JP2005037936A - Optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber cable which facilitates intermediate after-branching of the coated optical fiber ribbons held in the optical fiber cable. <P>SOLUTION: The optical fiber cable 1 of this invention holds a plurality of secondary coated optical fiber ribbons 10 stacked inside grooves 4 formed in a long-length form spacer 3, and a secondary coated optical fiber ribbon 10 holds four pieces of optical fibers 11 in parallel, and the whole length of these four optical fibers 11 and the whole circumference of the parallel state are covered with an resin outer jacket 12 into one body, and when the maximum thickness value of the secondary coated optical fiber ribbon 10 is expressed by T(μm), and the outer diameter of the optical fiber 11 is expressed by d(μm), T ≤ d + 40 (μm). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical fiber cable in which a plurality of optical fiber ribbons are stacked and accommodated inside a groove formed in a long spacer.

In recent years, as the demand for optical communication systems increases, optical fiber cables, which are optical transmission lines, are often laid on pipes, utility poles, and the like.
In general, a tape slot type optical fiber cable is widely used as an optical fiber cable laid on a communication main route such as a pipeline or a utility pole (see, for example, Non-Patent Document 1).

FIG. 22 shows an example of a conventional tape slot type optical fiber cable.
As shown in FIG. 22, a conventional tape slot type optical fiber cable 100 has a plurality of optical fiber ribbons 110 accommodated in a groove 103 of a spacer 102 having a strength member 101 at the center. This optical fiber cable 100 is a 100-fiber optical cable, and five four-fiber optical fiber ribbons 110 are laminated and accommodated in each of the five grooves 103. Moreover, each groove | channel 103 is formed in the spiral shape of one direction in the state parallel to each other along the elongate direction. Alternatively, in some cases, the grooves 103 are formed in a spiral shape that is alternately reversed in the circumferential direction while maintaining a state parallel to each other along the longitudinal direction. In general, a spacer in which a groove is formed in a spiral shape in one direction is called a unidirectional twisted spacer, and a spacer in which a groove is formed in a spiral shape in which grooves are alternately inverted is called an SZ spacer.

  Further, in order to prevent the optical fiber ribbon 110 from coming off the groove 103, a presser roll 104 is wound around the spacer 102. Further, a plastic sheath 105 is coated on the outside of the presser winding 104.

  The tensile body 101 is a tensile body provided to prevent the tension from being transmitted directly to the optical fiber ribbon 110 when a tension is applied to the optical fiber cable 100. For example, a steel wire is used. ing.

  The optical fiber tape core 110 is formed, for example, by placing four optical fiber cores having an outer diameter of 250 μm in parallel contact with each other and covering the whole with an ultraviolet curable resin to form a tape. For example, the outer shape has a thickness of about 0.3 mm to 0.4 mm and a width of about 1.1 mm. The five optical fiber ribbons 110 accommodated in one groove 103 are laminated in a state of being in close contact with each other in the thickness direction.

Optical cable network wiring system general catalog, Sumitomo Electric Industries, Ltd., August 2002, p9

By the way, the above-mentioned optical fiber cable laid on the communication trunk route is obtained by, for example, pulling out the contained optical fiber tape core wire in order to wire the optical fiber from the accommodation station to the subscriber-side building or the like. Any optical fiber may be connected to the optical fiber on the subscriber side.
In that case, first, the sheath and the presser winding are peeled off from an arbitrary portion of the laid optical fiber cable by a predetermined length, and a desired optical fiber tape core wire is pulled out from the groove of the spacer. Then, a desired optical fiber is branched from the drawn optical fiber ribbon and connected to the optical fiber on the subscriber side.

  Since the already installed optical fiber cable contains many optical fibers that transmit optical signals, branching in a live line state, so-called hot line branching work, is performed while suppressing deterioration in the transmission quality. Is required. Therefore, when branching a desired optical fiber, the so-called intermediate post-branch is used to branch the desired optical fiber from the middle portion of the optical fiber ribbon drawn from the groove without cutting the optical fiber ribbon. There is an increasing demand to perform this method.

However, it is difficult to remove the resin covering the plurality of optical fibers in the optical fiber ribbon accommodated in the conventional optical fiber cable, and one optical fiber is selected from them and branched after the middle. That was a difficult situation.
For example, if the resin is scraped off with a sandpaper or a canna-shaped tool, the optical fiber may be damaged or cut.

Under such circumstances, conventionally, intermediate post-branching cannot be performed, and in order to branch a desired optical fiber, all of a plurality of optical fibers integrated as an optical fiber ribbon are cut, and a single portion is cut from the cut portion. It was branched to the optical fiber of the heart. For this reason, it has been impossible to perform a hot branching operation on an optical fiber ribbon including an optical fiber that is in use (that is, in a live line) as a transmission line.
In addition, if the optical fiber ribbon is cut, the remaining optical fibers other than the optical fiber connected at that point cannot be used as a transmission line. Cost becomes high.

  An object of the present invention is to provide an optical fiber cable that can easily perform intermediate post-branching of an optical fiber ribbon housed in an optical fiber cable.

  An optical fiber cable according to the present invention capable of achieving the above object is a groove of a spacer in which a substantially spiral groove is provided on the outer peripheral surface of a substantially cylindrical plastic long body having a tensile body at the center. Is an optical fiber cable in which one or a plurality of optical fiber ribbons are stacked and accommodated, and the optical fiber tape core includes a plurality of optical fibers arranged in parallel. The total length of the fiber is integrated with resin. When the maximum thickness of the optical fiber ribbon is T (μm) and the outer diameter of the optical fiber is d (μm), T ≦ d + 40 (μm) It is characterized by being.

  An optical fiber cable according to the present invention that can achieve the above object is a spacer having a substantially cylindrical groove on the outer peripheral surface of a substantially cylindrical plastic long body having a tensile body at the center. An optical fiber cable in which one or a plurality of optical fiber ribbons are stacked and accommodated inside the groove, wherein the optical fiber tape cores include a plurality of optical fibers arranged in parallel. The total length of the optical fiber and the entire circumference of the optical fiber in parallel are covered and integrated with resin, the maximum value of the thickness of the optical fiber ribbon is T (μm), and the outer diameter of the optical fiber is d (μm). ), T ≦ d + 40 (μm).

According to the optical fiber cable having such a configuration, since the thickness of the resin in which a plurality of optical fibers are integrated is thinner than the conventional one, the intermediate post branching operation can be easily performed.
Therefore, it is possible to connect the optical fiber contained in the optical fiber ribbon other than the one after the intermediate branch, by pulling it out from the optical fiber cable at another location, and a large number of light contained in the optical fiber cable. The fiber can be used effectively.

  In the optical fiber cable according to the present invention, it is preferable that at least two adjacent optical fibers are arranged in contact with each other in the optical fiber ribbon. Alternatively, it is preferable that the optical fiber ribbons are arranged so that adjacent optical fibers are not in contact with each other and have an interval of 10 (μm) or less.

  In the optical fiber cable according to the present invention, the optical fiber ribbon is preferably T ≧ d + 1 (μm).

  Moreover, the optical fiber cable which concerns on this invention WHEREIN: It is preferable that the recessed part according to the hollow between adjacent optical fibers is formed in resin of the optical fiber tape core wire.

  In the optical fiber cable according to the present invention, the optical fiber ribbon is preferably T ≦ d + 30 (μm).

  In the optical fiber cable according to the present invention, it is preferable that the optical fiber tape core wire satisfy (T−d) /2Y≦4.0 when the depth of the recess is Y (μm).

  In the optical fiber cable according to the present invention, it is preferable that the optical fiber ribbon is g ≦ d, where g (μm) is the thickness of the optical fiber ribbon in the recess. Alternatively, it is preferable that g ≦ 0.8d.

  Further, in the optical fiber cable according to the present invention, when a recess corresponding to a recess between the optical fibers adjacent to the resin of the optical fiber ribbon is formed, the optical fiber included in the optical fiber ribbon When the parallel pitch is P (μm) and the natural number including 0 which is 1/2 or less of the number of optical fibers included in the optical fiber ribbon is m, a plurality of optical fiber ribbons are adjacent to each other. It is preferable that the optical fiber tape cores are laminated so as to be shifted by mP + P / 2 (μm) in the width direction of the optical fiber tape cores. At that time, it is preferable that the m is 0, and it is more preferable that a plurality of optical fiber ribbons are stacked alternately and sequentially shifted in the width direction with respect to adjacent optical fiber ribbons. preferable.

  In the optical fiber cable according to the present invention, it is preferable that the optical fiber ribbon is T ≦ d + 25 (μm).

  Further, in the optical fiber cable according to the present invention, the optical fiber ribbon is perpendicular to a straight line connecting the centers of two adjacent optical fibers in the cross section, and the centers of the two optical fibers. Where the Young's modulus is E and the cross-sectional area is S, the ratio of the ES product of the resin to the sum of the ES products of the optical fibers is 0.026. The following is preferable. Alternatively, the ES product ratio is preferably 0.020 or less.

