Optical cable with connector and optical transmission system

Abstract

An optical cable (1) with a connector is provided with: a multi-core optical fiber (31); a first optical connector (3) attached to a first end of the multi-core optical fiber (31); and a second optical connector (4) attached to the second end of the multi-core optical fiber (31). The arrangement of the first to Nth cores is rotationally asymmetrical about the central axis in a cross-section perpendicular to the central axis of the multi-core optical fiber (31). The first optical connector (3) and the second optical connector (4) are optical connectors of the type connected to the optical connector to be connected in a state in which the upward orientation coincides with the optical connector to be connected. When the connection end surfaces of the first optical connector (3) and the second optical connector (4) are observed in a manner that the upward directions are consistent. The arrangement of the end surfaces of the first core to the Nth core among the connection end surfaces of the second optical connector (4) is an arrangement in which the arrangement of the end surfaces of the first core to the Nth core among the connection end surfaces of the first optical connector (3) is turned over with respect to a central axis (A3) along the connection end surfaces in a direction in which the upward direction is aligned.

Description

Technical Field

[0001] The present disclosure relates to an optical fiber cable with a connector and an optical transmission system. This application claims priority based on Japanese Application No. 2022-196942 filed on December 9, 2022, and incorporates by reference the entire disclosure of the Japanese application. Background Art

[0002] Patent Document 1 and Patent Document 2 disclose an optical fiber cable with a connector having a multi-core optical fiber.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Specification of U.S. Patent No. 10859772

[0006] Patent Document 2: International Publication No. 2022 / 118985 Summary of the Invention

[0007] An optical fiber cable with a connector according to one aspect of the present disclosure includes: a multi-core optical fiber having a first core to an Nth core, where N is an integer of 2 or more; a first optical connector assembled to a first end of the multi-core optical fiber; and a second optical connector assembled to a second end of the multi-core optical fiber. The arrangement of the first core to the Nth core is rotationally asymmetric about the central axis in a cross-section of the multi-core optical fiber perpendicular to the central axis of the multi-core optical fiber. The first optical connector and the second optical connector are optical connectors of a type that are connected to an optical connector of a connection target in a state where the upward orientation is the same as that of the optical connector of the connection target. When observing the connection end faces of the first optical connector and the second optical connector in a manner that makes the upward orientations of the optical connectors the same, the arrangement of the end faces of the first core to the Nth core in the connection end face of the second optical connector is obtained by flipping the arrangement of the end faces of the first core to the Nth core in the connection end face of the first optical connector with respect to the central axis of the connection end face along the direction in which the upward orientations of the optical connectors are the same. Brief Description of the Drawings

[0008] Figure 1A It is a perspective view for explaining the type of optical connector.

[0009] Figure 1B It is a perspective view for explaining the type of optical connector.

[0010] Figure 2 It is a perspective view showing a case where a plurality of optical fiber cables with connectors are connected to each other.

[0011] Figure 3A It is a diagram schematically showing an example of a cross-section perpendicular to the central axis of the multi-core optical fiber included in the optical fiber cable.

[0012] Figure 3B is a diagram schematically showing an example of a cross section perpendicular to the central axis of the multi-core optical fiber included in the optical cable.

[0013] Figure 4A is a diagram schematically showing another example of a cross section perpendicular to the central axis of the multi-core optical fiber included in the optical cable.

[0014] Figure 4B is a diagram schematically showing another example of a cross section perpendicular to the central axis of the multi-core optical fiber included in the optical cable.

[0015] Figure 5 is a diagram showing the core configuration of each of the first optical connector and the second optical connector in a single optical cable with connectors when viewed from the front of the connection end face.

[0016] Figure 6 is a chart showing the correspondence of the cores.

[0017] Figure 7A is a perspective view showing the appearance of an MPO connector.

[0018] Figure 7B is a perspective view showing the appearance of the MT ferrule included in the MPO connector.

[0019] Figure 8A is a front view of the connection end face of the MT ferrule.

[0020] Figure 8B is a side view of the MT ferrule.

[0021] Figure 8C is a side view of the MT ferrule.

[0022] Figure 9A is a side view showing the situation where the connection end faces of two MT ferrules face each other.

[0023] Figure 9B is a side view showing the situation where the connection end faces of two MT ferrules face each other.

[0024] Figure 10 is a diagram showing the core configuration of each optical fiber of the first optical connector and the second optical connector in a single optical cable with connectors when the first optical connector and the second optical connector are MPO connectors and viewed from the front of the connection end face. It should be noted that Figure 10 shows the core configuration of a representative one of the multiple optical fibers included in the optical cable with connectors, and the core configurations of the other optical fibers are also Figure 10 the same.

[0025] Figure 11 is a chart showing the correspondence of the cores.

[0026] Figure 12A It is a diagram showing a modified example of the number and arrangement of cores.

[0027] Figure 12B It is a diagram showing a modified example of the number and arrangement of cores.

[0028] Figure 12C It is a diagram showing a modified example of the number and arrangement of cores.

[0029] Figure 12D It is a diagram showing a modified example of the number and arrangement of cores.

[0030] Figure 13 It is a diagram showing another form of the core arrangement when observing the connection end faces of the first optical connector and the second optical connector in a single optical cable with connectors from the front.

[0031] Figure 14A It is used to explain the effect obtained through Figure 13 the core arrangement shown.

[0032] Figure 14B It is used to explain the effect obtained through Figure 13 the core arrangement shown.

[0033] Figure 14C It is used to explain the effect obtained through Figure 13 the core arrangement shown.

[0034] Figure 14D It is used to explain the effect obtained through Figure 13 the core arrangement shown.

[0035] Figure 14E It is used to explain the effect obtained through Figure 13 the core arrangement shown.

[0036] Figure 14F It is used to explain the effect obtained through Figure 13 the core arrangement shown.

[0037] Figure 14G It is used to explain the effect obtained through Figure 13 the core arrangement shown.

[0038] Figure 14H It is used to explain the effect obtained through Figure 13 the core arrangement shown.

[0039] Figure 15A It is used to explain the effect obtained through Figure 13A diagram for explaining the effects obtained from the core configurations shown.

[0040] Figure 15B It is used to Figure 13 explain the effects obtained from the core configurations shown.

[0041] Figure 15C It is used to Figure 13 explain the effects obtained from the core configurations shown.

[0042] Figure 15D It is used to Figure 13 explain the effects obtained from the core configurations shown.

[0043] Figure 15E It is used to Figure 13 explain the effects obtained from the core configurations shown.

[0044] Figure 15F It is used to Figure 13 explain the effects obtained from the core configurations shown.

[0045] Figure 15G It is used to Figure 13 explain the effects obtained from the core configurations shown.

[0046] Figure 15H It is used to Figure 13 explain the effects obtained from the core configurations shown.

[0047] Figure 16A A diagram showing variations in the number and configuration of cores.

[0048] Figure 16B A diagram showing variations in the number and configuration of cores.

[0049] Figure 16C A diagram showing variations in the number and configuration of cores.

[0050] Figure 16D A diagram showing variations in the number and configuration of cores.

