JP4016807B2 - Manufacturing method of optical cable group - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical cable groups preparation of how to configure the optical fiber transmission line by a plurality of optical cables.
[0002]
[Prior art]
When laying an optical fiber transmission line, it is usually laid by connecting a plurality of optical cables having the same structure. However, the plurality of optical cables used are not necessarily manufactured in the same production lot, and may be used in combination with optical cables manufactured in different production lots. In addition, even if a plurality of optical cables are produced in the same production lot, they do not always use a series of optical fibers produced from the same origin (one optical fiber preform), Sometimes optical fibers of different origins in the longitudinal direction are used.
[0003]
Further, the length of each of the plurality of optical cables differs depending on the laying configuration such as the structure of the way to be laid in addition to the limitation in manufacturing, and may be different depending on the arrangement position of the manhole to be connected. When laying one optical fiber transmission line, a plurality of optical cables required for the laying are selected, and the selected plurality of optical cables are regarded as one unit body including the connection order, etc. Are treated as
[0004]
In the laying of the optical cable, the connection between the optical cables is formed by connecting the optical fibers at the relatively same positions in the optical cable by fusion or the like. The optical cables are defined so that the characteristics of the optical fibers accommodated in the respective optical cables are within a certain range, and the variation between the optical fibers is arbitrary within the specified range. According to “JIS C 6835 Table 3 Note (3)”, a mode field diameter (hereinafter referred to as MFD) that means a spread diameter of light when an optical signal propagates inside an optical fiber is also “center value ± 10”. % "Is defined as an allowable value.
[0005]
[Problems to be solved by the invention]
Among optical fiber characteristics, MFD is related to splice loss when optical fibers are fusion spliced. When an optical fiber having a large MFD difference is fusion-spliced, the connection loss component due to the MFD difference becomes large, and when combined with other factors, the loss of the connection portion becomes considerably large. Conventionally, if the MFD is within the standard range, the variation is arbitrary, so that the MFD is connected even if there is a large difference in MFD. For this reason, the transmission loss of the transmission line is increased, resulting in a decrease in transmission characteristics. The “MFD difference” here is (maximum MFD−minimum MFD) / minimum MFD (%). However, the maximum MFD and the minimum MFD indicate the maximum and minimum in the optical cable group constituting the series of optical fiber transmission lines.
[0006]
If the allowable value of MFD variation is “center value ± 10%”, in the worst case, an optical fiber having an MFD difference of 20% is connected. In this case, only the connection loss component due to the MFD difference is 0.1 dB, which increases the loss of the entire transmission line. Usually, the connection loss is often required to be 0.6 dB or less per connection (for example, Ministry of Land, Infrastructure, Transport and Tourism construction standard "Guideline for fiber optic cable installation and explanation"), but the difference in MFD of this optical fiber. The connection loss component due to is not negligible in laying optical cables.
[0007]
The present invention has been made in view of the above, the connection loss component due to the difference of MFD at ordinary fusion splicing is an object of the invention to provide a substantially caused no optical cable groups manufacturing how.
[0008]
[Means for Solving the Problems]
A method for manufacturing an optical cable group according to the present invention is a method for manufacturing an optical cable group composed of a plurality of optical cables for forming a series of optical fiber transmission lines by fusion splicing a plurality of optical fibers of different origins, A large number of optical fibers collected for storage in an optical cable are divided into a plurality of subgroups with a MFD difference of 4% or less, and a series of optical fibers at the same position where the optical cables are connected to each other are all the same small fiber. Select from the group and store.
