaining optical fiber 22 which are connected to each other by return connection. Two fiber ends 25
It consists of c and 25d. The second optical connection 26 for return connection has two return connection portions 26b and 2b for connecting two return connections of the optical connector 26a and the two optical fibers 22 forming the multi-core optical fiber core 23, respectively.
6c and.

In such an optical cable 21, a folded connection fiber is formed for each multi-core optical fiber core wire 23. Therefore, when laying work is performed using the optical cable 21 as in the above-described embodiment, only the measurement at the starting end of laying is performed,
The transmission loss can be measured for each multi-core optical fiber 23. It should be noted that the two optical components 2 for the first folded connection are provided.
By connecting one fiber ends of 5
It is also possible to construct a folded connection fiber of a book. Further, also in the case of an optical cable in which a plurality of multi-core optical fibers are integrated, one or several folded connection fibers can be similarly constructed.

Further, in the above embodiment, an example in which the transmission loss is measured during the laying work has been described. However, when the above-mentioned optical cable is used, the light source located at the laying start end is used so that the cable connection point It is possible to talk in both directions using optical telephones at various places. An example of this is shown in FIG. As shown in FIG. 7, the optical cables 11A, 11B and 11
Optical transmitter 31 at each connection point when C is sequentially connected and installed
A and 31B are installed and one folded connection fiber 14D is constructed. Then, the light source 32 is connected to one end portion 14a of the folded connection fiber 14D at the start end via the optical communication device 31C. In such a configuration, the optical cable 1
Since the folded-back connection portion 13 is present at the end of 1C, bidirectional communication is possible between the optical communication device 31A and the optical communication device 31B, for example. It is assumed that the optical communication here is performed by applying vibration to the optical cable from the outside to modulate the light, but the optical communication is not limited to this and may be an optical communication device that can be placed in the middle without disconnection. For example, the present invention can be applied.

[0023]

As described above, according to the present invention, the optical cable having the folded connection is laid, so that it is possible to measure the transmission loss at the laying start end in the section where the laying work is completed, and The effect is that bidirectional optical communication can be carried out using the optical cable. Therefore, the transmission loss can be measured quickly and easily while laying the optical cable, the construction period of the optical cable laying work can be shortened, and the required personnel can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an optical cable according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an example of a folded connection of the optical cable of the present invention.

FIG. 3 is a schematic diagram showing an optical cable laying method according to an embodiment of the present invention.

FIG. 4 is a graph showing an example of measurement of transmission loss in the optical cable laying method according to the embodiment of the present invention.

FIG. 5 is a schematic view showing an optical cable laying method according to another embodiment of the present invention.

FIG. 6 is a schematic diagram showing a configuration of an optical cable according to another embodiment of the present invention.

FIG. 7 is a schematic diagram showing optical communication using the optical cable of the present invention.

FIG. 8 is a schematic view showing an optical cable according to a conventional technique.

FIG. 9 is a schematic diagram showing a transmission loss measurement of an optical cable according to a conventional technique.

FIG. 10 is a schematic diagram showing a transmission loss measurement result of an optical cable according to a conventional technique.

[Explanation of symbols]

11, 21 Optical cable 12, 22 Optical fiber 13 Folding connection part 14, 14A, 14B, 14C, 14D Folding connection fiber 14a, 14b End part 23 Multi-core optical fiber core wire 24 Optical connector 25, 26 Folding connection optical component

Claims (8)

[Claims] 1. An optical cable in which a plurality of optical fibers are integrated and both ends thereof are exposed, and substantially all the optical fibers are folded and connected in pairs at least at one end of the optical cable. An optical cable that constitutes a folded connection fiber whose both ends are present at the other end of the optical cable is formed by at least one folded connection, is laid for each section, and the folded connection is provided between the sections. A method for laying an optical cable, characterized in that the optical fibers are unwound and connected to each other. 2. The laying of an optical cable according to claim 1, wherein the optical cable is laid from one end side of the laying section, and the connection loss of the optical cable laid from the one end side is measured each time the laying of each section is completed. Method. 3. The method according to claim 1, wherein the optical cable is laid from one end side of the laying section, and the optical cable laid between the one end side and each section is used for optical communication. A method for laying an optical cable, characterized in that a two-way communication is performed by making a two-way call through the return connection. 4. An optical cable in which a plurality of optical fibers are integrated and both ends thereof are exposed, and substantially all the optical fibers are folded back and connected in pairs at least at one end of the optical cable. An optical cable, characterized in that at least one turn-around connection constitutes a series, and both ends thereof constitute a turn-around connection fiber present at the other end of the optical cable. 5. The optical cable according to claim 4, wherein the optical cable is formed by integrating a plurality of tape core wires. 6. The optical cable according to claim 5, wherein the pair of folded connections are formed for each of the tape cores. 7. The optical cable according to claim 4, 5 or 6, wherein the pair of folded connections are formed by fusion splicing. 8. The optical cable according to claim 4, 5 or 6, wherein the pair of folded connections are formed through an optical connector.