WO2023239577A1

WO2023239577A1 - Direction independent and polarity invariant multicore fiber optic cables, cable assemblies, connector interfaces, and structured cabling systems

Info

Publication number: WO2023239577A1
Application number: PCT/US2023/024091
Authority: WO
Inventors: Qi Wu
Original assignee: Corning Research & Development Corporation
Priority date: 2022-06-07
Filing date: 2023-06-01
Publication date: 2023-12-14

Abstract

Multi-core fiber optic ribbons (24), cable assemblies (38), connectors (40, 70, 98, 100), structured cabling systems (84), and methods of making same. Multicore optical fibers (10) are arranged relative to each other so that the core patterns have mirror-image symmetry at both ends of a fiber optic ribbon (24). Connectors (40, 70, 98, 100) are configured so that the end faces (16) of the multicore optical fibers (10) are placed in the connector interface (62) to define a connector core pattern having mirror-image symmetry about an interface axis of symmetry (64). Cabling systems (84) include a multicore fiber optic cable assembly (38) and a plurality of network components (88, 90). One half of the multicore optical fibers (10) in the cable assemblies (38) have a first draw direction, and the other half of the multicore optical fibers (10) have a second draw direction opposite the first draw direction. Network components (88, 90) include port connectors (70) having the connector core pattern.

Description

DIRECTION INDEPENDENT AND POLARITY INVARIANT MULTICORE FIBER OPTIC CABLES, CABLE ASSEMBLIES, CONNECTOR INTERFACES, AND STRUCTURED CABLING SYSTEMS

Priority Application

[0001] This application claims the benefit of priority of U.S. Provisional Application No. 63/349,610, filed on June 7, 2022, U.S. Provisional Application No. 63/399,423, filed on August 19, 2022, and U.S. Provisional Application No. 63/420,217, filed on October 28, 2022, the content of which is relied upon and incorporated herein by reference in entirety.

Technical Field

[0002] This disclosure relates generally to fiber optic cables, connectors, and cable assemblies, and more particularly, to direction independent multicore fiber optic cables and cable assemblies, as well as polarity invariant connector interfaces and structured multicore fiber optic cabling systems, that provide direction-independent connectivity, and methods of making direction independent multicore fiber optic cables and cable assemblies, as well as polarity invariant connector interfaces and structured multicore fiber optic cabling systems that provide direction-independent connectivity.

Background

[0003] Optical fibers are useful in a wide variety of applications, the most common being as part of the physical layer of a communication protocol through which network nodes communicate over a data network. Benefits of optical fibers include wide bandwidth and low noise operation. Continued growth of the Internet has resulted in a corresponding increase in demand for network capacity. This demand for network capacity has, in turn, generated a need for increased bandwidth between network nodes.

[0004] Multicore optical fibers are optical fibers in which multiple cores are contained within a common cladding. Multicore optical fibers function essentially as a bundle of single-core fibers, thereby providing increased capacity as compared to individual single-core optical fibers. The use of multicore optical fibers has yet to be widely adopted for long haul applications due to advances in technology that have enabled increased transmission rates over existing single-core optical fibers, such as dense wavelength division multiplexing and coherent optical communication techniques. Nevertheless, with the rapid growth of hyperscale data centers, and the maturing of dense wavelength division multiplexing and coherent optical communication technologies, the use of multicore fiber optic cables is expected to increase. [0005] Data center campuses provide computing spaces for housing computer systems and associated network components. These computing spaces are typically spread across multiple buildings located on the campus. To facilitate connections between these computing spaces, conduits or other cable ducts configured to carry fiber optic cables are typically installed between the computing spaces when the data center campus is constructed. The distances between computing spaces within a data center campus are typically less than two kilometers, and massive numbers of optical fibers are used to interconnect these spaces both within each campus as well as between regional campuses. Preexisting cable ducts between computer spaces have a limited amount of space that is difficult to expand. Accordingly, as the need for higher fiber counts continues to increase, multicore optical fibers have the potential to provide a solution to this limited amount of cable duct space.

[0006] Figs. 1A and 1 B depict exemplary multicore optical fibers 10 each representing a separate fiber span. Each multicore optical fiber 10 includes a cladding 12, a plurality of cores 14a-14d contained within the cladding 12, a front end face 16a, a back end face 16b, and a fiber draw direction extending from the front end face 16a to the back end face 16b, as indicated diagrammatically by single-headed arrows 20. The cores 14a-14d are spaced symmetrically around a center axis of the cladding 12, and each end face 16a, 16b includes a marker 22 that identifies a reference core (e.g., core 14a) of the multicore optical fiber 10. In Fig. 1A, the multicore optical fibers 10 are oriented so that the fiber draw direction of each fiber span is in the same direction. In Fig. 1B, the multicore optical fibers 10 are oriented so that their fiber draw directions are in opposite directions.

[0007] In order to maintain a consistent core polarity between connected fiber spans, the multicore optical fibers 10 are oriented so that they have the same fiber draw direction. In the depicted case, core polarity is maintained when the front end face 16a of one multicore optical fiber 10 interfaces with the back end face 16b of another multicore optical fiber. As shown by Fig. 1A, matching fiber draw directions enable the end faces 16a, 16b to be coupled such that each core 14a-14d on the front end face 16a is aligned with a correspondingly positioned core 14a-14d on the back end face 16b. Core polarity can thereby be maintained across multiple fiber spans that have matching fiber draw directions.

[0008] In contrast, when the multicore optical fibers 10 of two spans are oriented so that they have opposing fiber draw directions as in Fig. 1 B, two like end faces (e.g., two back end faces 16b) need to be interfaced. With the exemplary multicore optical fibers 10 of Figs. 1A and 1 B, fiber spans having opposite fiber draw directions can at best be connected such that the optical fibers are cross-connected. This cross-connection results in an optical beam entering a specific core (e.g., core 14a) of one span being emitted from a different core (e.g., core 14b) of the other fiber span.

[0009] Figs. 2A and 2B depict another variation of the exemplary multicore optical fibers 10 in which the cores 14a-14d are arranged in an asymmetrical pattern. Specifically, one core (e.g., core 14a) is radially offset relative to the other cores (e.g., cores 14b-14d). This asymmetrical arrangement enables individual cores 14a-14d to be identified without the need for a marker 22. As with the fiber spans depicted by Fig. 1A, the multicore optical fibers 10 depicted by Fig 2A are oriented so that they have the same fiber draw direction. This enables the end faces 16a, 16b to be operatively coupled such that each core 14a-14d on the front end face 16a is aligned with a corresponding core 14a-14d on the back end face 16b. Core polarity can thereby be maintained across the fiber spans of Fig. 2A. In contrast, the multicore optical fibers 10 depicted by Fig 2B are oriented so that they have opposing fiber draw directions. This prevents the end faces 16a, 16b from being coupled in a way that maintains either core polarity or connectivity across the fiber spans of Fig. 2B.

[0010] As can be seen from Figs. 1A-2B, in order to distinguish each core in a multicore optical fiber, radial symmetry of the core patten is broken. Radial symmetry may be broken by introducing a marker 22 in parallel with the cores 14a-14d, as illustrated in Figs 1A and 1 B, or by positioning at least one of the cores 14a-14d so that the core 14a-14d is in an “off position” (e.g., a radially non-symmetric position), as illustrated by Figs. 2A and 2B. The marker 22 or off position core 14a may be observed in any cross section of the multicore optical fiber 10. By designating the off position/marked core as a reference core, the rest of the cores can be identified through a naming convention. In other words, the core polarity of a multicore optical fiber may be defined by including at least one core with a mark-based or position-based asymmetry. A core polarity defined in this way is maintained regardless of the observer’s viewpoint. Asymmetric core patterns look different at the front and back end faces 16a, 16b of the multicore optical fiber 10 because each core pattern as viewed at one end face is a mirror-image of the core pattern as viewed at the other end face. The resulting directional nature of multicore optical fiber connectivity is both profoundly different from a single core optical fiber and a source of connectivity issues.

[0011] Duplex patch cord cable assemblies are widely used in data center networks as part of a structured cabling system for connecting network nodes using single core optical fibers. The term “structured cabling system” is generally used to refer to cabling systems that include cable assemblies and other network components having standardized pre-terminated connection interfaces. For example, duplex transceivers are typically connected via duplex patch cords to cassettes or harnesses, which may then be connected to a trunk cable through a Multi-fiber Push On (MPO) connector. Because the receive port of each transceiver is connected to the transmission port of the other receiver, an optical fiber polarity switch typically occurs at some point between the transceivers being connected.

[0012] TIA-568 is a technical standard issued by the Telecommunications Industry Association (TIA), and defines three methods (methods A, B, and C) for connecting transceivers using structured cabling. Method-A uses key-up to key-down straight-through MPO terminated trunk cables in which a fiber polarity switch occurs in the duplex patch cords on one side. Methods B and C use what is referred to as A-to-B type or “straight-through” duplex cables, with polarity switching occurring at the MPO trunk cables. Method-B uses key-up to key-up type B symmetric MPO terminated trunk cables, and is widely used due to its simplicity. Method C is less common, and uses pair-wise flipped type-C trunk cables. The multitude of options in single core fiber based structured cabling leads to significant complexity when migrating to multicore fiber. With multicore fiber, in addition to managing the optical fiber polarity, one must also trace the path of each core in each multicore optical fiber. The use of multicore optical fibers therefore adds a new dimension of complexity to connections between nodes in fiber optic networks.