[0051] Figure 17 A top view schematically showing one SC connector and another SC connector that is the connection object of the former when the connection end face of the ferrule of the SC connector is inclined laterally.

[0052] Figure 18 It shows that in the case where the first optical connector and the second optical connector are Figure 17Diagram showing the core configurations of the first and second optical connectors in an optical fiber cable with connectors when viewed from the front of the SC connector shown.

[0053] Figure 19A Diagram for explaining the core configuration in the following case: The first and second optical connectors are optical connectors of a type that are connected to the optical connector of the connection target in a state where the upward orientations are the same, and the configuration of the first core to the Nth core is rotationally asymmetric about the central axis.

[0054] Figure 19B Diagram for explaining the core configuration in the following case: The first and second optical connectors are optical connectors of a type that are connected to the optical connector of the connection target in a state where the upward orientations are the same, and the configuration of the first core to the Nth core is rotationally asymmetric about the central axis.

[0055] Figure 20A Diagram for explaining the core configuration in the following case: The first and second optical connectors are optical connectors of a type that are connected to the optical connector of the connection target in a state where the upward orientation is flipped, and the configuration of the first core to the Nth core is rotationally asymmetric about the central axis.

[0056] Figure 20B Diagram for explaining the core configuration in the following case: The first and second optical connectors are optical connectors of a type that are connected to the optical connector of the connection target in a state where the upward orientation is flipped, and the configuration of the first core to the Nth core is rotationally asymmetric about the central axis.

[0057] Figure 21A Diagram for explaining the effects obtained from the core configuration shown in Figure 20.

[0058] Figure 21B Diagram for explaining the effects obtained from the core configuration shown in Figure 20.

[0059] Figure 21C Diagram for explaining the effects obtained from the core configuration shown in Figure 20.

[0060] Figure 21D Diagram for explaining the effects obtained from the core configuration shown in Figure 20.

[0061] Figure 21E Diagram for explaining the effects obtained from the core configuration shown in Figure 20.

[0062] Figure 21F Diagram for explaining the effects obtained from the core configuration shown in Figure 20.

[0063] Figure 21G It is a diagram for explaining the effects obtained by the core configuration shown in FIG. 20.

[0064] Figure 21H It is a diagram for explaining the effects obtained by the core configuration shown in FIG. 20.

[0065] Figure 22A It is a diagram for explaining the effects obtained by the core configuration shown in FIG. 20.

[0066] Figure 22B It is a diagram for explaining the effects obtained by the core configuration shown in FIG. 20.

[0067] Figure 22C It is a diagram for explaining the effects obtained by the core configuration shown in FIG. 20.

[0068] Figure 22D It is a diagram for explaining the effects obtained by the core configuration shown in FIG. 20.

[0069] Figure 22E It is a diagram for explaining the effects obtained by the core configuration shown in FIG. 20.

[0070] Figure 22F It is a diagram for explaining the effects obtained by the core configuration shown in FIG. 20.

[0071] Figure 22G It is a diagram for explaining the effects obtained by the core configuration shown in FIG. 20.

[0072] Figure 22H It is a diagram for explaining the effects obtained by the core configuration shown in FIG. 20.

[0073] Figure 23 It is a diagram schematically showing an optical transmission system including two types of optical cables with connectors as a first modification example.

[0074] Figure 24A It is a diagram showing an example where the first optical connector and the second optical connector are optical connectors of a type that are connected to the optical connector of the connection object in a state where the upper direction is flipped with respect to the optical connector of the connection object, and in the connection end face, the end faces of the first to Mth optical fibers are arranged in multiple columns.

[0075] Figure 24BIt is a diagram showing the following example: The first optical connector and the second optical connector are optical connectors of a type that are connected to the optical connector of the connection object in a state where the upward orientation is flipped with respect to the optical connector of the connection object, and in the connection end face, the end faces of the first optical fiber to the Mth optical fiber are arranged in multiple columns.

[0076] Figure 25A It is a diagram showing the following example: The first optical connector and the second optical connector are optical connectors of a type that are connected to the optical connector of the connection object in a state where the upward orientation is flipped with respect to the optical connector of the connection object, and in the connection end face, the end faces of the first optical fiber to the Mth optical fiber are arranged in multiple columns.

[0077] Figure 25B It is a diagram showing the following example: The first optical connector and the second optical connector are optical connectors of a type that are connected to the optical connector of the connection object in a state where the upward orientation is flipped with respect to the optical connector of the connection object, and in the connection end face, the end faces of the first optical fiber to the Mth optical fiber are arranged in multiple columns. Detailed implementation mode

[0078] [Problems to be solved by the present disclosure]

[0079] When connecting multi-core optical fibers (MCF: Multi-Core Fiber) to each other, in order to suppress connection loss, it is necessary to match the rotation angles of these multi-core optical fibers (MCF) around the central axis in such a way that the positions of the respective cores in the end face of the first MCF are aligned with the positions of the respective cores in the end face of the second MCF (refer to Patent Document 1 and Patent Document 2). However, if the cores are not determined individually and only the alignment of multiple cores is performed between MCFs, it is necessary to manage for each optical cable pair which core the light propagating in a certain core of one optical cable propagates in the other optical cable connected to that optical cable, and thus the connection operation becomes extremely complicated.

[0080] An object of the present disclosure is to provide an optical cable with a connector and an optical transmission system that do not require management of which core the light propagates in for each optical cable pair, thereby simplifying the connection operation.

[0081] [Effects of the present disclosure]

[0082] According to the present disclosure, an optical cable with a connector and an optical transmission system can be provided that do not require management of which core the light propagates in for each optical cable pair, thereby simplifying the connection operation.

[0083] [Description of the embodiments of the present disclosure]

[0084] First, the contents of the embodiments of the present disclosure will be listed and described.

[0085] [1] An optical cable with connectors according to one aspect of the present disclosure includes: a multi-core optical fiber having a first core to an Nth core (N is an integer of 2 or more); a first optical connector assembled to a first end of the multi-core optical fiber; and a second optical connector assembled to a second end of the multi-core optical fiber. The arrangement of the first core to the Nth core is rotationally asymmetric about the central axis in a cross-section of the multi-core optical fiber perpendicular to the central axis of the multi-core optical fiber. The first optical connector and the second optical connector are optical connectors of a type that are connected to the optical connector of the connection target in a state where the upward orientation is the same as that of the optical connector of the connection target. When observing the connection end faces of the first optical connector and the second optical connector in such a way that the upward orientations of the optical connectors are the same, the arrangement of the end faces of the first core to the Nth core in the connection end face of the second optical connector is an arrangement obtained by flipping the arrangement of the end faces of the first core to the Nth core in the connection end face of the first optical connector with respect to the central axis of the connection end face along the direction in which the upward orientations of the optical connectors are the same.

