JPH0690339B2 - Optical cable connection method and optical cable used therefor - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method of connecting an optical cable having a plurality of optical fiber cores and an optical cable suitable for the method, and particularly, to the optical fiber cores to be connected to each other through light. It is applied to a method of connecting while monitoring the axis alignment state.

[Prior art]

In constructing an optical cable line for optical communication, some optical cables are sequentially laid along the laying route and are adjacent to each other because the length of the optical cable is limited due to factors in manufacturing, transportation or laying. Optical cables must be connected to each other to form a series of lines. The connection of the optical cable at this time is generally performed as shown in FIG.

That is, A and B are optical cables to be connected, and a plurality of optical fiber core wires 2 ₁ , 2 ₂ , 2, ₃ ...
Is stored. An optical fiber fusion splicer 3 is installed at the connection point (usually a manhole) of these two optical cables A and B, and the outer end side of the first optical cable A (the opposite side of the connection part, usually in the station building). Is provided with a light emitting device 4 such as an LED, and a light receiving device 5 such as an optical power meter is installed at the outer end side (usually a manhole) of the second optical cable B. Data transmitters 6 and 7 are connected to the light receiver 5 and the connection device 3, respectively, and these two data transmitters 6 and 7 are connected to the signal line 8 respectively.
Tied together. The signal line 8 is generally a metal core wire and may be housed in the optical cable B or may be provided separately from the optical cable B.

The optical fiber cores are connected one by one. That is, the optical fiber cores (in the example shown) 2 ₂ and 2 ₂ to be connected from both cables A and B are selected and set to the fusion splicer 3 so that the end faces of both optical fibers face each other. At the same time, the outer end of the first optical cable A light fiber core wire 2 ₂ is combined with the light emitting device 4, the outer end of the second optical cable B is combined with the light receiver 5 optical fibers 2 _2. Light receiver 5
Since the amount of light received by is the maximum when the alignment condition of the optical fiber on the fusion splicer 3 is the best, the light receiver 5 converts the received light amount into an electric signal proportional thereto, and the signal is converted into a data signal. Feed back to the fusion splicer 3 via the transmission device 6, the signal line 8 and the data transmission device 7. The fusion splicer 3 automatically or manually adjusts the axes so that the feedback signal is maximized, and the fusion splicing is performed when the best state of axis alignment is obtained. When this is completed, the optical fiber core wires to be connected next, for example, 2 ₃ and 2 ₃ are selected from both cables A and B, and the connection work is performed in the same procedure.

As described above, when connecting an optical cable having a plurality of optical fiber core wires, it is necessary to perform the setting to the fusion splicer, the light emitter, and the light receiver for each core wire. Therefore, it is necessary to always arrange workers not only at the connection point but also at the light emitter side and the light receiver side, and there is a problem that the number of work steps is increased. In particular, since the connection of optical cables is done at the construction site, the increase in the number of dispatched staff causes a rise in construction costs.

[Object of the Invention]

In view of the above problems, an object of the present invention is to provide an optical cable connecting method and an optical cable suitable for the method, which saves labor on the side of the optical receiver when connecting the multi-core optical cable.

[Structure of Invention]

In order to achieve the above object, the present invention provides a light-emitting device on the outer end side of the first optical cable when connecting the first optical cable and the second optical cable having a plurality of optical fiber core wires, A multicore-single core coupler for connecting a plurality of optical fiber core wires to a single-core optical fiber is attached to the outer end side of the optical fiber of 2, and a light receiver is connected to the single core side of the coupler.
In such a state, the optical fiber core wires to be connected of both cables are abutted at the connection position, and the light emitter is coupled to the optical fiber core wires to be connected at the outer end side of the first optical cable to allow light to enter. The light receiver detects that the light is transmitted through the abutting portion, the optical fiber core wire to be connected to the second optical cable, and the multicore-single core coupler,
It is characterized in that the connection work is performed while monitoring the abutting state of the optical fiber core wires to be connected based on the detected value.

Further, the optical cable of the present invention is used for carrying out the above connecting method, and in an optical cable having a plurality of optical fiber core wires in a sheath, a plurality of optical fiber core wires are provided at one end side thereof. A multi-fiber / single-fiber coupler to be coupled to the optical fiber of the core is attached, and a plurality of optical fiber core wires are individually separated on the other end side.

〔Example〕

FIG. 2 shows an embodiment of the optical cable of the present invention. This optical cable is similar to the conventional one in that a plurality of optical fiber core wires 2 are twisted together with a tension member and an interposition (not shown) and the outer circumference thereof is covered with a sheath 1, but at one end side thereof, The optical fiber core wires 2 are respectively connected to the multi-fiber side optical fibers 11 of the multi-core / single-core coupler 10 by a connector 9, and are optically coupled to the single fiber side optical fibers 12, respectively, and the other end side. Is characterized in that each optical fiber core wire 2 is individually separated. A V-groove connector is suitable as the connector 9 when importance is placed on simplicity, but a sleeve connector may be used or this portion may be fusion-bonded.