[0009]
Further, according to another method of manufacturing an optical cable group according to the present invention, a plurality of optical cables are connected in the order in which a plurality of optical fibers having different origins are fusion-connected to form a series of optical fiber transmission lines . A method of manufacturing an optical cable group consisting of a plurality of optical cables, in which a large number of optical fibers collected for storage in an optical cable are divided into a plurality of small groups having a MFD difference of 2% or less, and in a predetermined connection order. a series of fiber-optic at the same position are connected to each other of the optical cable, in each of the connection points, so as to house and sorted all the same subset or subset of neighbors.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a diagram showing an optical cable group consisting of a plurality of optical cables for constituting an optical fiber transmission line, FIG. 1B is a diagram showing a connection state between optical cables to be connected, and FIG. 2 is an optical fiber to be connected FIG. 3 and FIG. 4 are diagrams for explaining an optical fiber allocation method based on the MFD difference. In the figure, 1 and 2 are optical cables, 3a to 3f are optical fibers, 4 is a jacket, 5 is a strength member, and 6 is a connection portion.
[0013]
As shown in FIG. 1A, when laying a series of optical fiber transmission lines a, b, c,..., A plurality of optical cables A, B, C, D,. The plurality of selected optical cables are selected and considered as one unit including the connection order and the like. In the present invention, the “optical cable group” means that a plurality of optical cables used for the optical cable transmission line are assembled when a plurality of optical cables are continuously connected within a predetermined distance to form a series of optical fiber transmission lines. It shall mean the unit. Further, in a long-distance optical fiber transmission line, there are cases where a plurality of optical fibers used in a divided range are divided into several sections from the start end to the end, and are used as one optical cable group.
[0014]
As shown in FIG. 1 (B), when the optical cables connected to each other in the optical cable group are optical cables 1 and 2, these optical cables, for example, attach a plurality of optical fibers 3a to 3f along with the tension member 5. It is configured to be housed in the cover 4. In addition, the optical cable may contain a single optical fiber. Also, a plurality of optical fiber tapes in a tape shape are accommodated in a plurality of slots, and several tens to several hundreds of optical fibers are accommodated. An optical fiber may be accommodated. The optical cables targeted by the present invention include all single-core and multi-core optical cables of various shapes generally called unit cables, loose tube cables, slot cables and the like.
[0015]
As shown in FIG. 1A, when laying optical fiber transmission lines a, b, c,... By connecting a plurality of optical cables A, B, C, D,. As shown in FIG. 1B, an optical cable having the same shape is used. The optical cables 1 and 2 to be connected are usually formed by connecting optical fibers (3a-3a, 3bb-3b,...) At the same position. The optical fiber at the same position is identified by the color or arrangement of the fiber coating.
[0016]
The connection portion 6 between the optical fibers between the optical cables may be formed by mechanical connection, but is generally formed by fusion splicing. This fusion splicing is performed by either single-core or multi-core batch fusion. In addition, when an optical fiber transmission line is formed by connecting a plurality of optical cables, the optical fiber accommodated in the optical cable is usually a single mode optical fiber having an MFD of 7 μm to 14 μm, a cladding outer diameter of 125 μm, The fiber coating outer diameter is 250 ± 15 μm. The present invention is also intended for an optical cable using an optical fiber in this range.
[0017]
When the optical fibers are fusion-spliced, if the MFD difference is large, the connection loss component due to the MFD difference becomes large as described in the section for solving the problem. FIG. 2 shows the data of the connection loss component due to the difference (%) in the MFD of the optical fiber when the four-fiber optical fiber ribbons most frequently used in the multi-fiber optical cable are fused together. The splice loss component increases in proportion to the difference. However, when the MFD difference is 4% or less, the splice loss component is almost zero. This is considered to be because the glass is melted at the time of fusion splicing, and if the MFD difference is as small as 4% or less, it is relaxed.
[0018]
The present invention focuses on this point and configures the optical cable group so that the difference in MFD between optical fibers connected to each other is 4% or less. That is, as shown in FIG. 1, a plurality of optical cables A, B, C, D,... Constituting a series of optical fiber transmission lines a, b, c,. The optical cable group is configured such that the difference in MFD (for example, 3a-3a, 3b-3b, 3c-3c,...) Is 4% or less.