  Moreover, in the optical fiber cable according to the present invention, the optical fiber tape core wire has an adhesion force between the optical fiber and the resin per optical fiber in the range of 0.025 (gf) to 0.25 (gf). Preferably there is.

  In the optical fiber cable according to the present invention, it is preferable that the optical fiber tape core wire has a resin yield point stress in the range of 20 (MPa) to 45 (MPa).

  In the optical fiber cable according to the present invention, the groove is preferably formed in a spiral shape in one direction along the longitudinal direction of the spacer.

Further, in the optical fiber cable according to the present invention, the link polarization mode dispersion of any wavelength within the range of the wavelength 1.26 (μm) to 1.65 (μm) in all the accommodated optical fibers, It is preferably 0.05 (ps / km ^1/2 ) or less.

  In the optical fiber cable according to the present invention, it is preferable that the groove is formed in a spiral shape that is alternately reversed along the longitudinal direction of the spacer.

Further, in the optical fiber cable according to the present invention, the link polarization mode dispersion of any wavelength within the range of the wavelength 1.26 (μm) to 1.65 (μm) in all the accommodated optical fibers, It is preferably 0.2 (ps / km ^1/2 ) or less. Alternatively, the link polarization mode dispersion is preferably 0.1 (ps / km ^1/2 ) or less.

  Further, in the optical fiber cable according to the present invention, when the groove is formed in a spiral shape that is alternately reversed along the longitudinal direction of the spacer, a plurality of optical fiber ribbons are formed inside the groove. The adjacent optical fiber ribbons are laminated alternately in the width direction by half the length of the parallel pitch of the optical fibers in the width direction. Concave portions are formed in accordance with the recesses between them, and the groove preferably has a size that encloses a circumscribed circle of a tape core laminated body composed of laminated optical fiber ribbons in a cross-sectional view. In that case, it is preferable that the cross section of a groove | channel is a substantially trapezoid and the groove width in the bottom part of a groove | channel is more than the width | variety of the accommodated optical fiber ribbon. Alternatively, in the cross section of the groove, it is preferable that the bottom of the groove has an arc shape, and the radius of the arc is equal to or greater than the radius of the circumscribed circle.

  In the optical fiber cable according to the present invention, the optical fiber preferably has a mode field diameter of 10 (μm) or less according to the definition of Petermann-I at a wavelength of 1.55 (μm). Alternatively, the mode field diameter is preferably 8 (μm) or less.

  In the optical fiber cable according to the present invention, it is preferable that the optical fiber ribbon has an increase in loss when the optical fiber is branched is 1.0 (dB) or less. Or it is preferable that the loss increase when branching an optical fiber is 0.5 (dB) or less.

  According to the optical fiber cable of the present invention, the intermediate post branching of the accommodated optical fiber ribbon can be easily performed.

Hereinafter, an example of an embodiment of an optical fiber cable according to the present invention will be described with reference to FIGS.
As shown in FIG. 1, in the optical fiber cable 1 of the present embodiment, a plurality of optical fiber ribbons 10 are accommodated in a groove 4 of a spacer 3 having a strength member 2 at the center. This optical fiber cable 1 is a 200-core type optical fiber cable, and five four-fiber optical fiber ribbons 10 are stacked and accommodated in each of the ten grooves 4. Further, the ten grooves 4 are formed in a spiral shape that is alternately reversed in the circumferential direction while maintaining a state parallel to each other along the longitudinal direction. That is, the spacer 3 is an SZ spacer. Moreover, the twist pitch of the groove | channel 4 is 500 mm. In addition, the outer diameter of the spacer 3 is 12 mm, for example.

Further, in order to prevent the optical fiber ribbon 10 from coming off the groove 4, a presser winding 5 is wound around the spacer 3. Further, a sheath 6 made of plastic (for example, polyethylene) is formed outside the presser winding 5. The outer diameter of the sheath 6 is, for example, 16 mm.
The strength member 2 is a strength member provided to prevent the tension from being transmitted directly to the optical fiber ribbon 10 when a tension is applied to the optical fiber cable 1. As this strength member 2, a steel wire is preferably used.

  Since the direction in which the groove 4 is twisted is periodically reversed in the optical fiber cable 1, the sheath 6 and the presser winding 5 are removed at an arbitrary position, and the optical fiber tape core wire is removed from the reversing portion of the groove 4. 10 can be easily taken out. Therefore, the optical fiber cable 1 using the SZ spacer has a structure suitable for intermediate rear branching.

Here, the aspect of the optical fiber ribbon 10 accommodated in the groove 4 will be described.
FIG. 2 is a sectional view showing the optical fiber ribbon 10. The optical fiber ribbon 10 includes a plurality of optical fibers 11 (four used here as an example) arranged in parallel, the entire circumference of the optical fibers 11 arranged in parallel, and the optical fibers 11. This is integrally covered with a jacket 12 made of resin over the entire length.

  2 shows the optical fiber ribbon in which all the adjacent optical fibers are in contact with each other, the optical fibers may not be in contact with each other and may be separated from each other. Here, “not in contact” means that at least two optical fibers included in the optical fiber ribbon are not in contact. Comparing the case where the optical fibers included in the optical fiber ribbon are in contact with the case where they are not in contact, it is easier to branch the optical fiber ribbon when they are in contact. When the optical fibers are in contact with each other, the resin between the optical fibers can be destroyed just by rubbing the resin with a brush, for example, where the resin between the optical fibers forming the jacket is not continuous, The resin in which a plurality of optical fibers are integrated can be removed from the optical fiber.

  When the optical fiber cores are not in contact with each other, the interval between the optical fiber cores is preferably 10 μm or less. If the distance is 10 μm or less, the amount of resin forming the outer sheath is not large between the optical fibers, so that the resin is likely to break down, which is almost the same as when the resin is not continuous between the optical fibers. The coat can be removed and branching is easy.

  In addition, since the optical fiber 11 is covered with the resin sheath 12 over the entire length of the optical fiber ribbon 10, the outer sheath 12 is destroyed or removed at any location, and can be easily removed from any location. It is a structure that can diverge into the heart.

The optical fiber 11 includes a glass fiber 13 composed of a core 13a and a clad 13b, an outer periphery of the glass fiber 13 covered with a primary protective coating 14, and an outer periphery of the protective coating 14 covered with a secondary protective coating 15. It has become. A colored layer having a thickness of about 1 μm to 10 μm may be formed on the outer periphery of the secondary protective coating 15. Further, a thin film carbon layer may be coated around the glass fiber 13. The optical fiber 11 preferably conforms to G652 defined by ITU-T (International Telecommunication Union-Telecommunication standardization sector).
As the glass fiber 13 applicable to the present invention, a glass fiber having any refractive index distribution, such as a glass fiber composed of a core and a clad having a plurality of layers, can be applied.

Moreover, as the glass fiber 13, it is preferable that the mode field diameter (MFD: Mode Field Diameter) by the definition of Petermann-I in wavelength 1.55 micrometer is 10 micrometers or less. Furthermore, the mode field diameter is more preferably 8 μm or less.
When the mode field diameter is reduced, microbend loss and bending loss (macrobend loss) can be reduced. Therefore, an increase in transmission loss due to an external force received by the optical fiber ribbon 10 in the groove can be suppressed. Further, even if the optical fiber 11 is bent with a small bending radius, the increase in transmission loss is small, so that the hot line is easily branched.

In the optical fiber ribbon 10, an ultraviolet curable resin is used as the jacket 12 formed on the outer periphery of the four optical fibers 11 arranged in parallel. As the jacket 12 other than the ultraviolet curable resin, a thermoplastic resin, a thermosetting resin, or the like can also be used.
The optical fiber ribbon 10 of the present embodiment is formed so that the thickness of the jacket 12 is thinner than the conventionally used optical fiber ribbon. It should be noted that the thickness t of the jacket 12 is t = (T− when the maximum value of the thickness of the optical fiber ribbon 10 is T (μm) and the outer diameter of the optical fiber 11 is d (μm). d) / 2, and the thickness of the jacket 12 of the optical fiber ribbon 10 is such that T ≦ d + 40 (μm), that is, the thickness t of the jacket 12 is 20 μm or less. Is set.
When the optical fiber tape core wire 10 having a thin sheath 12 is used, the optical fiber tape core wire can be taken out from the intermediate portion while ensuring the high storage density and mechanical characteristics that the conventional optical fiber cable of the SZ spacer has. Can be obtained at low cost.

  Thus, since the thickness t of the outer sheath 12 of the optical fiber ribbon 10 is thin, the outer sheath 12 is cracked or peeled off by manual operation by an operator or by a branch tool. Easy to start peeling. Therefore, it is easy to split the optical fiber 11 by peeling off the outer sheath 12 from the optical fiber ribbon 10. That is, the optical fiber ribbon 10 has a structure that facilitates the intermediate post branching operation.