[0013] Figs. 3A-3C depict exemplary fiber optic ribbons 24 each including a plurality of multicore optical fibers 10 (e.g., two multicore optical fibers 10) arranged in a ribbon configuration suitable for use in an A-to-B type duplex cable assembly. Each multicore optical fiber 10 is configured as described above for Figs 1A-2B, and each ribbon 24 represents a separate fiber span 26, 28. Because the ribbons 24 in Fig. 3A have the same draw directions, both the multicore optical fibers 10 of each span, and the cores 14a-14b of each multicore optical fiber 10, can be aligned to maintain core polarity.

[0014] Fig. 3B depicts the effects of a change in the draw direction of the ribbon 24 of lower fiber span 28 so that the draw directions of the ribbons 24 are in opposite directions. As can be seen, the multicore optical fibers 10 of the upper fiber span 26 are no longer aligned with the corresponding multicore optical fibers 10 of the lower fiber span 28. Specifically, multicore optical fiber A of the upper fiber span 26 is aligned with multicore optical fiber B of the lower fiber span 28, and multicore optical fiber B of the upper fiber span 26 is aligned with multicore optical fiber A of the lower fiber span 28. In addition, the cores within each multicore optical fiber 10 do not have matching core polarities. Specifically, core 1 of each upper multicore optical fiber 10 is aligned with core 2 of its respective lower multicore optical fiber 10, core 2 of each upper multicore optical fiber 10 is aligned with core 1 of its respective lower multicore optical fiber 10, core 3 of each upper multicore optical fiber 10 is aligned with core 4 of its respective lower multicore optical fiber 10, and core 4 of each upper multicore optical fiber 10 is aligned with core 3 of its respective lower multicore optical fiber 10.

[0015] Fig. 3C depicts the effects rotating the ribbon 24 of lower fiber span 28 180 degrees about its longitudinal axis in an attempt to correct the polarity of the multicore optical fibers 10. Although rotating the ribbon 24 of lower fiber span 28 brings each multicore optical fiber 10 into alignment with its respective multicore optical fiber 10 in the upper fiber span 26 (i.e. , A — > A and B — > B) the polarities of the cores 14a-14d remain mismatched. Specifically, core 1 of each upper multicore optical fiber 10 is aligned with core 3 of its respective lower multicore optical fiber 10, core 2 of each upper multicore optical fiber 10 is aligned with core 4 of its respective lower multicore optical fiber 10, core 3 of each upper multicore optical fiber 10 is aligned with core 1 of its respective lower multicore optical fiber 10, and core 4 of each upper multicore optical fiber 10 is aligned with core 2 of its respective lower multicore optical fiber 10. In any case, for cables that include angled physical contact connectors to minimize back-reflection, rotation would not be an option even if it corrected the core polarity. Thus, it should be apparent that it is not possible to maintain core polarity across spans of conventional fiber optic cables having opposite draw directions which include multicore optical fibers 10.

[0016] Figs. 4A-4C depict exemplary fiber optic ribbons 24 (e.g., fiber optic ribbons) each comprising a plurality of multicore optical fibers 10, e.g., four multicore optical fibers 10 in a ribbon configuration. Each multicore optical fiber 10 is configured as described above for Figs 1A-3C. Each fiber optic ribbon 24 represents a separate fiber span 26, 28. Because the fiber optic ribbons 24 in Fig. 4A have the same draw directions, both the multicore optical fibers 10 of each span, and the cores 14a-14b of each multicore optical fiber 10, can be aligned to maintain core polarity.

[0017] Fig. 4B depicts the effects of a change in the draw direction of the fiber optic ribbon 24 of lower fiber span 28 so that the draw directions of the fiber optic ribbons 24 are in opposite directions. As can be seen, the multicore optical fibers 10 of the upper fiber span 26 are no longer aligned with the corresponding multicore optical fibers 10 of the lower fiber span 28.

Specifically, multicore optical fiber A of the upper fiber span 26 is aligned with multicore optical fiber D of the lower fiber span 28, multicore optical fiber B of the upper fiber span 26 is aligned with multicore optical fiber C of the lower fiber span 28, multicore optical fiber C of the upper fiber span 26 is aligned with multicore optical fiber B of the lower fiber span 28, and multicore optical fiber D of the upper fiber span 26 is aligned with multicore optical fiber A of the lower fiber span 28.

[0018] In addition, the cores within each multicore optical fiber 10 do not have matching core polarities, with core 1 of each upper fiber span multicore optical fiber 10 aligned with core 2 of its respective lower fiber span multicore optical fiber 10, core 2 of each upper fiber span multicore optical fiber 10 aligned with core 1 of its respective lower fiber span multicore optical fiber 10, core 3 of each upper fiber span multicore optical fiber 10 aligned with core 4 of its respective lower fiber span multicore optical fiber 10, and core 4 of each upper fiber span multicore optical fiber 10 aligned with core 3 of its respective lower fiber span multicore optical fiber 10.

[0019] Fig. 4C depicts the effects rotating the fiber optic ribbon 24 of lower fiber span 28 180 degrees about its longitudinal axis in an attempt to correct the polarity of the multicore optical fibers 10. Although rotating the fiber optic ribbon 24 of lower fiber span 28 brings each multicore optical fiber 10 into alignment with its respective multicore optical fiber 10 in the upper fiber span 26 (i.e. , A —> A, B — > B, etc.) the polarities of the cores 14a-14d remain mismatched. Specifically, core 1 of each upper fiber span multicore optical fiber 10 is aligned with core 3 of its respective lower fiber span multicore optical fiber 10, core 2 of each upper fiber span multicore optical fiber 10 is aligned with core 4 of its respective lower fiber span multicore optical fiber 10, core 3 of each upper fiber span multicore optical fiber 10 is aligned with core 1 of its respective lower fiber span multicore optical fiber 10, and core 4 of each upper fiber span multicore optical fiber 10 is aligned with core 2 of its respective lower fiber span multicore optical fiber 10. Thus, it should be apparent that it is not possible to maintain core polarity across spans of conventional fiber optic cables which include multicore optical fibers 10 and that have opposite draw directions.

[0020] In order for an optical beam coupled into a specific core at one end of a multicore optic fiber to emerge from the corresponding core at the opposite end of a fiber optic link including multiple fiber spans, core polarity must be maintained across each fiber span of the fiber optic link. This leads to a requirement that multicore fiber spans in a multi-span fiber optic link have the same fiber draw direction. This consistent fiber draw direction requirement means that multicore fiber spans with opposite fiber draw directions cannot be connected to provide a multi-span fiber optic link. In cases of symmetrically positioned multi-core arrangements, this leads to cross-connected signals in which optical beams coupled to one core emerge from a different core at the other end of the multi-span fiber optic link. In cases of asymmetrically positioned multicore arrangements, connecting the same end of each multicore optical fiber to each other leads to both core polarity mismatches and an inability to couple the optical beam across the fiber span for at least some of the cores.

[0021] When cable assemblies including multicore fibers are deployed as part of a structured cabling system in hyperscale data centers, the difficulties in managing core polarities of thousands of multicore optical fibers become intractable. Maintaining all multicore optical fiber spans so that they are directionally aligned is impractical at best, as it entails both tedious tracking of the cable ends and a requirement that network components have two types of multicore connector interfaces so that they are compatible with both the front and back ends of the multicore optical fibers.

[0022] Single core cable assemblies in data centers are often pre-terminated with connectors in a factory to improve installation efficiency. These pre-terminated optical cables may be tested and used individually or pre-packaged into cable bundles including multiple pre-terminated optical cables. Depending on the application, cable assemblies in pre-engineered cable bundles may have different lengths to facilitate connections to different racks, shelves, and/or ports in a row of equipment racks. At the data center, the installer merely needs to unpack and route the cable sub- assemblies/bundles, snap in connectors, install patch cords to end equipment, etc. Thus, pre-terminated cable assemblies and bundles can save significant amounts of time and effort as compared to fabricating separate cable assemblies on-site. However, the directionality of multicore optical fibers creates complications with pre-term inated cable assemblies and bundles. For example, if even one fiber optic cable in a cable bundle is running in the wrong direction, or an arrangement of network equipment in an equipment rack changes, the cable assembly or bundle in question may need to be re-run or replaced at significant cost in time and money.

[0023] Although the optical fiber count in data centers can be reduced by replacing standard single core optical fiber with multicore optical fiber, large numbers of optical fibers are still needed. For example, replacing an ultra-high count fiber optic cable having 6,912 single mode optical fibers with multicore optical fibers having four cores each would still require a fiber optic cable with 1 ,728 multicore optical fibers. Moreover, because fusion splicing of multicore optical fibers in the field is difficult, pre-term inated structured cabling systems would provide an even more significant advantage with multicore optical fiber than they do with single core optical fiber. Accordingly, in order to take advantage of the increased bandwidth provided by multicore optical fibers, structured multicore fiber optic cabling systems will need to manage the direction dependent connectivity requirements of multicore optical fibers to maintain core polarity between network nodes.

[0024] Thus there is a need in the fiber optic industry for improved fiber optic cables and cable assemblies that include multicore optical fibers which maintain core polarity between fiber spans, and for improved structured multicore fiber optic cabling systems that use these cables and cable assemblies, as well as improved methods of making these fiber optic cables, cable assemblies, and structured multicore fiber optic cabling systems.

