Optical fiber cable

Abstract

An optical fiber cable (10) comprises: first optical fibers (11) each provided with a first resin part (11b) that surrounds the outer periphery of a first glass optical fiber part (11a) including a core part, the outer diameter of the first resin part (11b) being a first fiber diameter; second optical fibers (12) each provided with a second resin part (12b) that surrounds the outer periphery of a second glass optical fiber part (12a) including a core part, the outer diameter of the second resin part (12b) being a second fiber diameter larger than the first fiber diameter. At least a portion of the first optical fiber (11) is disposed in a region (A) surrounded by the outer peripheral surfaces of two second optical fibers (12) adjacent to each other and a virtual plane (VS) that is in contact with the outer peripheral surfaces of the two second optical fibers (12) and that is on the same side with respect to the central axes of the two second optical fibers (12).

Description

Optical fiber cable

[0001] The present invention relates to an optical fiber cable.

[0002] A hollow core fiber (HCF) can potentially significantly reduce transmission loss by transmitting light through a core mainly filled with air, as compared to a solid core optical fiber. Also, various characteristics (such as low latency, ultra-low non-linearity, harsh environment resistance, etc.) that are impossible to achieve with conventional solid core optical fibers can be realized, and many new applications are expected.

[0003] As hollow core fibers, photonic band gap fibers (PBG fibers) and anti-resonant fibers (AR fibers) are known. Also, in Non-Patent Documents 1 and 2, techniques for cabling hollow core fibers have been reported. Further, in Non-Patent Document 3, a photonic band gap fiber having a structure called a PRISM (Perturbed Resonance for Increased Single Modedness) structure has been reported.

[0004] B. Zhu et al, “First demonstration of Hollow-Core-Fiber Cable for Low Latency Data Transmission”, OFC 2020, paper Th4B.3, (2020). M. A. Iqbal et al, “First Demonstration of 400ZR DWDM Transmission through Field Deployable Hollow-Core-Fiber Cable”, OFC 2021, paper F4C.2, (2021). Kazunori Takekasa, “Hollow Core Fiber Cable”, Furukawa Electric Times No. 140 (July 2021), pp. 32 - 39

[0005] Incidentally, photonic bandgap fibers and anti-resonant fibers have different microbend loss characteristics. Specifically, anti-resonant fibers tend to have lower microbend loss characteristics than photonic bandgap fibers (for example, they tend to have higher microbend loss under the same conditions). In optical fiber cables where optical fibers with such different microbend loss characteristics are mixed, not just with hollow core fibers, the difference in microbend loss characteristics between the two can be narrowed by increasing the outer diameter of the optical fiber that tends to have higher microbend loss.

[0006] However, the structure of optical fiber cables containing two or more optical fibers with different outer diameters had not been sufficiently studied.

[0007] The present invention has been made in view of the above, and its object is to provide an optical fiber cable that includes two or more optical fibers having different outer diameters and is suitable for densely housing or miniaturizing optical fibers.

[0008] To solve the above-mentioned problems and achieve the objective, one aspect of the present invention is an optical fiber cable comprising: one or more first optical fibers comprising: a first glass optical fiber portion including a core portion and a first resin portion surrounding the outer circumference of the first glass optical fiber portion, wherein the outer diameter of the first resin portion is a first fiber diameter; and two or more second optical fibers comprising: a second glass optical fiber portion including a core portion and a second resin portion surrounding the outer circumference of the second glass optical fiber portion, wherein the outer diameter of the second resin portion is a second fiber diameter larger than the first fiber diameter; wherein at least a portion of the first optical fibers is arranged in a region enclosed by the outer circumferential surfaces of two adjacent second optical fibers and a virtual plane that is in contact with the outer circumferential surfaces of the two second optical fibers and is on the same side with respect to the central axis of the two second optical fibers.

[0009] If the second optical fiber has a second glass diameter, which is the outer diameter of the second glass optical fiber portion, that is the same as the first glass diameter, which is the outer diameter of the first glass optical fiber portion, and the second fiber diameter is the same as the first fiber diameter, then the microbend loss of the second optical fiber may be greater than the microbend loss of the first optical fiber.