  An example of a branching method for the above-described intermediate post-branching will be described. As shown in FIG. 3A, the optical fiber tape core wire 10 is sandwiched between the upper base 61 and the lower base 62 of the branch tool 60, and the wire 63 erected on the upper and lower bases 61, 62 is used as the optical fiber tape core. The wire 10 is brought closer to the jacket 12. FIG. 3B shows a cross-sectional view at that time. Further, when the branch tool 60 is pressed against the optical fiber ribbon 10, the wire 63 is bent as shown in FIG. 3C, and the corner of the bent wire 63 has a corner at the outside of the optical fiber ribbon 10. It makes strong contact with the cover 12.

  With the branch tool 60 pressed, the branch tool 60 is moved relatively in the longitudinal direction of the optical fiber ribbon 10 (left and right as viewed in FIG. 3C). When the wire 10 is rubbed, the optical fiber 11 is branched by scratching or peeling off the outer sheath 12 at the tip of the wire 63. In that case, you may move either the branch tool 60, the optical fiber ribbon 10, or both.

Since the wire 63 has flexibility, when the wire 63 is pressed against the outer sheath 12 of the optical fiber ribbon 10, the wire 63 warps and the tip of the wire 63 hits the outer sheath 12. In this state, when the branch tool 60 or the optical fiber ribbon 10 is moved, the wire 63 (flexible member) damages the outer sheath 12 or peels off the outer sheath 12. When rubbing the optical fiber ribbon 10 with the branch tool 60 is repeated, peeling occurs at the interface between the optical fiber 11 and the jacket 12. When this operation is further repeated, the jacket 12 at the top or bottom of the central axis of the optical fiber 11 is scraped and cracks are generated, and then cracks develop in the jacket 12 and the jacket 12 is peeled off.
In this way, the jacket 12 of the optical fiber ribbon 10 is broken and branched into optical fibers.

  If the force for pressing the flexible wire 63 against the optical fiber ribbon is adjusted, the fluctuation amount of the optical signal transmission loss at the time of branching will be 1.0 or less, and depending on the way of branching, it will be 0.5 dB or less. Can be branched without interrupting the optical transmission of the live wire.

  Here, Table 1 shows the relationship between the workability of the intermediate post-branch due to the difference in the thickness t of the jacket 12 and the increase in the hot wire loss at that time. Table 1 also shows the results of a separation test showing the intensity of the polarization mode dispersion (SZ cable PMD) in the optical fiber cable 1, that is, in the state accommodated in the SZ spacer, and the optical fiber integration. ing. The outer diameter d of the optical fiber of the optical fiber ribbon shown in Table 1 is 250 μm. Further, the Young's modulus of the resin constituting the outer jacket 12 is 900 MPa.

In addition, the optical fiber tape core wire of the jacket thickness t = 0.0 shown in Table 1 is one in which the resin does not cover the entire optical fiber. An example of such an optical fiber ribbon is shown in FIG.
In an optical fiber ribbon 10a shown in FIG. 4, adjacent optical fibers 11 are integrated with a resin 12a over the entire length. The resin 12a is formed so as to fill in the recesses between the optical fibers 11, and bonds the adjacent optical fibers 11 together. Further, the thickness of the optical fiber ribbon 10 a is designed not to be larger than the outer diameter d of the optical fiber 11. Therefore, the thickness T of the optical fiber ribbon 10a in this case is equal to the outer diameter d of the optical fiber 11.

The intermediate post-branch property shown in Table 1 indicates the ease of branching when the intermediate portion of the optical fiber ribbon is branched to each optical fiber with an increase in transmission loss of 1.0 dB or less. As evaluation criteria in this specification, ◎ indicates that it can branch within an average of 2 minutes, ○ indicates that it can branch over an average of over 2 minutes and within 3 minutes, and △ indicates a branch over of an average of over 3 minutes and within 5 minutes Show what you can do. Moreover, x shows that it takes a branch work time exceeding 5 minutes on average.
Note that an increase in transmission loss at the time of branching of 1.0 dB or less means that the hot line can be branched.

Here, the intermediate post-branching test will be described.
First, as shown in FIG. 5 (A), the optical fiber tape core wire 10 is left with a jacket of a length of about 1 m, for example, and light having a wavelength of 1.55 μm is applied to the first optical fiber 11a on one side. A light source 20 for incidence is connected, and a light receiver 21 and a storage oscilloscope 22 are connected to the other optical fiber 11a. In this state, light having a wavelength of 1.55 μm is incident from the light source 20 to the first optical fiber 11a. The incident light is transmitted to the other side of the optical fiber 11 a and is received by the light receiver 21. The amount of received light is observed by the storage oscilloscope 22 in a timely manner.

Then, in the state where the light from the light source 20 is incident, as shown in FIG. 5B, the optical fiber ribbon 10 is branched after the middle. In other words, the optical fiber ribbon 10 is branched into a single core (hot branching) while the first optical fiber 11a is hot. At this time, the storage oscilloscope 22 measures the increase in transmission loss due to the intermediate post branch.
The length of branching after the middle was 50 cm. The method of branching after the intermediate is based on the above procedure described with reference to FIG.

Of the optical fiber ribbons shown in Table 1, those having an intermediate post-branch property of ◎, ○ or Δ are those having a tape thickness T of 290 μm or less, that is, T ≦ d + 40 (μm). . Both of these can be branched after an intermediate period within 5 minutes with an increase in transmission loss at the time of branching of 1.0 dB or less. That is, the hot line can be branched within 5 minutes.
On the other hand, the optical fiber tape core wire having a thick outer sheath, which has been used in the past and whose tape thickness T exceeds 40 μm from the outer diameter d of the optical fiber, has an intermediate post-branch property x, and transmission at the time of branching Even if the increase in loss exceeds 1.0 dB or can be branched, the time required for more than 5 minutes is required, and it was not possible to branch the hot line in practice.

  The hot line loss increase shown in Table 1 is an increase in transmission loss that occurs during the work of intermediate post-branching. As evaluation criteria in this specification, ◎ indicates that the transmission loss does not increase by more than 0.1 dB during the branching operation, and ○ indicates that the transmission loss does not increase by more than 0.5 dB during the branching operation. And Δ indicates that the transmission loss does not increase beyond 1.0 dB during the branching operation. Further, x indicates that the increase value of the transmission loss exceeds 1.0 dB during the branching operation.

Of the optical fiber ribbons shown in Table 1, those having a hot wire loss increase of ◯ or Δ are those having a tape thickness T of 290 μm or less, that is, T ≦ d + 40 (μm). In both cases, the increase in transmission loss at the time of branching is 1.0 dB or less, and the optical fiber ribbon of the live line can be branched after the middle. Of these, tapes having a tape thickness T of 275 μm or less, that is, T ≦ d + 25 (μm), are more preferable because the increase in the live line loss is ○ and the increase in transmission loss is further suppressed.
On the other hand, the optical fiber tape core wire having a thick outer sheath that has been used in the past and whose tape thickness T exceeds 40 μm from the outer diameter d of the optical fiber has an increase in hot wire loss, and during the branching operation The increase value of the transmission loss exceeds 1.0 dB.

  The SZ cable PMD shown in Table 1 is the link polarization mode dispersion in a state where the optical fiber ribbon 10 is accommodated in the groove 4 as shown in FIG. Here, the link polarization mode dispersion means that the values of the polarization mode dispersion (PMD) of all the optical fibers 11 accommodated in the optical fiber cable 1 are statistically processed, and many equivalent optical fiber cables are provided. It shows the maximum value of PMD that can occur when connected in series. Here, the statistical processing is performed based on the central limit theorem. PMD was measured under the condition that the length of the optical fiber cable 1 was 1000 m or more, and an interferometry measuring instrument (Suntech 6000B) was used.

As evaluation criteria in this specification, ◎ indicates that the link polarization mode dispersion (link PMD) is 0.05 (ps / km ^1/2 ) or less, and ○ indicates 0.05 (ps / km ^1/2 ). And 0.1 (ps / km ^1/2 ) or less, and Δ is 0.1 (ps / km ^1/2 ) and 0.2 (ps / km ^1/2 ) or less. Show. Further, x indicates a case where the link polarization mode dispersion exceeds 0.2 (ps / km ^1/2 ).

  In a tape slot type optical fiber cable, optical fiber tape cores are laminated in the groove, so that stress from a certain direction is generated and birefringence occurs in the optical fiber. Birefringence is also likely to occur due to curing shrinkage of the outer casing. The outer sheath (resin) of the optical fiber ribbon is shrunk by about 5% due to curing during its manufacture. Due to this curing shrinkage, an external force is applied to the optical fiber, and a stress is generated in the optical fiber. The stress differs in the width direction and the thickness direction because the cross-sectional shape of the optical fiber ribbon is wide in the width direction. End up. In particular, the outer sheath in the thickness direction of the optical fiber ribbon with respect to the optical fiber is continuous in the width direction of the optical fiber ribbon. The stress generated in the direction increases, and the stress difference generated between the width direction and the thickness direction increases.