An example of the multi-core / single-core coupler 10 is shown in FIG. That is, the optical fiber 11 on the multi-core side is stripped of the reinforcing coating such as nylon coating at its end, and is densely focused with or without the primary coating and inserted into the first centering sleeve 13. Has been done. The sleeve 13 is made of metal or ceramic, and the voids in the sleeve 13 are filled with an adhesive resin 14 such as an epoxy resin, so that the plurality of optical fibers 11 and the sleeve 13 are integrated. Focused optical fiber 11
The end faces of are fully polished together with the sleeve 13 so as to be a mirror surface perpendicular to the axis, and are flush with each other.
On the other hand, the optical fiber 12 on the single core side is similarly stripped of the reinforcing coating on the end portion and inserted into the second centering sleeve 15 made of metal or ceramic. The voids in the sleeve 15 are also filled with the adhesive resin 14. The end face of the optical fiber 12 is also sufficiently polished together with the sleeve 15 so as to be perpendicular to the axis. These sleeves 13, 15 are inserted from both sides into a metal centering collar 16 in which the lens 17 and ring are
Opposite 18 on the same axis. Thereby, the optical fibers 11 on the multi-core side are optically coupled to the optical fibers 12 on the single-core side. The outer circumference of the centering collar 16 and the outer circumferences of the multi-fiber side optical fiber 11 and the single-fiber side optical fiber 12 are covered with a jacket 19 made of a heat-shrink sleeve, and integrated by heat shrinking.

4 (a), (b) and (c) show the end faces of the optical fibers 11 focused in the first centering sleeve 13. As shown in FIG. (I)
Shows the case where three optical fibers 11 are focused, (b) shows the case where four optical fibers are focused, and (c) shows the case where seven optical fibers are focused. As described above, it is desirable that the optical fibers 11 are densely focused so that the entire optical fibers 11 are circular.

FIG. 5 shows an embodiment of the connection method of the present invention when the above optical cable is used. When the second optical cable B is connected to the end of the first optical cable A, the optical cable as described above is used as the second optical cable B so that the multicore-single core coupler 10 side comes to the light receiver 5 side. To lay. The end face of the optical fiber 12 on the single core side of the coupler 10 is made to face the light receiver 5. That is, the light receiver 5 is coupled to the all-optical fiber cores 2 ₁ , 2 _2, ... Of the optical cable B via the multi-core / single-core coupler 10. The light emitter 4 side is the same as the conventional one.

In addition, when the connection of the optical fiber cores 2 ₁ and 2 ₁ of both cables A and B is completed and the next optical fiber cores 2 ₂ and 2 ₂ are to be connected, the optical fiber fusion splicer 3 is used. and excisional concentric line 2 _2, 2 ₂ of the inner end side, and excisional the outer end side of the light emitting device 4 while the core wire 2 _2. At this time, the work on the side of the light receiver 5 is unnecessary. In this state, light is passed through the optical fiber core wires 2 ₂ and 2 ₂ to detect the axial alignment state, which is fed back to the fusion splicer 3 so that the fusion splicing is performed when the best axial alignment state is obtained. To do. The same applies to the case where the next optical fiber core wires 2 ₃ and 2 ₃ are connected. That is, the optical fiber 5 on the single fiber side of the multi-fiber / single fiber coupler 10 is first included in the optical receiver 5.
It is only necessary to set 12, and after that, there is no need for a worker to be at that position at all times, so it is possible to save a great deal of labor at the laying site. After connecting the first and second optical cables A and B as described above, when further connecting the third optical cable to the end of the second optical cable B, the end portion of the second optical cable B is Core-single core coupler
It suffices to remove 10 by cutting the optical fiber core wire 2.

FIG. 6 shows another embodiment of the connection method of the present invention. In this connection method, as the second optical cable B to be connected to the end of the first optical cable A, the optical fiber core wire 20 for feedback is provided in the sheath 1 in addition to the normal optical fiber core wires 2 ₁ , 2 _2. , And the normal optical fiber cores 2 ₁ , 2 ₂ ... Are provided on the optical fiber 11 on the multi-fiber side of the multi-fiber / single-fiber coupler 10, and the optical fiber core fiber 20 for feedback is on the single fiber side of the coupler 10. The ones connected to the optical fiber 12 are used. As in the previous embodiment, this optical cable B is laid so that the coupler 10 side is on the outer end side. Further, the light receiver 5 is installed at the connection position so as to receive the light emitted from the inner end side of the fiber back optical fiber core wire 20. That is, the light receiver 5 is connected to the single-core side of the multi-core / single-core coupler 10 via the fiber-optic fiber core wire 20 for feedback. The output of the photodetector 5 are input to the fusion splicing device 3, the optical fiber cores 2 ₂ to be _connected, 2 _second alignment state is monitored.