[0010] One aspect of the present invention is an optical fiber cable comprising one or more first optical fibers, each comprising a first glass optical fiber portion having a photonic bandgap structure and a first resin portion surrounding the outer circumference of the first glass optical fiber portion, wherein the outer diameter of the first resin portion is a first fiber diameter; and two or more second optical fibers, each comprising a second glass optical fiber portion having an antiresonant structure and a second resin portion surrounding the outer circumference of the second glass optical fiber portion, wherein the outer diameter of the second resin portion is a second fiber diameter larger than the first fiber diameter, and at least a portion of the first optical fibers is arranged in a region enclosed by the outer circumferential surfaces of two adjacent second optical fibers and a virtual plane that is in contact with the outer circumferential surfaces of the two second optical fibers and is on the same side with respect to the central axis of the two second optical fibers.

[0011] The optical fiber cable may have a slotless structure.

[0012] The second fiber diameter may be in the range of 2 ± 0.4 times the first fiber diameter.

[0013] The first resin part and the second resin part may each have a two-layer coating.

[0014] The first resin portion and the second resin portion may each have a colored layer surrounding the outer periphery of the coating layer.

[0015] According to the present invention, it is possible to realize an optical fiber cable that includes two or more optical fibers with different outer diameters and is suitable for densely housing or miniaturizing the optical fibers.

[0016] Figure 1 is a schematic cross-sectional view of an optical fiber cable according to Embodiment 1 in a plane perpendicular to the longitudinal direction. Figure 2 is a schematic cross-sectional view of the first optical fiber in a plane perpendicular to the longitudinal direction. Figure 3 is a schematic cross-sectional view of the second optical fiber in a plane perpendicular to the longitudinal direction. Figure 4 is a diagram showing an example of the relationship between wavelength and microbend loss. Figure 5 is a diagram illustrating the arrangement of the first optical fiber and the second optical fiber. Figure 6 is a schematic cross-sectional view of an optical fiber cable according to Embodiment 2 in a plane perpendicular to the longitudinal direction. Figure 7 is a schematic cross-sectional view of an optical fiber cable according to Embodiment 3 in a plane perpendicular to the longitudinal direction. Figure 8 is a schematic cross-sectional view of an optical fiber cable according to Embodiment 4 in a plane perpendicular to the longitudinal direction. Figure 9 is a schematic cross-sectional view of an optical fiber cable according to Embodiment 5 in a plane perpendicular to the longitudinal direction. Figure 10 is a schematic cross-sectional view of an optical fiber cable according to Embodiment 6 in a plane perpendicular to the longitudinal direction. Figure 11 is a schematic cross-sectional view of an optical fiber cable according to Embodiment 7 in a plane perpendicular to the longitudinal direction.

[0017] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the embodiments described below. Furthermore, in each drawing, the same or corresponding components are denoted by the same reference numerals as appropriate, and redundant explanations are omitted as appropriate. In addition, terms not specifically defined in this specification shall be defined and measured according to the definitions and measurement methods in ITU-T G. 650.1 and G. 650.2 of the International Telecommunication Union (ITU).

[0018] (Embodiment 1) Figure 1 is a schematic cross-sectional view of an optical fiber cable according to Embodiment 1 in a plane perpendicular to the longitudinal direction. The optical fiber cable 10 comprises nine first optical fibers 11, ten second optical fibers 12, and a sheath 13. The first optical fibers 11 are an example of one or more first optical fibers, and the second optical fibers 12 are an example of two or more second optical fibers. Furthermore, the optical fiber cable 10 is an optical fiber cable having a so-called slotless structure.

[0019] In this embodiment, the first optical fiber 11 is a photonic bandgap fiber. Figure 2 is a schematic cross-sectional view of the first optical fiber 11 in a plane perpendicular to the longitudinal direction. The first optical fiber 11 is a photonic bandgap fiber having a PRISM structure. Specifically, the first optical fiber 11 is made of glass and comprises a first glass optical fiber portion 11a having a photonic bandgap structure and a first resin portion 11b surrounding the outer circumference of the first glass optical fiber portion 11a. The first glass optical fiber portion 11a is provided with a micro-vacuum region 11aa. Micro-vacuum regions 11aa have fine vacancies arranged in a triangular lattice pattern. The fine vacancies form a photonic bandgap in a wavelength band that includes a predetermined wavelength. Furthermore, the micro-vacuum region 11aa is provided with a main core 11ab, which is a vacuum core portion, and a side core 11ac, which is a vacuum core portion, positioned on either side of the main core 11ab. The outer diameter of the first glass optical fiber portion 11a is the first glass diameter, and the outer diameter of the first resin portion 11b is the first fiber diameter.