  Thus, PMD tends to be high in a tape slot type optical fiber cable. In particular, in the case of an optical fiber cable with SZ spacers, the PMD tends to be high because the optical fiber is bent in a complicated manner due to the inverted groove shape.

In this embodiment, since the optical fiber tape core wire having a thinner jacket than that of the conventional one is used, birefringence generated due to curing shrinkage can be suppressed to be extremely small. Therefore, the optical fiber cable of the present embodiment can keep PMD low.
Among the optical fiber ribbons shown in Table 1, when T ≦ d + 25 (μm), the SZ cable PMD becomes ◯, and it can be seen that it is particularly good.

The presence / absence of fiber separation shown in Table 1 indicates the result of a separation test indicating the strength of integration of optical fibers.
In this separation test, as shown in FIG. 6, the winding bobbin 24 around which the optical fiber ribbon 10 to be tested is wound is rewinded to the take-up bobbin 25, and the optical fiber tape is in the middle of the pass line. An external force is applied to the core wire 10. The external force applied to the optical fiber ribbon 10 is given a constant tension to the optical fiber ribbon 10 by a load applying portion 26 composed of a dancer roller and a weight, and has a small diameter using two round bars 27 having a diameter of 3 mm. It is generated by giving the bending of the opposite direction.

  As an evaluation standard for fiber separation in this specification, ◯ indicates a case where there is no separation between the optical fiber and the jacket (resin), and the optical fiber tape core wire remains integrated in the longitudinal direction. Indicates a case where a separation point between the optical fiber and the jacket (resin) occurs.

Of the optical fiber ribbons shown in Table 1, when T ≧ d + 1 (μm), separation of the optical fiber ribbons did not occur, which was good. That is, it has been found that when the thickness t of the jacket is 0.5 μm or more, sufficient strength can be obtained to keep the optical fibers integrated.
Of the optical fiber ribbons shown in Table 1, those with T = d (see FIG. 4) have separation points in this separation test, but the optical fiber is in the line when manufacturing the optical fiber cable. By taking into consideration that the external force such as ironing applied to the tape core is reduced, it is possible to prevent a problem that the core is separated in the cable manufacturing process. Since the optical fiber tape core wire with T = d is substantially interrupted in the thickness direction of the optical fiber tape core wire passing through the center of each optical fiber, It is easy to separate in the width direction of the fiber tape core wire, and the intermediate post-branching property is better than the optical fiber tape core wire having a shape that covers the entire optical fiber with the jacket.

  Note that the optical fiber tape core wire 10a in which the resin 12a does not cover the entire optical fiber 11 as shown in FIG. 4 is obtained by integrating the optical fibers 11 only by the adhesive force between the resin 12 and the optical fiber. Yes. On the other hand, in the optical fiber ribbon 10 as shown in FIG. 2, since the resin integrally covers the entire optical fiber 11 as the outer cover 12, only the adhesive force between the resin and the optical fiber is obtained. In addition, it is easy to keep the entire optical fiber ribbon 10 in an integrated state due to the force of the outer sheath 12 itself to maintain its shape.

  Further, the optical fiber tape core wire (see FIG. 2) as described above is the sum of the products (ES product sum) of the outer sheath (resin) 12 and the respective Young's modulus E and cross-sectional area S of the optical fiber 11. PMD can be reduced by setting the ratio to an appropriate value. The magnitude of the stress acting on the optical fiber 11 when the outer sheath 12 undergoes curing shrinkage increases as the Young's modulus of the resin constituting the outer sheath 12 increases and the thickness of the outer sheath 12 increases. Here, it is distortion generated in the glass fiber 13 of the optical fiber 11 that causes PMD to increase. The magnitude of this strain is determined by the magnitude of the force reaching the glass fiber 13 through the coating layer including the primary protective coating 14, the secondary protective coating 15, and the colored layer, and the Young's modulus of the glass fiber 13.

  Therefore, in each condition where the Young's modulus of the jacket 12 is 700 MPa, 900 MPa, 1200 MPa, and 1500 MPa, the light when the thickness T of the optical fiber ribbon 10 is different, that is, when the thickness of the jacket 12 is different. The relationship between the ES product ratio of the jacket 12 to the fiber 11 and the SZ cable PMD was examined.

  The glass fiber 13 has a Young's modulus of 73000 MPa and an outer diameter of 125 μm. The primary protective coating 14 has a Young's modulus of 1 MPa and an outer diameter of 200 μm. The secondary protective coating 15 has a Young's modulus of 700 MPa and an outer diameter of 240 μm. The colored layer has a Young's modulus of 1500 MPa and an outer diameter of 250 μm.

  In the present specification, the ratio of the ES product is calculated in a region where the thickness of the optical fiber ribbon 10 is constant in order to accurately obtain the ES product per one optical fiber. That is, two wires that are perpendicular to a straight line connecting the centers of two adjacent optical fibers 11 in the cross section of the optical fiber ribbon 10 and pass through the centers of the two optical fibers 11 respectively. The sum of the ES products of the optical fiber 11 and the ES product of the jacket 12 are calculated in the inner region partitioned by the straight line (for example, broken lines X and Y shown in FIG. 2) and compared under each condition.

Table 2 shows the relationship between the ES product ratio and the SZ cable PMD when the Young's modulus of the jacket 12 is 700 MPa.

Table 3 shows the relationship between the ES product ratio and the SZ cable PMD when the Young's modulus of the jacket 12 is 900 MPa.

Table 4 shows the relationship between the ES product ratio and the SZ cable PMD when the Young's modulus of the jacket 12 is 1200 MPa.

Table 5 shows the relationship between the ES product ratio and the SZ cable PMD when the Young's modulus of the jacket 12 is 1500 MPa.

  Here, the fiber ES products shown in Tables 2 to 5 are the sum of the ES products of the regions composed of the glass fiber 13, the primary protective coating 14, the secondary protective coating 15, and the colored layer. The resin ES product is the ES product of the jacket 12. The ES product ratio is represented by “resin ES product / fiber ES product sum”.

As shown in Tables 2 to 5, the conditions under which the SZ cable PMD is ○ or Δ, that is, the link PMD of the entire optical fiber accommodated in the optical fiber cable of the SZ spacer is 0.2 (ps / km ^{1 / 2} ) The condition that is equal to or less is the case where the ES product ratio is 0.026 or less. Further, the condition that the SZ cable PMD is ◯, that is, the condition that the link PMD is 0.1 (ps / km ^1/2 ) or less is a case where the ES product ratio is 0.020 or less.
Thus, the PMD of the optical fiber 11 can be kept low by setting the ES product ratio of the jacket 12 to the optical fiber 11 to be a desired value.

Next, another preferred aspect of the optical fiber ribbon housed in the optical fiber cable of this embodiment will be described.
FIG. 7A is a cross-sectional view of the optical fiber ribbon, and FIG. 7B is a perspective view.
As shown in FIG. 7, the optical fiber ribbon 10 b is formed in the outer cover 12 b covering the optical fiber 11, according to the recess formed between the adjacent optical fibers 11, 11. Is formed. As for this recessed part 16, the bottom part 17 is formed as a part with the largest hollow.

As described above, the thickness of the jacket formed around the optical fiber 11 is preferably thinner from the viewpoint of reducing PMD, and may be about 0.5 μm. However, when actually manufacturing such an optical fiber ribbon, it is preferable to have a certain thickness. The reason is that if the thickness of the resin serving as the outer cover is reduced, the resin is not partially applied (this is called “out of resin”). Therefore, it is desirable to form a jacket with a thickness of 2.5 μm or more on the optical fiber 11. In that case, in order to reduce the amount of the resin in the thickness direction of the optical fiber ribbon while maintaining the desired thickness of the jacket, it is sufficient to reduce the jacket formed in the recess between the adjacent optical fibers. The location where resin breakage is likely to occur is the location where the outer diameter of the optical fiber is the largest in the thickness direction of the optical fiber ribbon, so reducing the amount of resin between adjacent optical fibers ensures the resin Does not interfere with application.
Therefore, forming the recess 16 as shown in FIG. 7 can suppress an increase in PMD while preventing the resin from being cut.

  Further, the recess 16 of the jacket 12b is effective when the jacket 12b is peeled off from the optical fiber ribbon 10b and the optical fiber 11 is branched. The more the portion of the outer cover 12b is thinner, the easier the outer cover 12b is broken, and the branching operation becomes easier. Further, since the branching work is facilitated, the external force applied to the optical fiber during the branching work can be reduced. Therefore, the increase in the loss of the hot line branch can be suppressed small.

