Fiber optic cable

Abstract

In this optical fiber cable in which an optical fiber ribbon formed by arranging a plurality of optical fiber cores parallel in an internal space, core parts of the optical fiber cores are constituted from pure quartz glass, the effective cross section of the core parts at a wavelength of 1550 nm is 110 µm2 to 150 µm2, and the optical fiber cores form an intermittently coupled optical fiber ribbon including an intermittent coupling section in which coupled sections in which an adhesive resin is applied and non-coupled sections in which an adhesive resin is not applied between adjacent optical fiber cores are alternately provided, thereby coupling the optical fiber cores. In the optical fiber ribbon, in a unit length of the optical fiber cores, the ratio of the total bonded length in which the adhesive resin is applied with respect to the total length between all cores is 40% or greater, and the occupancy of the optical fiber ribbon with respect to the cross-sectional area of the internal space is 30-40%.

Description

Technical Field

[0001] The present disclosure relates to an optical fiber cable. This application claims priority based on Japanese Patent Application No. 2021-137057 filed on August 25, 2021, and incorporates all the descriptions described in the above application.

Background Art

[0002] Patent Document 1 describes an optical fiber cable in which an optical fiber ribbon core wire is accommodated in a SZ twist slot rod. In this optical fiber cable, in order to reduce the diameter of the optical fiber cable while ensuring good transmission characteristics without increasing loss, the optical fiber ribbon core wire has connecting portions and non-connecting portions intermittently formed in the longitudinal direction between adjacent optical fiber core wires. And the occupancy rate of the optical fiber ribbon core wire calculated from the cross-sectional area of the optical fiber ribbon core wire with respect to the cross-sectional area of the slot groove is 35% or more and 60% or less.

[0003] Patent Document 2 describes an optical fiber cable in which an optical fiber ribbon core wire is accommodated in a slot rod having a plurality of slot grooves. In this optical fiber cable, in order to densely mount the optical fiber core wire, the outer diameter dimension of the optical fiber core wire is 0.22 mm or less, and the optical fiber ribbon core wire has connecting portions and non-connecting portions intermittently formed in the longitudinal direction between adjacent optical fiber core wires. And the density of the number of cores of the optical fiber core wire is 4.8 cores / mm or more in the cross-section of the optical fiber cable.

[0004] Patent Document 3 describes an optical fiber cable that houses an optical unit in which multiple optical fiber ribbon fibers, each composed of multiple optical fiber cores, are gathered in a slot rod having multiple grooves. In this optical fiber cable, even when the optical fiber ribbon fibers are mounted in the grooves at high density, the optical unit is housed in the grooves in a twisted state in order to suppress the occurrence of macrobend loss. Furthermore, the occupancy rate of the optical unit, calculated from the cross-sectional area of ​​the optical unit relative to the cross-sectional area of ​​the groove, is set to be between 25% and 60%. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-211511 [Patent Document 2] Japanese Patent Application Publication No. 2017-223730 [Patent Document 3] Japanese Patent Application Publication No. 2017-32749 [Overview of the project] [Means for solving the problem]

[0006] An optical fiber cable relating to one aspect of this disclosure is An optical fiber cable that implements an optical fiber ribbon core, formed by arranging multiple optical fiber cores in parallel, in its internal space, The core portion of the optical fiber is made of pure quartz glass, and the effective cross-sectional area of ​​the core portion at a wavelength of 1550 nm is 110 μm² or more and 150 μm² or less. The optical fiber cores constitute an intermittently connected optical fiber ribbon cable, which includes intermittently connected sections where connecting sections coated with adhesive resin and non-connecting sections not coated with adhesive resin are alternately provided between adjacent optical fiber cores. In the optical fiber ribbon, the ratio of the total adhesive length to which the adhesive resin is applied to the total length between all the cores in a unit length of the optical fiber ribbon is 73% or more and 85% or less And, The occupancy rate of the optical fiber ribbon cores relative to the cross-sectional area of ​​the internal space is 30% or more and 40% or less. [Modes for carrying out the invention]