[0086] [2] An optical cable with connectors according to one aspect of the present disclosure includes: a multi-core optical fiber having a first core to an Nth core (N is an integer of 2 or more); a first optical connector assembled to a first end of the multi-core optical fiber; and a second optical connector assembled to a second end of the multi-core optical fiber. The arrangement of the first core to the Nth core is rotationally asymmetric about the central axis in a cross-section of the multi-core optical fiber perpendicular to the central axis of the multi-core optical fiber. The first optical connector and the second optical connector are optical connectors of a type that are connected to the optical connector of the connection target in a state where the upward orientation is flipped with respect to the optical connector of the connection target. When observing the connection end faces of the first optical connector and the second optical connector in such a way that the upward orientations of the optical connectors are the same, the arrangement of the end faces of the first core to the Nth core in the connection end face of the second optical connector is an arrangement obtained by flipping the arrangement of the end faces of the first core to the Nth core in the connection end face of the first optical connector with respect to the central axis of the connection end face along a direction orthogonal to the direction in which the upward orientations of the optical connectors are the same.

[0087] [3] An optical cable with connectors according to one aspect of the present disclosure includes: a multi-core optical fiber having a first core to an Nth core (N is an integer of 2 or more); a first optical connector assembled to a first end of the multi-core optical fiber; and a second optical connector assembled to a second end of the multi-core optical fiber. The arrangement of the first core to the Nth core has rotational symmetry about the central axis in a cross-section of the multi-core optical fiber perpendicular to the central axis of the multi-core optical fiber. When observing the connection end faces of the first optical connector and the second optical connector in such a way that the upward orientations of the optical connectors are the same, the arrangement of the end faces of the first core to the Nth core in the connection end face of the second optical connector is an arrangement obtained by flipping the arrangement of the end faces of the first core to the Nth core in the connection end face of the first optical connector with respect to the central axis of the connection end face along the direction in which the upward orientations of the optical connectors are the same.

[0088] [4]In the optical cable with connectors in the above [3], it is also possible that the first optical connector and the second optical connector are optical connectors of a type that are connected to the optical connector of the connection object in a state where the upward orientation is the same as that of the optical connector of the connection object.

[0089] [5]In the optical cable with connectors in the above [3], it is also possible that the first optical connector and the second optical connector are optical connectors of a type that are connected to the optical connector of the connection object in a state where the upward orientation is flipped with respect to the optical connector of the connection object.

[0090] [6]The optical cable with connectors according to one aspect of the present disclosure includes: a multi-core optical fiber having a first core to an Nth core (N is an integer of 2 or more); a first optical connector assembled to the first end of the multi-core optical fiber; and a second optical connector assembled to the second end of the multi-core optical fiber. The arrangement of the first core to the Nth core has rotational symmetry about the central axis in a cross-section of the multi-core optical fiber perpendicular to the central axis of the multi-core optical fiber. The first optical connector and the second optical connector are optical connectors of a type that are connected to the optical connector of the connection object in a state where the upward orientation is flipped with respect to the optical connector of the connection object. When observing the connection end faces of the first optical connector and the second optical connector in a manner that makes the upward orientations of the optical connectors the same, the arrangement of the end faces of the first core to the Nth core in the connection end face of the second optical connector is obtained by flipping the arrangement of the end faces of the first core to the Nth core in the connection end face of the first optical connector with respect to the central axis of the connection end face along a direction orthogonal to the direction in which the upward orientations of the optical connectors are the same.

[0091] [7]In any of the optical cables with connectors in the above [1] to [6], it is also possible that the structures of the portions of the first optical connector and the second optical connector that are engaged with the optical connector of the connection object are different from each other.

[0092] [8]In any of the optical cables with connectors in the above [1] to [7], it is also possible that the connection end face is perpendicular to the central axis of the multi-core optical fiber.

[0093] [9]In any of the optical cables with connectors in the above [2], [5], [6], it is also possible that the connection end face is inclined with respect to an imaginary plane perpendicular to the central axis of the multi-core optical fiber.

[0094]

[10] In any of the optical cables with connectors in the above [3] to [6], it is also possible that the multi-core optical fiber has a mark for identifying the first core to the Nth core.

[0095]

[11] An optical transmission system according to an aspect of the present disclosure includes: a first connector-equipped optical cable, which is the connector-equipped optical cable of [1] above; and a second connector-equipped optical cable, which is the connector-equipped optical cable of [2] above. The appearance of the second connector-equipped optical cable is different from the appearance of the first connector-equipped optical cable.

[0096]

[12] An optical transmission system according to an aspect of the present disclosure includes: a third connector-equipped optical cable, which is the connector-equipped optical cable of [3] above; and a fourth connector-equipped optical cable, which is the connector-equipped optical cable of [6] above. The appearance of the fourth connector-equipped optical cable is different from the appearance of the third connector-equipped optical cable.

[0097] [Details of Embodiments of the Present Disclosure]

[0098] Specific examples of the connector-equipped optical cable and the optical transmission system of the present embodiment will be described with reference to the accompanying drawings as needed. It should be noted that the present disclosure is not limited to these examples, but is shown by the claims, and is intended to include all changes within the meaning and scope equivalent to the claims. In the following description, the same reference numerals are given to the same elements in the description of the drawings, and repeated descriptions are omitted.

[0099] Figure 1A and Figure 1B is a perspective view for explaining the types of optical connectors. Figure 1A An SC connector 10, which is a type of optical connector, is shown. As Figure 1A shown, the SC connector 10 includes a resin housing 11. An optical cable 30 extends from a sheath 16 assembled to the rear end 12 of the housing 11. The number of optical fibers included in the optical cable 30 is one. A cylindrical ferrule 40 projects from the front end 13 of the housing 11. The ferrule 40 holds the tip portion of the optical fiber included in the optical cable 30. In the connection end face 41 of the ferrule 40, the end face of the optical fiber is exposed. The connection end face 41 may be perpendicular to the central axis of the optical fiber or may be inclined with respect to a hypothetical plane perpendicular to the central axis of the optical fiber. The inclination angle of the connection end face 41 with respect to this hypothetical plane is, for example, 8°.

[0100] The cross-section of the housing 11 perpendicular to the central axis of the optical fiber is rectangular. On the upper surface 14 of the housing 11 corresponding to one side of the rectangle, a protrusion (key) 15 extending in the direction of the central axis of the optical fiber is provided. That is, the protrusion 15 is provided on a part of the circumferential direction of the SC connector 10, that is, a part of the outer peripheral surface. The protrusion 15 is received in a recess (keyway) formed in an adapter (not shown) into which the SC connector 10 is fitted. When the SC connector 10 is inserted into the adapter, the protrusion 15 guides the SC connector 10 with respect to the adapter. In addition, the protrusion 15 defines the orientation of the SC connector 10 in the circumferential direction. In the following description, the orientation with the protrusion 15 provided when viewed from the central axis of the SC connector 10 (that is, the central axis of the optical fiber 31) is defined as the upward orientation.

[0101] Figure 1B Fig. shows an LC connector 20 as another type of optical connector. As Figure 1B shown, the LC connector 20 includes a resin housing 21. An optical cable 30 extends from a sheath 26 assembled to the rear end 22 of the housing 21. The ferrule 40 projects from the front end 23 of the housing 21. Similar to the SC connector 10, the connection end face 41 of the ferrule 40 in the LC connector 20 can be perpendicular to the central axis of the optical fiber or inclined with respect to a hypothetical plane perpendicular to the central axis of the optical fiber.