[0019]
When laying the optical fiber transmission line, by selecting the optical fibers in the optical cables connected to each other as described above, the connection loss component due to the MFD difference may be substantially zero. it can. Thereby, the increase in the transmission loss of the optical fiber transmission line can be suppressed, and the deterioration of the transmission characteristics can be reduced.
[0020]
Next, an example of an optical fiber allocation method for obtaining the above-described optical cable group according to the present invention will be described with reference to FIG. Optical fibers manufactured from the same preform are considered to have little variation, although there is some variation in MFD. Therefore, in order to obtain the optical cable group described above, an optical cable is manufactured by housing optical fibers of the same origin manufactured from the same preform, and is further divided into a plurality of optical cables to form one optical cable group. Is preferred.
[0021]
However, due to the large number of optical fiber cores, the total distance that is laid by the optical cable group, and due to delivery problems, the optical cable is manufactured by selecting from the optical fibers in stock, and the optical cable group is configured. There are also many. In this case, an optical cable is manufactured by combining optical fibers manufactured from different preforms or manufactured under different conditions and having different origins, and a plurality of optical cables are assembled into an optical cable group. In this case, depending on the combination form of the optical fibers and the connection order of the optical cables, the difference in MFD between the connected optical fibers becomes large.
[0022]
Therefore, in the present invention, as shown in FIG. 3, a large number of optical fibers that are candidates for storage in an optical cable are collected, and the MFD value and frequency (quantity) distribution are obtained. Then, it is divided into small groups (for example, hm) in which the MFD difference is 4% or less as shown in FIG. 3 within the range of the MFD central value ± 10%. Further, this small group may be further divided and divided into small groups having a MFD difference of 2% or less as shown in FIG. 4A, which will be described later. In addition, 3% or less or 1% or less. It may be divided into small groups such as
[0023]
As shown in FIG. 3, when a large number of optical fibers are divided into small groups having an MFD difference of 4% or less and then converted into cables, the optical cables A, B, C, D,. Optical fibers (for example, 3a-3a, 3b-3b, 3c-3c,...) Arranged at predetermined positions are selected from the same small group and assigned to each optical cable. By using the allocation method of FIG. 3, when the series of optical fiber transmission lines a, b, c,... Is used, the difference in MFD between optical fibers connected to each other is all within 4%. The connection loss component due to can be made substantially zero.
[0024]
Next, an example of another allocation method for obtaining the optical cable group according to the present invention will be described with reference to FIG. When the number of optical fiber cores is increased or the laying distance of the optical cable is increased, the allocation method of FIG. In such a case, as shown in FIG. 4A, the selection range is expanded by dividing the MFD difference into small groups (n, o, p, q,...) Within 2%. Is possible.
[0025]
Assume that optical cables A, B, C, D,... That form a series of optical fiber transmission lines are connected in the order shown in FIG. Here, the optical fibers arranged at predetermined positions of the optical cable D are, for example, from (u) of a small group (n, o, p, q,...) In which the MFD difference is divided into 2% or less. Suppose you have selected. In this case, the optical fiber of one optical cable C connected to the optical cable D is selected from (u) or the adjacent (t) where the difference in MFD is within 4%, and the optical fiber of the other optical cable E is It is possible to select from (u) or adjacent (v) where the difference of MFD is within 4%.
[0026]
In other words, the optical cable D and the optical cables C and E on both sides thereof can be selected from the adjacent three small groups (t, u, v), and the PMD difference between the connected optical fibers is maintained at 4%. , PMD difference can be selected from a range of 6%. In this case, half of the plurality of optical cables are optical fibers selected from the same small group (for example, u), and the other half are optical fibers selected from the adjacent small group (t, v). If these optical cables are alternately arranged and connected, even if the connection order of all optical cables is not clear (the order of connection is not determined) , the difference in PMD at all connection points can be kept within 4%. it can.