Summary

[0025] In an aspect of the disclosure, an improved fiber optic ribbon is disclosed. The fiber optic ribbon includes a first multicore optical fiber and a second multicore optical fiber. The first multicore optical fiber has a first core pattern and a first draw direction, and the second multicore optical fiber has a second core pattern that is the same as the first core pattern and a second draw direction that is opposite the first draw direction. The first multicore optical fiber and the second multicore optical fiber are arranged relative to each other in the fiber optic ribbon so that the first core pattern has a mirror-image symmetry with the second core pattern at both a first end and a second end of the fiber optic ribbon.

[0026] In an embodiment of the disclosed fiber optic ribbon, the first multicore optical fiber and the second multicore optical fiber are arranged in an anti-parallel configuration.

[0027] In another embodiment of the disclosed fiber optic ribbon, the first multicore optical fiber and the second multicore optical fiber are part of a plurality of multicore optical fibers consisting of a first number of multicore optical fibers with the first core pattern and the first draw direction, and a second number of multicore optical fibers with the second core pattern and the second draw direction, and the first number of multicore optical fibers is equal to the second number of multicore optical fibers.

[0028] In another embodiment of the disclosed fiber optic ribbon, the mirrorimage symmetry at both the first end and the second end of the fiber optic ribbon is about an axis of symmetry of the fiber optic ribbon at the respective end, there is a third number of the plurality of multicore optical fibers with the first draw direction on one side of the axis of symmetry, there is a fourth number of the plurality of multicore optical fibers with the second draw direction on the other side of the axis of symmetry, and the third number of the plurality of multicore optical fibers is equal to the fourth number of the plurality of multicore optical fibers.

[0029] In another embodiment of the disclosed fiber optic ribbon, the plurality of multicore optical fibers is arranged so that the draw direction of equally-sized subunits of multicore optical fibers alternates between the first draw direction and the second draw direction.

[0030] In another embodiment of the disclosed fiber optic ribbon, each subunit of the multicore optical fibers includes at least one multicore optical fiber and not more than the first number of multicore optical fibers.

[0031] In another embodiment of the disclosed fiber optic ribbon, the fiber optic ribbon has a longitudinal axis at each end normal to a cross section of the fiber optic ribbon, each longitudinal axis passes through a geometric center of the cross section of the fiber optic ribbon, and each axis of symmetry is normal to the longitudinal axis of the respective end of the fiber optic ribbon.

[0032] In another embodiment of the disclosed fiber optic ribbon, the fiber optic ribbon has an even number of the multicore optical fibers.

[0033] In another embodiment of the disclosed fiber optic ribbon, each of the first core pattern and the second core pattern includes a reference core indicated by one or more of a mark-based asymmetry or a position based asymmetry.

[0034] In another embodiment of the disclosed fiber optic ribbon, both the first core pattern and the second core pattern follow a predetermined naming convention that uniquely identifies each core of the respective core pattern based on a position of the core relative to the respective reference core. [0035] In another aspect of the disclosure, an improved fiber optic cable assembly is disclosed. The fiber optic cable assembly includes the first multicore optical fiber having the first core pattern and the first draw direction, the second multicore optical fiber having the second core pattern that is the same as the first core pattern and the second draw direction that is opposite the first draw direction, a first connector defining a first end of the optical cable assembly, wherein the first end of the first multicore optical fiber and the first end of the second multicore optical fiber are each secured to the first connector, and a second connector defining a second end of the optical cable assembly, wherein the second end of the first multicore optical fiber and the second end of the second multicore optical fiber are each secured to the second connector. The first multicore optical fiber and the second multicore optical fiber are arranged relative to each other in each of the first connector and the second connector so that the first core pattern has the mirror-image symmetry with the second core pattern at both the first end and the second end of the optical cable assembly.

[0036] In another aspect of the disclosure, an improved method of making a fiber optic ribbon is disclosed. The method includes providing the first multicore optical fiber having the first core pattern in the first draw direction, providing the second multicore optical fiber having the second core pattern that is the same as the first core pattern in the second draw direction that is opposite the first draw direction, and arranging the first multicore optical fiber and the second multicore optical fiber relative to each other in the fiber optic ribbon so that the first core pattern has the mirror-image symmetry with the second core pattern at both the first end of the fiber optic ribbon and the second end of the fiber optic ribbon.

[0037] In an embodiment of the disclosed method, arranging the first multicore optical fiber and the second multicore optical fiber relative to each other so that the first core pattern has the mirror-image symmetry with the second core pattern includes arranging the first multicore optical fiber and the second multicore optical fiber in an anti-parallel arrangement.

[0038] In another embodiment of the disclosed method, the first multicore optical fiber and the second multicore optical fiber are part of the plurality of multicore optical fibers consisting of the first number of multicore optical fibers having the first draw direction and the second number of multicore optical fibers having the second draw direction, and the first number of multicore optical fibers is equal to the second number of multicore optical fibers.

[0039] In another embodiment of the disclosed method, the fiber optic ribbon includes an axis of symmetry, and the method further includes arranging the third number of the plurality of multicore optical fibers with the first draw direction on one side of the axis of symmetry, and arranging the fourth number of the plurality of multicore optical fibers with the second draw direction on the other side of the axis of symmetry, the third number of the plurality of multicore optical fibers being equal to the fourth number of the plurality of multicore optical fibers.

[0040] In another embodiment of the disclosed method, the method further includes arranging the plurality of multicore optical fibers so that the draw direction of equally-sized subunits of the multicore optical fibers alternates between the first draw direction and the second draw direction.

[0041] In another embodiment of the disclosed method, each subunit of the multicore optical fibers includes at least one multicore optical fiber and not more than the first number of multicore optical fibers.

[0042] In another embodiment of the disclosed method, the first multicore optical fiber is provided from a first reel of multicore optical fiber wound in the first draw direction, and the second multicore optical fiber is provided from a second reel of multicore optical fiber wound in the second draw direction.

[0043] In another embodiment of the disclosed method, the method further includes winding a length of multicore optical fiber from a third reel onto the second reel, wherein the third reel of multicore optical fiber is wound in the first draw direction.

[0044] In another embodiment of the disclosed method, the method further includes identifying the reference core in each of the first core pattern and the second core pattern by providing one or more of the mark-based asymmetry or the position based asymmetry to the core pattern.

[0045] In another aspect of the disclosure, an improved method of making a fiber optic cable assembly including a first end and a second end is disclosed. The method includes providing the first multicore optical fiber having the first core pattern and the first draw direction, providing the second multicore optical fiber having the second core pattern that is the same as the first core pattern and the second draw direction that is opposite the first draw direction, securing the first connector to the first end of the first multicore optical fiber and the first end of the second multicore optical fiber to define the first end of the fiber optic cable assembly, and securing the second connector to the second end of the first multicore optical fiber and the second end of the second multicore optical fiber to define the second end of the fiber optic cable assembly. The first multicore optical fiber and the second multicore optical fiber are arranged relative to each other in each of the first connector and the second connector so that the first core pattern has the mirror-image symmetry with the second core pattern at both the first end and the second end of the optical cable assembly. [0046] In another aspect of the disclosure, an improved fiber optic cable assembly is disclosed. The fiber optic cable assembly includes a first connector, a second connector, a first multicore optical fiber, and a second multicore optical fiber. The first connector defines a first end of the fiber optic cable assembly, and includes a first connector interface having a first interface axis of symmetry. The second connector defines a second end of the fiber optic cable assembly, and includes a second connector interface having a second interface axis of symmetry. The first multicore optical fiber includes a first front end face having a front end face core pattern and a first back end face having a back end face core pattern that is a mirror image of the front end face core pattern. The second multicore optical fiber includes a second front end face having the front end face core pattern and a second back end face having the back end face core pattern. The first connector is configured so that the first front end face of the first multicore optical fiber and the second back end face of the second multicore optical fiber are placed in the first connector interface to define, at least in part, a first connector core pattern having mirrorimage symmetry about the first interface axis of symmetry. The second connector is configured so that the first back end face of the first multicore optical fiber and the second front end face of the second multicore optical fiber are each placed in the second connector interface to define, at least in part, a second connector core pattern having mirror-image symmetry about the second interface axis of symmetry, wherein the first connector core pattern and the second connector core pattern are the same. [0047] In an embodiment of the disclosed fiber optic cable assembly, the first connector includes a first alignment key that defines an orientation of the first connector, and the second connector includes a second alignment key that defines the orientation of the second connector.

[0048] In another embodiment of the disclosed fiber optic cable assembly, the first connector interface includes a first key-axis that is aligned with the first alignment key, the second connector interface includes a second key-axis that is aligned with the second alignment key, the first interface axis of symmetry is parallel to the first key-axis, and the second interface axis of symmetry is parallel to the second key axis.

[0049] In another embodiment of the disclosed fiber optic cable assembly, the first connector interface includes the first key-axis that is aligned with the first alignment key, the second connector interface includes the second key-axis that is aligned with the second alignment key, the first interface axis of symmetry is orthogonal to the first key-axis, and the second interface axis of symmetry is orthogonal to the second key axis.

[0050] In another embodiment of the disclosed fiber optic cable assembly, the front end face core pattern has mirror-image symmetry about a fiber axis of symmetry in each of the first front end face and the second front end face, and the back end face core pattern has mirror-image symmetry about the fiber axis of symmetry in each of the first back end face and the second back end face. [0051] In another embodiment of the disclosed fiber optic cable assembly, the first interface axis of symmetry divides the first connector interface into a first side and a second side thereof, the second interface axis of symmetry divides the second connector interface into a first side and a second side thereof, the first side of the first connector interface has the same position relative to the first interface axis of symmetry as the first side of the second connector interface relative to the second interface axis of symmetry, the second side of the first connector interface has the same position relative to the first interface axis of symmetry as the second side of the second connector interface relative to the second interface axis of symmetry, the first front end face of the first multicore optical fiber is on the first side of the first connector interface, the second back end face of the second multicore optical fiber is on the second side of the first connector interface, the first back end face of the first multicore optical fiber is on the second side of the second connector interface, and the second front end face of the second multicore optical fiber is on the first side of the second connector interface.

