Optical fiber assembly

Abstract

The purpose of the present invention is to provide an optical fiber assembly capable of identifying a specific multi-core optical fiber when connected to an optical communication member. In a tape core wire (T) in which two or more multi-core optical fibers (10a-10d) including a plurality of cores (11a-11d) and a cladding (12) surrounding the respective cores (11a-11d) are bundled, the optical characteristics of a specific core (11a) of a specific multi-core optical fiber (10a) differ from the optical characteristics of a core (11a) corresponding to the specific core (11a) of the multi-core optical fiber (10a) among other multi-core optical fibers (10b-10d).

Description

Technical Field

[0001] The present invention relates to an optical fiber assembly. Background Art

[0002] To increase the transmission capacity of optical fiber communication devices, it is known to use multi-core optical fibers, which consist of multiple cores surrounded by a cladding as waveguides, to transmit multiple signals using light propagating through each core. Patent Document 1 below describes a ribbon cable, which is an optical fiber assembly formed by bundling such multi-core optical fibers.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-173514 Summary of the Invention

[0006] (1) Technical issues to be resolved

[0007] In such an optical fiber assembly, when connecting it to an optical communication component such as another optical fiber assembly, it is desired to identify a specific multi-core optical fiber.

[0008] Therefore, an object of the present invention is to provide an optical fiber aggregate that can identify a specific multi-core optical fiber when connected to an optical communication component.

[0009] (2) Technical solution

[0010] Mode 1 of the present invention is an optical fiber aggregate, which is an optical fiber aggregate formed by bundling two or more multi-core optical fibers including multiple cores and cladding surrounding each of the cores, and is characterized in that the optical properties of a specific core in a specific multi-core optical fiber are different from the optical properties of the core corresponding to the specific core in other multi-core optical fibers.

[0011] Method 1 allows identification of a specific multi-core optical fiber by examining the optical properties of the fiber core when connected to an optical communication component. These optical properties can be measured using, for example, an OTDR (Optical Time Domain Reflectometer), an OFDR (Optical Frequency Domain Reflectometry), or an OLTS (Optical Loss Test Set).

[0012] Mode 2 of the present invention is an optical fiber assembly, which is an optical fiber assembly formed by bundling multiple multi-core optical fibers including multiple cores and claddings surrounding each of the cores, and is characterized in that it has multiple optical fiber bundles formed by bundling two or more of the multi-core optical fibers, and the optical properties of the specific core in the specific multi-core optical fiber of a specific optical fiber bundle are different from the optical properties of the core corresponding to the specific core in the multi-core optical fiber corresponding to the specific multi-core optical fiber in other optical fiber bundles.

[0013] According to the second aspect, similarly to the first aspect, when connected to an optical communication component, a specific multi-core optical fiber can be identified by examining the optical characteristics, and as a result, a specific optical fiber bundle can be identified.

[0014] A third aspect of the present invention is the optical fiber aggregate of the first or second aspect, characterized in that the number of the specific cores is plural, and the optical characteristics are predetermined values obtained based on the loss of light of a specific wavelength in the plurality of cores.

[0015] In method 3, the predetermined value is a value caused by a plurality of cores in the multi-core optical fiber. Therefore, compared with a case where the predetermined value is a value caused by one core in the multi-core optical fiber, a specific multi-core optical fiber can be identified with high accuracy.

[0016] A fourth aspect of the present invention is the optical fiber aggregate according to the third aspect, characterized in that the specific cores are all the cores of the specific multi-core optical fiber.

[0017] In method 4, the predetermined value is a value caused by all the cores in the multi-core optical fiber. Therefore, compared with the case where the predetermined value is a value caused by one core in the multi-core optical fiber, a specific multi-core optical fiber can be identified with higher accuracy.

[0018] Mode 5 is the optical fiber aggregate of Mode 3 or 4, characterized in that the specific wavelength is a wavelength outside the communication band.

[0019] In optical communications, it is desirable to minimize variations in the loss of light propagating through each core. According to Method 5, by using light of a specific wavelength outside the communication band to investigate a specific multi-core optical fiber, it is possible to identify a specific multi-core optical fiber even when there is minimal variation in the propagation of light of wavelengths within the communication band within the cores.

[0020] Mode 6 is the optical fiber aggregate of Mode 5, characterized in that the specific wavelength is shorter than the communication band.

[0021] The shorter the wavelength of light propagating through the core, the more the inter-core crosstalk of that light tends to be suppressed. Therefore, according to Example 6, when examining characteristic values using light of a specific wavelength outside the communication band, inter-core crosstalk of light propagating through the core can be suppressed, compared to when the specific wavelength is longer than the communication band and the wavelength is the same as the communication band. Therefore, according to Example 8, it is easier to identify a specific multi-core optical fiber.

[0022] Mode 7 is the optical fiber aggregate according to any one of Modes 3 to 6, characterized in that the specific wavelength is not less than 1360 nm and not more than 1460 nm.

[0023] It is known that when the wavelength of light propagating in the core is the so-called E-band, that is, greater than 1360nm and less than 1460nm, the light loss caused by the hydroxyl groups contained in the core becomes greater, sometimes referred to as OH loss. According to method 7, by making the hydroxyl content different in a specific core in a specific multi-core optical fiber and in the cores corresponding to the specific core of other multi-core optical fibers, the propagation loss of the specific core can be made different from the propagation loss of the core corresponding to the specific core. In addition, the wavelength of light used in optical communications is sometimes set to greater than 1360nm and less than 1460nm, and there are existing OTDRs, OFDRs, OLTSs, etc. that use light in this wavelength band. Therefore, according to method 9, for example, even existing OTDRs, OFDRs, OLTSs, etc. can measure propagation loss. Therefore, it is easy to identify a specific multi-core optical fiber.

[0024] Mode 8 is the optical fiber aggregate according to any one of Modes 3 to 6, characterized in that the specific wavelength is 800 nm or more and 950 nm or less.

[0025] The wavelength of light used in multimode optical fiber communications is sometimes set to between 800 nm and 950 nm, and existing OTDRs and OLTS systems utilize light in this wavelength range. Therefore, according to Method 8, even existing OTDRs and OLTS systems can measure propagation loss, making it easier to identify specific multi-core optical fibers.

[0026] Method 9 is an optical fiber aggregate of method 1, characterized in that the specific multi-core optical fiber is formed by connecting the ends of multiple optical fiber parts to each other, and the light loss at the connection between the optical fiber parts in the specific multi-core optical fiber is different from the light loss at the position corresponding to the connection of the specific multi-core optical fiber in other multi-core optical fibers.

[0027] In the case of a short multi-core optical fiber, the propagation loss is small, so the error in the measured propagation loss may become large. However, according to method 9, since the loss of light at the connection portion is used, it is possible to suppress the error and identify a specific multi-core optical fiber even if the multi-core optical fiber is short.

[0028] Method 10 is an optical fiber aggregate of method 2, characterized in that the specific multi-core optical fiber is formed by connecting the ends of multiple optical fiber parts to each other, and the light loss at the connection parts between the optical fiber parts in the specific multi-core optical fiber is different from the light loss at the position corresponding to the connection part of the specific multi-core optical fiber in the multi-core optical fiber corresponding to the specific multi-core optical fiber.

[0029] According to aspect 10, similarly to aspect 9, since the light loss due to the connection portion is used, even if the multi-core optical fiber is short, it is possible to suppress errors and identify a specific multi-core optical fiber.

[0030] Method 11 is an optical fiber assembly of method 1, characterized in that the specific multi-core optical fiber and the other multi-core optical fibers are formed by connecting the ends of multiple optical fiber parts to each other, and the number of connection parts between the optical fiber parts in the specific multi-core optical fiber is different from the number of connection parts between the optical fiber parts in the other multi-core optical fibers.

[0031] According to method 11, a specific multi-core optical fiber is identified based on a discrete natural number such as the number of connectors. However, losses such as propagation loss are not usually natural numbers. Therefore, compared to identifying a specific multi-core optical fiber based on differences in losses such as propagation loss, identification is easier.

[0032] Method 12 is an optical fiber aggregate of method 2, characterized in that the specific multi-core optical fiber and the multi-core optical fiber corresponding to the specific multi-core optical fiber are formed by connecting the ends of a plurality of optical fiber parts to each other, and the number of connection parts between the optical fiber parts in the specific multi-core optical fiber is different from the number of connection parts between the optical fiber parts in the multi-core optical fiber corresponding to the specific multi-core optical fiber.

[0033] According to aspect 12, similarly to aspect 11, identification can be facilitated compared to the case where a specific multi-core optical fiber is identified based on a difference in loss such as propagation loss.