[0027]
Also, as shown in FIG. 4B, the connection order of all the optical cables A, B, C, D,... Constituting the optical fiber transmission line is clear (the order of connection is determined) . In this case, the selection range can be further expanded. For example, in the same manner as described above, the optical fiber of the optical cable D is selected from (u), the optical fiber of the optical cable C is selected from (u + t), and the optical fiber of the optical cable E is selected from (u + v). The optical fiber of the other optical cable B connected to the optical cable C is selected from (t), and the optical fiber of the other optical cable A connected to the optical cable B is selected from (s + t). Further, the optical fiber of the other optical cable F connected to the optical cable E is selected from (v), and the optical fiber of the other optical cable G connected to the optical cable F is selected from (v + w).
[0028]
In the example of FIG. 4 (B) described above, the seven optical cables (A to G) have five MFD differences in the range of 10% while maintaining the MFD difference of 4% connected to each other. It is possible to select from a small population (s to w). That is, according to the connection order of the optical cables, the optical fibers connected to each other are selected from the same small group at each connection point or by sequentially shifting the selection from the adjacent small group. The scope of the group can be expanded.
[0029]
As described above, when manufacturing a plurality of optical cables constituting an optical cable group, a plurality of optical fibers housed in the cables are divided into small groups by the difference in MFD and arranged at respective positions in the optical cables to be connected. By assigning optical fibers, the difference in MFD between the optical fibers to be connected can be suppressed to 4% or less. Therefore, there is no need to suppress the difference in MFD of all the optical fibers in the optical cable to a predetermined value or less, and therefore, an optical cable group can be formed relatively easily and according to an arbitrary request using the manufactured optical fiber. can do.
[0030]
Further, when an optical fiber transmission line is laid in an optical cable group composed of a plurality of optical cables manufactured as described above, the difference in MFD between optical fibers connected to each other is 4% or less. For this reason, when connected by fusion, the connection loss component due to MFD becomes zero or negligible, and transmission loss in the entire transmission line can be reduced.
[0031]
【The invention's effect】
As described above, according to the present invention, when a plurality of optical cables are connected and an optical fiber transmission line is laid, a connection loss component due to a difference in MFD of the optical fiber does not substantially occur, and the transmission loss of the transmission line. Can be reduced. In addition, the formation of the optical cable group for this purpose can be easily realized only by assigning the created optical fiber.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the outline of the present invention.
FIG. 2 is a diagram illustrating a splice loss component due to a difference in MFD of an optical fiber.
FIG. 3 is a diagram illustrating an optical fiber allocation method according to the present invention.
FIG. 4 is a diagram illustrating another method for assigning optical fibers according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 2 ... Optical cable, 3a-3f ... Optical fiber, 4 ... Outer sheath, 5 ... Strength body, 6 ... Connection part.

Claims (3)

A method of manufacturing an optical cable group composed of a plurality of optical cables for forming a series of optical fiber transmission lines by fusing together a plurality of optical fibers having different origins,
A large number of optical fibers collected to be accommodated in the optical cable are divided into a plurality of small groups having a mode field diameter difference of 4% or less, and a series of optical fibers at the same position where the optical cables are connected to each other are , A method for producing an optical cable group, wherein all of the optical cables are selected and stored from the same small group.   The plurality of subgroups are divided into subgroups having a mode field diameter difference of 2% or less, and a series of optical fibers in the same position connected to each other of the optical cable are all the same subgroup or adjacent subgroups. The method for manufacturing an optical cable group according to claim 1, wherein the optical cable group is sorted and stored. A method of manufacturing an optical cable group consisting of a plurality of optical cables in which the connection order of all optical cables for constructing a series of optical fiber transmission lines by fusing and connecting a plurality of optical fibers of different origins,
A large number of optical fibers collected for storage in the optical cable are divided into a plurality of small groups having a mode field diameter difference of 2% or less, and a series of optical cables connected to each other in the connection order in the same position. A method of manufacturing an optical cable group, wherein the optical fibers are all selected from the same small group or an adjacent small group at each connection point.

Images