  In the optical fiber ribbon 10b shown in FIG. 7, the depth Y of the recess 16 is formed to be shorter than the distance between the common tangent S1 of the jacket 12b and the common tangent S2 of each optical fiber 11. That is, the concave portion 16 is formed so that the position of the bottom portion 17 is located outside the common tangent line S <b> 2 of each optical fiber 11.

Further, as the optical fiber tape core wire accommodated in the optical fiber cable of the present embodiment, the optical fiber tape shown in FIG. 8, which is another aspect obtained by partially changing the configuration of the optical fiber tape core wire 10b shown in FIG. Examples thereof include a fiber tape core wire 10c.
FIG. 8A is a cross-sectional view of the optical fiber ribbon 10c, and FIG. 8B is a perspective view. The basic configuration of the optical fiber ribbon 10c is the same as that of the optical fiber ribbon 10b shown in FIG. 7, and the description of the common configuration is omitted.
The outer cover 12c covering the outer periphery of the optical fiber 11 has a concave shape according to the recess formed between the adjacent optical fibers 11c. The recess 16c of the outer cover has a deeper recess shape than in the case of FIG. The optical fiber ribbon 10 c is formed so that the bottom 17 c of the recess 16 c is located inside the common tangent S <b> 2 c of the optical fiber 11.

  When the optical fiber ribbon is housed in the groove as shown in FIG. 1, the optical fiber located at the end in the width direction of the optical fiber ribbon and the optical fiber located inside the optical fiber are not separated. The distance from the center is different. Therefore, in the state accommodated in the spirally formed groove, a length difference in the groove occurs between the optical fiber at the end and the inner optical fiber, and stress is generated in the optical fiber. This stress causes anisotropic stress in the glass fiber together with the stress caused by bending in the groove, causing birefringence and increasing PMD.

  On the other hand, the optical fiber tape core wire 10c as shown in FIG. 8 is easily bent in the width direction as shown in FIG. When the wire 10c is accommodated in the groove, an excessive force is not applied to the optical fiber ribbon 10c, and the length difference in the groove generated between the end optical fiber and the inner optical fiber is eliminated. Thus, it is considered that the cable PMD can be improved. Further, since the outer sheath 12c of the optical fiber ribbon 10c approaches a circular shape along the outer periphery of the optical fiber 11, the anisotropy of the curing shrinkage stress of the outer sheath 12c when the optical fiber ribbon 11c is manufactured. It is considered that the PMD in the cable state of the optical fiber ribbon 10c can be improved. This effect can also be obtained in the optical fiber ribbon 10b shown in FIG. 7, but the optical fiber ribbon 10c having a deeper recess is more prominently obtained.

  Here, with respect to the depth of the recess formed in the jacket as shown in FIGS. 7 and 8, a plurality of optical fibers are lined up and integrated with the jacket to produce an optical fiber ribbon. We examined the prevention of peeling, prevention of peeling of the jacket when laying the optical fiber ribbon (causes scattering of the optical fiber), good branching work, increase / decrease of transmission loss when hot-line branching, etc. . As a result, it has been found that the recess is preferably formed so as not to exceed the common tangent formed by the adjacent optical fibers, in other words, to enter the inside of the common tangent.

The specific examination results will be described next.
When the thickness T (μm) of the optical fiber ribbon is 270 μm, 280 μm, and 290 μm, the thickness t (μm) of the jacket with respect to the depth Y (μm) of the recess when the depth of the recess is different The ratio t / Y of the optical fiber and the ratio g / d of the thickness g (μm) of the optical fiber tape core wire at the concave portion to the outer diameter d (μm) of the optical fiber are calculated. Then, the hot wire loss increase and the SZ cable PMD were examined.

Table 6 shows the relationship among intermediate post-branching property, increase in hot wire loss, and SZ cable PMD when the thickness T of the optical fiber ribbon is 270 μm. The ratio (Td) / 2Y in the table is the same value as t / Y.

Table 7 shows the relationship between the intermediate post-branching property, the increase in hot wire loss, and the SZ cable PMD when the thickness T of the optical fiber ribbon is 280 μm.

Table 8 shows the relationship among the intermediate post-branching property, the increase in the hot wire loss, and the SZ cable PMD when the thickness T of the optical fiber ribbon is 290 μm.

As shown in Tables 6 to 8, in any of the intermediate post-branching property, the hot wire loss increase, and the SZ cable PMD, a better result was obtained as the depth Y of the concave portion was increased.
In addition, when the thickness T of the optical fiber ribbon was 270 μm or 280 μm, that is, when T ≦ d + 30 (μm), the results of intermediate post-branching and increased hot-wire loss were particularly good. This is considered to be because, when a branching tool as shown in FIG. 3 is used, the branching property becomes better than the optical fiber ribbon having a thin outer jacket due to the effect of the recess. For example, when the tape thickness T shown in Table 1 is 270 μm, the intermediate post-branching property is ○, whereas the tape thickness T shown in Table 7 is 280 μm and the recess depth Y is 5 μm. Further, the intermediate post-branching property is ◎, and the effect of the concave portion can be confirmed.

Further, when attention is paid to the intermediate post-branching property, it can be seen that it is particularly related to the ratio (T−d) / 2Y. For example, when the ratio (Td) / 2Y is 4.0 or less, the intermediate post-branching property is good.
Further, when attention is paid to the SZ cable PMD, it can be seen that it is particularly related to the value of the ratio g / d. For example, when the ratio g / d is 1.0 or less, that is, when the bottom is inside the common tangent of the optical fiber, the amount of resin is sufficiently reduced, and a remarkable PMD suppressing effect is obtained. .
If the ratio g / d is 1.0 or less, the outer cover is thin so that the bottom portion does not come outside the common tangent line, so that it is easy to bend in the length direction or the concave portion is deep. It is considered that the bending as shown in the figure tends to occur and the cable PMD can be effectively improved.

Furthermore, when the ratio g / d is 0.8 or less, PMD in the state accommodated in the spacer is further effectively suppressed.
In a general optical fiber coating, a primary protective coating with a low Young's modulus covers the periphery of the glass fiber, and a secondary protective coating with a high Young's modulus and a colored layer cover the outer periphery. Further, the outer diameter of the primary protective coating is about 0.8 times the outer diameter d of the optical fiber. Therefore, when the resin in the recess is in a range not exceeding the primary protective coating, the outer cover is easily deformed, and bending as shown in FIG. 9 is likely to occur. Therefore, it becomes easier to suppress PMD.

  In the optical fiber tape core wire in which the concave portion is formed as shown in FIGS. 7 and 8, it is desirable that the concave portion has a smooth curved shape R. For example, if the concave portion has a shape in which the bottom portion is sharp along the shape of the optical fiber core wire, stress concentrates on the bottom portion, and cracks, cracks, and the like are likely to occur.

  Further, in the optical fiber ribbon used in the optical fiber cable of the present invention as shown in FIGS. 2, 4, 7, and 8, the adhesion between the optical fiber and the jacket is determined when the live line is branched. There are times when the increase in transmission loss and the branching work efficiency are affected. The adhesive strength between the optical fiber and the outer sheath (resin) is 0.025 (gf) to 0.25 (gf) per optical fiber in consideration of prevention of increase in transmission loss and branching workability. It is desirable to be within the range. If the adhesion force is smaller than the above range, the outer sheath may be broken during cable formation, and the optical fibers may be separated. Moreover, when the said adhesive force is larger than the said range, branching property will worsen.

The adhesion force between the optical fiber and the jacket can be measured, for example, by the following method.
As shown in FIG. 10, the blade C of the cutter knife is applied to the optical fiber ribbon 10 to cut the glass. The blade is moved in the length direction to the end of the tape core, and the resin on one side of the tape core is peeled off. The outer cover 12 at the end of the optical fiber ribbon 10 is peeled off by about 30 mm by hand and folded.
Then, as shown in FIG. 11, the optical fiber 11 from which the jacket 12 has been peeled is gripped by the lower chuck 50L, and the tip of the folded jacket 12 is gripped by the upper chuck 50U. The distance between the upper and lower chucks 50L and 50U is about 40 mm. The outer chuck 12 is peeled off by moving the upper chuck 50U and the lower chuck 50L by about 50 mm at a speed of 200 mm / min in a direction that makes a relative angle of 180 degrees.
The maximum value and minimum value of the measured values are taken as the maximum value and its next point value, the minimum value and its next point value, a total of 4 points, the average value is obtained, and the average value of the optical fiber contained in the optical fiber ribbon is obtained. The value divided by the number of hearts is taken as the adhesion per core.

  In the optical fiber ribbon used in the present invention, when the main purpose is to maintain the integrity of the optical fiber without scattering, the thickness of the jacket is preferably 0.5 μm or more, and the optical fiber in this case The maximum thickness T of the tape core wire satisfies T ≧ optical fiber outer diameter d + 1 (μm).