[0034] Method 13 is an optical fiber assembly of method 1, characterized in that the difference between the propagation loss of light of a specific wavelength in a specific core of a specific multi-core optical fiber and the propagation loss of light of a specific wavelength in the core corresponding to the specific core in other multi-core optical fibers is greater than 0.1 dB / km.

[0035] Method 14 is an optical fiber aggregate of method 2, characterized in that the difference between the propagation loss of light of a specific wavelength in a specific core of a specific multi-core optical fiber and the propagation loss of light of a specific wavelength in the core corresponding to the specific core in the multi-core optical fiber corresponding to the specific multi-core optical fiber is greater than 0.1 dB / km.

[0036] According to aspects 13 and 14, even a measuring device with a large minimum measurable value of propagation loss (for example, a general-purpose measuring device) can measure the difference in propagation loss, and thus a specific multi-core optical fiber can be easily identified.

[0037] Mode 15 is the optical fiber aggregate according to any one of modes 1, 2, 13, and 14, characterized in that the optical characteristic is a propagation loss at a specific wavelength of the core, and the specific wavelength is 360 nm to 830 nm.

[0038] Light with a wavelength of 360 nm or longer and less than 830 nm is visible light, which appears darker as its energy decreases. Therefore, according to Method 15, for example, a specific multi-core optical fiber can be identified by visually observing the brightness of the return light when light of the specific wavelength is incident on the core of each multi-core optical fiber from one end.

[0039] (3) Beneficial effects

[0040] As described above, according to the present invention, there is provided an optical fiber aggregate capable of identifying a specific multi-core optical fiber when connected to an optical communication component. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a conceptual diagram showing an optical communication device including the optical fiber aggregate according to the first embodiment of the present invention.

[0042] Figure 2 It is a perspective view schematically showing a cored wire.

[0043] Figure 3 This is a diagram showing a cross section of a tape core wire perpendicular to the longitudinal direction.

[0044] Figure 4 It is a diagram showing a cross section perpendicular to the longitudinal direction of a single-core optical fiber.

[0045] Figure 5 It is a diagram showing the optical characteristics of the optical communication device according to the first embodiment.

[0046] Figure 6 This is a conceptual diagram showing an optical communication device according to a second embodiment.

[0047] Figure 7This is a diagram schematically showing a cross section perpendicular to the longitudinal direction of a banding unit in a third embodiment.

[0048] Figure 8 It is a diagram schematically showing a cross section perpendicular to the longitudinal direction of a cable in a fourth embodiment. DETAILED DESCRIPTION

[0049] Preferred embodiments of the optical fiber aggregate of the present invention are described in detail below with reference to the accompanying drawings. The following exemplary embodiments are provided to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention can be modified and improved from the exemplary embodiments without departing from its spirit. Furthermore, for ease of understanding, the scales of the various figures may differ from those described in the following description.

[0050] (First embodiment)

[0051] Figure 1 This is a conceptual diagram showing an optical communication device including an optical fiber assembly according to this embodiment. The optical fiber assembly according to this embodiment is a ribbon cable T, and the optical communication device 1 includes two ribbon cables T and a plurality of fan-in / fan-out devices 20 as main components.

[0052] In the present embodiment, the configurations of the respective tape cores T are identical. Therefore, one tape core T will be described below, and the other tape cores T will be denoted by the same reference numerals unless otherwise specified, and redundant description will be omitted.

[0053] Figure 2 It is a stereoscopic diagram schematically showing a cored wire T. The cored wire T of the present embodiment is a so-called intermittently bonded cored wire. In the present embodiment, the cored wire T has the following structure: two or more multi-core optical fibers 10a~10d are arranged in a direction perpendicular to the long side direction, and adjacent multi-core optical fibers 10a~10d are connected and bundled to each other by intermittently arranged connecting materials T1. As materials constituting the connecting material T1, resins such as ultraviolet curing resins can be cited, for example. The cored wire T can be easily deformed, for example, it can be rolled into a roughly quadrangular prism shape. In Figure 2 In FIG. 1 , an example is shown in which the ribbon T is composed of four multi-core optical fibers 10 a to 10 d . However, the number of multi-core optical fibers constituting the ribbon T may be two or more.

[0054] Figure 3 : is a diagram showing a cross section perpendicular to the longitudinal direction of the tape core wire T. Figure 3 It is a cross-sectional view of the core wire T at a position that does not intersect with the connecting material T1. Figure 3As shown, in this embodiment, the structures of the multi-core optical fibers 10a to 10d are substantially the same. Therefore, the multi-core optical fiber 10a will be described below, and the other multi-core optical fibers 10b to 10d will be denoted by the same reference numerals unless otherwise specified, and repeated description will be omitted.

[0055] The multi-core optical fiber 10a of this embodiment has the following components as its main structure: a plurality of cores 11a to 11d; a cladding 12 that surrounds the outer circumference of each core 11a to 11d without a gap; a primary cladding 13 that covers the cladding 12; a secondary cladding 14 that covers the primary cladding 13; a coloring layer 15 that covers the secondary cladding 14; and a marker 16. Figure 3 Although an example in which four cores 11 a to 11 d are provided is shown, there is no limitation on the number of cores as long as the number is plural.

[0056] In this embodiment, the outer shape of the cladding 12 in a cross section perpendicular to the longitudinal direction is substantially circular, and the cores 11a to 11d are arranged at positions substantially four-fold rotationally symmetrical about the center of the cladding 12. There is no limitation on the arrangement of the cores.

[0057] The refractive index of each core 11a-11d is higher than that of the cladding 12. In this embodiment, the relative refractive index difference between each core 11a-11d and the cladding 12 is the same. For example, the cores 11a-11d are made of silica glass doped with a dopant such as germanium that increases the refractive index, while the cladding 12 is made of silica glass without a dopant. Alternatively, the cores 11a-11d may be made of silica glass without a dopant, while the cladding 12 is made of silica glass doped with a dopant such as fluorine that lowers the refractive index.

[0058] In this embodiment, the hydroxyl content of core 11a is greater than that of cores 11b to 11d. One method for increasing the hydroxyl content of core 11a relative to cores 11b to 11d is, for example, to shorten the dehydration process for the core rod that will become core 11a compared to the dehydration process for core rods that will become cores 11b to 11d during the manufacturing process of the preform of multi-core optical fiber 10a. Furthermore, the hydroxyl content of cores 11a to 11d in multi-core optical fibers 10b to 10d is substantially the same as that of cores 11b to 11d in multi-core optical fiber 10a.

[0059] The marker 16 is disposed within the cladding 12. The refractive index of the marker 16 is different from that of the cladding 12 and may be higher or lower than that of the cladding 12. In this embodiment, the distance between the core 11a and the marker 16 is smaller than the distance between the other cores 11b to 11d and the marker 16, so that the cores 11a to 11d can be identified by the marker 16. Furthermore, the core 11a of the multi-core optical fiber 10a corresponds to the core 11a of the multi-core optical fibers 10b to 10d, the core 11b of the multi-core optical fiber 10a corresponds to the core 11b of the multi-core optical fibers 10b to 10d, the core 11c of the multi-core optical fiber 10a corresponds to the core 11c of the multi-core optical fibers 10b to 10d, and the core 11d of the multi-core optical fiber 10a corresponds to the core 11d of the multi-core optical fibers 10b to 10d.

[0060] The primary cover layer 13 and the secondary cover layer 14 are made of resin such as ultraviolet curable resin.

[0061] The colored layer 15 is the outermost layer of the multi-core optical fiber 10a and is made of a resin such as an ultraviolet curable resin. In this embodiment, the colors of the colored layers 15 in the multi-core optical fibers 10a to 10d are different from each other.

[0062] In this structure, one end of each multi-core optical fiber 10a to 10d with a core T is connected to the other end of each multi-core optical fiber 10a to 10d with another core T. In this case, the multi-core optical fibers 10a to 10d with the same color of the colored layer 15 are connected to each other. Furthermore, the cores 11a to 11d of each multi-core optical fiber 10a to 10d with a core T are optically connected to the cores 11a to 11d of the multi-core optical fiber 10a to 10d with another core T at the same position relative to the mark 16 as the cores 11a to 11d. In addition, below, for easy understanding, the cores 11a~11d of the multi-core optical fiber 10a are sometimes set as cores 11aa~11ad, the cores 11a~11d of the multi-core optical fiber 10b are set as cores 11ba~11bd, the cores 11a~11d of the multi-core optical fiber 10c are set as cores 11ca~11cd, and the cores 11a~11d of the multi-core optical fiber 10d are set as cores 11da~11dd.

[0063] Next, the fan-in / fan-out device 20 will be described. The fan-in / fan-out device is sometimes referred to as a FIFO, and hereinafter, the fan-in / fan-out device 20 is sometimes referred to as a FIFO 20.