[0007] (Issues that this disclosure aims to resolve) To accommodate the transition to next-generation mobile communication systems and the increase in signal capacity due to the increase in video information, there is a growing need for optical fiber cables that enable efficient signal transmission. To meet these needs, there is room for improvement in the configuration of optical fiber cables as shown in Patent Documents 1 to 3. In particular, to input high-power optical signals, it is desirable to increase the effective cross-sectional area of ​​the optical fiber, but increasing the density of optical fibers with a large effective cross-sectional area tends to increase losses. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a cross-sectional view showing an optical fiber cable according to the first embodiment. [Figure 2] Figure 2 is a cross-sectional view of the optical fiber cores housed in the optical fiber cable shown in Figure 1. [Figure 3] Figure 3 is a plan view of an intermittently connected optical fiber ribbon cable, where each core is housed within the optical fiber cable. [Figure 4] Figure 4 is a plan view of a two-core intermittently connected optical fiber ribbon cable housed in an optical fiber cable. [Figure 5] Figure 5 is a cross-sectional view showing an optical fiber cable according to the second embodiment.

[0009] (Effects of this disclosure) According to this disclosure, it is possible to provide an optical fiber cable that can suppress transmission loss, accept high-power optical signals, and accommodate optical fiber ribbon cores at high density.

[0010] (Description of the embodiments of this disclosure) First, the embodiments of this disclosure will be listed and described. An optical fiber cable according to one aspect of the present disclosure is (1) an optical fiber cable in which an optical fiber tape core wire formed by arranging a plurality of optical fiber core wires in parallel is mounted in an internal space, The core part of the optical fiber core wire is made of pure silica glass, and the effective cross-sectional area of the core part at a wavelength of 1550 nm is 110 μm2 or more and 150 μm2 or less, The optical fiber core wire includes an intermittent connection type optical fiber tape core wire connected by alternately providing a connection part coated with an adhesive resin and a non-connection part not coated with the adhesive resin between adjacent optical fiber core wires. For the optical fiber tape core wire, in the unit length of the optical fiber core wire, the ratio of the total length of the adhesive lengths coated with the adhesive resin to the total length between all the core wires is 73% or more and 85% or less and the occupancy rate of the optical fiber tape core wire with respect to the cross-sectional area of the internal space is 30% or more and 40% or less. According to this configuration, since the effective cross-sectional area of the core part is 110 μm2 or more and 150 μm2 or less, a high-power optical signal can be input. The occupancy rate, which is the ratio of the cross-sectional area of the optical fiber tape core wire mounted with respect to the cross-sectional area of the internal space, is 30% or more and 40% or less, so that the optical fiber tape core wire can be accommodated at a high density. Further, in the unit length of the optical fiber core wire, the ratio of the adhesive length coated with the adhesive resin to the total length between all the core wires is 73 % or more, so the bending rigidity of the optical fiber tape core wire is high, and even when a bending stress is applied to the cable, buckling of the optical fiber core wire is unlikely to occur. Thereby, an optical fiber cable with low transmission loss can be realized.

[0011] Note that pure silica glass means silica glass that does not contain a dopant, but a certain amount of impurities is allowed as long as it does not affect the characteristics.

[0012] Also, an optical fiber cable according to one aspect of the present disclosure is (2) The intermittent connection part may be provided every two optical fibers in the optical fiber ribbon core wire. Since the intermittent connection part is provided every two optical fibers in the optical fiber ribbon core wire, the non-connection part is also provided every two optical fibers. At this time, the bending rigidity of the optical fiber ribbon core wire is increased, so that even when bending stress is applied to the cable, buckling of the optical fiber core wire is less likely to occur. Thereby, an optical fiber cable with further reduced transmission loss can be realized.