[0052] In another embodiment of the disclosed fiber optic cable assembly, the first interface axis of symmetry divides the first connector interface into the first side and the second side thereof, the second interface axis of symmetry divides the second connector interface into the first side and the second side thereof, the first side of the first connector interface has the same position relative to the first interface axis of symmetry as the first side of the second connector interface relative to the second interface axis of symmetry, the second side of the first connector interface has the same position relative to the first interface axis of symmetry as the second side of the second connector interface relative to the second interface axis of symmetry, the first front end face of the first multicore optical fiber is on the first side of the first connector interface, the second back end face of the second multicore optical fiber is on the second side of the first connector interface, the first back end face of the first multicore optical fiber is on the first side of the second connector interface, and the second front end face of the second multicore optical fiber is on the second side of the second connector interface.

[0053] In another embodiment of the disclosed fiber optic cable assembly, the fiber axis of symmetry of each of the first front end face and the second back end face is orthogonal to the first interface axis of symmetry, and the fiber axis of symmetry of each of the first back end face and the second front end face is orthogonal to the second interface axis of symmetry.

[0054] In another embodiment of the disclosed fiber optic cable assembly, the fiber axis of symmetry of each of the first front end face and the second back end face is parallel to the first interface axis of symmetry, and the fiber axis of symmetry of each of the first back end face and the second front end face is parallel to the second interface axis of symmetry.

[0055] In another aspect of the disclosure, an improved method of making a fiber optic cable assembly is disclosed. The method includes providing the first multicore fiber, the second multicore fiber, the first connector including the first connector interface having the first interface axis of symmetry, and the second connector including the second connector interface having a second interface axis of symmetry. The first multicore optical fiber includes the first front end and the first back end, the first front end including the first front end face having the front end face core pattern and the first back end including the first back end face having the back end face core pattern that is the mirror image of the front end face core pattern. The second multicore optical fiber includes the second front end and the second back end, the second front end including the second front end face having the front end face core pattern and the second back end including the second back end face having the back end face core pattern. The method further includes coupling the first front end of the first multicore optical fiber and the second back end of the second multicore optical fiber to the first connector, coupling the first back end of the first multicore optical fiber and the second front end of the second multicore optical fiber to the second connector, placing the first front end face of the first multicore optical fiber and the second back end face of the second multicore optical fiber in the first connector interface to define, at least in part, the first connector core pattern having mirrorimage symmetry about the first interface axis of symmetry, and placing the first back end face of the first multicore optical fiber and the second front end face of the second multicore optical fiber in the second connector interface to define, at least in part, the second connector core pattern having mirror-image symmetry about the second interface axis of symmetry, wherein the first connector core pattern and the second connector core pattern are the same.

[0056] In an embodiment of the disclosed method, the method further includes providing the first alignment key to the first connector that defines the orientation of the first connector, and providing the second alignment key to the second connector that defines the orientation of the second connector.

[0057] In another embodiment of the disclosed method, the method further includes defining the first key-axis of the first connector interface that is aligned with the first alignment key, and defining the second key-axis of the second connector interface that is aligned with the second alignment key such that the first interface axis of symmetry is parallel to the first key-axis, and the second interface axis of symmetry is parallel to the second key axis.

[0058] In another embodiment of the disclosed method, the method further includes defining the first key-axis of the first connector interface that is aligned with the first alignment key, and defining the second key-axis of the second connector interface that is aligned with the second alignment key such that the first interface axis of symmetry is orthogonal to the first key-axis, and the second interface axis of symmetry is orthogonal to the second key axis.

[0059] In another embodiment of the disclosed method, the method further includes configuring the first and second multicore optical fibers so that the front end face core pattern has mirror-image symmetry about the fiber axis of symmetry in each of the first front end face and the second front end face, and the back end face core pattern has mirror-image symmetry about the fiber axis of symmetry in each of the first back end face and the second back end face. [0060] In another embodiment of the disclosed method, the first interface axis of symmetry divides the first connector interface into the first side and the second side thereof, the second interface axis of symmetry divides the second connector interface into the first side and the second side thereof, the first side of the first connector interface has the same position relative to the first interface axis of symmetry as the first side of the second connector interface relative to the second interface axis of symmetry, the second side of the first connector interface has the same position relative to the first interface axis of symmetry as the second side of the second connector interface relative to the second interface axis of symmetry, and the method further includes placing the first front end face of the first multicore optical fiber in the first connector interface so that the first front end face is on the first side of the first connector interface, placing the second back end face of the second multicore optical fiber in the first connector interface so that the second back end face is on the second side of the first connector interface, placing the first back end face of the first multicore optical fiber in the second connector interface so that the first back end face is on the second side of the second connector interface, and placing the second front end face of the second multicore optical fiber in the second connector interface so that the second front end face is on the first side of the second connector interface.

[0061] In another embodiment of the disclosed method, the first interface axis of symmetry divides the first connector interface into the first side and the second side thereof, the second interface axis of symmetry divides the second connector interface into the first side and the second side thereof, the first side of the first connector interface has the same position relative to the first interface axis of symmetry as the first side of the second connector interface relative to the second interface axis of symmetry, the second side of the first connector interface has the same position relative to the first interface axis of symmetry as the second side of the second connector interface relative to the second interface axis of symmetry, and the method further includes placing the first front end face of the first multicore optical fiber in the first connector interface so that the first front end face is on the first side of the first connector interface, placing the second back end face of the second multicore optical fiber in the first connector interface so that the second back end face is on the second side of the first connector interface, placing the first back end face of the first multicore optical fiber in the second connector interface so that the first back end face is on the first side of the second connector interface, and placing the second front end face of the second multicore optical fiber in the second connector interface so that the second front end face is on the second side of the second connector interface.

[0062] In another embodiment of the disclosed method, the method further includes placing each of the first front end face and the second back end face in the first connector interface so that the fiber axis of symmetry of each of the first front end face and the second back end face is orthogonal to the first interface axis of symmetry, and placing each of the first back end face and the second front end face in the second connector interface so that the fiber axis of symmetry of each of the first back end face and the second front end face is orthogonal to the second interface axis of symmetry.

[0063] In another embodiment of the disclosed method, the method further includes placing each of the first front end face and the second back end face in the first connector interface so that the fiber axis of symmetry of each of the first front end face and the second back end face is parallel to the first interface axis of symmetry, and placing each of the first back end face and the second front end face in the second connector interface so that the fiber axis of symmetry of each of the first back end face and the second front end face is parallel to the second interface axis of symmetry.

[0064] In another aspect of the disclosure, an improved fiber optic connector is disclosed. The fiber optic connector includes the connector interface having the interface axis of symmetry, the front end face of the first multicore optical fiber, and the back end face of the second multicore optical fiber. The front end face of the first multicore optical fiber includes the front end face core pattern, and the back end face of the second multicore optical fiber includes the back end face core pattern that is the mirror image of the front end face core pattern. The front end face of the first multicore optical fiber and the back end face of the second multicore optical fiber are placed in the connector interface so that the front end face and the second back end face define, at least in part, a connector core pattern having mirror-image symmetry about the interface axis of symmetry.

[0065] In an embodiment of the disclosed fiber optic connector, the front end face core pattern has mirror-image symmetry about the fiber axis of symmetry of the front end face, and the back end face core pattern has mirror-image symmetry about the fiber axis of symmetry of the back end face.

[0066] In an aspect of the disclosure, a structured multicore fiber optic cabling system is disclosed. The structured multicore fiber optic cabling system includes one or more multicore fiber optic cable assemblies and a plurality of network components. Each multicore fiber optic cable assembly includes a first cable connector including a first cable connector interface, a second cable connector including a second cable connector interface, and a first plurality of multicore optical fibers. Each of the multicore optical fibers includes a first end face having a first end face core pattern and a second end face having a second end face core pattern that is a mirror image of the first end face core pattern. The first plurality of multicore optical fibers is configured so that a first half thereof has a first draw direction, and a second half thereof has a second draw direction opposite the first draw direction. The first cable connector is configured so that the first end face of each multicore optical fiber having the first draw direction and the second end face of each multicore optical fiber having the second draw direction is placed in the first cable connector interface to define a first connector core pattern having a first mirror-image symmetry. The second cable connector is configured so that the first end face of each multicore optical fiber having the second draw direction and the second end face of each multicore optical fiber having the first draw direction is placed in the second cable connector interface to define the first connector core pattern. Each network component of the plurality of network components includes a port connector having a port connector interface. The port connector interface includes a plurality end faces with a first half thereof having the first end face core pattern and a second half thereof having the second end face core pattern, and each end face of the plurality of end faces is placed in the port connector interface to define the first connector core pattern. Core polarity is preserved between a first port connector of a first network component of the plurality of network components and a second port connector of a second network component of the plurality of network components when the first cable connector of a first multicore fiber optic cable assembly of the one or more multicore fiber optic cable assemblies is operatively coupled to the first port connector, and the second cable connector of the first multicore fiber optic cable assembly is operatively coupled to the second port connector. The core polarity is also preserved between the first port connector of the first network component and the second port connector of the second network component when the first cable connector of the first multicore fiber optic cable assembly is operatively coupled to the second port connector, and the second cable connector of the first multicore fiber optic cable assembly is operatively coupled to the first port connector.