[0064] like Figure 1As shown, the plurality of FIFOs 20 correspond one-to-one to the plurality of multi-core optical fibers 10a-10d included in the cored cable T, and each FIFO 20 is connected to a corresponding multi-core optical fiber 10a-10d. Therefore, the number of FIFOs 20 in this embodiment is four. In this embodiment, the structures of the FIFOs 20 are identical. Therefore, the following description will focus on the FIFO 20 connected to the multi-core optical fiber 10a. The other FIFOs 20 will be denoted by the same reference numerals unless otherwise specified, and duplicate descriptions will be omitted.

[0065] The FIFO 20 of this embodiment mainly includes a plurality of single-core optical fibers 30 and a waveguide member 40. The number of single-core optical fibers 30 is the same as the number of cores of the multi-core optical fiber 10a, which is four in this embodiment.

[0066] The structures of the single-core optical fibers 30 are identical to each other. Figure 4 3 is a diagram showing a cross section perpendicular to the longitudinal direction of a single-core optical fiber 30. The single-core optical fiber 30 of this embodiment includes a core 31, a cladding 32 surrounding the outer peripheral surface of the core 31 without a gap, and a coating 33 covering the outer peripheral surface of the cladding 32.

[0067] In this embodiment, the outer shape of the cladding 32 in a cross section perpendicular to the longitudinal direction is substantially circular, and the core 31 is arranged at the center of the cladding 32. The diameter of the core 31 is substantially the same as the diameter of the cores 11a to 11d of the multi-core optical fibers 10a to 10d with cores T.

[0068] The refractive index of the core 31 is higher than that of the cladding 32. For example, the core 31 is made of silica glass doped with a dopant that increases the refractive index, while the cladding 32 is made of silica glass without a dopant. Alternatively, the core 31 may be made of silica glass without a dopant, while the cladding 32 may be made of silica glass doped with a dopant that lowers the refractive index.

[0069] The cover layer 33 is formed of a resin such as an ultraviolet curable resin.

[0070] The waveguide component 40 optically couples the core 31 of the single-core optical fiber 30 and the cores 11 a to 11 d of the multi-core optical fiber 10 a with a core wire T. In this embodiment, the waveguide component 40 includes a multi-core optical fiber 50 and a pitch conversion portion 60 .

[0071] The multi-core optical fiber 50 of the present embodiment is different from the multi-core optical fiber 10a with a core wire T in that the hydroxyl content of the cores 11a to 11d is the same as one another and that the coloring layer 15 is not provided. Therefore, the multi-core optical fiber 50 has four cores 11a to 11d, a cladding 12, a primary covering layer 13, a secondary covering layer 14, and a marker 16. One end of the multi-core optical fiber 50 is connected to one end of the multi-core optical fiber 10a with a core wire T so that each core 11a to 11d of the multi-core optical fiber 50 is optically coupled individually with the core 11a to 11d of the multi-core optical fiber 10a with a core wire T. In addition, the lengths of the multi-core optical fibers 50 in each FIFO 20 are approximately the same as one another, but in order to prevent the drawings from becoming complicated, Figure 1 The lengths of the multi-core optical fibers 50 are made different.

[0072] The pitch conversion unit 60 of this embodiment is a component that optically couples the core 31 of each single-core optical fiber 30 to the cores 11a to 11d of the multi-core optical fiber 10a with a core T via a waveguide (not shown). Examples of the waveguide component 40 include a waveguide substrate in which a waveguide is formed by irradiating a light-transmitting substrate with a femtosecond laser, a PLC (Planer Lightwave Circuit) in which a waveguide is formed by adding elements to a substrate made of quartz glass, a silicon photonics waveguide made of silicon, and a polymer waveguide.

[0073] Furthermore, the waveguide component 40 only needs to be able to optically couple the cores 31 of each single-core optical fiber 30 individually with the cores 11a to 11d of the multi-core optical fiber 10a with core wire T. For example, the waveguide component 40 may consist solely of the pitch conversion section 60. Alternatively, the pitch conversion section 60 may be a spatial optical system composed of multiple lenses. Furthermore, the pitch conversion section 60 may be formed integrally with the multiple single-core optical fibers 30, without forming a connection between the single-core optical fibers 30 and the waveguide component 40. Such a waveguide component 40 can be formed, for example, by extending the end of a fiber bundle in which multiple single-core optical fibers 30 are bundled. Alternatively, the waveguide component 40 can be formed by bundling one end of multiple single-core optical fibers 30, or by bundling one end of multiple single-core optical fibers 30 whose cladding has a reduced outer diameter at one end. In these cases, the individual cores 31 of the single-core optical fibers 30 and the individual waveguides of the waveguide component 40 are optically coupled without intervening through a boundary surface.

[0074] Figure 5 is a diagram showing the optical characteristics of the optical communication device 1 of this embodiment, and is a diagram showing the optical characteristics of the optical communication device 1 of this embodiment. Figure 1The waveform measured by the OTDR70 shown in the figure. The incident position of the measurement light of the OTDR70, which is light of a specific wavelength, is the end of each single-core optical fiber 30 in each FIFO20 on the side opposite to the waveguide component 40. In addition, the measurement light is light of a wavelength outside the communication band, and the wavelength of the measurement light is the so-called E-band, that is, greater than 1360nm and less than 1460nm. In addition, the wavelength of the measurement light is shorter than the communication band. In this embodiment, the communication band is the so-called C-band, that is, greater than 1530nm and less than 1565nm, and the so-called L-band, that is, greater than 1565nm and less than 1625nm. In Figure 5 , arranged in the up-down direction are: a waveform WFa when the measuring light is incident on the single-core optical fiber 30 optically coupled to the core 11aa of the multi-core optical fiber 10a with the core wire T; and a waveform WFb when the measuring light is incident on the single-core optical fiber 30 optically coupled to the core 11ab of the multi-core optical fiber 10a.

[0075] like Figure 5 As shown, in this embodiment, the slope of the portion of waveform WFa corresponding to the two ribbon cores T is greater than the slope of the portion of waveform WFb corresponding to the two ribbon cores T. In other words, the propagation loss of the measurement light in core 11aa of multi-core optical fiber 10a is greater than the propagation loss in core 11ab. It is known that when the wavelength of light propagating in the core is in the E band, the light loss due to hydroxyl groups contained in the core increases, sometimes referred to as OH loss. In this embodiment, due to OH loss, the propagation loss of the measurement light in core 11aa of multi-core optical fiber 10a is greater than the propagation loss in core 11ab.

[0076] Although illustrations are omitted, the waveforms when measurement light is incident on the single-core optical fiber 30 optically coupled to the cores 11ac and 11ad of the multi-core optical fiber 10a and the cores 11ba to 11bd, 11ca to 11cd, and 11da to 11dd of the multi-core optical fibers 10b to 10d are substantially the same as waveform WFb. Therefore, the propagation loss of the measurement light in core 11aa of the multi-core optical fiber 10a differs from the propagation loss of the cores 11ba, 11ca, and 11da corresponding to core 11aa in the other multi-core optical fibers 10b to 10d. Furthermore, the waveforms when light in the communication band is incident on each of the single-core optical fibers 30 are substantially the same as waveform WFb. Therefore, the difference between the propagation loss of the measurement light in core 11aa and the propagation loss in cores 11ba, 11ca, and 11da corresponding to core 11aa is greater than the difference between the propagation loss of light in core 11aa at a wavelength in the communication band and the propagation loss in cores 11ba, 11ca, and 11da corresponding to core 11aa. Here, cores 11ba, 11ca, and 11da corresponding to core 11aa are positioned approximately the same as core 11aa, based on marker 16. In other words, cores 11ba, 11ca, and 11da corresponding to core 11aa can be identified using the same identification method as core 11aa, based on marker 16.

[0077] As described above, the ribbon T, which serves as the optical fiber assembly of this embodiment, is constructed by bundling two or more multi-core optical fibers 10a-10b. The propagation loss of the measurement light in core 11aa of multi-core optical fiber 10a differs from the propagation loss of the measurement light in cores 11ba, 11ca, and 11da corresponding to core 11aa in other multi-core optical fibers 10b-10d. Therefore, when the ribbon T of this embodiment is connected to other ribbons T or FIFO 20 as optical communication components, the propagation loss of the measurement light in cores 11aa, 11ba, 11ca, and 11da can be measured to identify the multi-core optical fiber 10a.

[0078] In optical communications, it is desirable to minimize variations in the loss of light propagating through each core. In the ribbon cable T of this embodiment, the wavelength of the measurement light is outside the communication band. Therefore, according to the ribbon cable T of this embodiment, by using the measurement light to inspect the multi-core optical fiber 10a, it is possible to identify the multi-core optical fiber 10a even when there is minimal variation in the propagation of light with wavelengths within the communication band within the cores.