[0102] The cross-section of the housing 21 perpendicular to the central axis of the optical fiber is square. On the upper surface 24 of the housing 21 corresponding to one side of the square, a latch lever 25 is provided, and the latch lever 25 is detachably engaged with an adapter (see Figure 2 ) into which the LC connector 20 is fitted. That is, the latch lever 25 is provided on a part of the circumferential direction of the LC connector 20, that is, a part of the outer peripheral surface. The latch lever 25 is received in a recess formed in the adapter. When the LC connector 20 is inserted into the adapter, the latch lever 25 guides the LC connector 20 with respect to the adapter. In addition, the latch lever 25 defines the orientation of the LC connector 20 in the circumferential direction. In the following description, the orientation with the latch lever 25 provided when viewed from the central axis of the LC connector 20 (that is, the central axis of the optical fiber 31) is defined as the upward orientation.

[0103] Figure 2 Fig. is a perspective view showing a case where a plurality of ribbon connectors of optical cables 1 (hereinafter, simply referred to as cables 1) are connected to each other. Figure 2In addition to showing three cables 1, two adapters 50 are also shown. Each cable 1 includes a first optical connector 3, a second optical connector 4, and an optical cable 30 having a multi-core optical fiber. In the following description, the three cables 1 may sometimes be referred to as cable A, cable B, and cable C, respectively. The first optical connector 3 and the second optical connector 4 are optical connectors of the same type as each other. That is, both the first optical connector 3 and the second optical connector 4 are SC connectors 10, or both are LC connectors 20. The SC connector 10 and the LC connector 20 are optical connectors of a type that are connected to the optical connector of the connection object in a state where the circumferential orientation (specifically, the upward orientation defined by the protrusion 15 and the latch lever 25) is consistent with the optical connector of the connection object.

[0104] Figure 3A and Figure 3B are diagrams schematically showing examples of cross-sections perpendicular to the central axis of the multi-core optical fiber 31 (hereinafter, simply referred to as the optical fiber 31) included in the optical cable 30. The optical fiber 31 has a first core 32 to an Nth core 32 (N is an integer of 2 or more), a marker 33, and a cladding 34 that embeds all the cores 32 and the marker 33 inside. In Figure 3A and Figure 3B , the case where N = 4 is shown as an example. It should be noted that the illustration of the resin coating covering the outer periphery of the cladding 34 is omitted. The core 32, the marker 33, and the cladding 34 are made of glass, for example. The refractive index of all the cores 32 is greater than the refractive index of the cladding 34. The refractive index of the marker 33 may be greater than the refractive index of the cladding 34, may be the same as the refractive index of the cladding 34, or may be less than the refractive index of the cladding 34. In the examples shown in Figure 3A and Figure 3B , the arrangement of the N cores 32 has rotational symmetry about the central axis A1 in the cross-section of the optical fiber 31 perpendicular to the central axis A1 of the optical fiber 31. The arrangement of the cores 32 having rotational symmetry means that when the cores 32 are rotated about the central axis A1, they will coincide with the original arrangement of the cores 32 at a rotation angle of 180° or less. In the case of Figure 3A and Figure 3B , the arrangement of the cores 32 is line-symmetric with respect to the symmetry axis A2 passing through the central axis A1.

[0105] The marker 33 is provided at a position far from the central axis A1 of the optical fiber 31. The marker 33 is distinguished from the core 32 by being colored, for example. The marker 33 may be provided at a position on the symmetry axis A2 as shown in Figure 3A , or may be as shown in Figure 3BIt is disposed at a position away from the symmetry axis A2 as shown. The mark 33 is provided to identify the first core 32 to the Nth core 32 respectively. That is, based on the position of the mark 33, it can be known which one of the first core 32 to the Nth core 32 each of the N cores 32 is.

[0106] Figure 4A and Figure 4B are diagrams respectively showing another example of a cross-section perpendicular to the central axis of the optical fiber 31 included in the optical cable 30. In this example, the arrangement of the N cores 32 is rotationally asymmetric about the central axis A1 in the cross-section of the optical fiber 31 perpendicular to the central axis A1 of the optical fiber 31. That is, when the core 32 is rotated about the central axis A1, if it is not rotated by 360°, it does not coincide with the original arrangement of the core 32.

[0107] Refer again to Figure 2 . The first optical connector 3 is inserted into an opening formed at one end (the first end) of the adapter 50. The second optical connector 4 is inserted into an opening 51 formed at the other end (the second end) of the adapter 50. The connection end face 41 of the ferrule 40 of the second optical connector 4 contacts the connection end face 41 of the ferrule 40 of the first optical connector 3 inside the adapter 50. At this time, the positions of the N cores 32 in the connection end face 41 of the second optical connector 4 coincide with the positions of the N cores 32 in the connection end face 41 of the first optical connector 3, whereby the N cores 32 of the second optical connector 4 are respectively optically coupled to the N cores 32 of the first optical connector 3.

[0108] Figure 5 is a diagram showing the core arrangement when the first optical connector 3 and the second optical connector 4 in one cable 1 are viewed from the front with respect to the connection end face 41. Figure 5 An example where N = 4 is illustrated, and the numbers of the first core 32 to the fourth core 32 are marked in the core 32 respectively. Figure 5 is an example of the following situation: The first optical connector 3 and the second optical connector 4 are optical connectors of a type that are connected to the optical connector of the connection object in a state where the upward orientation is consistent with that of the connection object, and the core arrangement has rotational symmetry about the central axis A1.

[0109] As Figure 5As shown, when observing the connection end faces 41 of the first optical connector 3 and the second optical connector 4 in such a way that the upper directions of the optical connectors are the same, the arrangement of the end faces of the first core 32 to the fourth core 32 in the connection end face 41 of the second optical connector 4 is obtained by flipping the arrangement of the end faces of the first core 32 to the fourth core 32 in the connection end face 41 of the first optical connector 3 with respect to the central axis A3 of the connection end face 41 along the direction (upper direction) in which the upper directions of the optical connectors are the same. The central axis A3 passes through the central axis A1 of the optical fiber 31 and coincides with Figure 3A the symmetry axis A2 shown.

[0110] Figure 6 is a diagram showing the correspondence of the cores 32 of the cables A to C when the first core 32 to the fourth core 32 are arranged as Figure 5 shown. When the first core 32 to the fourth core 32 are arranged as Figure 5 shown, as Figure 6 shown, each core 32 of the cable A is connected to the core 32 with the same number in the cable B, and each core 32 of the cable B is connected to the core 32 with the same number in the cable C. Therefore, it is not necessary to manage in which core the light propagates for each cable 1, and the connection operation can be simplified.