The procedure of the connection work is the same as that of the embodiment of FIG. 5, but in this embodiment, since the photodetector 5 can be installed at the connection position, the second optical cable B having the multicore-single core coupler at one end is connected. If it is manufactured in a factory, there is a great advantage that no worker needs to be arranged on the outer end side of the second optical cable B at the time of connection.

In the case of each of the above embodiments, the connection between each optical fiber core wire of the optical cable and each optical fiber of the multicore-single core coupler,
In order to reduce the loss and to perform it easily, the optical fiber having a larger core diameter may be used as it is closer to the light receiver. For example, the core diameter of the optical fiber 11 on the multi-core side of the multi-fiber / single-fiber coupler 10 is larger than that of the optical fiber cores 2 ₁ , 2 ₂ of the optical cable B, and the multi-fiber / single-fiber coupler is also used.
The core diameter of the optical fiber core wire 20 for feeding back is made larger than that of the optical fiber 12 on the single core side of 10. In this way, when the connection is made by the connector, the connection loss does not increase even if there is a slight misalignment of the axis, which is an advantage that the connection can be easily performed.

Further, in the above embodiment, an example in which the optical fiber core wire of the optical cable and the optical fiber core of the multi-core-single core coupler are connected by a connector or the like has been described. The section may be inserted into a centering sleeve within the coupler to form a multi-core to single-core coupler.

Further, in the above-mentioned embodiment, a plurality of optical fiber core wires are all connected to one multicore-single core coupler on one end side of the optical cable. May be divided into several units, and a multi-core / single-core coupler may be attached to each unit.

〔The invention's effect〕

As described above, according to the present invention, a plurality of optical fiber core wires of an optical cable are combined with a photodetector by a multicore-single core coupler, so that one optical fiber core wire is connected. There is no need to set the next optical fiber core wire in the photoreceiver each time, which is an advantage that the number of man-hours in the connection work of the multi-core optical cable can be significantly reduced.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an example of a conventional optical cable connecting method, FIG. 2 is a front view showing an embodiment of the optical cable of the present invention, and FIG. 3 is a multicore-single core used in the cable. Sectional drawing which shows an example of a coupler, FIG. 4 (a) (b) (c)
FIG. 3 is an end view showing a focused state of optical fibers in the coupler, and FIGS. 5 and 6 are overall configuration diagrams showing an embodiment of an optical cable connecting method of the present invention. 1 ... Sheath, 2 ... Optical fiber core wire, 3 ... Fusion splicer, 4 ... Light emitter, 5 ... Photoreceiver, 9 ... Splicer, 10 ...
… Multi-fiber / single-fiber coupler, 20… Fiber optic fiber for feedback.

Claims (7)

[Claims] 1. When connecting a first optical cable having a plurality of optical fiber core wires and a second optical cable, a light emitter is arranged on the outer end side of the first optical cable, and the outer end of the second optical cable. Attach a multicore-single-core coupler that connects multiple optical fibers to a single-core fiber, connect the optical receiver to the single-core side of the coupler, and in this state, connect both cables at the connection position. The optical fiber core wires to be connected are butted, and at the outer end side of the first optical cable, the light emitter is coupled to the optical fiber core wires to be connected and the light is made incident. The optical fiber cable to be connected to the optical cable and the signal transmitted through the multi-fiber / single fiber coupler are detected by the above-mentioned photodetector, and the butt state of the optical fiber cable to be connected is monitored from the detected value. Characterized by connection work Optical cable connection method. 2. The optical cable connecting method according to claim 1, wherein the photodetector is arranged on the outer end side of the second optical cable, and the detected value is at a connecting position via a metal core wire. Things that are designed to be fed back. 3. The optical cable connecting method according to claim 1, wherein the photodetector is arranged at a connecting position, and a single core of the multicore-single core coupler is provided through a fiber back optical fiber core wire. The one that is connected to the side. 4. An optical cable connecting method according to claim 1, wherein a plurality of optical fiber core wires are divided into a plurality of units for each of the plurality of optical fiber core wires on the outer end side of the first optical cable. Unit with the above multi-fiber / single-fiber coupler attached. 5. An optical cable having a plurality of optical fiber core wires in a sheath, wherein a multi-core-single core coupler for connecting the plurality of optical fiber core wires to a single optical fiber core is attached to one end side thereof, An optical cable characterized in that a plurality of optical fiber core wires are individually separated on the other end side. 6. The optical cable according to claim 5, wherein the single-core side of the multicore-single-core coupler is connected to the fiber back optical fiber core wire in the sheath. 7. The optical cable according to claim 5, wherein a plurality of optical fiber core wires are divided into a plurality of units for each of the plurality of optical fiber core wires on the one end side, and the multi-core fiber is connected to each unit. A single core coupler is attached.