[0079] Furthermore, the method for measuring propagation loss is not limited to measurement using an OTDR 70; for example, measurement using an OFDR, OLTS, etc. is also possible. When using an OTDR or OFDR, the propagation loss can be measured simply by injecting light from one end of the ribbon cable T. This reduces costs because no operator is required at the other end of the ribbon cable T.

[0080] In this embodiment, the wavelength of the measurement light is shorter than the communication band. The shorter the wavelength of the light propagating through the core, the more the inter-core crosstalk of that light tends to be suppressed. Therefore, according to the ribbon cable T of this embodiment, when using the measurement light to investigate the propagation loss of the cores 11aa, 11ba, 11ca, and 11da, inter-core crosstalk can be suppressed compared to a case where the communication band is the same but the wavelength of the measurement light is longer than the communication band. Therefore, according to the ribbon cable T of this embodiment, identification of the multi-core optical fiber 10a is made easier.

[0081] In this embodiment, the wavelength of the measurement light is in the so-called E-band, which is between 1360 nm and less than 1460 nm. According to this embodiment, by increasing the hydroxyl content in core 11aa to a greater level than in the corresponding cores 11ba, 11ca, and 11da, as described above, the propagation loss of the measurement light in core 11aa can be made greater than the propagation loss in the corresponding cores 11ba, 11ca, and 11da. Therefore, the difference between the propagation loss in core 11aa and the propagation loss in the corresponding cores 11ba, 11ca, and 11da can be made greater than the difference between the propagation loss in core 11aa and the propagation loss in the corresponding cores 11ba, 11ca, and 11da of light with a wavelength in the communication band. The wavelength of light used in optical communications is sometimes set to the E-band, and existing OTDRs, OFDRs, and OLTSs utilize light in this wavelength band. Therefore, according to this embodiment, the propagation loss can be measured even with an existing OTDR, OFDR, OLTS, etc. Therefore, the multi-core optical fiber 10a can be easily identified.

[0082] Furthermore, the propagation loss of light of a specific wavelength can be different in core 11aa from that of the corresponding cores 11ba, 11ca, and 11da. For example, the wavelength of the measurement light can be within the communications band, and the propagation loss of light of a specific wavelength in core 11aa can be smaller than the propagation loss of light of a specific wavelength in cores 11ba, 11ca, and 11da. Alternatively, the propagation losses of light of a specific wavelength in cores 11ba, 11ca, and 11da can be different from one another. Furthermore, the propagation losses of light of a specific wavelength in cores 11aa to 11da can be the same in each of the multi-core optical fibers 10a to 10d.

[0083] Furthermore, there are no restrictions on the communication band or the wavelength of the measurement light. For example, when the wavelength of light propagating through the core is greater than 400 nm and less than 600 nm, optical loss tends to increase depending on the core's nickel, chromium, cobalt, iron, or copper content. When the wavelength of light propagating through the core is greater than 600 nm and less than 800 nm, optical loss tends to increase depending on the core's nickel, chromium, cobalt, or iron content. When the wavelength of light propagating through the core is greater than 800 nm and less than 900 nm, optical loss tends to increase depending on the core's chromium content. When the wavelength of light propagating through the core is greater than 900 nm and less than 1000 nm, optical loss tends to increase depending on the core's chromium and hydroxyl content. When the wavelength of light propagating through the core is within the so-called T band, i.e., greater than 1000 nm and less than 1260 nm, optical loss tends to increase depending on the core's nickel, cobalt, or hydroxyl content. When the wavelength of light propagating through the core is in the so-called O-band, i.e., 1260 nm to less than 1360 nm, optical loss tends to increase depending on the core's nickel and cobalt contents. When the wavelength of light propagating through the core is in the E-band, optical loss tends to increase depending on the core's nickel, cobalt, and hydroxyl contents. When the wavelength of light propagating through the core is in the so-called S-band, i.e., 1460 nm to less than 1530 nm; the so-called C-band, i.e., 1530 nm to less than 1565 nm; the so-called L-band, i.e., 1565 nm to less than 1625 nm; and the so-called U-band, i.e., 1625 nm to less than 1675 nm, optical loss tends to increase depending on the core's nickel and cobalt contents. When the wavelength of light propagating through the core is 1675 nm or greater, optical loss tends to increase depending on the core's hydroxyl, cobalt, and nickel contents. Therefore, for example, the above-mentioned structure can be achieved by adjusting the content of the above-mentioned substances in the core 11a of the multi-core optical fiber 10a. Therefore, for example, the communication band can be set to at least one of the C-band, L-band, O-band, and S-band, and the band other than the communication band can be set to at least one of the T-band, E-band, U-band, the ultraviolet band with a wavelength of 10 nm or more and less than 360 nm, the visible light band with a wavelength of 360 nm or more and less than 830 nm, and the infrared region with a wavelength of 830 nm or more and less than 2.5 μm, excluding the C-band, L-band, O-band, and S-band. Furthermore, the method of varying the propagation loss is not limited to adjusting the content of the above-mentioned substances in the core.

[0084] Alternatively, the wavelength of the measurement light can be set between 800 nm and 950 nm. The wavelength of light used in multimode fiber communications is sometimes set between 800 nm and 950 nm, and existing OTDRs and OLTS systems utilize light in this wavelength range. Therefore, with this configuration, even existing OTDRs and OLTS systems can measure propagation loss, making it easy to identify multi-core optical fibers 10a.

[0085] Alternatively, the wavelength of the measurement light can be in the so-called U-band, which is between 1625 nm and less than 1675 nm. The wavelength of light used in multimode fiber communications is sometimes set to the U-band, and existing OTDRs and OLTS systems utilize light in this band. Therefore, with this configuration, even existing OTDRs and OLTS systems can measure propagation loss, for example. This makes it possible to easily identify the multi-core optical fiber 10a.

[0086] Alternatively, the wavelength of the measurement light can be greater than or equal to 360 nm and less than or equal to 830 nm. Light with a wavelength greater than or equal to 360 nm and less than or equal to 830 nm is visible light, which appears dimmer as its energy decreases. Therefore, with this configuration, for example, the multi-core optical fiber 10a can be identified by visually observing the brightness of the return light when the measurement light is incident on each of the cores 11aa, 11ba, 11ca, and 11da from one end of the ribbon cable T. Furthermore, since the multi-core optical fiber 10a can be identified without using a device for measuring propagation loss, costs can be reduced.

[0087] Furthermore, when the wavelength of the measurement light is within the communications band, the difference between the propagation loss in core 11aa of the measurement light and the propagation loss in cores 11ba, 11ca, and 11da corresponding to core 11aa is preferably 0.005 dB / km or greater, more preferably 0.01 dB / km or greater, even more preferably 0.03 dB / km or greater, and even more preferably 0.05 dB / km or greater. This configuration allows even measurement equipment with a large minimum measurable propagation loss (e.g., a general-purpose measurement equipment) to measure the difference in propagation loss, thus enabling easy identification of the multi-core optical fiber 10a. Furthermore, when the wavelength of the light is within the communications band, the difference in propagation loss is preferably 0.1 dB / km or less, more preferably 0.06 dB / km or less. This configuration suppresses variations in communication quality between cores. Furthermore, when the wavelength of light is outside the communication band, the difference in propagation loss is preferably 0.1 dB / km or greater, more preferably 0.5 dB / km or greater, and even more preferably 1.0 dB / km or greater. Since the wavelength of light is outside the communication band, even large optical losses do not affect communication quality. This configuration allows for easy identification of the multi-core optical fiber 10a. Furthermore, when the difference is 0.1 dB / km or greater, even measurement equipment with a large minimum measurable propagation loss value (such as a general-purpose measurement equipment) can measure the difference in propagation loss, making it easy to identify the multi-core optical fiber 10a. In particular, in the case of short multi-core optical fibers, the small propagation loss can lead to large errors in the measured propagation loss. However, since the difference in propagation loss is 0.1 dB / km or greater, even short multi-core optical fibers 10a can suppress errors and easily identify the multi-core optical fiber 10a. Furthermore, the difference in propagation loss between the cores in a typical multi-core optical fiber tends to be less than 0.1 dB / km. Therefore, by adopting such a configuration, the multi-core optical fiber 10 a can be easily identified.

[0088] (Second embodiment)

[0089] The second embodiment of the present invention will be described in detail. Components identical or equivalent to those of the first embodiment are denoted by the same reference numerals unless otherwise specified, and duplicate descriptions will be omitted.