[0067] In an embodiment of the disclosed structured multicore fiber optic cabling system, the first cable connector includes a first cable alignment key having a first placement relative to the first connector core pattern of the first cable connector, and the second cable connector includes a second cable alignment key having the first placement relative to the first connector core pattern of the second cable connector.

[0068] In another embodiment of the disclosed structured multicore fiber optic cabling system, the first port connector includes a first port alignment key having a second placement relative to the first connector core pattern of the first port connector, the second port connector includes a second port alignment key having the second placement relative to the first connector core pattern of the second port connector, and the second placement relative to the first connector core pattern is opposite the first placement relative to the first connector core pattern. Each cable connector and each port connector includes a key-axis that lies in a plane which bisects the respective connector and is aligned with the cable alignment key or port alignment key of the respective connector. In each cable connector and port connector interface, the first and second end faces of the first plurality of multicore optical fibers is aligned in one or more arrays that are orthogonal to the key-axis of the respective connector. In this embodiment, the core polarity is preserved between the first port connector of the first network component and the second port connector of the second network component when each of the first and second cable alignment key orientations is opposite that of the first or second port alignment key orientation of the respective first or second port connector to which the first or second cable connector is operatively coupled.

[0069] In another embodiment of the disclosed structured multicore fiber optic cabling system, the first port connector includes the first port alignment key having the first placement relative to the first connector core pattern of the first port connector, and the second port connector includes the second port alignment key having the first placement relative to the first connector core pattern of the second port connector. Each cable connector and each port connector includes the key-axis that lies in the plane which bisects the respective connector and is aligned with the cable alignment key or the port alignment key of the respective connector. In each cable connector interface and each port connector interface, the first and second end faces of the first plurality of multicore optical fibers is aligned in one or more arrays that are parallel to the key-axis of the respective connector. In this embodiment, the core polarity is preserved between the first port connector of the first network component and the second port connector of the second network component when each of first and second cable alignment key orientations is the same as the first or second port alignment key orientation to which the respective first and second cable connector is operatively coupled.

[0070] In another embodiment of the disclosed structured multicore fiber optic cabling system, the first and second end faces of the first plurality of multicore optical fibers is aligned in one array that is parallel to the key-axis of the respective connector, and the first mirror-image symmetry of the first connector core pattern of each connector is about an axis of symmetry that is orthogonal to the key- axis.

[0071] In another embodiment of the disclosed structured multicore fiber optic cabling system, the first and second end faces of the first plurality of multicore optical fibers is aligned in an even number of two or more arrays that are parallel to the key-axis of the respective connector, and the first mirror-image symmetry of the first connector core pattern of each connector is about an axis of symmetry that is parallel to the key-axis.

[0072] In another embodiment of the disclosed structured multicore fiber optic cabling system, the first and second end faces of the first plurality of multicore optical fibers is arranged in at least two linear arrays, and each linear array of end faces includes 4, 8, 12, or 16 end faces.

[0073] In another embodiment of the disclosed structured multicore fiber optic cabling system, the first port connector of each of the first and second network components is a trunk connector, and at least one of the first and second network components is one of a plurality of breakout modules. Each breakout module of the plurality of breakout modules includes the trunk connector having the first connector core pattern, a second plurality of multicore optical fibers each including the first end face and the second end face, and a plurality of branch connectors. The second plurality of multicore optical fibers is configured so that a first half thereof has the first draw direction, and a second half thereof has the second draw direction. Each branch connector includes a branch connector interface and is operatively coupled to the trunk connector by a respective multicore optical fiber from each of the first and second halves of the second plurality of multicore optical fibers. Each branch connector is configured so that the second end face of the multicore optical fiber having the first draw direction and the first end face of the multicore optical fiber having the second draw direction is placed in the branch connector interface to define a second connector core pattern having a second mirror-image symmetry.

[0074] In another embodiment of the disclosed structured multicore fiber optic cabling system, the plurality of breakout modules includes a third breakout module and a fourth breakout module, the one or more multicore fiber optic cable assemblies includes a second multicore fiber optic cable assembly, and the structured multicore fiber optic cabling system further includes a plurality of multicore duplex patch cords. Each multicore duplex patch cord includes first and second multicore optical fibers, and first and second patch cord connectors. The first multicore optical fiber includes the first end face having the first end face core pattern and the second end face having the second end face core pattern. The second multicore optical fiber includes the first end face having the first end face core pattern and the second end face having the second end face core pattern. The first patch cord connector defines a first end of the multicore duplex patch cord and includes a first patch cord connector interface. The first end face of the first multicore optical fiber and the second end face of the second multicore optical fiber is placed in the first patch cord connector interface to define the second connector core pattern. The second patch cord connector defines a second end of the multicore duplex patch cord and includes a second patch cord connector interface. The second end face of the first multicore optical fiber and the first end face of the second multicore optical fiber is placed in the first patch cord connector interface to define the second connector core pattern. The trunk connector of the third network component is operatively coupled to the trunk connector of the fourth network component by the second multicore fiber optic cable assembly, and each of the branch connectors of the second network component is operatively coupled to a respective branch connector of the third network component to define a cross- connection between the first network component and the fourth network component.

[0075] In another embodiment of the disclosed structured multicore fiber optic cabling system, the system further includes a third network component including one or more transceivers each having a high-density transceiver interface, and one or more multicore duplex patch cords each including first and second multicore optical fibers and first and second patch cord connectors. The first multicore optical fiber includes the first end face having the first end face core pattern and the second end face having the second end face core pattern. The second multicore optical fiber includes the first end face having the first end face core pattern and the second end face having the second end face core pattern. The first patch cord connector defines a first end of the multicore duplex patch cord, and includes a patch cord alignment key defining a key-axis and a first patch cord connector interface having a cross-axis orthogonal to the key-axis. The second patch cord connector defines a second end of the multicore duplex patch cord, and includes the patch cord alignment key defining the key-axis and a second patch cord connector interface having the cross-axis orthogonal to the key-axis. Each of the first and second end face core patterns includes a plurality of cores arranged in a linear array of cores. The first end face of the first multicore optical fiber and the second end face of the second multicore optical fiber is placed in the first patch cord connector interface so that each linear array of cores is aligned with the cross axis of the first patch cord connector and to define the second connector core pattern having the second mirror-image symmetry. The second end face of the first multicore optical fiber and the first end face of the second multicore optical fiber is placed in the second patch cord connector interface so that each linear array of cores is aligned with the cross axis of the second patch cord connector and to define the second connector core pattern having the second mirror-image symmetry. The second network component is one of the plurality of breakout modules, each branch connector of the second network component includes a branch alignment key defining the key-axis of the branch connector, and the branch connector interface has the cross axis orthogonal to the key-axis and the second connector core pattern. The high-density transceiver interface includes a transceiver connector having a transceiver alignment key defining the key-axis of the transceiver connector, and a transceiver connector interface having the cross-axis orthogonal to the key-axis and the second connector core pattern. Each transceiver connector is operatively coupled to a respective branch connector by a respective multicore duplex patch cord of the one or more multicore duplex patch cords with the same key orientation.

[0076] In another embodiment of the disclosed structured multicore fiber optic cabling system, the first cable connector includes a first cable alignment key having a first placement relative to the first connector core pattern of the first cable connector, and the second cable connector includes a second cable alignment key having a second placement relative to the first connector core pattern of the second cable connector that is opposite the first placement relative to the first connector core pattern.

[0077] In another embodiment of the disclosed structured multicore fiber optic cabling system, the first port connector includes the first port alignment key having the second placement relative to the first connector core pattern of the first port connector, and the second port connector includes the second port alignment key having the first placement relative to the first connector core pattern of the second port connector. In this embodiment, the core polarity is preserved between the first port connector of the first network component and the second port connector of the second network component when each of the first and second cable alignment key orientations is the opposite of the first or second port alignment key orientation to which the respective first and second cable connector is operatively coupled.

[0078] In another aspect of the disclosure, a breakout module for a structured multicore fiber optic cabling system is disclosed. The breakout module includes a plurality of multicore optical fibers, a trunk connector, and a plurality of branch connectors. Each of the multicore optical fibers includes a first end face having a first end face core pattern and a second end face having a second end face core pattern that is a mirror-image of the first end face core pattern. The plurality of multicore optical fibers is configured so that a first half thereof has a first draw direction, and a second half thereof has a second draw direction opposite the first draw direction. The trunk connector includes a trunk connector interface configured so that the first end face of each multicore optical fiber having the first draw direction and the second end face of each multicore optical fiber having the second draw direction is placed in the trunk connector interface to define a first connector core pattern having a first mirror image symmetry. Each of the branch connectors includes a branch connector interface and is operatively coupled to the trunk connector by a respective multicore optical fiber from each of the first and second halves of the plurality of multicore optical fibers. Each branch connector is configured so that the second end face of the multicore optical fiber having the first draw direction and the first end face of the multicore optical fiber having the second draw direction is placed in the branch connector interface to define a second connector core pattern having a second mirror-image symmetry.