[0111] Next, a case where the first optical connector 3 and the second optical connector 4 shown in Figure 2 are MPO connectors, which are another type of optical connector, will be described. Figure 7A is a perspective view showing the appearance of the MPO connector 60. Figure 7B is a perspective view showing the appearance of the MT ferrule 70 included in the MPO connector 60. The MPO connector 60 includes a resin housing 61. An optical cable 35 extends from a sheath 66 assembled to the rear end 62 of the housing 61. The optical cable 35 has a plurality of optical fibers 31 arranged in a direction intersecting the extending direction of the optical cable 35. A rectangular parallelepiped-shaped MT ferrule 70 projects from the front end 63 of the housing 61. The MT ferrule 70 holds the tip portions of the optical fibers 31 included in the optical cable 35. The connection end face 71 of the MT ferrule 70 exposes the end faces of the optical fibers 31. The MT ferrule 70 has an upper surface 73 facing the same direction as the upper surface 64 of the housing 61. A resin injection hole 74 is formed in the upper surface 73.

[0112] The cross-section of the housing 61 perpendicular to the central axis of the optical fiber 31 is rectangular. On the upper surface 64 of the housing 61 corresponding to one side of the rectangle, a protrusion (key) 65 extending in the central axis direction of the optical fiber 31 is provided. That is, the protrusion 65 is provided on a part of the circumferential direction of the MPO connector 60, that is, a part of the outer peripheral surface. The protrusion 65 is received in a recess (keyway) formed in an adapter (not shown) into which the MPO connector 60 is fitted. When the MPO connector 60 is inserted into the adapter, the protrusion 65 guides the MPO connector 60 with respect to the adapter. In addition, the protrusion 65 defines the orientation of the MPO connector 60 in the circumferential direction. In the following description, the orientation in which the protrusion 65 is provided when observing the front end 63 from the central axis of the MPO connector 60 (that is, from the axis passing through the center of gravity in the cross-section of the MT ferrule 70 perpendicular to the central axes of the plurality of optical fibers 31 and extending along the central axes of the plurality of optical fibers 31) is defined as the upward orientation.

[0113] Figure 8A It is a front view of the connection end face 71 of the MT ferrule 70. In the connection end face 71, the end faces of the optical fibers 31 are arranged in the lateral direction orthogonal to the upward direction. Figure 8A An example in which the end faces of the optical fibers 31 are arranged in one row is shown, but the end faces of the optical fibers 31 may also be arranged in multiple rows. In addition, a pair of guide pin holes 72 for inserting guide pins are formed in the connection end face 71 of the MT ferrule 70. The pair of guide pin holes 72 are arranged in the lateral direction, and the end faces of the optical fibers 31 are disposed between the pair of guide pin holes 72.

[0114] Figure 8B It is a side view of the MT ferrule 70 when the connection end face 71 of the MT ferrule 70 is perpendicular to the central axis of the optical fiber 31. Figure 8C It is a side view of the MT ferrule 70 when the connection end face 71 of the MT ferrule 70 is inclined with respect to the imaginary plane H perpendicular to the central axis of the optical fiber 31. The inclination angle of the connection end face 71 with respect to the imaginary plane H is, for example, 8°.

[0115] The connection end face 71 of the MT ferrule 70 and the connection end face 71 of another MT ferrule 70 to be connected are opposed to each other according to the Figure 9A and Figure 9B schemes shown. Figure 9A The case where the connection end face 71 is perpendicular to the central axis of the optical fiber 31 is shown. Figure 9B The case where the connection end face 71 is inclined with respect to the imaginary plane H is shown. As Figure 9A and Figure 9B shown, the MPO connector 60 is a type of optical connector that is connected to the optical connector of the connection object in a state where it is flipped with respect to the optical connector of the connection object in the upward orientation (in other words, in a state where it is rotated 180° with respect to the optical connector of the connection object).

[0116] Figure 10 It represents the case where Figure 2 when the first optical connector 3 and the second optical connector 4 shown are MPO connectors 60, it is a diagram showing the core arrangement of each of the first optical connector 3 and the second optical connector 4 in a cable 1 when observing the connection end face 71 from the front. It should be noted that Figure 10 it shows the core arrangement of a representative one of the multiple optical fibers 31 included in the optical cable 35, and the core arrangements of the other optical fibers 31 are also the same as Figure 10 each other. Figure 10 An example where N = 4 is illustrated, and the numbers of the first core 32 to the fourth core 32 are marked in the core 32 respectively. Figure 10 It is an example of the following situation: the first optical connector 3 and the second optical connector 4 are optical connectors of a type that are connected to the optical connector of the connection object in a state where the upper direction is flipped relative to the optical connector of the connection object, and the core arrangement has rotational symmetry about the central axis A1.

[0117] As Figure 10 shown, when observing the connection end faces 71 of the first optical connector 3 and the second optical connector 4 in such a way that the upper directions of the optical connectors are aligned, the arrangement of the end faces of the first core 32 to the fourth core 32 in the connection end face 71 of the second optical connector 4 is obtained by flipping the arrangement of the end faces of the first core 32 to the fourth core 32 in the connection end face 71 of the first optical connector 3 with respect to the central axis A3 of the connection end face 41 along the direction (upper direction) in which the upper directions of the optical connectors are aligned.

[0118] Figure 11 It is a diagram showing the correspondence of the cores 32 of cables A to C in the case where the first core 32 to the fourth core 32 of each optical fiber 31 are arranged as Figure 10 shown. In the case where the first core 32 to the fourth core 32 are arranged as Figure 10 shown, as Figure 11 shown, each core 32 of cable A is connected to a core 32 with a different number in cable B, and each core 32 of cable B is connected to a core 32 with a further different number in cable C. However, each core 32 of cable C is connected to the core 32 with the same number in cable A via cable B. Therefore, if the number of connections of the cable 1 is an even number, there is no need to manage in which core the light propagates for each cable 1, thus simplifying the connection operation.

[0119] It should be noted that the number N of the cores 32 and the arrangement of the cores 32 are not limited to the examples shown in Figure 5 and Figure 10 shown Figure 12A . Figure 12B ,Figure 12C and Figure 12D FIG. Figure 12D is a diagram showing a modified example of the number N of the cores 32 and the arrangement of the cores 32. In any of these figures, when observing the connection end faces 41 (or connection end face 71) of the first optical connector 3 and the second optical connector 4 in such a manner that the upper directions of the optical connectors are aligned, the arrangement of the end faces of the first core 32 to the Nth core 32 in the connection end face 41 (or connection end face 71) of the second optical connector 4 is an arrangement obtained by flipping the arrangement of the end faces of the first core 32 to the Nth core 32 in the connection end face 41 (or connection end face 71) of the first optical connector 3 with respect to the central axis A3.

[0120] Figure 13 FIG.

[0120] is a diagram showing another form of the core arrangement when observing the connection end faces 71 of the first optical connector 3 and the second optical connector 4 of one cable 1 from the front. Figure 13 FIG. Figure 13 is an example where the first optical connector 3 and the second optical connector 4 are optical connectors of a type that are connected to the optical connector to be connected in a state where the upper direction is flipped with respect to the optical connector to be connected (for example, the MPO connector 60), and the core arrangement has rotational symmetry about the central axis A1.