[0020] The side core 11ac is configured to optically couple with the higher-order propagation mode at a predetermined wavelength in the main core 11ab. As a result, light propagating in the higher-order propagation mode in the main core 11ab is transferred to the side core 11ac and propagates while leaking. Consequently, the main core 11ab propagates only the ground mode at the predetermined wavelength with low loss, so the first optical fiber 11 is essentially a single-mode optical fiber. The predetermined wavelength is a wavelength belonging to the wavelength band used for optical transmission, for example, 1550 nm.

[0021] The size of the main core 11ab is approximately equivalent to 19 of the minute voids that form the photonic band gap. Such a main core 11ab is sometimes called a 19-cell type.

[0022] The first resin portion 11b is made of a known structure and material, such as those used to protect glass optical fibers in optical fibers. The first resin portion 11b may, for example, include a two-layer coating layer, and may further include a colored layer surrounding the outer periphery of the coating layer.

[0023] Returning to Figure 1, the second optical fiber 12 in this embodiment is an antiresonant fiber. Figure 3 is a schematic cross-sectional view of the second optical fiber in a plane perpendicular to the longitudinal direction. The second optical fiber 12 has a structure also known as NANF (Nested Antiresonant Nodeless Fiber). Specifically, the second optical fiber 12 is made of glass and comprises a second glass optical fiber portion 12a having an antiresonant structure and a second resin portion 12b surrounding the outer circumference of the second glass optical fiber portion 12a. The second glass optical fiber portion 12a comprises an outer tube 12aa and inner capillaries 12ab, 12ac. The outer diameter of the second glass optical fiber portion 12a is the second glass diameter, and the outer diameter of the second resin portion 12b is the second fiber diameter.

[0024] The inner capillaries 12ab are arranged to form a regular pentagon in the cross-section of the outer tube 12aa. Each inner capillary 12ac is nested with the inner capillaries 12ab. A void core 12ad is formed in the region surrounded by the inner capillaries 12ab. In the second optical fiber 12, light of a predetermined wavelength is confined to the void core 12ad and transmitted due to the anti-resonant phenomenon generated by the inner capillaries 12ab and 12ac. The predetermined wavelength is a wavelength belonging to the wavelength band used for optical transmission, for example, 1550 nm.

[0025] The second resin portion 12b is made of a known structure and material, such as those used to protect glass optical fibers in optical fibers. The second resin portion 12b may, for example, have a two-layer coating layer and may further have a colored layer surrounding the outer periphery of the coating layer.

[0026] Returning to Figure 1, the sheath 13 surrounds the first optical fiber 11 and the second optical fiber 12. The sheath 13 consists of a known structure and material, which is provided in optical fiber cables for purposes such as protecting the optical fibers.

[0027] [Microbend Loss Characteristics] Figure 4 shows an example of the relationship between wavelength and microbend loss for a typical photonic bandgap fiber and antiresonant fiber having the configuration shown in Figure 2 or 3. Here, the microbend loss is a value measured by the fixed-diameter drum method specified in JIS C6823:2010.

[0028] In Figure 4, both the photonic bandgap fiber and the antiresonant fiber have a glass diameter of 135 μm and a fiber diameter of 250 μm. PBGF refers to a photonic bandgap fiber, and ARF refers to an antiresonant fiber.

[0029] As shown in Figure 4, anti-resonant fibers tend to have relatively higher microbend losses compared to photonic bandgap fibers. Figure 4 is an example where, assuming the second optical fiber has the same glass diameter as the first optical fiber and the second fiber diameter is the same as the first fiber diameter, the microbend loss is greater than that of the first optical fiber.