  In addition, the physical properties of the outer sheath of the optical fiber ribbon may affect the increase in transmission loss at the time of hot line branching and branching efficiency. As a characteristic of the material of the jacket, the yield point stress is desirably in the range of 20 MPa to 45 MPa, and branching can be easily performed, or transmission loss at the time of hot line branching can be suppressed. The yield point stress is measured in accordance with JIS K7113 with a No. 2 test piece at a pulling speed of 50 mm / min. If the yield point stress is less than 20 MPa, the optical fibers may be separated by an external force applied in the process of gathering the optical fiber ribbons into a cable, and may not be cabled. If the yield point stress exceeds 45 MPa, the outer sheath is difficult to break, and it is difficult to branch the optical fiber ribbon in the middle.

Here, the transmission loss value and the polarization mode dispersion (PMD) value at a wavelength of 1.55 μm were measured for the optical fiber cable 1 shown in FIG. In addition, the amount of increase in transmission loss during intermediate post-branching was measured.
The optical fiber ribbon used here is the optical fiber ribbon 10c shown in FIG. 8, and its thickness T is 260 μm. The outer diameter d of the optical fiber 11 is 250 μm. The thickness t of the jacket is 5 μm, the depth Y of the recess is 30 μm, and the thickness g of the optical fiber ribbon in the recess is 200 μm. However, among the optical fibers integrated as the optical fiber ribbon, 100 fibers conforming to G652 were used, and the remaining 100 fibers having a mode field diameter of 10 μm or less were used.

The transmission loss value of the optical fiber in the state accommodated in the optical fiber cable 1 was a G652 optical fiber, the maximum value was 0.23 dB / km, and the average value was 0.21 dB / km. In an optical fiber having a mode field diameter of 10 μm or less, the maximum value was 0.21 dB / km, and the average value was 0.20 dB / km.
The polarization mode dispersion value is G652 optical fiber, the average value is 0.025 (ps / km ^1/2 ), the standard deviation is 0.020 (ps / km ^1/2 ), and the link The PMD was 0.046 (ps / km ^1/2 ). In an optical fiber having a mode field diameter of 10 μm or less, the average value is 0.022 (ps / km ^1/2 ), the standard deviation is 0.018 (ps / km ^1/2 ), and the link PMD is 0.00. 042 (ps / km ^1/2 ).
As described above, the transmission loss and PMD of the optical fiber after being cabled were particularly good when the mode field diameter was 10 μm or less.

Further, as described above, the optical fiber cable using the SZ spacer has good intermediate post-branching properties. For this reason, it is often used for a subscriber communication channel that connects a station to a general subscriber. For this reason, the length of the optical fiber cable of the SZ spacer is often shorter than that of the relay system connecting stations, and is several tens of kilometers at the longest. However, if one optical fiber from the station to the subscriber is assigned to one subscriber, an optical fiber cable having a large number of accommodating cores is required when the number of subscribers is large, and the diameter is increased. For example, it is not preferable when laying in a pipeline. For this reason, a wavelength division multiplexing (WDM) technique for overlapping a number of subscriber signals on one optical fiber is effective, and an optical fiber cable capable of high-speed transmission is desired.
When the link PMD is 0.2 (ps / km ^1/2 ) or less as in the optical fiber cable according to the present invention, the transmittable distance is 156 km when the transmission speed is 40 Gbps, and A sufficient communication amount can be obtained.
Further, when the link PMD is 0.1 (ps / km ^1/2 ) or less, the transmittable distance is 625 km when the transmission speed is 40 Gbps, and 156 km when the transmission speed is 80 Gbps, which is more preferable.

Here, a method for measuring the transmission loss by branching from the optical fiber cable in the middle will be described with reference to FIG.
First, as shown in FIG. 12, on one side of the optical fiber cable 1, a light source 20 for making light having a wavelength of 1.55 μm incident on the first optical fiber 11a out of an arbitrary optical fiber ribbon. The light receiver 21 and the storage oscilloscope 22 are connected to the other optical fiber 11a. In this state, light having a wavelength of 1.55 μm is incident from the light source 20 to the first optical fiber 11a. The incident light is transmitted to the other side of the optical fiber 11 a and is received by the light receiver 21. The amount of received light is observed by the storage oscilloscope 22 in a timely manner.

  Then, in a state where light from the light source 20 is incident, the sheath and the presser winding are removed at a length of about 500 mm at the intermediate portion of the optical fiber cable 1, the spacer 3 is bent while twisting, and the light source is emitted from the groove. The optical fiber ribbon 10c including the optical fiber 11a into which 20 light is incident is taken out. Then, the optical fiber ribbon 10c was branched into a single core, and the fourth core 11b was cut. The method of branching the optical fiber ribbon 10c is based on the above-described procedure described with reference to FIG.

The measurement of the transmission loss was performed by observing with the storage oscilloscope 22 from the time when the sheath of the optical fiber cable 1 was removed until the end of the work.
As a result, the amount of increase in transmission loss during work was not observed to be 1.0 dB or more for the G652 optical fiber, and 0.5 dB or more was not recognized for the optical fiber having a mode field diameter of 10 μm or less. .

Moreover, the test similar to said optical fiber cable 1 was done also about the optical fiber cable of the other aspect which concerns on this invention.
The optical fiber cable 1 shown in FIG. 1 is an optical fiber cable having an SZ spacer, but a 200-fiber optical fiber cable (not shown) having a unidirectionally twisted spacer is transmitted at a wavelength of 1.55 μm. Loss values and polarization mode dispersion (PMD) values were measured. In addition, the amount of increase in transmission loss during intermediate post-branching was measured.
The cross section of the optical fiber cable to be tested is substantially the same as that of the optical fiber cable 1 shown in FIG. 1, and the spacer has a diameter of 12 mm and the sheath has an outer diameter of 16 mm. The tensile body disposed at the center is a steel wire, and the ten grooves are formed in a spiral shape in one direction in a state parallel to each other along the longitudinal direction. The twisting direction of this groove is left-handed twisting, and the twisting pitch is 500 mm.

The optical fiber ribbon used here is the same as that of the optical fiber cable 1 described above. However, optical fibers compliant with G652 were used for all 200 cores.
The maximum transmission loss value of the optical fiber in the state accommodated in the optical fiber cable was 0.22 dB / km, and the average value was 0.20 dB / km. The polarization mode dispersion value has an average value of 0.027 (ps / km ^1/2 ), a standard deviation of 0.021 (ps / km ^1/2 ), and a link PMD of 0.048 ( ps / km ^1/2 ).
Further, in the intermediate post-branching test similar to the above optical fiber cable 1, an increase in transmission loss of 1.0 dB or more was not recognized.

Moreover, the test similar to said optical fiber cable 1 was done also about the optical fiber cable of the other aspect which concerns on this invention shown in FIG.
The optical fiber cable 1 shown in FIG. 1 is a 200-core type optical fiber cable having an SZ spacer, but the optical fiber cable shown in FIG. 13 is a 1000-core type optical fiber cable having a unidirectional twisted slot. 1a. With respect to this optical fiber cable 1a, a transmission loss value and a polarization mode dispersion (PMD) value at a wavelength of 1.55 μm were measured. In addition, the amount of increase in transmission loss during intermediate post-branching was measured.

  In the optical fiber cable 1a to be tested, the spacer 3a has a diameter of 23 mm and the sheath 6d has an outer diameter of 28 mm. The tensile body arranged in the center is a structure in which seven steel wires 2a are spirally twisted, and the 13 grooves 4a are parallel to each other along the longitudinal direction in a spiral direction in one direction. Is formed. Of the 13 grooves 4a, 10 optical fiber tape cores 10d are stacked and accommodated in 12 grooves 4a, and the remaining one groove 4a formed shallow has an optical fiber tape core. Five lines 10d are stacked and accommodated. The twisting direction of the groove 4a is left-handed twisting, and the twisting pitch is 500 mm.

  The optical fiber ribbon 10d accommodated in the optical fiber cable 1a is an 8-core optical fiber ribbon 10d shown in FIG. This optical fiber tape core wire 10d is a four-core optical fiber tape core wire 10c shown in FIG. Of the 1000 optical fibers accommodated, 500 fibers conforming to G652 were used, and the remaining 500 fibers having a mode field diameter of 10 μm or less were used.

The transmission loss value of the optical fiber in the state accommodated in the optical fiber cable 1a was a G652 optical fiber, the maximum value was 0.22 dB / km, and the average value was 0.20 dB / km. For an optical fiber having a mode field diameter of 10 μm or less, the maximum value was 0.21 dB / km, and the average value was 0.19 dB / km.
The polarization mode dispersion value is G652 optical fiber, the average value is 0.020 (ps / km ^1/2 ), the standard deviation is 0.015 (ps / km ^1/2 ), and the link PMD was 0.042 (ps / km ^1/2 ). In an optical fiber having a mode field diameter of 10 μm or less, the average value is 0.026 (ps / km ^1/2 ), the standard deviation is 0.018 (ps / km ^1/2 ), and the link PMD is 0.00. 044 (ps / km ^1/2 ).