[0121] As Figure 13 shown, when observing the connection end faces 71 of the first optical connector 3 and the second optical connector 4 in such a manner that the upper directions of the optical connectors are aligned, the arrangement of the end faces of the first core 32 to the fourth core 32 in the connection end face 71 of the second optical connector 4 is an arrangement obtained by flipping the arrangement of the end faces of the first core 32 to the fourth core 32 in the connection end face 71 of the first optical connector 3 with respect to the central axis A4 of the transverse connection end face 41 along the direction (upward direction) orthogonal to the direction in which the upper directions of the optical connectors are aligned. It should be noted that the central axis A4 passes through the central axis A1 of the optical fiber 31 and is orthogonal to the Figure 3A symmetry axis A2 shown.

[0122] When the first core 32 to the fourth core 32 are arranged as Figure 13 shown, the correspondence of the cores 32 of the cables A to C becomes Figure 6 as shown. That is, each core 32 of the cable A is connected to the core 32 with the same number in the cable B, and each core 32 of the cable B is connected to the core 32 with the same number in the cable C. Therefore, it is not necessary to manage in which core the light propagates for each cable 1, and thus the connection operation can be made simple.

[0123] Figures 14A to 14H and Figures 15A to 15H FIG. Figures 15A to 15H is a diagram for explaining the effect obtained by the core arrangement shown in Figure 13 FIG. Figure 13 .Figures 14A to 14H shows a case where the core configuration is Figure 13 the one shown in the scheme. Figures 15A to 15H shows a case where the core configuration is not particularly specified. Figure 14A and Figure 14B are respectively front views showing the connection end faces 71 of the first optical connector 3 and the second optical connector 4 in the cable A. In addition, Figure 14C and Figure 14D are respectively front views showing the connection end faces 71 of the first optical connector 3 and the second optical connector 4 in the cable B connected to the cable A. Figure 14E , Figure 14F , Figure 14G and Figure 14H respectively show Figure 14A , Figure 14B , Figure 14C and Figure 14D the end faces of the respective optical fibers 31 in the optical connectors respectively shown. Among these end faces, it is assumed that light propagates in a certain core 32, and the core 32 through which the light propagates is marked with dots. In addition, Figure 15A and Figure 15B are respectively front views showing the connection end faces 71 of the first optical connector 3 and the second optical connector 4 in the cable A. In addition, Figure 15C and Figure 15D are respectively front views showing the connection end faces 71 of the first optical connector 3 and the second optical connector 4 in the cable B connected to the cable A. Figure 15E , Figure 15F , Figure 15G and Figure 15H respectively show Figure 15A , Figure 15B , Figure 15C and Figure 15D the end faces of the respective optical fibers 31 in the optical connectors respectively shown. Among these end faces, it is assumed that light propagates in a certain core 32, and the core 32 through which the light propagates is marked with dots.

[0124] As Figures 15A to 15H shown, when the core configuration in the optical connector is not particularly specified, the positions of the cores through which the light propagates are different in the cable A and the cable B. As a result, if the correspondence relationship between the N cores 32 of the cable A and the N cores 32 of the cable B is not managed, the connection operation will become extremely complicated. In contrast, according to Figure 13 the core configuration shown, as Figures 14A to 14H shown, the positions of the cores 32 through which the light propagates are the same in the cable A and the cable B. Therefore, it is not necessary to manage the correspondence relationship between the N cores 32 of the cable A and the N cores 32 of the cable B, and thus the connection operation can be made easy.

[0125] Note that the number N of the optical fibers 32 and the configuration of the optical fibers 32 are not limited to Figures 15A to 15H the example shown. Figures 16A to 16D is a diagram showing a modified example of the number N of the optical fibers 32 and the configuration of the optical fibers 32. In any of these diagrams, when observing the connection end faces 41 (or connection end faces 71) of the first optical connector 3 and the second optical connector 4 in such a manner that the upper directions of the optical connectors are the same, the configuration of the end faces of the first optical fiber 32 to the Nth optical fiber 32 in the connection end face 41 of the second optical connector 4 is a configuration obtained by flipping the configuration of the end faces of the first optical fiber 32 to the Nth optical fiber 32 in the connection end face 41 of the first optical connector 3 with respect to the central axis A4.

[0126] Figure 17 is a top view schematically showing a case where the connection end face 41 of the ferrule 40 of the SC connector 10 is inclined laterally orthogonally to the direction (upward direction) in which the upper direction of the optical connector is the same. In addition, Figure 18 is showing in Figure 2 the case where the first optical connector 3 and the second optical connector 4 shown are Figure 17 the SC connectors 10 shown, a diagram of the optical fiber configuration when observing the connection end face 41 of each of the first optical connector 3 and the second optical connector 4 in the cable 1 from the front. Figure 18 is an example of the following situation: The first optical connector 3 and the second optical connector 4 are optical connectors of a type that are connected to a connection target optical connector in a state where the upper direction is the same as that of the connection target optical connector, the optical fiber configuration has rotational symmetry about the central axis A1, and the inclination direction of the connection end face 41 is lateral.

[0127] In Figure 18 the form shown, when observing the connection end faces 41 of the first optical connector 3 and the second optical connector 4 in such a manner that the upper directions of the optical connectors are the same, the configuration of the end faces of the first optical fiber 32 to the fourth optical fiber 32 in the connection end face 41 of the second optical connector 4 is a configuration obtained by flipping the configuration of the end faces of the first optical fiber 32 to the Nth optical fiber 32 in the connection end face 41 of the first optical connector 3 with respect to the central axis A3 of the connection end face 41 along the direction (upward direction) in which the upper directions of the optical connectors are the same. In this case, the correspondence of the optical fibers 32 of the cables A to C becomes Figure 6 as such. That is, each optical fiber 32 of the cable A is connected to the optical fiber 32 with the same number in the cable B, and each optical fiber 32 of the cable B is connected to the optical fiber 32 with the same number in the cable C. Therefore, it is not necessary to manage in which optical fiber the light propagates for each cable 1, and thus the connection operation can be simplified.

[0128] Figure 19A And Figure 19B are diagrams for explaining the core configuration in the following cases: The first optical connector 3 and the second optical connector 4 are optical connectors of a type that are connected to the optical connector of the connection target in a state where the upward orientations are the same (for example, SC connector 10 or LC connector 20), and the configurations of the first core 32 to the Nth core 32 are rotationally asymmetric about the central axis A1. Figure 19A shows the case where the number N of cores 32 is 2, Figure 19B shows the case where the number N of cores 32 is 4. In Figure 19A and Figure 19B In the configurations shown, the end faces of the first core 32 to the Nth core 32 are arranged as follows. That is, when observing the connection end face 41 of the first optical connector 3 and the second optical connector 4 in a manner that makes the upward orientations of the optical connectors the same, the configuration of the end faces of the first core 32 to the Nth core 32 in the connection end face 41 of the second optical connector 4 is a configuration obtained by flipping the configuration of the end faces of the first core 32 to the Nth core 32 in the connection end face 41 of the first optical connector 3 with respect to the central axis A3.