[0090] Figure 6 : is a conceptual diagram showing an optical communication device of this embodiment. Figure 6As shown, the multi-core optical fiber 10a with a core wire T of the optical communication device 1 of this embodiment is different from the multi-core optical fiber 10a of the first embodiment. In addition, the hydroxyl content of the core 11aa of the multi-core optical fiber 10a is substantially the same as the hydroxyl content of the cores 11ba, 11ca, and 11da of the multi-core optical fibers 10b to 10d corresponding to the core 11aa.

[0091] In the present embodiment, the multi-core optical fiber 10a is formed by connecting the ends of a plurality of optical fiber parts to each other, and the multi-core optical fibers 10b to 10d are formed by one optical fiber part. Therefore, in the cores 11aa, 11ab, 11ac, and 11ad of the multi-core optical fiber 10a, light loss, i.e., connection loss, occurs at the connection part 10CT between the optical fiber parts. Therefore, the light loss at the connection part 10CT in the core 11aa is different from the light loss at the position P1 corresponding to the connection part 10CT of the core 11aa in the cores 11ba, 11ca, and 11da of the multi-core optical fibers 10b to 10d corresponding to the core 11aa. Specifically, the position P1 is the same as the following position: a distance D1 away from the front end of the other multi-core optical fibers 10b to 10d on the waveguide component 40 side in the long side direction, and the distance D1 is the distance from the front end of the multi-core optical fiber 10a on the waveguide component 40 side to the connection part 10CT along the long side direction of the multi-core optical fiber 10a. Figure 6 Indicated by dashed lines. In this embodiment, for example, the multi-core optical fiber 10a can also be easily identified using an OTDR 70. In the case of short multi-core optical fibers, the propagation loss is small, so the error in the measured propagation loss may increase. However, according to this embodiment, even if the multi-core optical fibers 10a to 10d are short, the error can be suppressed and the multi-core optical fiber 10a can be identified.

[0092] Furthermore, the optical loss at the connection 10CT in core 11aa can be different from the optical loss at the aforementioned position P1 in cores 11ba, 11ca, and 11da corresponding to core 11aa. In this case, for example, the other multi-core optical fibers 10b-10d can also be configured with multiple optical fiber sections connected to each other in the longitudinal direction. Furthermore, as long as the optical loss at the connection 10CT in core 11aa is different from the optical loss at the aforementioned position P1 in cores 11ba, 11ca, and 11da, a connection 10CT between the optical fiber sections can be provided at the aforementioned position P1 in the multi-core optical fibers 10b-10d. In this case, for example, the inclination of the joint surface of the optical fiber sections at the connection 10CT in multi-core optical fibers 10b-10d can be different from the inclination of the joint surface of the optical fiber sections at the connection 10CT in multi-core optical fiber 10a. The inclination of the joint surface of the optical fiber sections is the inclination relative to a direction perpendicular to the direction in which the optical fiber sections extend. This configuration allows the optical loss at the connection portion 10CT in the core 11aa to differ from the optical loss at the position P1 in the cores 11ba, 11ca, and 11da. The difference between the optical loss at the connection portion 10CT in the core 11aa and the optical loss at the position P1 in the cores 11ba, 11ca, and 11da is preferably 0.01 dB or greater, more preferably 0.1 dB or greater, and even more preferably 0.5 dB or greater.

[0093] There is no limit to the number of splices 10CT; the number of splices 10CT in the multi-core optical fiber 10a can differ from the number of splices 10CT in the other multi-core optical fibers 10b to 10d. In this case, even if the light loss at the splice 10CT in core 11aa is the same as the light loss at position P1 in cores 11ba, 11ca, and 11da, the multi-core optical fiber 10a can be identified by measuring the number of splices 10CT using, for example, an OTDR 70. Furthermore, while multi-core optical fibers 10a are identified based on a discrete natural number such as the number of splices 10CT, losses such as propagation loss are not typically natural numbers. Therefore, identification is easier than when identifying multi-core optical fibers 10a based on differences in losses such as propagation loss. Furthermore, even if the multi-core optical fiber 10a is short, it is possible to minimize errors and identify the multi-core optical fiber 10a.

[0094] When the number of connection portions 10CT of the multi-core optical fiber 10a is the same as the number of connection portions 10CT of the other multi-core optical fibers 10b to 10d, at least one connection portion 10CT of the other multi-core optical fibers 10b to 10d may be located at a position other than the position P1.

[0095] (Third embodiment)

[0096] The third embodiment of the present invention will now be described in detail. Components identical or equivalent to those of the first embodiment are denoted by the same reference numerals unless otherwise specified, and duplicate descriptions will be omitted.

[0097] The optical communication device 1 of this embodiment is different from the optical communication device 1 of the first embodiment in that it includes two bundling units B as optical fiber aggregates instead of two ribbon core wires T. Figure 1 Will Figure 1 The following describes how to replace the core wire T with a bundling unit.

[0098] In this embodiment, the structures of the respective binding units are identical to each other. Therefore, one binding unit will be described below, and the other binding units will be denoted by the same reference numerals unless otherwise specified, and duplicate descriptions will be omitted.

[0099] Figure 7 Schematically shows a cross section perpendicular to the long side direction of the bundling unit in this embodiment. Figure 7 In the figure, the hatching of the multi-core optical fiber is omitted, and the outer diameter and core of the multi-core optical fiber are shown. Figure 7 As shown, the bundling unit B has an optical fiber bundle formed by bundling more than two multi-core optical fibers, namely, a plurality of ribbon cores Ta~Td and a bundling member B1 as main structures. The bundling member B1 of this embodiment is a ribbon-shaped component, and the bundling member B1 is wound around the plurality of ribbon cores Ta~Td, thereby bundling these ribbon cores Ta~Td. The bundling member B1 only needs to be able to bundle the plurality of ribbon cores Ta~Td, for example, it can also be a filamentous or mesh-shaped component. As the material constituting the bundling member B1, for example, resin can be cited. In Figure 7 , an example is shown in which the binding unit B is composed of four tape cores Ta to Td, but the number of tape cores constituting the binding unit B is not limited.

[0100] The structure of the tape core wires Ta to Td of the present embodiment is the same as that of the tape core wire T of the first embodiment. In the present embodiment, different identification marks are provided on the outer peripheral surfaces of the respective tape core wires Ta to Td.

[0101] In this embodiment, the propagation loss of the measurement light in the core 11aa of the multi-core optical fiber 10a in the ribbon core Ta is different from the propagation loss of the measurement light in the cores 11aa of the multi-core optical fibers 10a in the other ribbon cores Tb to Td corresponding to this core 11aa. For example, a method for making the propagation loss different can be to vary the amount of an element that easily absorbs the measurement light added to each core 11aa.

[0102] In this structure, one end of each ribbon cable Ta to Td in one bundling unit B is connected to the other end of each ribbon cable Ta to Td in another bundling unit B. In this case, the ribbon cables Ta to Td with the same identification mark are connected to each other. Furthermore, as in the first embodiment, between the connected ribbon cables Ta to Td, multi-core optical fibers 10a to 10d with the same color of the colored layer 15 are connected to each other. In this way, the cores 11aa to 11ad of each multi-core optical fiber 10a to 10d in one bundling unit B are optically connected to the corresponding cores 11aa to 11ad in the other bundling unit B.

[0103] In this embodiment, the number of FIFOs 20 is the same as the number of multi-core optical fibers in the bundling unit B. The FIFOs 20 are connected to each multi-core optical fiber, and each core of each multi-core optical fiber is optically coupled to the core 31 of each single-core optical fiber 30 of the FIFO 20 .

[0104] In this embodiment, as described above, the propagation loss of measurement light in a specific core 11aa of a specific multi-core optical fiber 10a in a specific ribbon Ta differs from the propagation loss of measurement light in cores 11aa of the multi-core optical fibers 10a corresponding to the specific multi-core optical fiber 10a in the other ribbons Tb to Td. Therefore, when the bundling unit B of this embodiment is connected to other bundling units B and FIFO 20 as optical communication components, the multi-core optical fiber 10a in the ribbon Ta can be identified by examining the propagation loss of measurement light in the cores 11aa of the multi-core optical fibers 10a in the respective ribbons Ta to Td. Consequently, the ribbon Ta can be identified. Here, the multi-core optical fiber 10a corresponding to the specific multi-core optical fiber 10a in the other ribbons Tb to Td has the same color of the colored layer 15 as the specific multi-core optical fiber 10a. That is, the multi-core optical fiber 10a among the other core fibers Tb to Td is identifiable based on the color of the multi-core optical fiber 10a of the core fiber Ta by the same identification method as that of the multi-core optical fiber 10a.