[0014] (4) The optical fiber cable according to any one of (1) to (3) above may be a tape slot type optical fiber cable having a slot rod. According to this configuration, in a tape slot type optical fiber cable, it is possible to suppress transmission loss and input a high-power optical signal, and a cable capable of accommodating optical fiber ribbon core wires at a high density can be realized.

[0015] ((s) The optical fiber cable according to any one of (1) to (3) above may be a slotless type optical fiber cable having a cable core formed by twisting a plurality of optical fiber ribbon core wires together and a cable jacket provided around the cable core. According to this configuration, even if the same number of fiber cores as in a tape slot type optical fiber cable are accommodated, a cable with a smaller diameter and lighter weight can be realized because it does not have a slot rod.

[0016] (Details of Embodiments of the Present Disclosure) A specific example of an optical fiber cable according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, and is intended to be indicated by the claims and to include all modifications within the meaning and scope equivalent to the claims.

[0017] (First Embodiment) FIG. 1 is a cross-sectional view of an optical fiber cable 1A according to the first embodiment. As shown in Figure 1, the optical fiber cable 1A is a tape-slot type optical fiber cable and comprises a slot rod 10, a tension member 12 embedded in the center of the slot rod 10, a retaining tape 14 wrapped around the slot rod 10, and an outer sheath 16 covering the retaining tape 14. The slot rod 10 has a plurality of (five in this example) slot grooves 11 (11a to 11e: examples of internal spaces) that can accommodate optical fiber ribbon cores 5. Position identification marks 18 are provided on the outer circumference of the slot rod 10 to identify the position of the slot grooves 11. In the first embodiment, the internal space corresponds to five slot grooves 11.

[0018] The slot rod 10 is a long body with a substantially circular cross-section. The slot groove 11 is formed spirally along the longitudinal direction on the outer surface of the slot rod 10. The spiral shape of the slot groove 11 may be a unidirectional spiral or an SZ shape that periodically reverses. The optical fiber cable 1A shown in Figure 1 is an example of a 100-core tape slot type cable in which five 4-core optical fiber ribbon cores 5 are stacked and housed in each slot groove 11a to 11e. The optical fiber ribbon cores 5, when housed in the slot groove 11, may be twisted with a twist pitch equal to the spiral pitch of the slot groove 11, and twisted in accordance with the twist direction of the slot groove 11. Details of the optical fiber ribbon cores 5 will be described later.

[0019] In the optical fiber cable 1A shown in Figure 1, the slot groove 11 is formed in a rectangular shape, but this is not limited to this. The shape of the slot groove 11 may be formed in a U-shape, for example. Furthermore, the way in which the optical fiber ribbon cores 5 are housed in the slot groove 11 is not limited to stacking multiple sheets, but for example, the optical fiber ribbon cores 5 may be rolled up by bending them in the width direction, that is, in the direction in which the optical fiber cores are parallel, and multiple sheets may be housed. Also, the number of optical fiber cores constituting the optical fiber ribbon core can be any number, and is not limited to four.

[0020] Figure 2 is a cross-sectional view of the optical fiber cores 20 that make up the optical fiber ribbon cable 5. As shown in Figure 2, the optical fiber core 20 has a glass fiber 23 composed of a core portion 21 with a refractive index higher than the surrounding glass and a cladding portion 22 surrounding the core portion 21, two coating layers 24 and 25 covering the glass fiber 23, and a colored layer 26 covering the coating layer 25. The inner coating layer 24 of the two coating layers is formed from a cured primary resin. The outer coating layer 25 of the two coating layers is formed from a cured secondary resin.