[0079] In an embodiment of the disclosed breakout module, the first mirror-image symmetry is about an axis of symmetry of the trunk connector interface. The first and second end faces of the plurality of multicore optical fibers is arranged in a linear array orthogonal to the axis of symmetry in the trunk connector interface such that each first end face is on one side of the axis of symmetry and each second end face is on the other side of the axis of symmetry. Each of the branch connectors is operatively coupled to a respective pair of multicore optical fibers associated with first and second end faces on each side of, and the same distance from, the axis of symmetry. [0080] In another embodiment of the disclosed breakout module, the first mirror-image symmetry is about an axis of symmetry of the trunk connector interface, the end faces of the trunk connector is arranged in a linear array orthogonal to the axis of symmetry such that the first end faces alternate with the second end faces, and each of the branch connectors are operatively coupled to a pair of multicore optical fibers having adjacent end faces at the trunk connector interface of the trunk connector.

[0081] In another aspect of the disclosure, a method of making the structured multicore fiber optic cabling system is disclosed. The method includes providing the first cable connector including the first cable connector interface, providing the second cable connector including the second cable connector interface, and providing the first plurality of multicore optical fibers each including the first end face having the first end face core pattern and the second end face having the second end face core pattern that is the mirror-image of the first end face core pattern. The method further includes arranging the first plurality of multicore optical fibers so that the first half thereof has the first draw direction, and the second half thereof has the second draw direction opposite the first draw direction. The method places the first end face of each multicore optical fiber having the first draw direction and the second end face of each multicore optical fiber having the second draw direction in the first cable connector interface to define the first connector core pattern having the first mirror-image symmetry, and places the first end face of each multicore optical fiber having the second draw direction and the second end face of each multicore optical fiber having the first draw direction in the second cable connector interface to define the first connector core pattern. The method further includes providing the plurality of network components each including the port connector having the port connector interface with the plurality of end faces. The first half of the plurality of end faces has the first end face core pattern, and the second half of the plurality of end faces has the second end face core pattern. The method further includes placing each end face of the plurality end faces in the port connector interface to define the first connector core pattern, operatively coupling one of the first cable connector or the second cable connector to the first port connector of the first network component of the plurality of network components, and operatively coupling the other of the first cable connector or the second cable connector to the second port connector of the second network component of the plurality of network components. Core polarity is thereby preserved between the first network component and the second network component regardless of whether the first cable connector or the second cable connector is operatively coupled to the first port connector. [0082] In an embodiment of the disclosed method, the method further includes providing the first alignment key to the first connector that defines the orientation of the first connector, and providing the second alignment key to the second connector that defines the orientation of the second connector.

[0083] In another embodiment of the disclosed method, the method further includes placing the first cable alignment key on the first cable connector at the first placement relative to the first connector core pattern of the first cable connector, placing the second cable alignment key on the second cable connector at the first placement relative to the first connector core pattern of the second cable connector, placing the first port alignment key on the first port connector at the second placement relative to the first connector core pattern of the first port connector, and placing the second port alignment key on the second port connector at the second placement relative to the first connector core pattern of the second port connector. The method further includes aligning, in each cable connector interface and each port connector interface, the first and second end faces of the first plurality of multicore optical fibers in one or more arrays that are orthogonal to the key-axis of the respective connector. The second placement relative to the first connector core pattern is opposite the first placement relative to the first connector core pattern. The key-axis of each connector lies in the plane which bisects the respective connector and is aligned with the cable alignment key or the port alignment key of the respective connector. The core polarity is preserved between the first and second network components when the first and second port connectors are operatively coupled to each other through the first and second cable connectors, and each of the first and second cable alignment key orientations are opposite the respective first or second port alignment key to which they are operatively coupled. [0084] In another embodiment of the disclosed method, the first port connector of each of the first and second network components is the trunk connector having the first connector core pattern, and at least one of the first and second network components is one of the plurality of breakout modules. In this embodiment, the method further includes providing each breakout module with the second plurality of multicore optical fibers each including the first end face and the second end face, configuring the second plurality of multicore optical fibers so that the first half thereof has the first draw direction and the second half thereof has the second draw direction, providing each breakout module with the plurality of branch connectors each including the branch connector interface, operatively coupling each branch connector to the trunk connector by the respective multicore optical fiber from each of the first and second halves of the second plurality of multicore optical fibers, and placing the second end face of the multicore optical fiber having the first draw direction and the first end face of the multicore optical fiber having the second draw direction in the branch connector to define the second connector core pattern having the second mirror-image symmetry in the branch connector interface.

[0085] In another embodiment of the disclosed method, the method further includes placing the first cable alignment key on the first cable connector in the first placement relative to the first connector core pattern of the first cable connector, and placing the second cable alignment key on the second cable connector in the second placement relative to the first connector core pattern of the second cable connector that is opposite the first placement relative to the first connector core pattern.

Brief Description of the Drawings

[0086] The accompanying drawings are included to provide a further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and operation of the various embodiments. Features and attributes associated with any of the embodiments shown or described may be applied to other embodiments shown, described, or appreciated based on this disclosure. [0087] Figs. 1 A and 1 B are perspective views of exemplary multicore optical fibers having a reference core identified by a marker and showing the effects of draw direction on core polarity.

[0088] Figs. 2A and 2B are perspective views of exemplary multicore optical fibers having a reference core identified by being in an off position and showing the effects of draw direction on core polarity.

[0089] Figs. 3A-3C are perspective views of exemplary fiber optic ribbons (“ribbons”) each including a plurality of multicore optical fibers and showing the effects of draw direction on core polarity.

[0090] Figs. 4A-4C are perspective views of additional exemplary ribbons each including a plurality of multicore optical fibers and showing the effects of draw direction on core polarity.

[0091] Figs. 5A and 5B are perspective views of exemplary ribbons having an antiparallel configuration in which core polarity is maintained without regard to the draw direction of the cables.

[0092] Figs. 6A and 6B are perspective views of additional exemplary ribbons having an antiparallel configuration in which core polarity is maintained without regard to the draw direction of the cables.

[0093] Fig. 7 is a perspective view of additional exemplary ribbons having an antiparallel configuration in which core polarity is maintained without regard to the draw direction of the cables.

[0094] Fig. 8 is a perspective view of additional exemplary ribbons having an antiparallel configuration in which core polarity is maintained without regard to the draw direction of the cables.

[0095] Fig. 9 is a diagrammatic view of exemplary feed and take-up reels that may be used to reverse the draw direction of any of the multicore optical fibers of Figs 5A-8.

[0096] Fig. 10 is a perspective view of an exemplary fiber optic cable assembly including connectors at each end in which multicore optical fibers are arranged relative to each other so that the core pattern has a mirror-image symmetry at both ends of the fiber optic cable assembly.

[0097] Fig. 11 is an exploded perspective view of one of the connectors of the fiber optic cable assembly of Fig. 10. [0098] Fig. 12 is an end view of one embodiment of the connectors of the fiber optic cable assembly of Fig. 10.

[0099] Fig. 13 is an end view of another embodiment of the connectors of the fiber optic cable assembly of Fig. 10.

[00100] Fig. 14 is a schematic view of a multicore fiber optic cable assembly including a plurality of multicore optical fibers each having a front end face and a back end face.

[00101] Fig. 15 is a schematic view of an exemplary multicore A-to-B duplex patch cord including two 2x2 multicore optical fibers in a parallel configuration. [00102] Figs. 16 and 17 are schematic views of exemplary multicore A-to-B duplex patch cords each including two 2x2 multicore optical fibers in an anti-parallel configuration.

[00103] Fig. 18 is a schematic view of an exemplary multicore A-to-B duplex patch cord including two of the duplex patch cords from Fig. 17 with connectors ganged together to form a quadruplex cable connector.

[00104] Figs. 19-21 are schematic views of exemplary multicore A-to-B duplex patch cords each including two 1 x4 multicore optical fibers in an anti-parallel configuration.

[00105] Figs. 22 and 23 are schematic views of exemplary multicore A-to-A duplex patch cords each corresponding to a respective multicore A-to-B duplex patch cord of a respective one of Figs. 16 and 17.

[00106] Figs. 24-26 are schematic views of exemplary multicore A-to-A duplex patch cords each corresponding to a respective multicore A-to-B duplex patch cord of a respective one of Figs. 19-21.

[00107] Fig. 27 is a schematic view of an exemplary multicore optical fiber loopback device including a single 2x2 multicore optical fiber.

[00108] Fig. 28 is a schematic view of an exemplary structured cabling system that includes a plurality of A-to-B duplex patch cords.

[00109] Fig. 29 is a schematic view of an exemplary structured multicore fiber optic cabling system including a fiber optic cable assembly and a pair of port connectors. The fiber optic cable assembly includes a plurality of multicore optical fibers terminated by cable connectors matching the port connectors. [00110] Figs. 30-32 are schematic views of exemplary connectors that may be used in the cabling system of Fig. 29. [00111] Fig. 33 is a schematic view of an exemplary structured multicore fiber optic cabling system including a plurality of multicore optical fibers having the same draw direction.

[00112] Figs. 34 and 35 are schematic views of exemplary structured multicore fiber optic cabling systems including a plurality of multicore optical fibers in which one half of the plurality of multicore optical fibers have one draw direction and the other half of the plurality of multicore optical fibers have a different draw direction.

[00113] Figs. 36 and 37 are schematic views of exemplary structured multicore fiber optic cabling systems each including a breakout module.

[00114] Fig. 38 is a schematic view of an exemplary structured multicore fiber optic cabling system that provides multicore optical fiber duplex connectivity with a cross connect structured cabling.

[00115] Fig. 39 is a schematic view of an exemplary structured multicore fiber optic cabling system that includes a two-way multicore fiber optic trunk cable in a key-down orientation.

[00116] Figs. 40A and 40B are schematic views of an exemplary structured multicore fiber optic cabling system including a two-way multicore fiber optic cable assembly in a key-down orientation.