[0129] In addition, Figure 20A and Figure 20B are diagrams for explaining the core configuration in the following cases: The first optical connector 3 and the second optical connector 4 are optical connectors of a type that are connected to the optical connector of the connection target in a state where the upward orientations are flipped, (for example, MPO connector 60), and the configurations of the first core 32 to the Nth core 32 are rotationally asymmetric about the central axis A1. Figure 20A shows the case where the number N of cores 32 is 2, Figure 20B shows the case where the number N of cores 32 is 4. In Figure 20A and Figure 20B In the configurations shown, the end faces of the first core 32 to the Nth core 32 are arranged as follows. That is, when observing the connection end face 41 of the first optical connector 3 and the second optical connector 4 in a manner that makes the upward orientations of the optical connectors the same, the configuration of the end faces of the first core 32 to the Nth core 32 in the connection end face 41 of the second optical connector 4 is a configuration obtained by flipping the configuration of the end faces of the first core 32 to the Nth core 32 in the connection end face 41 of the first optical connector 3 with respect to the central axis A4.

[0130] According to Figure 19A , Figure 19B , Figure 20A and Figure 20B In the configurations shown, the correspondence of the cores 32 of the cables A to C becomes Figure 6Like this. That is, each core 32 of cable A is connected to the core 32 with the same number in cable B, and each core 32 of cable B is connected to the core 32 with the same number in cable C. Therefore, there is no need to manage which core the light propagates in for each cable 1, which can simplify the connection operation.

[0131] Figures 21A to 21H and Figures 22A to 22H is used to illustrate the effect obtained through Figure 20A and Figure 20B the core configuration shown. Figures 21A to 21H shows the case where the core configuration is Figure 20A and Figure 20B the scheme shown. Figures 22A to 22H shows the case where the core configuration is not specifically specified. Figure 21A , Figure 21B , Figure 22A and Figure 22B are respectively the front views showing the connection end faces 71 of the first optical connector 3 and the second optical connector 4 in cable A. In addition, Figure 21C , Figure 21D , Figure 22C and Figure 22D are respectively the front views showing the connection end faces 71 of the first optical connector 3 and the second optical connector 4 in cable B connected to cable A. Figures 21E to 21H respectively show Figures 21A to 21D the end faces of the respective optical fibers 31 in the optical connectors shown. Similarly, Figures 22E to 22H respectively show Figures 22A to 22D the end faces of the respective optical fibers 31 in the optical connectors shown. Among these end faces, it is assumed that light propagates in a certain core 32, and the core 32 through which the light propagates is marked with dots.

[0132] As Figures 22A to 22H shown, when the core configuration in the optical connector is not specifically specified, the core positions through which the light propagates are different in cable A and cable B. As a result, if the correspondence between the N cores 32 of cable A and the N cores 32 of cable B is not managed, the connection operation will become extremely complicated. In contrast, according to Figure 20A and Figure 20B the core configuration shown, as Figures 21A to 21H shown, the positions of the cores 32 through which the light propagates are the same in cable A and cable B. Therefore, there is no need to manage the correspondence between the N cores 32 of cable A and the N cores 32 of cable B, which can simplify the connection operation.

[0133] (First Variation Example)

[0134] Figure 23FIG. 90 schematically shows an optical transmission system 90 including an optical cable 1A with a connector and an optical cable 1B with a connector (hereinafter, simply referred to as cables 1A and 1B). The cables 1A and 1B have optical connectors of a type that are connected in a state where the upper direction is flipped with respect to the optical connector of the connection target (for example, MPO connector 60) as the first optical connector 3 and the second optical connector 4. In addition, the first cable 1A has Figure 10 the configuration of the optical fibers 32 shown. The second cable 1B has Figure 13 the configuration of the optical fibers 32 shown.

[0135] When the cables 1A and 1B with different configurations of the optical fibers 32 coexist in the optical transmission system 90 in this way, in order to easily identify the cables 1A and 1B, the appearance of the cable 1B may also be different from the appearance of the cable 1A. The difference in appearance means, for example, that the color of the coating resin of the optical cable 30 is different; the color of the resin housing 61 of the MPO connector 60 is different; the colors of the sheaths 16, 26, and 66 are different, etc.

[0136] (Second Modified Example)

[0137] Figure 24A 、 Figure 24B 、 Figure 25A and Figure 25B are diagrams showing an example where the first optical connector 3 and the second optical connector 4 are optical connectors of a type that are connected to the optical connector of the connection target in a state where the upper direction is flipped with respect to the optical connector of the connection target (for example, MPO connector 60), and in the connection end face 71, the end faces of the first optical fiber 31 to the Mth optical fiber 31 are arranged in multiple columns (for example, two columns). Figure 24A and Figure 25A respectively show the connection end face 71 of the first optical connector 3, Figure 24B and Figure 25B respectively show the connection end face 71 of the second optical connector 4. In the figure, the numbers with "#" indicate the numbers of the optical fibers 31.

[0138] In Figure 24A and Figure 24B shown examples, when observing the connection end faces 71 of the first optical connector 3 and the second optical connector 4 in such a way that the upper directions of the optical connectors are aligned, the configuration of the end faces of the first optical fiber 31 to the Mth optical fiber 31 in the connection end face 71 of the second optical connector 4 is obtained by flipping the configuration of the end faces of the first optical fiber 31 to the Mth optical fiber 31 in the connection end face 71 of the first optical connector 3 in the vertical direction. In addition, in Figure 25A and Figure 25BIn the example shown, when observing the connection end faces 71 of the first optical connector 3 and the second optical connector 4 in such a manner that the upper directions of the optical connectors are the same, the arrangement of the end faces of the first optical fiber 31 to the M-th optical fiber 31 in the connection end face 71 of the second optical connector 4 is the same as the arrangement of the end faces of the first optical fiber 31 to the M-th optical fiber 31 in the connection end face 71 of the first optical connector 3.

[0139] (Third Modified Example)

[0140] In the above-described embodiment, the structures of the portions of the first optical connector 3 and the second optical connector 4 that are engaged with the optical connector to be connected may also be different from each other. For example, when the first optical connector 3 and the second optical connector 4 are SC connectors 10, it may be that the housing 11 of one of the first optical connector 3 and the second optical connector 4 has a recess (keyway) instead of the protrusion 15. Similarly, when the first optical connector 3 and the second optical connector 4 are MPO connectors 60, it may be that the housing 61 of one of the first optical connector 3 and the second optical connector 4 has a recess (keyway) instead of the protrusion 65. Or, when the first optical connector 3 and the second optical connector 4 are MPO connectors 60, it may be that only one of the first optical connector 3 and the second optical connector 4 is provided with a guide pin to be inserted into the guide pin hole 72 in advance. Thus, by making the structures of the portions of the first optical connector 3 and the second optical connector 4 that are engaged with the optical connector to be connected different from each other, the first optical connector 3 and the second optical connector 4 can be easily identified.