[0021] The glass fiber 23 has a core portion 21 in the center, and a cladding portion 22 surrounding the core portion 21. The core portion 21 is made of pure quartz glass without additives. The effective cross-sectional area (Aeff) of the core portion 21 at a wavelength of 1550 nm is 110 μm². 2 More than 150μm 2 It is formed as follows:

[0022] The primary resin constituting the inner primary coating layer 24 that contacts the glass fiber 23 uses a relatively soft resin with a low Young's modulus as a buffer layer. The secondary resin constituting the outer secondary coating layer 25 uses a relatively hard resin with a high Young's modulus as a protective layer. The Young's modulus of the cured primary resin is 1.0 MPa or less, preferably 0.7 MPa or less, at room temperature (e.g., 23°C). The Young's modulus of the cured secondary resin is 900 MPa or more, preferably 1000 MPa or more, and more preferably 1500 MPa or more, at room temperature (e.g., 23°C). The outer diameter of the optical fiber core 20 is formed to be, for example, 220 μm or less.

[0023] In an optical fiber cable 1A with this configuration, the occupancy rate, which is the ratio of the sum of the cross-sectional areas of the optical fiber ribbon cores 5 housed in each slot groove 11a to 11e (total cross-sectional area of ​​the optical fiber ribbon cores 5) to the sum of the cross-sectional areas of each slot groove 11a to 11e, is designed to be between 30% and 40%. If the cross-sectional area of ​​each slot groove and the number of ribbon cores housed in each slot groove are equal in each slot groove, the occupancy rate of the total cross-sectional area of ​​the optical fiber ribbon cores 5 will be "total cross-sectional area of ​​optical fiber ribbon cores housed in each slot groove" / "cross-sectional area of ​​each slot groove".

[0024] (Intermittent connection of each core in optical fiber ribbon cable) Next, the optical fiber ribbon cable 5 in this embodiment will be described. Figure 3 is a plan view of the optical fiber ribbon cable 5 housed in the optical fiber cable 1A (see Figure 1). Note that Figure 3 shows the optical fiber ribbon cable 5 with the optical fiber cores 20 opened in the arrangement direction.

[0025] As shown in Figure 3, the optical fiber ribbon cable 5 has intermittent connection sections 8 that alternately and repeatedly run along the longitudinal direction, where adjacent optical fiber cores 20 are connected by adhesive resin in a state where four optical fiber cores 20 are arranged in parallel, and there are connection sections 6 where adjacent optical fiber cores 20 are connected and unconnected sections 7 where adjacent optical fiber cores 20 are not connected. Since the intermittent connection sections 8 are provided between each adjacent optical fiber core 20, the optical fiber ribbon cable 5 is an optical fiber ribbon cable of the intermittent connection type for each individual core.

[0026] Referring to Figure 3, we will now explain the adhesive length ratio of an intermittently connected optical fiber ribbon cable, in which n optical fiber cores (n=4 in Figure 3) are arranged in parallel. The adhesive length ratio is the ratio of the total adhesive length to which adhesive resin is applied to the total length between all optical fiber cores in a unit length of the optical fiber ribbon cable.

[0027] The length of the intermittent connection section 8, which is the sum of one connection section 6 and one disconnection section 7 (pitch p), is defined as the unit length of the optical fiber ribbon cable 5. If the length of one connection section 6 is a and the length of one disconnection section 7 is c, then the pitch p = a + c. In this case, since n optical fiber cores are arranged in parallel, the total length between all cores corresponding to the unit length of the optical fiber ribbon cable 5 is expressed as (n-1) × p.

[0028] Furthermore, the total length of adhesive resin applied can be expressed as (n-1) × a, since there are (n-1) connecting sections (adhesive length a).

[0029] Therefore, the adhesive length ratio is {(n-1)×a} / {(n-1)×p}=a / p.

[0030] (Two-core intermittently connected optical fiber ribbon cable) Next, another example of the optical fiber ribbon cable 5 will be described. Figure 4 is a plan view of the optical fiber ribbon cable 105 housed in the optical fiber cable 1A (see Figure 1). Note that Figure 4 shows the optical fiber ribbon cable 105 with the optical fiber cores 20 opened in the arrangement direction.