[00117] Figs. 41 A and 41 B are schematic views of an exemplary structured multicore fiber optic cabling system including a two-way multicore fiber optic cable in a key-up orientation suitable for use with VSFF array connectors.

[00118] Figs. 42A and 42B are schematic views of an exemplary structured multicore fiber optic cabling system including a two-way multicore fiber optic cable in a key-up orientation suitable for use with MPO multi-fiber connectors. [00119] Figs. 43A and 43B are schematic views of an exemplary structured multicore fiber optic cabling system suitable for use with VSFF array connectors having connector fiber polarities based on TIA-568 Method-A.

[00120] Figs. 44A and 44B are schematic views of an exemplary structured multicore fiber optic cabling system suitable for use with a multicore fiber optic trunk cable based on TIA-568 Method-A.

[00121] Figs. 45A and 45B are schematic views of an exemplary structured multicore fiber optic cabling system including a multicore optical fiber based on TIA-586 Method-C in which the trunk cable has pair-wise flipped optical fibers to change the fiber polarity.

Detailed Description

[00122] Various embodiments will be further clarified by examples described below. Portions of the description generally relate to fiber optic ribbons (“ribbons”) and/or groups of ribbons including anti-parallel multicore optical fibers arranged in a pattern having mirror-image symmetry. The term “fiber optic ribbon” or “ribbon” in this disclosure refers to a group of optical fibers (e.g., 4, 8, 12, or 24 optical fibers) that are arranged side-by-side in an array, with adjacent optical fibers being held together at least intermittently by a binding material (e.g., adhesive), tape, or the like. The mirror-image symmetry of the ribbons disclosed herein enables connections between fiber spans to maintain core polarity independent of the direction, or “ribbon direction”, of the ribbons being connected. The ribbons may, for example, be contained in cables and have ends terminated by cable connectors. Ribbons configured in accordance with the disclosed embodiments allow consistent core polarity mapping from one span to another independent of the ribbon direction, and thereby facilitate deployment of efficient structured multicore fiber optic cabling systems that include such ribbons.

[00123] In particular, ribbons of the present disclosure include anti-parallel multicore optical fibers. The anti-parallel multicore optical fibers may be arranged in the ribbon in any manner that results in the ribbon having mirrorimage symmetry with regard to core patterns. This core pattern mirror-image symmetry allows the ribbon (typically as part of a fiber optic cable or cable assembly) to be connected to another ribbon having the same mirror-image symmetry without regard to the ribbon direction of either ribbon. As described in detail below, this bi-directional connectivity provides unique advantages over known arrangements.

[00124] Other portions of the below description generally relate to structured multicore fiber optic cabling systems, cable assemblies, and other fiber optic network components including one or more fiber optic connectors. A fiber optic connector may also be referred to herein as a “cable connector”, a “port connector”, or simply as a “connector”. The term “port connector” is generally used herein to differentiate between a connector terminating a cable (i.e. , a “cable connector”) and a connector configured to receive the cable connector. Port connectors may include, but are not limited to, connectors of a transceiver, breakout module, cross-connect, or other network component. In some cases, the term port connector may be used refer to the combination of a cable connector and an adapter, or a cable connector that is otherwise configured to receive another cable connector. In some cases, a cable connector or a port connector may be referred to as a “trunk connector”, a “branch connector”, a “transceiver connector”, a “patch cord connector”, or other type of connector merely to provide an indication of the function of the connector and/or differentiate between different connectors within a depicted network element or cabling system.

[00125] Connectors may include an anti-parallel multicore optical fiber arrangement that provides a connector core pattern having mirror-image symmetry at the connector interface. The connector core pattern is the pattern of the cores in the multicore fiber arrangement, at the connector interface. Thus, the connector core pattern is defined by the placement of the end faces of the multicore optical fibers in the connector interface. Placement of the end faces refers to selecting both the position and orientation of each end face in the connector interface such that the core pattern of each end face provides a portion of the desired connector core pattern.

[00126] The front and back end faces of each of the multicore optical fibers may be operatively coupled to respective front and back cable connectors such that a resulting fiber optic cable assembly can be used as a full duplex patch cord. The terms “front” and “back” are merely used in this disclosure in a relative sense to distinguish between different ends of a component (e.g., a multicore optical fiber, a cable assembly, etc.). The disclosed fiber optic cable assemblies may be used to provide at least part of a structured multicore optical fiber cabling system that maintains consistent core polarity between network nodes at both the connector and optical fiber level.

[00127] Aspects of the disclosure may be applied, but are not limited, to duplex LC connectors (e.g., according to IEC 61754-20: 2012) and very-small form factor (VSFF) dual-ferrule connectors such as CS, SN, or M DC-type connectors (e.g., each according to the Quad Small Form Factor Pluggable Double Density Multi Source Agreement hardware specification revision 6.3 and the documents referred to therein). VSFF dual-ferrule connectors include two single-fiber ferrules within a common housing. Corresponding connector interfaces for network components such as transceivers and cassettes (also referred to as “modules”) are also disclosed.

[00128] Another class of very small form factor array connectors include the MMC connector available from US Conec of Hickory NC, United States, and the SN-MT connector available from Senko of Boston MA, United States. VSFF connectors may increase front panel density by about three times as compared to standard MPO connectors. A VSFF connector typically includes an alignment key located on the narrow side of the connector body to enable easy stacking of multiple VSFF connectors. This feature may impact multicore fiber optic trunk cable design in methods not covered by the TIA-568 standard. By way of comparison with standard MPO connectors (which may be considered as “row connectors”) the MMC/SN-MT connectors may be considered as “column connectors”. For angled single mode connectors, the mating connectors may have the alignment keys aligned in the same orientation.

[00129] The above general statements may be better understood when considering the definitions of terms used in the statement. With respect to multicore optical fibers having a draw direction due to an asymmetric end face core pattern (see Background section above), the term “anti-parallel” refers to at least two of such multicore optical fibers being terminated by one or more connectors, but having opposite draw directions at each connector. And finally, term “mirror-image symmetry” refers to there being intended symmetry of the connector core pattern and/or fiber end face core pattern about an axis of symmetry of the connector interface and/or fiber end face that: a) is in a plane orthogonal to a longitudinal axis of the connector and/or optical fiber, and b) bisects the connector interface and/or fiber end face.

[00130] The mirror-image symmetry of the connector core patterns at the connector interfaces enables connections between fiber spans to maintain core polarity independent of the direction of the cable assemblies being connected. Cable assemblies and other fiber optic network components (e.g., transceivers, fan-in/fan-out devices, etc.) configured in accordance with the disclosed embodiments allow consistent core polarity mapping from one span to another independent of direction, and thereby facilitate deployment of efficient structured multicore fiber optic cabling systems that include such fiber optic network components.

[00131] In particular, fiber optic network components of the present disclosure may include anti-parallel multicore optical fibers. The anti-parallel multicore optical fibers may be arranged in the fiber optic network component in any manner that results in the connector interfaces thereof having mirror-image symmetry with regard to the connector core pattern. This mirror-image symmetry allows one fiber optic network component to be connected to another fiber optic network component by a cable assembly having the same mirrorimage symmetry without regard to the direction of the cable assembly. As described in detail below, this bi-directional connectivity provides unique advantages over known arrangements.

[00132] Multicore optical fibers are manufactured with different core configurations. Common configurations of multicore optical fiber have a cladding diameter of 125 pm and a 2x2 or 1 x4 core configuration. This enables the use of cores with mode field diameters similar to those of a standard single core fiber. However, larger numbers of cores may be accommodated by reducing the mode field diameter, increasing the diameter of the cladding, or both reducing the mode field diameter and increasing the diameter of the cladding.

[00133] Disclosed embodiments may also include an optimized structured multicore fiber optic cabling system for high fiber count connectivity in data centers. The structured multicore fiber optic cabling system may include one or more pre-terminated (e.g., MPO) multicore fiber optic trunk cables, breakout modules (e.g., breakout cassettes, breakout harnesses, fan-in/fan-out components, etc.), transceiver interfaces, and duplex patch cords to support different network configurations and transceiver types. These network components may enable the structured multicore fiber optic cabling system to manage fiber polarity and alignment key orientations with consistent interfaces on both sides of each multicore fiber optic trunk cable in the structured multicore fiber optic cabling system.

[00134] Figs. 5A and 5B depict two fiber spans 26, 28 each including an exemplary fiber optic ribbon 24 comprising a plurality of multicore optical fibers 10, e.g., two multicore optical fibers 10. Each multicore optical fiber 10 includes a plurality of cores 14 (e.g., two cores) within a common cladding 12, and a marker 22 that identifies one of the cores 14 as a reference core. For purposes of illustration only, and to facilitate identification by the reader, each multicore optical fiber 10 in Figs. 5A and 5B, as well as in subsequent figures, is depicted with a letter (e.g., “A” or “B”), and each core 14 is depicted with a number (e.g., “1”, “2”, “3” or “4”, with the reference core being depicted by number “1”). The marker 22 defines an asymmetry in the core pattern of each multicore optical fiber 10. This asymmetry allows the identity of each core 14 of the multicore optical fiber 10 to be determined based on its position relative to the reference core 14. For example, once the reference core 14 is identified, the remaining cores 14 may be identified based on a predetermined naming convention for the cores 14. Although the core pattern asymmetry is depicted in this and the following examples as being provided by a marker 22 for purposes of simplicity and clarity, it should be understood that a core pattern asymmetry can also be provided by arranging the cores in an asymmetric pattern within each individual multicore optical fiber 10, e.g., by using an off position reference core.