[0030] In Figure 4, the wavelengths in which PBGF exhibits relatively high microbend loss correspond to wavelength bands where transmission loss is high due to leaky mode effects. PBGF is known to have such high transmission loss wavelength bands within the photonic bandgap. On the other hand, antiresonant fibers are known to have lower transmission loss over a wider bandwidth than the photonic bandgap.

[0031] In contrast, the second glass diameter of the second optical fiber 12 is larger than the first glass diameter of the first optical fiber 11, and the second fiber diameter is larger than the first fiber diameter. For example, the first glass diameter is approximately 135 μm, and the second glass diameter is approximately 250 μm. Also, the first fiber diameter is 250 μm, and the second fiber diameter is 500 μm. That is, the second fiber diameter is twice the first fiber diameter. In this way, by making the size (glass diameter and fiber diameter) of the second optical fiber 12, which is an anti-resonant fiber that tends to have a large microbend loss, larger than the size of the first optical fiber 11, which is a photonic bandgap fiber, the difference in microbend loss characteristics between the two can be narrowed. In this embodiment, the second glass diameter of the second optical fiber 12 is larger than the first glass diameter of the first optical fiber 11, but this is not limited to this, and the second glass diameter may be equal to the first glass diameter, or the second glass diameter may be smaller than the first glass diameter. Even when the second glass diameter is equal to the first glass diameter, or when the second glass diameter is smaller than the first glass diameter, the difference in microbend loss characteristics between the two can be reduced by making the second fiber diameter larger than the first fiber diameter (for example, by increasing the thickness of the second resin portion 12b).

[0032] In particular, it is preferable that the microbend loss of the first optical fiber 11 and the second optical fiber 12 has the characteristics specified in G. 652 and is 10 times or less that of a standard single-mode optical fiber (SMF) having a standard fiber diameter of 250 μm.

[0033] Microbend loss can also be measured using a measurement method similar to the fixed-diameter drum method, called the sandpaper method, as described below. The sandpaper method defines the microbend loss as the difference between the transmission loss in state A, where a predetermined length (400 m or more) of optical fiber is wound in a single layer without overlapping at a tension of 100 gf on a fixed drum wound with #1000 grit sandpaper, and the transmission loss of the optical fiber in state B, where the optical fiber is wound on the same fixed drum as in state A, but without sandpaper, at the same tension and length as in state A. Here, the transmission loss of the optical fiber in state B does not include microbend loss and is considered to be the transmission loss inherent to the optical fiber itself. Also, in this measurement method, the transmission loss is measured at a wavelength of 1550 nm, so the microbend loss is also the value at a wavelength of 1550 nm. Hereafter, unless otherwise specified, the microbend loss is the value at a wavelength of 1550 nm.

[0034] [Arrangement of Optical Fibers] Next, the arrangement of the first optical fiber 11 and the second optical fiber 12 will be explained in detail. As shown in Figure 1, in the optical fiber cable 10, one second optical fiber 12 is placed in the center, surrounded by nine first optical fibers 11 on its outer circumference, and further surrounded by nine second optical fibers 12 on its outer circumference.

[0035] Figure 5 illustrates the arrangement of the first and second optical fibers. As shown in Figure 5, in the optical fiber cable 10, at least a portion of the first optical fiber 11 is arranged in a region A enclosed by the outer surfaces of two adjacent second optical fibers 12 and a virtual plane VS that is in contact with the outer surfaces of the two second optical fibers 12 and is on the same side with respect to the central axis O of the two second optical fibers. Region A is the area enclosed by the thick line in Figure 5. By arranging at least a portion of the first optical fiber 11 in a region formed between second optical fibers 12 with a larger outer diameter in this way, the space utilization efficiency within the optical fiber cable 10 is improved, and a structure suitable for densely housing optical fibers or reducing their diameter is realized.