[0031] As shown in Figure 4, in the optical fiber ribbon cable 105, when four optical fiber cores 20 are arranged in parallel, the arrangement alternates between adjacent optical fiber cores 20 that are entirely bonded with adhesive resin without intermittent connecting sections, and adjacent optical fiber cores 20 that have intermittent connecting sections 108, repeating this pattern every single core. Since the intermittent connecting sections 108 are provided every two cores, the optical fiber ribbon cable 105 is an optical fiber ribbon cable with intermittent connections every two cores.

[0032] Referring to Figure 4, we will now explain the ratio of the total adhesive length to which adhesive resin is applied to a unit length of optical fiber ribbon cable with n optical fiber cores arranged in parallel in a 2-core intermittent connection type (n=12 in Figure 4).

[0033] The length (pitch p) of the intermittent connection section 108, which is the sum of one connection section 106 and one disconnection section 107 of the optical fiber ribbon cable, is defined as the unit length of the optical fiber ribbon cable 105. In this case, since n optical fiber cores 20 are arranged in parallel, the unit length of the optical fiber ribbon cable 105 is expressed as the sum of the lengths between all cores (n-1) × p.

[0034] Furthermore, the total length to which the adhesive resin is applied is calculated by subtracting the total length of the unconnected sections (unconnected length c) from the total length between all the core wires, which is (n-1) × p. Since there are (n / 2-1) unconnected sections, this can be expressed as (n-1) × p - (n / 2-1) × c.

[0035] Therefore, the adhesive length ratio is {(n-1)×p-(n / 2-1)×c} / {(n-1)×p}.

[0036] In both the intermittently connected optical fiber ribbon cable 5 with one core at a time and the intermittently connected optical fiber ribbon cable 105 with two cores at a time in this embodiment, the ratio of the total length to which adhesive resin is applied to the total length between all cores is 40% or more.

[0037] In recent years, there has been a growing need for fiber optic cables that can efficiently transmit signals, for example, to cope with the transition to 5G mobile communication systems and the increased capacity of backbone systems due to the increase in video information. Furthermore, fiber optic cables are constantly required to be thinner and lighter in terms of securing conduit space and ease of installation. However, if the occupancy rate of the fiber optic ribbon core (in the case of slot-type cables, the cross-sectional area of ​​the ribbon core / the cross-sectional area of ​​the slot groove; in the case of slotless cables, the cross-sectional area of ​​the ribbon core / the cross-sectional area inside the sheath) becomes too large in pursuit of thinner cables, the fiber optic ribbon core cannot move freely within the slot groove or sheath, and microbend loss and macrobend loss increase due to external pressure from the side walls. For this reason, in order to ensure good transmission characteristics, it is necessary to keep the occupancy rate of the fiber optic ribbon core within a predetermined range.

[0038] Therefore, in this embodiment, the optical fiber cable 1A has a core portion 21 of the optical fiber core 20 made of pure quartz glass, and the effective cross-sectional area of ​​the core portion 21 is 110 μm². 2 More than 150μm 2 The optical fiber core is formed as follows: Since the core portion 21 of the optical fiber core 20 is made of pure quartz glass without additives, the increase in transmission loss can be suppressed compared to ordinary optical fiber cores in which germanium is doped into the core. In addition, the effective cross-sectional area of ​​the core portion of the optical fiber core 20 is 110 μm². 2 More than 150μm 2 By increasing the size to the following level, the power density of the input optical signal can be reduced, simplifying the distortion of the signal waveform during transmission (preventing the distortion from becoming more complex).