  Further, in the intermediate post-branch test similar to the above optical fiber cable 1 (however, the removal length of the sheath 6d is 750 mm), an increase in transmission loss of 1.0 dB or more is not recognized in the G652 optical fiber, and the mode field No increase in transmission loss of 0.5 dB or more was observed in an optical fiber having a diameter of 10 μm or less.

As described above, an optical fiber cable having an increase in loss at the time of intermediate post-branching of 1.0 dB or less can perform the intermediate post-branch in a live state, so that only a desired optical fiber is appropriately branched. The other optical fiber can be used on the downstream side. Therefore, all the optical fibers accommodated in the optical fiber cable can be effectively used. Therefore, the construction cost of the communication line can be kept low.
In addition, an optical fiber cable with an increase in loss of 0.5 dB or less at the time of branching after the intermediate is desired even if high-speed communication is performed using an optical fiber that is not branched or communication is performed in a region having a small dynamic range. The optical fiber can be branched and taken out. Therefore, the degree of freedom in designing the optical communication network is improved.

Next, a preferable arrangement of the optical fiber ribbon in the spacer groove will be described.
As in the optical fiber ribbons 10b and 10c shown in FIGS. 7 and 8, recesses 16 and 16c corresponding to the depressions between the adjacent optical fibers 11 are formed in the resins 12b and 12c constituting the outer cover. In the case where the optical fiber tape cores 10b and 10c are laminated adjacent to each other, the optical fiber tape cores 10b and 10c may be laminated so as to be shifted in the width direction by an odd multiple of the half of the parallel pitch of the optical fibers 11. That is, as shown in FIG. 15, the parallel pitch of the optical fibers 11 included in the optical fiber ribbon 10c is P (μm), and the number of optical fibers 11 included in the optical fiber ribbon 10c is ½ or less. Where m is a natural number including 0, each of the optical fiber ribbons 10c is mP + P / 2 (μm) in the width direction of the optical fiber ribbon 10c with respect to the adjacent optical fiber ribbon 10c. It is good if they are stacked with a gap.

  In this case, since the optical fiber ribbon 10c has an outer shape having irregularities in the width direction along the outer periphery of the optical fiber 11, the adjacent optical fiber ribbons 10c come into contact so as to complement each other's irregularities. . Therefore, the thickness of the tape core laminated body (stack) 30 constituted by the plurality of optical fiber ribbons 10c laminated in the groove 4 is reduced. Therefore, the depth of the groove 4 can be reduced, and the diameter of the optical fiber cable can be reduced. Moreover, the unevenness | corrugation of adjacent optical fiber tape core wire 10c fits, the integration effect | action as the tape core wire laminated body 30 generate | occur | produces, and a lamination state becomes easy to become stable.

  Further, in order to reduce the length in the width direction of the tape core laminate 30 formed by laminating the optical fiber ribbons 10c, the value of m is set to 0, and the adjacent optical fiber ribbons 10c are connected to each other. It is preferable that the layers are stacked with being shifted by / 2 (μm). In this case, the length of the groove 4 in the width direction can be shortened, and the diameter of the optical fiber cable can be reduced.

  Also, as shown in FIG. 16, if the laminating direction in the width direction is sequentially alternated and shifted by a half distance of the parallel pitch P with respect to the adjacent optical fiber tape cores 10c, The length in the width direction of the body 30 can be further reduced. Moreover, it becomes easier to maintain the stable laminated state of the tape core laminate 30.

  When the adjacent optical fibers 11 included in the optical fiber ribbon 10c are arranged in contact with each other, the parallel pitch P and the outer diameter d of the optical fiber 11 are equal, and the shift amount mP + P in the width direction is equal. / 2 can also be calculated by md + d / 2. On the other hand, when the adjacent optical fibers 11 are not in contact with each other, the sum of the interval between the optical fibers 11 and the outer diameter d is a value of the parallel pitch P.

  Further, when the spacer of the optical fiber cable is an SZ spacer, the twist direction of the groove 4 is periodically reversed. Therefore, the optical fiber ribbon core 30c of the optical fiber ribbon 10c accommodated therein is used. In the inner side of the groove 4, its posture is rotated relative to the groove 4 along the longitudinal direction, and is periodically reversed. At that time, the optical fiber ribbon 10c is laminated by sequentially shifting the optical fiber ribbon 10c in the width direction by half the length of the parallel pitch P of the optical fibers 11 as described above. It is easy to maintain the state, and it is possible to prevent the optical fiber 11 from being distorted due to the collapse of the laminated state, thereby suppressing an increase in transmission loss.

Moreover, the figure which represented typically the preferable magnitude | size of the groove | channel with respect to a tape core laminated body in FIG. 17 is shown.
As described above, in the case of the SZ spacer, the tape core laminated body 30 rotates along the longitudinal direction with respect to the groove 4. Therefore, the size of the groove 4 in a sectional view may be set to a size that can enclose the circumscribed circle 33 of the tape core laminate 30. As a result, the tape core laminated body 30 can be rotated without difficulty in the groove 4 while maintaining the laminated state, and an excessive distortion can be prevented from being applied to the optical fiber 11 and an increase in transmission loss can be suppressed. Further, by alternating the stacking deviations of the optical fiber ribbons 10c in the tape core laminate 30, the radius of the circumscribed circle 33 is reduced, and the size of the groove 4 can be reduced accordingly.

  Moreover, it is good also as the substantially trapezoidal groove | channel 4b instead of the groove | channel 4 of a substantially rectangular cross section. In that case, by making the groove width Wsb at the bottom of the groove 4b equal to or greater than the width W of the accommodated optical fiber ribbon 10c, application of lateral pressure to the optical fiber ribbon 10c disposed at the bottom of the groove 4b is prevented. it can.

The diameter 2R of the circumscribed circle 33 of the tape core laminate 30 is determined from the length of the diagonal line 32 of the quadrangle 31 circumscribing the optical fiber tape core 10c located at the bottom and top of the tape core laminate 30. The length excluding the distance between the apex of the quadrilateral 31 and the tape core laminate 30 can be calculated. That is, the diameter 2R of the circumscribed circle 33 is obtained by the following equations (1) to (3) using the respective lengths shown in FIG. 18 in which the upper left portion of the quadrangle 31 in FIG. 17 is enlarged.
2R = {(nT− (n−1) z) ² + (W + P / 2) ² } ^1/2 −2C (1)
z = T− (T ² − (P / 2) ² ) ^1/2 (2)
C = {(T / 2) ² + (d / 2 + t ₂ ) ² } ^1/2 − {d / 2 + (t + t ₂ ) / 2} (3)
In the formulas (1) to (3), W is the width of the optical fiber ribbon 10c, n is the number of laminated optical fiber ribbons 10c, T is the thickness of the optical fiber ribbon 10c, and d is The outer diameter of the optical fiber 11, f is the number of optical fibers 11 included in the optical fiber ribbon 10 c, z is the overlap length between adjacent optical fiber ribbons 10 c, and C is the apex of the rectangle 31 and the tape core The distance from the wire laminate 30, t ₂ is the thickness of the jacket 12 c at the edge of the optical fiber ribbon 10 c.

In the embodiment shown in FIG. 17, the optical fiber tape cores 10c constituting the tape core laminate 30 are an even number, and the diagonal length of the quadrangle 31 is {(nT− (n− 1) z) ² + (W + P / 2) ² } ^1/2 is calculated, but the number of the optical fiber ribbons 10c constituting the ribbon ribbon 30a is an odd number as shown in FIG. In some cases, the diagonal length of the quadrilateral 31a circumscribing the tape core laminate 30a is calculated by {(nT− (n−1) z) ² + W ² } ^1/2 . Therefore, when the tape core laminated body 30a is constituted by an odd number of optical fiber tape cores 10c, the following equation (4) may be used instead of the above equation (1) in obtaining the circumscribed circle 33a.
2R = {(nT− (n−1) z) ² + W ² } ^1/2 −2C (4)

  Also, as shown in FIGS. 20 and 21, the cross-sectional shape of the bottom of the grooves 4c and 4e is an arc shape, and the radius of the arc portions 4d and 4f is equal to or greater than the radius of the circumscribed circles 33 and 33a. , 4e, the tape core laminates 30, 30a can be smoothly rotated. Thereby, the increase in transmission loss can be prevented more effectively.