[0036] For example, if three second optical fibers 12, each with a second fiber diameter of 2R, are arranged in a triangular lattice to form a closely packed structure, the cross-sectional area of ​​the region enclosed by the outer surfaces of these three second optical fibers 12 is 0.16R. ２ Therefore, if the outer diameter of the first fiber of the first optical fiber 11 is R, then the cross-sectional area of ​​the region enclosed by the outer surfaces of the two second optical fibers 12 and the virtual plane VS that is in contact with the outer surface of one first optical fiber 11 and is on the same side with respect to the central axis O of the two second optical fibers, as shown in Figure 5, is 0.13R. ２ Therefore, the arrangement shown in Figure 5 allows for a saving of approximately 19% of the cross-sectional area.

[0037] Furthermore, for example, if we compare an optical fiber cable in which seven second optical fibers 12 are arranged in a densely packed structure with the optical fiber cable 10, the number of optical fibers per unit area can be increased by 2.47 times in the optical fiber cable 10.

[0038] The optical fiber cable 10 configured as described above is suitable for densely accommodating optical fibers or for reducing their diameter. Furthermore, since both the first optical fiber 11 and the second optical fiber 12 are hollow-core optical fibers, desirable characteristics such as low latency, extremely low nonlinearity, and resistance to harsh environments can be enjoyed. In addition, because the second optical fiber 12, which has low microbend loss characteristics, is relatively large in diameter, the microbend loss characteristics of the optical fiber cable 10 are also improved.

[0039] (Embodiment 2) Figure 6 is a schematic cross-sectional view of the optical fiber cable according to Embodiment 2 in a plane perpendicular to the longitudinal direction. This optical fiber cable 10A has a configuration in which nine first optical fibers 11 are added to the optical fiber cable 10 shown in Figure 1. The nine added first optical fibers 11 surround the outer circumference of nine second optical fibers 12 arranged in a circle.

[0040] In the optical fiber cable 10A as well, at least a part of the additional nine first optical fibers 11 is arranged in a region surrounded by the outer peripheral surfaces of two adjacent second optical fibers 12 and a virtual plane that is in contact with the outer peripheral surfaces of the two second optical fibers 12 and on the same side with respect to the central axes of the two second optical fibers. Therefore, in the optical fiber cable 10A as well, the same effect as that of the optical fiber cable 10 can be obtained.

[0041] (Embodiment 3) FIG. 7 is a schematic cross-sectional view in a plane perpendicular to the longitudinal direction of the optical fiber cable according to Embodiment 3. This optical fiber cable 10B is a so-called slotted optical fiber cable, and a slot material 14B is provided. A tension member 15B is provided at the center of the slot material 14B.

[0042] Grooves 14B1, 14B2, and 14B3 are formed in the slot material 14B from the surface toward the center. The first optical fiber 11 and the second optical fiber 12 are alternately laminated in the grooves 14B1, 14B2, and 14B3.

[0043] In the optical fiber cable 10B having a slot structure as well, at least a part of some of the first optical fibers 11 is arranged in a region surrounded by the outer peripheral surfaces of two adjacent second optical fibers 12 and a virtual plane that is in contact with the outer peripheral surfaces of the two second optical fibers 12 and on the same side with respect to the central axes of the two second optical fibers. Therefore, in the optical fiber cable 10B as well, the same effect as that of the optical fiber cable 10 can be obtained.

[0044] (Embodiment 4) FIG. 8 is a schematic cross-sectional view in a plane perpendicular to the longitudinal direction of the optical fiber cable according to Embodiment 4. This optical fiber cable 10C has a configuration in which 36 first optical fibers 11 and 18 second optical fibers 12 are added to the optical fiber cable 10 shown in FIG. 1. The additional 36 first optical fibers 11 surround the outer periphery of nine second optical fibers 12 arranged in a circular shape, and the additional 18 second optical fibers 12 surround the outer periphery of the additional 36 first optical fibers 11.

[0045] In the optical fiber cable 10C as well, at least a part of the first optical fiber 11 is disposed in a region surrounded by the outer peripheral surfaces of two adjacent second optical fibers 12 and a virtual plane that contacts the outer peripheral surfaces of the two second optical fibers 12 and is on the same side with respect to the central axes of the two second optical fibers. Therefore, in the optical fiber cable 10C as well, the same effect as that of the optical fiber cable 10 can be obtained.