[0039] Furthermore, the optical fiber ribbon cores 5,105 are formed such that their occupancy rate within the slot groove 11 (internal space), calculated by the ratio of the cross-sectional area of ​​the slot groove 11 to the cross-sectional area of ​​the optical fiber ribbon cores 5,105, is between 30% and 40%. While a larger effective cross-sectional area tends to increase losses, losses do not increase significantly if the occupancy rate is 40% or less. In other words, by setting the occupancy rate of the optical fiber ribbon cores 5,105 within the slot groove 11 to 40% or less, the optical fiber cores 20 are allowed to move somewhat freely within the slot groove 11. This reduces external pressure from the sidewalls of the slot groove 11 when, for example, the optical fiber cable 1A is bent, thereby suppressing bending losses (microbend loss and macrobend loss). Additionally, by setting the occupancy rate to 30% or more, high-density mounting of the optical fiber ribbon cores 5,105 can be ensured. Therefore, by setting the occupancy rate of the optical fiber ribbon cores 5,105 in the slot groove 11 to 30% or more and 40% or less, the optical fiber ribbon cores 5,105 can be densely accommodated while maintaining good transmission characteristics even when the effective cross-sectional area of ​​the core portion 21 is increased.

[0040] Furthermore, the optical fiber ribbon cable 5,105 is an intermittently connected ribbon cable, and the ratio of the total length to which adhesive resin is applied to the total length between all cores in a unit length of the optical fiber ribbon cable 5,105 is 40% or more. This ensures sufficient rigidity of the optical fiber ribbon cable 5,105. As a result, even if the optical fiber cable 1A is bent, the optical fiber ribbon cable 5,105 will be less likely to deform.

[0041] With the above configuration, it becomes possible to input high-power optical signals, and a fiber optic cable suitable for long-distance transmission can be provided.

[0042] Furthermore, the intermittent connection section 108 may be provided every two cores in the optical fiber ribbon cable 105. When the optical fiber ribbon cable 105 is an intermittent connection type every two cores, the length over which the adhesive resin is applied and connected is longer, and the rigidity of the optical fiber ribbon cable 105 is increased, making it easier to maintain good transmission characteristics in the optical fiber cable 1A.

[0043] Furthermore, the optical fiber ribbon cores 5,105 may be configured such that the ratio of the total length to which adhesive resin is applied to the total length between all cores is 73% or more. In this case, the rigidity of the optical fiber ribbon cores 5,105 is increased, making it easier to maintain good transmission characteristics in the optical fiber cable 1A. However, if the ratio of the total adhesive length becomes too high, the transmission loss will worsen, so it is preferable that the ratio of the total adhesive length be 85% or less.

[0044] (Second embodiment) This disclosure is also applicable to slotless optical fiber cables. Figure 5 is a cross-sectional view of a slotless optical fiber cable 1B.

[0045] As shown in Figure 5, the optical fiber cable 1B comprises a cable core 50 formed by twisting together multiple optical fiber ribbon cores 5, a retaining tape 31 provided around the cable core 50, and a cable sheath 32 covering the retaining tape 31. A tension member 33 is provided inside the cable sheath 32 along the longitudinal direction of the optical fiber cable 1B. Furthermore, a tear cord 34 is provided inside the cable sheath 32 along the longitudinal direction of the optical fiber cable 1B. In the second embodiment, the internal space corresponds to the space inside the cable sheath 32.

[0046] In this example, the cable core 50 is formed by twisting together multiple optical fiber units 51, each consisting of five 4-core optical fiber ribbon cores 5 stacked and bundled together. Therefore, the optical fiber cable 1B in this example is a 100-core slotless cable in which the cable core 50, consisting of five optical fiber units 51, is housed in an internal space 35 formed inside the cable sheath 32 and the retaining tape 31. The form in which the optical fiber ribbon cores 5 housed within the cable sheath 32 is not limited to stacking multiple cores; for example, multiple optical fiber ribbon cores 5 may be rolled up by bending them in the width direction and twisted together before being housed.