It is sectional drawing which shows one Embodiment of the optical fiber cable which concerns on this invention. It is sectional drawing of the optical fiber tape core wire accommodated in the optical fiber cable shown in FIG. It is a schematic diagram which shows the branching method of an optical fiber ribbon. It is sectional drawing of the optical fiber tape core wire accommodated in the optical fiber cable shown in FIG. It is a schematic diagram which shows the mode of the intermediate | middle post branching test of an optical fiber ribbon. It is a schematic diagram which shows the mode of the isolation | separation test of an optical fiber ribbon. It is a figure which shows the optical fiber ribbon core accommodated in the optical fiber cable shown in FIG. 1, (A) is sectional drawing, (B) is a perspective view. It is a figure which shows the optical fiber ribbon core accommodated in the optical fiber cable shown in FIG. 1, (A) is sectional drawing, (B) is a perspective view. It is sectional drawing which shows the state which the optical fiber tape core wire shown in FIG. 8 is bent. It is a perspective view which shows the mode at the time of measuring the adhesive force of an optical fiber and a jacket. It is a schematic diagram which shows the mode at the time of measuring the adhesive force of an optical fiber and a jacket. It is a schematic diagram which shows the mode of the test which branches an optical fiber tape core wire from an optical fiber cable after intermediate | middle. It is sectional drawing which shows other embodiment of the optical fiber cable which concerns on this invention. It is sectional drawing which shows the optical fiber tape core wire accommodated in the optical fiber cable shown in FIG. It is typical sectional drawing which shows an example of preferable arrangement | positioning of an optical fiber tape core wire. It is typical sectional drawing which shows the other example of preferable arrangement | positioning of an optical fiber tape core wire. It is typical sectional drawing which shows an example of the preferable magnitude | size of the groove | channel of a spacer. It is a schematic diagram which shows the length used when calculating the diameter of the circumscribed circle in FIG. It is typical sectional drawing which shows the other example of the preferable magnitude | size of the groove | channel of a spacer. It is typical sectional drawing which shows an example of the preferable magnitude | size of the groove | channel where a bottom part has circular arc shape. It is typical sectional drawing which shows the other example of the preferable magnitude | size of the groove | channel where a bottom part has circular arc shape. It is sectional drawing which shows an example of the conventional optical fiber cable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical fiber cable 2 Strength body 3 Spacer 4 Groove 5 Holding winding 6 Sheath 10 Optical fiber tape core wire 11 Optical fiber 12 Jacket (resin)
13 Glass fiber 14 Primary protective coating 15 Secondary protective coating 16 Recess 17 Bottom

Claims (30)

One or a plurality of optical fiber ribbons are disposed on the inner side of the spacer in which a substantially spiral groove is formed on the outer peripheral surface of a substantially cylindrical plastic long body having a tensile body at the center. A fiber optic cable housed in layers,
In the optical fiber ribbon, a plurality of optical fibers are juxtaposed, and the total length of the optical fibers is integrated with a resin, and the maximum thickness of the optical fiber ribbon is T ( μm), and T ≦ d + 40 (μm) when the outer diameter of the optical fiber is d (μm). One or a plurality of optical fiber ribbons are disposed on the inner side of the spacer in which a substantially spiral groove is formed on the outer peripheral surface of a substantially cylindrical plastic long body having a tensile body at the center. A fiber optic cable housed in layers,
The optical fiber tape core is formed by arranging a plurality of optical fibers in parallel and covering and integrating the total length of the plurality of optical fibers and the entire circumference of the optical fibers with a resin. An optical fiber cable, wherein T ≦ d + 40 (μm), where T (μm) is the maximum value of the thickness of the wire and d (μm) is the outer diameter of the optical fiber. The optical fiber cable according to claim 1 or 2,
The optical fiber cable, wherein the adjacent optical fibers are arranged in contact with each other. The optical fiber cable according to claim 1 or 2,
In the optical fiber ribbon, at least two adjacent optical fibers are not in contact with each other, and are arranged with an interval of 10 (μm) or less. Fiber cable. The optical fiber cable according to any one of claims 1 to 4,
An optical fiber cable, wherein the optical fiber ribbon is T ≧ d + 1 (μm). The optical fiber cable according to any one of claims 1 to 5,
The resin of the optical fiber ribbon is formed with a recess corresponding to a recess between adjacent optical fibers. The optical fiber cable according to claim 6,
The optical fiber cable is characterized in that the optical fiber ribbon is T ≦ d + 30 (μm). The optical fiber cable according to claim 6 or 7,
The optical fiber cable is characterized in that (T−d) /2Y≦4.0 (μm) when the depth of the recess is Y (μm). An optical fiber cable according to claim 8,
The optical fiber cable is characterized in that g ≦ d when the thickness of the optical fiber ribbon in the recess is g (μm). An optical fiber cable according to claim 9,
An optical fiber cable, wherein the optical fiber ribbon is g ≦ 0.8d. The optical fiber cable according to any one of claims 6 to 10,
The parallel pitch of the optical fibers included in the optical fiber ribbon is P (μm), and a natural number including 0 which is 1/2 or less of the number of the optical fibers included in the optical fiber ribbon is m. Sometimes, a plurality of the optical fiber ribbons are stacked with a deviation of mP + P / 2 (μm) in the width direction of the optical fiber ribbon with respect to the adjacent optical fiber ribbons. Features an optical fiber cable. An optical fiber cable according to claim 11,
The optical fiber cable, wherein m is 0. An optical fiber cable according to claim 12,
An optical fiber cable, wherein a plurality of the optical fiber ribbons are stacked alternately and sequentially shifted in the width direction with respect to the adjacent optical fiber ribbons. The optical fiber cable according to any one of claims 1 to 4,
An optical fiber cable, wherein the optical fiber ribbon is T ≦ d + 25 (μm). The optical fiber cable according to any one of claims 1 to 14,
The optical fiber ribbons are two straight lines passing through the centers of the two optical fibers perpendicular to a straight line connecting the centers of the two adjacent optical fibers in the cross section. In the inner area to be partitioned,
The ratio of the ES product of the resin to the sum of the ES products of the optical fibers when the Young's modulus is E and the cross-sectional area is S is 0.026 or less. The optical fiber cable according to claim 15,
The optical fiber ribbons are two straight lines passing through the centers of the two optical fibers perpendicular to a straight line connecting the centers of the two adjacent optical fibers in the cross section. In the inner area to be partitioned,
The ratio of the ES product of the resin to the sum of the ES products of the optical fibers is 0.020 or less. The optical fiber cable according to any one of claims 1 to 16,
In the optical fiber ribbon, the optical fiber and the resin per one optical fiber have an adhesion force between 0.025 (gf) and 0.25 (gf). Fiber cable. The optical fiber cable according to any one of claims 1 to 17,
The optical fiber cable, wherein the resin has a yield point stress of 20 (MPa) to 45 (MPa). The optical fiber cable according to any one of claims 1 to 18,
The groove is formed in a spiral shape in one direction along the longitudinal direction of the spacer. The optical fiber cable according to claim 19,
The link polarization mode dispersion of any wavelength within the wavelength range of 1.26 (μm) to 1.65 (μm) in all the optical fibers accommodated is 0.05 (ps / km ^1/2). ) An optical fiber cable characterized by: The optical fiber cable according to any one of claims 1 to 18,
The optical fiber cable is characterized in that the groove is formed in a spiral shape that is alternately inverted along the longitudinal direction of the spacer. The optical fiber cable according to claim 21,
The link polarization mode dispersion of any wavelength within the wavelength range of 1.26 (μm) to 1.65 (μm) in all the optical fibers accommodated is 0.2 (ps / km ^1/2). ) An optical fiber cable characterized by: The optical fiber cable according to claim 21,
The link polarization mode dispersion of any wavelength within the wavelength range of 1.26 (μm) to 1.65 (μm) in all the optical fibers accommodated is 0.1 (ps / km ^1/2). ) An optical fiber cable characterized by: The optical fiber cable according to claim 21,
Inside the groove, a plurality of the optical fiber ribbons are sequentially and alternately shifted in the width direction by half the parallel pitch of the optical fibers with respect to the adjacent optical fiber ribbons. And
The resin of the optical fiber ribbon is formed with a recess corresponding to a recess between the adjacent optical fibers,
The optical fiber cable, wherein the groove has a size that encloses a circumscribed circle of a laminated core of optical fiber tapes formed of the laminated optical fiber ribbons in a sectional view. An optical fiber cable according to claim 24,
The cross section of the groove is substantially trapezoidal, and the groove width at the bottom of the groove is equal to or greater than the width of the accommodated optical fiber ribbon. An optical fiber cable according to claim 24,
In the cross section of the groove, the bottom of the groove has an arc shape, and the radius of the arc is not less than the radius of the circumscribed circle. An optical fiber cable according to any one of claims 1 to 26, wherein
The optical fiber has a mode field diameter of 10 (μm) or less according to the definition of Petermann-I at a wavelength of 1.55 (μm). The optical fiber cable according to any one of claims 1 to 27,
The optical fiber has a mode field diameter of 8 (μm) or less according to the definition of Petermann-I at a wavelength of 1.55 (μm). The optical fiber cable according to any one of claims 1 to 28, wherein:
The optical fiber cable has an increase in loss when the optical fiber is branched is 1.0 (dB) or less. The optical fiber cable according to any one of claims 1 to 29,
The optical fiber cable has a loss increase of 0.5 (dB) or less when the optical fiber is branched.

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