[0046] (Embodiment 5) FIG. 9 is a schematic cross-sectional view in a plane perpendicular to the longitudinal direction of the optical fiber cable according to Embodiment 5. This optical fiber cable 10D has a configuration in which 37 first optical fibers 11 and 18 second optical fibers 12 are added to the optical fiber cable 10 shown in FIG. 1. Nine of the added 37 first optical fibers 11 surround the outer periphery of the nine first optical fibers 11 that surround the central second optical fiber 12. Also, the other 28 added first optical fibers 11 surround the outer periphery of the nine second optical fibers 12 arranged in a circular shape. Further, the 18 added second optical fibers 12 surround the outer periphery of the 28 added first optical fibers 11.

[0047] In the optical fiber cable 10D as well, at least a part of some of the first optical fibers 11 is disposed in a region surrounded by the outer peripheral surfaces of two adjacent second optical fibers 12 and a virtual plane that contacts the outer peripheral surfaces of the two second optical fibers 12 and is on the same side with respect to the central axes of the two second optical fibers. Therefore, in the optical fiber cable 10D as well, the same effect as that of the optical fiber cable 10 can be obtained.

[0048] (Embodiment 6) FIG. 10 is a schematic cross-sectional view in a plane perpendicular to the longitudinal direction of the optical fiber cable according to Embodiment 6. This optical fiber cable 10E has six second optical fibers 12, eleven second optical fibers 12, and twenty-two second optical fibers arranged in a circular shape so as to surround the center in sequence. Further, 69 first optical fibers 11 are disposed between these second optical fibers 12.

[0049] In the optical fiber cable 10E, at least a portion of some of the first optical fibers 11 are arranged in a region enclosed by the outer surfaces of two adjacent second optical fibers 12 and a virtual plane that is in contact with the outer surfaces of the two second optical fibers 12 and is on the same side with respect to the central axis of the two second optical fibers. In this way, even in the optical fiber cable 10E where there is no regularity in the arrangement of the first optical fibers 11 (where n is a natural number, and the arrangement is not rotationally symmetrical n times), the same effect as in the optical fiber cable 10 can be obtained. Furthermore, even when there is no regularity in the arrangement of the second optical fibers 12 (where n is a natural number, and the arrangement is not rotationally symmetrical n times), the same effect as in the optical fiber cable 10 can be obtained.

[0050] (Embodiment 7) Figure 11 is a schematic cross-sectional view of an optical fiber cable according to Embodiment 7 in a plane perpendicular to the longitudinal direction. In this optical fiber cable 10F, four second optical fibers 12, eight second optical fibers 12, and seventeen second optical fibers are arranged sequentially in a circular pattern surrounding the center. Furthermore, 25 first optical fibers 11 are arranged between these second optical fibers 12.

[0051] In the optical fiber cable 10F, at least a portion of several first optical fibers 11 are arranged in a region enclosed by the outer surfaces of two adjacent second optical fibers 12 and a virtual plane that is in contact with the outer surfaces of the two second optical fibers 12 and is on the same side with respect to the central axis of the two second optical fibers. Therefore, the same effect as in the optical fiber cable 10 can be obtained in the optical fiber cable 10E.

[0052] In the above embodiment, the first optical fiber 11 is a photonic bandgap fiber and the second optical fiber 12 is an antiresonant fiber, but the invention is not limited to this. For example, if the second optical fiber has the same glass diameter as the first glass diameter and the same fiber diameter as the first fiber diameter, the second optical fiber may be of a different type, such that its microbend loss is greater than that of the first optical fiber. For example, the second optical fiber may be a so-called Aeff-expanded fiber, which has a larger effective core cross-sectional area (Aeff) than the first optical fiber. That is, the first optical fiber may have an Aeff of 110 μm ２ The glass diameter is 125 μm, the fiber diameter is 250 μm, and the second optical fiber has an Aef of 150 μm. ２ The glass diameter may be 125 μm and the fiber diameter 350 μm. In this case, the microbend loss of both is about the same, but if the second fiber diameter is the same as the first fiber diameter, 250 μm, the microbend loss is about 10 times greater than the microbend loss of the first optical fiber.