[0047] The optical fiber ribbon conductors 5 forming the cable core 50 have the same configuration as the optical fiber ribbon conductors 5 described in the first embodiment above. The optical fiber conductors 20 constituting the optical fiber ribbon conductors 5 also have the same configuration as the optical fiber conductors 20 described in the first embodiment above. The optical fiber ribbon conductors forming the cable core 50 may also be optical fiber ribbon conductors 105 of the type where every two conductors are intermittently connected. In the optical fiber cable 1B, the occupancy rate of the total cross-sectional area of ​​the optical fiber ribbon conductors 5 to the cross-sectional area of ​​the internal space 35, that is, the value calculated as "total cross-sectional area of ​​optical fiber ribbon conductors housed in the internal space" / "cross-sectional area of ​​the internal space", is designed to be 30% or more and 40% or less, similar to the optical fiber cable 1A of the first embodiment.

[0048] In the optical fiber cable 1B of the second embodiment, as in the first embodiment, it is possible to input high-power optical signals, and an optical fiber cable suitable for long-distance transmission can be provided.

[0049] (Example of experiment) The slotless optical fiber cable 1B is described below with specific experimental examples. In the experimental example, the effective cross-sectional area is 110 μm at a wavelength of 1550 nm. 2 A fiber optic ribbon cable 5, formed using four fiber optic cores 20, was housed inside a fiber optic cable 1B. Multiple samples were prepared with different occupancy rates of the fiber optic ribbon cable 5 within the space inside the cable sheath 32 (ribbon cross-sectional area / internal space cross-sectional area) and adhesive length ratios. Samples with intermittent single-core and two-core intermittent double-core connections were also used. For these samples, the relationship between each parameter and the transmission loss of the fiber optic cable was evaluated.

[0050] The evaluation results are shown in Table 1. The transmission loss is shown for the optical fiber core 20, representing the transmission loss value of signal light at a wavelength of 1550 nm. The temperature characteristics of the transmission loss (transmission loss increase α) from -30 to +70°C are also shown. Generally, α is required to be 0.15 dB / km or less.

[0051] In determining transmission loss, each sample number is assigned a rating from A to C. Rating A is given to samples that meet the criteria for low transmission loss cables for long-distance transmission, which is a transmission loss of 0.21 dB / km or less. Rating B is given to samples that do not meet the criteria for low transmission loss cables for long-distance transmission, but meet the standard required for general cables, which is a transmission loss of 0.25 dB / km or less. Rating C is given to samples that do not meet the standard required for general cables.

[0052] [Table 1]

[0053] As shown in Table 1, the optical fiber cables from sample numbers No. 1 to No. 3, i.e., optical fiber cables with an optical fiber ribbon core occupancy rate of 45%, had a transmission loss greater than 0.25 dB / km, and the transmission loss quality rating was rated C. In contrast, the optical fiber cables from sample numbers No. 4 to No. 9, i.e., optical fiber cables with an optical fiber ribbon core occupancy rate of 40% or less, had a transmission loss of at least 0.25 dB / km or less, and the transmission loss quality rating was rated either A or B, respectively. It was confirmed that if the adhesive length ratio is 40% or more, the transmission loss decreases as the optical fiber ribbon core occupancy rate decreases. However, if the occupancy rate does not reach 30%, it is possible to maintain a good transmission loss quality rating, but it is not possible to achieve high density of optical fiber ribbon cores 5.

[0054] This section will explain the intermittent connection points in the optical fiber cables of sample numbers 4 to 9, focusing on how often they are intermittently connected. While the optical fiber ribbon fiber occupancy rate for sample numbers 4 to 6 is 40%, sample number 4 uses an intermittent connection type ribbon fiber with one core at a time, while sample numbers 5 to 6 use an intermittent connection type ribbon fiber with two cores at a time. It was confirmed that the transmission loss was reduced in sample numbers 5 to 6 compared to sample number 4. Specifically, the transmission loss of sample number 4 was rated B, while the transmission loss of sample numbers 5 to 6 was rated A.