[0141] The optical cable with a connector and the optical transmission system of the present disclosure are not limited to the above-described embodiments, and various other modifications can be made. For example, in the above-described embodiment, the SC connector 10 and the LC connector 20 are given as examples of the types of optical connectors that are connected to the optical connector to be connected in a state where the upper directions are the same. However, as such types of optical connectors, in addition to the SC connector 10 and the LC connector 20, various optical connectors can also be applied. Further, in the above-described embodiment, the MPO connector 60 is given as an example of the type of optical connector that is connected to the optical connector to be connected in a state where the upper direction is reversed. However, as such types of optical connectors, in addition to the MPO connector 60, various optical connectors can also be applied.

[0142] Description of Reference Numerals

[0143] 1, 1A, 1B: Fiber optic cable with connector; 3: First optical connector; 4: Second optical connector; 10: SC connector; 11: Housing; 12: Rear end; 13: Front end; 14: Upper surface; 15: Protrusion; 16: Sheath; 20: LC connector; 21: Housing; 22: Rear end; 23: Front end; 24: Upper surface; 25: Latch lever; 26: Sheath; 30: Fiber optic cable; 31: Multi-core optical fiber; 32: Core; 33: Mark; 34: Cladding; 35: Fiber optic cable; 40: Ferrule; 41: Connection end face; 50: Adapter; 51: Opening; 60: MPO connector; 61: Housing; 62: Rear end; 63: Front end; 64: Upper surface; 65: Protrusion; 66: Sheath; 70: MT ferrule; 71: Connection end face; 72: Guide pin hole; 73: Upper surface; 74: Resin injection hole; 90: Optical transmission system; A, B, C: Fiber optic cable with connector; A1: Central axis; A2: Axis of symmetry; A3, A4: Central axis; H: Imaginary plane.

Claims

1. An optical cable with connectors, comprising: Multi-core optical fiber, having a first core to an Nth core, wherein, N is an integer of 2 or more; A first optical connector assembled to the first end of the multi-core optical fiber; and A second optical connector assembled to the second end of the multi-core optical fiber, The arrangement of the cores from the first core to the Nth core is rotationally asymmetric about the central axis in the cross-section of the multi-core optical fiber perpendicular to the central axis of the multi-core optical fiber. The first optical connector and the second optical connector are optical connectors of a type that are connected to the optical connector of the connection object in a state where the upward orientation is the same as that of the optical connector of the connection object. When observing the connection end faces of the first optical connector and the second optical connector in a manner that makes the upward orientations the same, the arrangement of the end faces of the first core to the Nth core in the connection end face of the second optical connector is an arrangement obtained by flipping the arrangement of the end faces of the first core to the Nth core in the connection end face of the first optical connector with respect to the central axis of the connection end face along the direction that makes the upward orientations the same.

2. An optical cable with connectors, comprising: Multi-core optical fiber, having a first core to an Nth core, wherein, N is an integer of 2 or more; A first optical connector assembled to the first end of the multi-core optical fiber; and A second optical connector assembled to the second end of the multi-core optical fiber, The arrangement of the first core to the Nth core is rotationally asymmetric about the central axis in the cross-section of the multi-core optical fiber perpendicular to the central axis of the multi-core optical fiber. The first optical connector and the second optical connector are optical connectors of a type that are connected to the optical connector of the connection object in a state where the upward orientation is flipped with respect to the optical connector of the connection object. When observing the connection end faces of the first optical connector and the second optical connector in a manner that makes the upward orientations the same, the arrangement of the end faces of the first core to the Nth core in the connection end face of the second optical connector is an arrangement obtained by flipping the arrangement of the end faces of the first core to the Nth core in the connection end face of the first optical connector with respect to the central axis of the connection end face along the direction orthogonal to the direction that makes the upward orientations the same.

3. An optical cable with connectors, comprising: Multi-core optical fiber, having a first core to an Nth core, wherein, N is an integer of 2 or more; A first optical connector assembled to the first end of the multi-core optical fiber; and A second optical connector assembled to the second end of the multi-core optical fiber, The arrangement of the first core to the Nth core has rotational symmetry about the central axis in the cross-section of the multi-core optical fiber perpendicular to the central axis of the multi-core optical fiber. When observing the connection end faces of the first optical connector and the second optical connector in a manner that makes the upward orientations the same, the arrangement of the end faces of the first core to the Nth core in the connection end face of the second optical connector is an arrangement obtained by flipping the arrangement of the end faces of the first core to the Nth core in the connection end face of the first optical connector with respect to the central axis of the connection end face along the direction that makes the upward orientations the same.

4. The optical cable with connectors according to claim 3, wherein The first optical connector and the second optical connector are optical connectors of a type that are connected to the optical connector of the connection object in a state where the upward orientation is the same as that of the optical connector of the connection object.

5. The optical cable with a connector according to claim 3, wherein, The first optical connector and the second optical connector are optical connectors of a type that are connected to the optical connector of the connection object in a state where the upward orientation is flipped with respect to the optical connector of the connection object.

6. An optical cable with a connector, comprising: Multi-core optical fiber, having a first core to an Nth core, wherein, N is an integer of 2 or more; A first optical connector, assembled at the first end of the multi-core optical fiber; and A second optical connector, assembled at the second end of the multi-core optical fiber, The arrangement of the first core to the Nth core has rotational symmetry about the central axis in the cross-section of the multi-core optical fiber perpendicular to the central axis of the multi-core optical fiber. The first optical connector and the second optical connector are optical connectors of a type that are connected to the optical connector of the connection object in a state where the upward orientation is flipped with respect to the optical connector of the connection object. When observing the connection end faces of the first optical connector and the second optical connector in a manner that makes the upward orientations consistent, the arrangement of the end faces of the first core to the Nth core in the connection end face of the second optical connector is obtained by flipping the arrangement of the end faces of the first core to the Nth core in the connection end face of the first optical connector with respect to the central axis of the connection end face along a direction orthogonal to the direction that makes the upward orientations consistent.

7. The optical cable with a connector according to any one of claims 1 to 6, wherein, The structures of the portions of the first optical connector and the second optical connector that are engaged with the optical connector of the connection object are different from each other.

8. The optical cable with a connector according to any one of claims 1 to 7, wherein, The connection end face is perpendicular to the central axis of the multi-core optical fiber.

9. The optical cable with a connector according to any one of claims 2, 5, and 6, wherein, The connection end face is inclined with respect to an imaginary plane perpendicular to the central axis of the multi-core optical fiber.

10. The optical cable with a connector according to any one of claims 3 to 6, wherein, The multi-core optical fiber has a mark for identifying the first core to the Nth core.

11. An optical transmission system, comprising: A first optical cable with a connector, which is the optical cable with a connector according to claim 1; and A second optical cable with a connector, which is the optical cable with a connector according to claim 2, The appearance of the second optical cable with a connector is different from the appearance of the first optical cable with a connector.

12. An optical transmission system, comprising: A third optical cable with a connector, which is the optical cable with a connector according to claim 3; and A fourth optical cable with a connector, which is the optical cable with a connector according to claim 6, The appearance of the fourth optical cable with a connector is different from the appearance of the third optical cable with a connector.

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