[0053] Furthermore, in the above embodiment, the second fiber diameter is twice the first fiber diameter, but the second fiber diameter may also be in the range of 2 ± 0.4 times the first fiber diameter. According to the inventors' research, if the second fiber diameter is in the range of 2 ± 0.4 times the first fiber diameter, it is relatively easy to arrange the two fibers in a regular manner.

[0054] Furthermore, when using an optical fiber cable according to the embodiment, if, for example, the transmission losses of the first optical fiber and the second optical fiber differ, a high-gain optical amplifier may be applied to the optical fiber with the greater transmission loss to match the transmission distance of the first and second optical fibers. Alternatively, only the optical fiber with the greater transmission loss may be branched off from the optical fiber cable and used separately. Also, the transmission bandwidths of the first and second optical fibers may differ. That is, for example, since anti-resonant fiber has a relatively wider transmission bandwidth than photonic bandgap fiber, relatively wideband transmission may be performed with anti-resonant fiber.

[0055] Furthermore, the present invention is not limited by the embodiments described above. Configurations that appropriately combine the above-described components are also included in the present invention. Moreover, further effects and modifications can be easily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the embodiments described above, and various modifications are possible.

[0056] This invention can be used in optical fiber cables.

[0057] 10, 10A, 10B, 10C, 10D, 10E, 10F: Optical fiber cable 11: First optical fiber 11a: First glass optical fiber section 11aa: Fine void region 11ab: Main core 11ac: Side core 11b: First resin section 12: Second optical fiber 12a: Second glass optical fiber section 12aa: Outer tube 12ab, 12ac: Inner capillary 12ad: Void core 12b: Second resin section 13: Sheath 14B: Slot material 14B1, 14B2, 14B3: Groove 15B: Tension member A: Region O: Central axis

Claims

1. An optical fiber cable comprising: one or more first optical fibers comprising: a first glass optical fiber portion including a core portion and a first resin portion surrounding the outer circumference of the first glass optical fiber portion, wherein the outer diameter of the first resin portion is a first fiber diameter; and two or more second optical fibers comprising: a second glass optical fiber portion including a core portion and a second resin portion surrounding the outer circumference of the second glass optical fiber portion, wherein the outer diameter of the second resin portion is a second fiber diameter larger than the first fiber diameter; wherein at least a portion of the first optical fibers is arranged in a region enclosed by the outer circumferential surfaces of two adjacent second optical fibers and a virtual plane that is in contact with the outer circumferential surfaces of the two second optical fibers and is on the same side with respect to the central axis of the two second optical fibers.

2. The optical fiber cable according to claim 1, wherein, if the second glass diameter, which is the outer diameter of the second glass optical fiber portion, is the same as the first glass diameter, which is the outer diameter of the first glass optical fiber portion, and the second fiber diameter is the same as the first fiber diameter, the microbend loss of the second optical fiber is greater than the microbend loss of the first optical fiber.

3. An optical fiber cable comprising: one or more first optical fibers comprising: a first glass optical fiber portion having a photonic bandgap structure and a first resin portion surrounding the outer circumference of the first glass optical fiber portion, wherein the outer diameter of the first resin portion is a first fiber diameter; and two or more second optical fibers comprising: a second glass optical fiber portion having an antiresonant structure and a second resin portion surrounding the outer circumference of the second glass optical fiber portion, wherein the outer diameter of the second resin portion is a second fiber diameter larger than the first fiber diameter; wherein at least a portion of the first optical fibers is arranged in a region enclosed by the outer surfaces of two adjacent second optical fibers and a virtual plane that is in contact with the outer surfaces of the two second optical fibers and is on the same side with respect to the central axis of the two second optical fibers.

4. The optical fiber cable according to claim 1 or 3, wherein the optical fiber cable has a slotless structure.

5. The optical fiber cable according to claim 1 or 3, wherein the second fiber diameter is in the range of 2 ± 0.4 times the first fiber diameter.

6. The optical fiber cable according to claim 1 or 3, wherein the first resin part and the second resin part each have a two-layer coating structure.

7. The optical fiber cable according to claim 6, wherein the first resin portion and the second resin portion are each provided with a colored layer surrounding the outer periphery of the coating layer.

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