[0105] Furthermore, the propagation loss of light of a specific wavelength may be different between the core 11aa of the multi-core optical fiber 10a in the ribbon Ta and the core 11aa of the multi-core optical fiber 10a corresponding to the multi-core optical fiber 10a in the other ribbons Tb to Td. For example, the propagation loss of light of a specific wavelength in the cores 11ba, 11ca, and 11da of the other multi-core optical fibers 10b to 10d corresponding to the core 11aa of the multi-core optical fiber 10a in the respective ribbons Ta to Td may be the same.

[0106] (Fourth embodiment)

[0107] The third embodiment of the present invention will now be described in detail. Components identical or equivalent to those of the first embodiment are denoted by the same reference numerals unless otherwise specified, and duplicate descriptions will be omitted.

[0108] The optical communication device 1 of this embodiment is different from the optical communication device 1 of the first embodiment in that it includes two cables as an optical fiber assembly instead of two ribbon core wires T. Figure 1 Will Figure 1 The following describes how to replace the core wire T with a cable.

[0109] In this embodiment, the structures of the cables are identical to each other. Therefore, one cable will be described below, and the other cables will be denoted by the same reference numerals unless otherwise specified, and duplicate descriptions will be omitted.

[0110] Figure 8 Schematically shows a cross section perpendicular to the longitudinal direction of the cable in this embodiment. Figure 8 In the figure, the shadow of the multi-core optical fiber is omitted and the outer diameter of the multi-core optical fiber is shown. Figure 8 As shown, the cable C includes, as main components, a plurality of bundled units Ba to Bd, which are optical fiber bundles formed by bundling two or more multi-core optical fibers, and a sheath C1.

[0111] The sheath C1 is a tubular member. A plurality of binding units Ba to Bd are accommodated in the internal space of the sheath C1, and the plurality of binding units Ba to Bd are bundled together by the sheath C1. Examples of the material constituting the sheath C1 include resin.

[0112] The structure of the binding units Ba to Bd of this embodiment is the same as that of the binding unit B of the third embodiment. In this embodiment, the colors of the binding members B1 in the respective binding units Ba to Bd are different from each other.

[0113] In this embodiment, the propagation loss of the measurement light in the core 11aa of the multi-core optical fiber 10a in the ribbon core Ta of the bundled unit Ba is different from the propagation loss of the measurement light in the core 11aa of the multi-core optical fiber 10a corresponding to the specific multi-core optical fiber 10a in the ribbon core Ta of the other bundled units Bb to Bd. As a method of making the propagation loss different, for example, the amount of an element that easily absorbs the measurement light added to each core 11aa can be used.

[0114] In this structure, one end of each bundling unit Ba to Bd of one cable C is connected to the other end of each bundling unit Ba to Bd of another cable C. At this point, the bundling units Ba to Bd of the same color as the bundling unit B1 are connected. Similarly to the third embodiment, the ribbons Ta to Td with the same identification marks are connected between the connected bundling units Ba to Bd. Furthermore, similarly to the first embodiment, the multi-core optical fibers 10a to 10d with the same color of the colored layer 15 are connected between the connected ribbons Ta to Td. In this way, the cores 11aa to 11ad of each multi-core optical fiber 10a to 10d in one cable C are optically connected to the corresponding cores 11aa to 11ad in the other cable C.

[0115] In this embodiment, the number of FIFOs 20 is the same as the number of multi-core optical fibers in the cable C. The FIFOs are connected to each multi-core optical fiber, and each core of each multi-core optical fiber is optically coupled to the core 31 of each single-core optical fiber 30 of the FIFO 20 .

[0116] In this embodiment, as described above, the propagation loss of the measurement light of a specific core 11aa in a specific multi-core optical fiber 10a in a specific bundling unit Ba is different from the propagation loss of the measurement light of a core 11aa in a multi-core optical fiber 10a corresponding to the specific multi-core optical fiber 10a in other bundling units Bb to Bd. Therefore, when the cable C of this embodiment is connected to other cables C and FIFO 20 as optical communication components, by examining the propagation loss of the measurement light of the core 11aa of the multi-core optical fiber 10a with core Ta in each bundling unit Bb to Bd, the multi-core optical fiber 10a with core Ta in the bundling unit Ba can be identified, and as a result, the bundling unit Ba can be identified. Here, the multi-core optical fibers 10a in other bundling units Bb~Bd corresponding to the specific multi-core optical fiber 10a of the bundling unit Ba are multi-core optical fibers contained in a core wire having an identification mark identical to the identification mark of the core wire Ta containing the specific multi-core optical fiber 10a, and the color of the coloring layer 15 is the same as that of the specific multi-core optical fiber 10a.

[0117] Furthermore, it is sufficient that the propagation loss of light of a specific wavelength is different between the core 11aa of the multi-core optical fiber 10a in the ribbon Ta of the bundling unit Ba and the core 11aa of the multi-core optical fiber 10a corresponding to the multi-core optical fiber 10a in the ribbon Ta of the other bundling units Bb to Bd. For example, the propagation loss of light of a specific wavelength in the cores 11ba, 11ca, and 11da of the other multi-core optical fibers 10b to 10d corresponding to the core 11aa of the multi-core optical fiber 10a in the ribbons Ta to Ta of the respective bundling units Bb to Bd may be the same.

[0118] The present invention has been described above using the aforementioned embodiments as examples, but the present invention is not limited thereto. In the first embodiment, a ribbon T is used as an example, in which the measured light propagation loss differs between the core 11aa in the multi-core optical fiber 10a and the cores 11ba, 11ca, and 11da corresponding to the core 11aa in the other multi-core optical fibers 10b to 10d. Furthermore, in the second embodiment, a ribbon T is used as an example, in which the connection loss differs between the core 11aa in the multi-core optical fiber 10a and the cores 11ba, 11ca, and 11da corresponding to the core 11aa in the other multi-core optical fibers 10b to 10d. However, it suffices that the optical characteristics of a specific core in a specific multi-core optical fiber differ from the optical characteristics of the cores corresponding to the specific core in the other multi-core optical fibers. Furthermore, there may be multiple specific cores, in which case the optical characteristics may be predetermined values calculated based on the loss of light of a specific wavelength in the multiple cores. Examples of the predetermined value include the average, maximum, minimum, value obtained by subtracting the minimum from the maximum, median, mode, quantile, and variance of inter-core crosstalk and the propagation loss of light of a specific wavelength. Furthermore, when there are three or more specific cores, the predetermined inter-core crosstalk value may also be the average, maximum, minimum, value obtained by subtracting the minimum from the maximum, median, mode, quantile, and variance of the inter-core crosstalk in the group of multiple cores. Examples of the quantiles include the first quartile and the third quartile.

[0119] These predetermined values are values caused by multiple cores in a multi-core optical fiber. Therefore, by setting the above-mentioned optical characteristics to these predetermined values, a specific multi-core optical fiber can be identified with high precision compared to the case where the predetermined value is a value caused by a single core in the multi-core optical fiber. In addition, the degree of freedom in the types of optical characteristics used to identify a specific multi-core optical fiber is increased, making it possible to easily identify a specific multi-core optical fiber. In addition, when using predetermined values that are arithmetic results, the degree of freedom in selecting a core with high loss as a specific core can be increased, making it possible to easily identify a specific multi-core optical fiber. In addition, the above-mentioned specific cores are preferably all the cores of a specific multi-core optical fiber. In this case, the predetermined value is a value caused by all the cores in the multi-core optical fiber. Therefore, by setting it to such a structure, a specific multi-core optical fiber can be identified with higher precision compared to the case where the predetermined value is a value caused by a single core in the multi-core optical fiber.

[0120] Furthermore, when the predetermined value is any of the average, maximum, minimum, value obtained by subtracting the minimum value from the maximum, and mode of the propagation loss of light at a specific wavelength, the difference between the predetermined value in a specific multi-core optical fiber and the predetermined values in other multi-core optical fibers is preferably 0.005 dB / km or greater. Furthermore, from the perspective of suppressing variations in communication quality among the cores in the multi-core optical fiber, the difference is preferably 0.1 dB / km or less, and more preferably 0.06 dB / km or less.

[0121] Furthermore, when the predetermined value is any one of the median, quantile, and variance of the propagation loss of light at a specific wavelength, the difference between the predetermined value in a specific multi-core optical fiber and the predetermined values in other multi-core optical fibers is preferably 0.005 dB / km or greater. Furthermore, from the perspective of suppressing variations in communication quality between the cores in the multi-core optical fiber, the difference is preferably 0.03 dB / km or less, and more preferably 0.01 dB / km or less.