[0055] Similarly, while the fiber optic ribbon fiber occupancy rate for sample numbers 7 to 9 is 35%, sample number 7 uses a single-core intermittently connected fiber optic ribbon fiber, while sample numbers 8 to 9 use a two-core intermittently connected fiber optic ribbon fiber. In this case, although there was no difference in the judgment of transmission loss, it was confirmed that the transmission loss was reduced in sample numbers 8 to 9 compared to sample number 7.

[0056] This confirmed that, in optical fiber ribbon cables, the intermittent coupling of two cores per fiber reduces transmission loss compared to the intermittent coupling of one core per fiber ribbon cable.

[0057] This section will focus on the adhesive length ratio for fiber optic cables No. 4 to No. 9. While the fiber optic ribbon core occupancy rate for fiber optic cables No. 4 to No. 6 is 40%, the adhesive length ratio for fiber optic cable No. 4 is 40%, for fiber optic cable No. 5 it is 73%, and for fiber optic cable No. 6 it is 80%. It was confirmed that the higher the adhesive length ratio, the lower the transmission loss. Specifically, the transmission loss for fiber optic cable No. 4 was rated B, while the transmission loss for fiber optic cables No. 5 and No. 6 was rated A.

[0058] Similarly, while the fiber optic ribbon core occupancy rate for fiber optic cables No. 7 to No. 9 is 35%, the adhesive length ratio for fiber optic cable No. 7 is 40%, for fiber optic cable No. 8 it is 73%, and for fiber optic cable No. 9 it is 80%. In this case, although there was no difference in the judgment of transmission loss, it was confirmed that the transmission loss was reduced in samples with a larger adhesive length ratio.

[0059] This confirmed that transmission loss can be further reduced if the adhesive length ratio is 73% or higher.

[0060] Although this disclosure has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of this disclosure. Furthermore, the number, position, shape, etc. of the components described above are not limited to the embodiments described above and can be changed to a number, position, shape, etc. that is suitable for carrying out this disclosure. [Explanation of Symbols]

[0061] 1A, 1B: Fiber optic cable 5,105: Fiber optic ribbon 6,106:Connection part 7,107: Unconnected part 8,108: Intermittent connection section 10: Slot Rod 11,11a,11b,11c,11d,11e: Slot groove (an example of internal space) 12,33: Tension Members 14,31: Retaining wrapping tape 16:Outer cover 18: Location identification mark 20: Optical fiber core 21: Core 22: Clad section 23: Glass fiber 24: Primary coating layer (primary resin) 25: Secondary coating layer (secondary resin) 26: Colored layer 32: Cable sheath 34: Tear cord 35: Interior space 50: Cable core 51: Fiber Optic Unit

Claims

1. An optical fiber cable that implements an optical fiber ribbon core, formed by arranging multiple optical fiber cores in parallel, in its internal space, The core of the optical fiber is made of pure quartz glass, and the effective cross-sectional area of ​​the core at a wavelength of 1550 nm is 110 μm². ２ 150 μm or more ２ The following: The optical fiber cores constitute an intermittently connected optical fiber ribbon cable, which includes intermittently connected sections where connecting sections coated with adhesive resin and non-connecting sections not coated with adhesive resin are alternately provided between adjacent optical fiber cores. In the optical fiber ribbon cable, the ratio of the total length to which the adhesive resin is applied to the total length between all the cores in a unit length of the optical fiber ribbon cable is 73% or more and 85% or less. The occupancy rate of the optical fiber ribbon core relative to the cross-sectional area of ​​the internal space is 30% or more and 40% or less. Fiber optic cable.

2. The optical fiber cable according to claim 1, wherein the intermittent connection portion is provided every two cores in the optical fiber ribbon cable.

3. The optical fiber cable according to claim 1 or claim 2, wherein the optical fiber cable is a tape-slot type optical fiber cable having slot rods.

4. The optical fiber cable according to claim 1 or claim 2, wherein the optical fiber cable is a slotless type optical fiber cable having a cable core formed by twisting together a plurality of optical fiber ribbon cores and a cable sheath provided around the cable core.

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