[0122] Furthermore, when the predetermined value is any one of the inter-core crosstalk of light of a specific wavelength, the average value, maximum value, minimum value, value obtained by subtracting the minimum value from the maximum value, median value, mode, quantile, and variance of the inter-core crosstalk, the difference between the predetermined value in a specific multi-core optical fiber and the predetermined values in other multi-core optical fibers is preferably 1 dB or greater, more preferably 2 dB or greater, even more preferably 3 dB or greater, and even more preferably 5 dB or greater. With such a configuration, even a measurement device with a large minimum measurable inter-core crosstalk value can easily identify a specific multi-core optical fiber. Furthermore, when the aforementioned difference is 1 dB or greater, difficulty in identifying a specific multi-core optical fiber due to measurement error can be suppressed. Furthermore, from the perspective of suppressing variations in communication quality caused by each core, the aforementioned difference is preferably 5 dB or less.

[0123] In the third embodiment, the bundle unit B is described as an example, in which the propagation loss of measurement light in a specific core 11aa of a specific multi-core optical fiber 10a in a specific ribbon Ta differs from the propagation loss of measurement light in a core 11aa of a multi-core optical fiber 10a corresponding to the specific multi-core optical fiber 10a in other ribbons Tb to Td. Furthermore, in the fourth embodiment, the cable C is described as an example, in which the propagation loss of measurement light in a specific core 11aa of a specific multi-core optical fiber 10a in a specific bundle unit Ba differs from the propagation loss of measurement light in a core 11aa of a multi-core optical fiber 10a corresponding to the specific multi-core optical fiber 10a in other bundle units Bb to Bd. However, it suffices that the optical characteristics of a specific core in a specific multi-core optical fiber in a specific optical fiber bundle differ from the optical characteristics of the cores corresponding to the specific core in the multi-core optical fibers corresponding to the specific multi-core optical fiber in other optical fiber bundles.

[0124] For example, in the bundling unit B illustrated in the third embodiment and the cable C illustrated in the fourth embodiment, the optical characteristic may also be connection loss. For example, in the third embodiment, as in the second embodiment, a specific multi-core optical fiber 10a of a specific ribbon Ta may be constructed by connecting the ends of multiple optical fiber sections. Furthermore, in the fourth embodiment, a specific multi-core optical fiber 10a of a bundling unit Ba may be constructed by connecting the ends of multiple optical fiber sections. Furthermore, in these cases, the optical loss at the connection between the optical fiber sections in a specific multi-core optical fiber 10a is made different from the optical loss at the position corresponding to the connection between the specific multi-core optical fibers 10a in the other ribbons Tb to Td and the other bundling units Bb to Bd. By setting this up, as in the second embodiment, even if the multi-core optical fibers 10a to 10d are short, it is possible to suppress errors and identify the multi-core optical fiber 10a.

[0125] In addition, in the bundling unit B illustrated in the third embodiment and the cable C illustrated in the fourth embodiment, as long as the light loss at the connection between the optical fiber parts in a specific multi-core optical fiber 10a is different from the light loss at the position corresponding to the connection part of the specific multi-core optical fiber 10a in the multi-core optical fiber 10a corresponding to the specific multi-core optical fiber 10a in other ribbons Tb to Td and other bundling units Bb to Bd, the following arrangement may be made. The specific multi-core optical fiber 10a and the multi-core optical fiber 10a corresponding to the specific multi-core optical fiber 10a in other ribbons Tb to Td and other bundling units Bb to Bd may also be a structure in which multiple optical fiber parts are connected to each other in the longitudinal direction. In this case, the connection part between the optical fiber parts may also be provided at the position corresponding to the connection part of the specific multi-core optical fiber 10a in the multi-core optical fiber 10a corresponding to the specific multi-core optical fiber 10a in other ribbons Tb to Td and other bundling units Bb to Bd.

[0126] In addition, in the bundling unit B illustrated in the third embodiment and the cable C illustrated in the fourth embodiment, when a specific multi-core optical fiber 10a and the multi-core optical fibers 10a corresponding to the specific multi-core optical fiber 10a in other ribbons Tb to Td and other bundling units Bb to Bd are also configured such that multiple optical fiber portions are connected to each other in the longitudinal direction, the number of each connection portion is not limited. For example, the number of connection portions between the optical fiber portions in the specific multi-core optical fiber 10a may be different from or the same as the number of connection portions between the optical fiber portions in the multi-core optical fibers 10a corresponding to the specific multi-core optical fiber 10a in other ribbons Tb to Td and other bundling units Bb to Bd. When the number of connection portions is the same, at least one connection portion of the multi-core optical fiber 10a corresponding to the specific multi-core optical fiber 10a in other ribbons Tb to Td and other bundling units Bb to Bd may be located at a position other than the position corresponding to the connection portion of the specific multi-core optical fiber 10a.

[0127] Furthermore, in the bundling unit B illustrated in the third embodiment and the cable C illustrated in the fourth embodiment, the specific cores may be multiple or all the cores of a specific multi-core optical fiber. In this case, the optical characteristics of the specific core in the specific multi-core optical fiber 10a that differ from those of the cores corresponding to the specific core in the other ribbons Tb-Td and the other bundling units Bb-Bd may be predetermined values calculated based on the loss of light of a specific wavelength in the core.

[0128] In addition, in the bundling unit B illustrated in the third embodiment and the cable C illustrated in the fourth embodiment, similarly to the first embodiment, the wavelength of the measuring light can be greater than 800 nm and less than 950 nm, greater than 1625 nm and less than 1675 nm, or greater than 360 nm and less than 830 nm.

[0129] Furthermore, in the bundling unit B illustrated in the third embodiment and the cable C illustrated in the fourth embodiment, the difference between the propagation loss of the measurement light in a specific core of a specific multi-core optical fiber 10a and the propagation loss of the measurement light in the corresponding cores of the other ribbons Tb-Td and the other bundling units Bb-Bd is preferably the same as in the first embodiment. Specifically, when the wavelength of the measurement light is within the communications band, the difference in propagation loss is preferably 0.005 dB / km or greater, more preferably 0.01 dB / km or greater, even more preferably 0.03 dB / km or greater, and even more preferably 0.05 dB / km or greater. Furthermore, when the wavelength of the measurement light is within the communications band, the difference in propagation loss is preferably 0.1 dB / km or less, more preferably 0.06 dB / km or less. Furthermore, when the wavelength of the measurement light is outside the communications band, the difference in propagation loss is preferably 0.1 dB / km or greater, more preferably 0.5 dB / km or greater, and even more preferably 1.0 dB / km or greater.

[0130] In the first to fourth embodiments, the cores 11ba, 11ca, and 11da corresponding to the core 11aa of the specific multi-core optical fiber 10a in the other multi-core optical fibers 10b-10d are positioned approximately identically to the core 11aa, based on the identifier mark 16. However, the corresponding cores are not limited to cores positioned identically based on the identifier mark 16; the multi-core optical fibers do not necessarily need to include the identifier mark 16. For example, if a portion of the outer circumference of the multi-core optical fibers 10a-10d is marked with printed text, a barcode, or other identifier, the corresponding cores may also be cores positioned identically based on the identifier mark. Furthermore, if the arrangement of the multiple cores is asymmetrical, the corresponding cores may be cores located identically within each multi-core optical fiber. Furthermore, if the multi-core optical fiber includes a core located at the center of the cladding 12, the corresponding cores may also be cores located at the center of the cladding 12. Furthermore, even if there are no identifiers such as marker 16 and the arrangement of the multiple cores is rotationally symmetrical, provided there is no twisting or rotation of the multi-core optical fiber, and if the cores of each multi-core optical fiber are arranged identically when viewed in cross-section, the corresponding cores may be cores arranged in the same direction relative to the center of the cladding 12. Furthermore, if multiple multi-core optical fibers are connected to multiple transceivers in a one-to-one correspondence via multiple single-core optical fibers, the corresponding cores may be cores with the same port number as the ports of the transceivers connected to each multi-core optical fiber. In other words, the cores that can be identified using the same visual recognition method as the specific core 11aa in the multi-core optical fiber 10a are the cores 11ba, 11ca, and 11da in the multi-core optical fibers 10b to 10d corresponding to core 11aa.

[0131] In addition, in the third embodiment, the multi-core optical fibers 10a in the other cored wires Tb to Td corresponding to the specific multi-core optical fiber 10a of the cored wire Ta are multi-core optical fibers whose color of the coloring layer 15 serving as an identifier is the same as that of the specific multi-core optical fiber 10a. However, the multi-core optical fibers corresponding to each other are not limited to the multi-core optical fibers having the same color of the coloring layer 15. The colors of the coloring layers 15 of the respective multi-core optical fibers may be the same as each other, or they may not have the coloring layer 15. For example, in the case where a mark such as printing or barcode serving as an identifier is applied to the outer peripheral surface of the multi-core optical fibers 10a to 10d, the multi-core optical fibers corresponding to each other may also be the multi-core optical fibers having the same mark. In the case where the arrangement of the multi-core optical fibers in the cored wires is regular and a specific multi-core optical fiber can be identified based on the regularity, for example, when the multi-core optical fibers in the cored wires are arranged as Figure 2When the multi-core optical fibers are arranged in a straight line as shown, the multi-core optical fibers corresponding to each other may also be multi-core optical fibers arranged at the same position in each ribbon. In addition, in the ribbon, when the outer diameter or shape of a specific multi-core optical fiber, or the outer diameter or shape of the cladding 12 is different from that of other multi-core optical fibers, the multi-core optical fibers corresponding to each other may also be multi-core optical fibers in which the outer diameter or shape of the multi-core optical fibers of the ribbon and other ribbons, or the outer diameter or shape of the cladding 12 are the same. In addition, as an example of the difference in the outer diameter of the multi-core optical fibers, for example, the case where the outer diameter of the cladding 12 is the same but the thickness of the covering layer is different can be cited. In other words, the multi-core optical fibers that can be identified by the same identification method based on visual recognition as the identification method of the specific multi-core optical fiber 10a of the ribbon Ta are the multi-core optical fibers 10a in the other ribbons Tb~Td corresponding to the multi-core optical fiber 10a.

[0132] Furthermore, in the fourth embodiment, the multi-core optical fibers 10a in the other bundling units Bb-Bd corresponding to the specific multi-core optical fiber 10a in the bundling unit Ba are multi-core optical fibers included in a ribbon having the same identification mark as the ribbon Ta containing the specific multi-core optical fiber 10a, and having the same color of the colored layer 15 as the specific multi-core optical fiber 10a. However, corresponding multi-core optical fibers are not limited to those having the same identification mark and the same colored layer 15 color as the ribbon containing the multi-core optical fiber. For example, if the outer circumferences of the multi-core optical fibers 10a-10d are marked with printed characters, barcodes, or other identifiers, the corresponding multi-core optical fibers may also be those having the same identification mark and the same marking as the ribbon containing the multi-core optical fiber. Furthermore, if the arrangement of the multi-core optical fibers in the ribbon is regular and a specific multi-core optical fiber can be identified based on this regularity, the corresponding multi-core optical fibers may also be those having the same identification mark as the ribbons containing the multi-core optical fiber and being arranged in the same position among the multi-core optical fibers in the ribbons. Furthermore, in a ribbon, if the outer diameter or outer shape of a particular multi-core optical fiber, or the outer diameter or outer shape of the cladding 12, differs from that of other multi-core optical fibers, the corresponding multi-core optical fibers may also be multi-core optical fibers having the same identification mark as the ribbons containing the multi-core optical fiber, and having the same outer diameter or outer shape of the multi-core optical fiber, or the outer diameter or outer shape of the cladding 12 in each ribbon. Examples of multi-core optical fibers having different outer diameters include, for example, having the same outer diameter of the cladding 12 but different thicknesses of the covering layer. In other words, the multi-core optical fibers that can be identified using the same visual recognition method as the specific multi-core optical fiber 10a of the bundling unit Ba are the multi-core optical fibers 10a in the other bundling units Bb to Bd corresponding to the multi-core optical fiber 10a.

[0133] In addition, the cable C may also be a so-called slot-type cable having a retaining body that independently retains a plurality of bundling units Ba~Bd. Although not illustrated, the retaining body is a cylindrical component having a plurality of slots formed on the outer peripheral surface, which are grooves extending along the longitudinal direction. The bundling units Ba~Bd are individually accommodated in the slots and retained in the retaining body. Furthermore, the retaining body is accommodated in the internal space of the sheath C1. In addition, markings such as printing, bar codes, etc. may be applied to the end faces of the retaining body as identifiers. According to such a structure, the bundling units Ba~Bd accommodated in the slots can be distinguished based on the position of the slots relative to the identifier. In such a case where the bundling units Ba~Bd can be distinguished, the colors of the bundling parts B1 of the bundling units Ba~Bd may be the same as each other, or the bundling parts B1 may not be provided.

[0134] In addition, in the above embodiment, the optical fiber assembly is described using the ribbon T, the bundling unit B, and the cable C as an example. However, the optical fiber assembly of the present invention may be in a manner other than the above embodiment, as long as it is an optical fiber assembly that bundles two or more multi-core optical fibers, and may also bundle them in a portion along the longitudinal direction. In addition, bundling two or more multi-core optical fibers means bundling each multi-core optical fiber along the longitudinal direction.

[0135] As described above, according to the present invention, an optical fiber aggregate capable of identifying a specific multi-core optical fiber when connected to an optical communication component is provided, and is expected to be used in fields such as optical fiber communications.

Claims

1. An optical fiber assembly comprising two or more multi-core optical fibers each including a plurality of cores and a cladding surrounding each of the cores, wherein: The optical characteristics of the specific core in the specific multi-core optical fiber are different from the optical characteristics of the cores corresponding to the specific core in the other multi-core optical fibers.

2. An optical fiber assembly comprising a plurality of multi-core optical fibers including a plurality of cores and a cladding surrounding each of the cores, wherein: A plurality of optical fiber bundles are provided, each of which is formed by bundling two or more of the multi-core optical fibers. The optical characteristics of the specific core in the specific multi-core optical fiber of the specific optical fiber bundle are different from the optical characteristics of the core corresponding to the specific core in the multi-core optical fibers corresponding to the specific multi-core optical fibers in the other optical fiber bundles.

3. The optical fiber aggregate according to claim 1 or 2, characterized in that: The number of the specific fiber cores is multiple, The optical characteristics are predetermined values obtained based on the loss of light of a specific wavelength in the plurality of cores.

4. The optical fiber aggregate according to claim 3, wherein: The specific cores are all the cores of the specific multi-core optical fiber.

5. The optical fiber aggregate according to claim 3 or 4, characterized in that: The specific wavelength is a wavelength outside the communication band.

6. The optical fiber aggregate according to claim 5, wherein: The specific wavelength is shorter than the communication band.

7. The optical fiber aggregate according to any one of claims 3 to 6, wherein: The specific wavelength is greater than or equal to 1360 nm and less than or equal to 1460 nm.

8. The optical fiber aggregate according to any one of claims 3 to 6, wherein: The specific wavelength is greater than or equal to 800 nm and less than or equal to 950 nm.

9. The optical fiber aggregate according to claim 1, wherein: The multi-core optical fiber is formed by connecting the ends of multiple optical fiber parts to each other. The light loss at the connection portion between the optical fiber portions in a specific multi-core optical fiber is different from the light loss at a position corresponding to the connection portion in the other multi-core optical fibers.

10. The optical fiber aggregate according to claim 2, wherein: The multi-core optical fiber is formed by connecting the ends of multiple optical fiber parts to each other. The light loss at the connection portion between the optical fiber portions in a specific multi-core optical fiber is different from the light loss at a position corresponding to the connection portion in the multi-core optical fiber corresponding to the specific multi-core optical fiber.

11. The optical fiber aggregate according to claim 1, wherein: The specific multi-core optical fiber and the other multi-core optical fibers are formed by connecting the ends of a plurality of optical fiber parts to each other. The number of connection portions between the optical fiber portions in a specific multi-core optical fiber is different from the number of connection portions between the optical fiber portions in the other multi-core optical fibers.

12. The optical fiber aggregate according to claim 2, wherein: The specific multi-core optical fiber and the multi-core optical fiber corresponding to the specific multi-core optical fiber are formed by connecting the ends of a plurality of optical fiber parts to each other. The number of connection portions between the optical fiber portions in the specific multi-core optical fiber is different from the number of connection portions between the optical fiber portions in the multi-core optical fiber corresponding to the specific multi-core optical fiber.

13. The optical fiber aggregate according to claim 1, wherein: The difference between the propagation loss of light of a specific wavelength in a specific core of the specific multi-core optical fiber and the propagation loss of light of the specific wavelength in the core corresponding to the specific core in the other multi-core optical fibers is 0.1 dB / km or more.

14. The optical fiber aggregate according to claim 2, wherein: The difference between the propagation loss of light of a specific wavelength in a specific core of the specific multi-core optical fiber and the propagation loss of light of the specific wavelength in the core corresponding to the specific core in the multi-core optical fiber corresponding to the specific multi-core optical fiber is 0.1 dB / km or more.

15. The optical fiber aggregate according to any one of claims 1, 2, 13 and 14, wherein: The optical characteristic is the propagation loss of a specific wavelength of the fiber core, The specific wavelength is greater than or equal to 360 nm and less than or equal to 830 nm.

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