[00135] The fiber optic ribbon 24 may be characterized in that the core patterns are arranged to collectively define a pattern of cores 14 across the fiber optic ribbon 24 which has mirror-image symmetry, i.e. , symmetry about an axis of symmetry 30. The axis of symmetry 30 may be normal to a longitudinal axis 32 of fiber optic ribbon 24. The longitudinal axis 32 of fiber optic ribbon 24 may pass through the geometric center of a cross-section of the fiber optic ribbon 24 located at the point where the axis of symmetry 30 is defined, and may be normal to the cross-section. That is, the longitudinal axis 32 of fiber optic ribbon 24 may be generally centered in and parallel with the fiber optic ribbon 24. [00136] Mirror-image symmetry may be achieved by the multicore optical fibers 10 having the same core pattern asymmetry and being in parallel with opposite draw directions, i.e., being in an anti-parallel configuration. In Fig. 5A, the fiber optic ribbon 24 of lower fiber span 28 has the same ribbon direction as the fiber optic ribbon 24 of upper fiber span 26. In Fig 5B, the fiber optic ribbon 24 of lower fiber span 28 has a ribbon direction opposite that of the fiber optic ribbon 24 of upper fiber span 26. As can be seen by comparing the positions of the cores 14 in Figs. 5A and 5B, the mirror-image symmetry of fiber optic ribbons 24 maintains core polarity across the multicore optical fibers 10.

[00137] Figs. 6A and 6B depict two fiber spans 26, 28 each including another exemplary fiber optic ribbon 24 comprising plurality of multicore optical fibers 10, e.g., four multicore optical fibers 10. Each multicore optical fiber 10 includes a plurality of cores 14 (e.g., four cores 14) within a common cladding 12, and a marker 22 that identifies one of the cores 14 as the reference core. The multicore optical fibers 10 are arranged so that they collectively define a pattern of cores 14 across the fiber optic ribbon 24 which has mirror-image symmetry about the axis of symmetry 30 of the fiber optic ribbon 24. In this case, mirror-image symmetry is achieved by alternating the draw direction of every-other multicore optical fiber 10 of each fiber optic ribbon 24.

[00138] In Fig. 6A, the fiber optic ribbon 24 of lower fiber span 28 has the same ribbon direction as the fiber optic ribbon 24 of upper fiber span 26. Accordingly, each core 14 of each multicore optical fiber 10 in the upper fiber span 26 is aligned with a correspondingly numbered core 14 of a respective multicore optical fiber 10 of the lower fiber span 28. In Fig 6B, the fiber optic ribbon 24 of lower fiber span 28 has a ribbon direction opposite that of the fiber optic ribbon 24 of upper fiber span 26. As can be seen by comparing the positions of the cores 14 in Figs. 6A and 6B, the mirror-image symmetry of fiber optic ribbons 24 maintains the core polarity of each multicore optical fiber 10. That is, although the multicore optical fibers 10 in the lower fiber span 28 are not aligned with the same multicore optical fibers 10 in the upper fiber span as in Fig. 6A, each core 14 of each multicore optical fiber 10 in the upper fiber span 26 is aligned with a correspondingly numbered core 14 of the fiber optic ribbons 24 of the lower fiber span 28. Thus, connecting fiber optic ribbons 24 with opposing ribbon directions maintains the core polarity of each multicore optical fiber 10 of fiber optic ribbons 24.

[00139] Fig. 7 depicts two fiber spans 26, 28 each including another exemplary fiber optic ribbon 24 having a plurality of multicore optical fibers 10 (e.g., eight multicore optical fibers 10) arranged so that they collectively define a pattern of cores 14 across the fiber optic ribbon 24 which has mirror-image symmetry. In the depicted embodiment, this symmetry is achieved by the multicore optical fibers 10 on one side of the axis of symmetry 30 having one draw direction, and the multicore optical fibers 10 on the other side of the axis of symmetry 30 having another draw direction opposite that of the other draw direction. That is, the multicore optical fibers 10 on the one side of the axis of symmetry 30 are anti-parallel to the multicore optical fibers 10 on the other side of the axis of symmetry.

[00140] The fiber optic ribbon 24 of lower fiber span 28 has a ribbon direction opposite that of the fiber optic ribbon 24 of upper fiber span 26. As can be seen by comparing the positions of the cores 14 in the upper and lower fiber spans, the mirror-image symmetry of fiber optic ribbons 24 maintains the core polarity of each multicore optical fiber 10. Although each multicore optical fiber 10 in the lower fiber span 28 is not aligned with the correspondingly lettered multicore optical fiber 10 in the upper fiber span 26, each core 14 of each multicore optical fiber 10 in the upper fiber span 26 is aligned with a correspondingly numbered core 14 of the fiber optic ribbons 24 of the lower fiber span 28. The mirror-image symmetry of the fiber optic ribbons 24 thus maintains the core polarity of each multicore optical fiber 10. Maintaining core polarity enables the individual optical signals caried by each core to be tracked by merely recording connections between multicore optical fibers. This greatly reduces the cable management burden as compared to conventional ribbons.

[00141] Fig. 8 depicts two fiber spans 26, 28 each including another exemplary fiber optic ribbon 24 having a plurality of multicore optical fibers 10, e.g., eight multicore optical fibers 10. The fiber optic ribbon 24 is similar to that depicted in Fig. 7, except that mirror-image symmetry is achieved by alternating the draw direction of equally-sized subunits (e.g., pairs) of multicore optical fibers 10 of each fiber optic ribbon 24. Thus, although the fiber optic ribbon 24 of lower fiber span 28 has a ribbon direction opposite that of the fiber optic ribbon 24 of upper fiber span 26, the mirror-image symmetry of the fiber optic ribbons 24 maintains the core polarity of each multicore optical fiber 10 across the fiber spans 26, 28.

[00142] It should be understood that many different core patterns and configurations of multicore optical fibers may be used to produce a ribbon having mirror-image symmetry. Moreover, although the exemplary ribbons described above are generally depicted as ribbon cables for purposes of clarity, embodiments are not limited solely to this type of arrangement. For example, ribbons may be expanded vertically by stacking arrangements of multicore optical fibers similar to those depicted herein.

[00143] Although the above examples are limited to ribbons having between two and eight multicore optical fibers, there is no specific limit to the number of multicore optical fibers that can be assembled into a ribbon. The multicore optical fibers may also have different numbers of cores and cores arranged in different patterns than shown. For example, cores may be arranged in patterns that have radial symmetry or that lack radial symmetry. Reference cores may be indicated by a marker embedded in the multicore optical fiber, or may be indicated by being in an off normal position.

[00144] Advantageously, the cost of manufacturing ribbons having mirror-image symmetry should not be significantly higher than for conventional fiber optic ribbons. The same manufacturing processes may be used to make the multicore optical fibers from which the ribbons are assembled, and for coating the ribbons after assembly. To form the desired pattern of anti-parallel multicore optical fibers, the end face of the multicore optical fiber on each fiber reel may be inspected to determine the draw direction, e.g., by observing the orientation of the core patterns.

[00145] Referring now to Fig. 9, a fiber reel having the wrong draw direction for the multicore optical fiber being added to a ribbon may be used as a feed reel 34, and the multicore optical fiber 10 wound onto a take up reel 36 as shown. The action of re-winding the multicore optical fiber 10 reverses the draw direction. The fiber reels with the corresponding draw direction may then be fed to a machine for making ribbons or loose tube cables using an otherwise standard process. The marked direction of a reference multicore optical fiber 10 may define the ribbon direction of the fiber optic ribbon 24. For ease of use, the outer sheath or jacket of the ribbon 24 (or a fiber optic cable including the ribbon) may have periodic markings that indicate the direction of the ribbon 24. [00146] The multicore optical fibers in the ribbon may be encapsulated in one or more layers of a suitable matrix in the same manner as conventional fiber optical cables. In the case of ribbons, individual multicore optical fibers or subunits thereof may be intermittently connected by adhesive spots to form a rollable ribbon. The multicore optical fibers may also be placed in loose tubes without a matrix or adhesive spots. [00147] A multicore fiber trunk cable may be assembled from multiple directionmanaged ribbons. Preferably, the direction of each ribbon of the multicore fiber trunk may be aligned in the same direction. The multicore fiber trunk cable design may be similar to that of fiber trunk cable using standard single mode fibers. In an alternative embodiment, a two-way ribbon cable such as depicted by Fig. 7 may be split into two anti-parallel one-way ribbons inside the multicore fiber trunk cable.

[00148] Ribbons may be used individually or in groups to form fiber optic cable assemblies. Figs. 10 and 11 depict an exemplary fiber optic cable assembly 38 that includes a fiber optic cable 39 terminated at each end by a respective cable connector 40, and Figs. 12 and 13 depict end views of the connectors 40. The fiber optic cable 39 includes an outer jacket 42 that surrounds and protects a plurality of optical fibers 10. The cable connector 40 is shown with a particular configuration for a multi-fiber connector, but the fiber optic cable assembly 38 may alternatively include other connector designs, such as MPO-type connectors, for example. While the fiber optic cable assembly 38 is illustrated as including one cable connector 40 at each end thereof, it should be realized that the fiber optic cable 39 may include a large number of optical fibers and be terminated by multiple connectors 40. Thus, aspects of the present disclosure are not limited to the particular fiber optic cable 39 and connectors 40 shown and described herein. The optical fibers 10 may be configured as one or more ribbons 24 (e.g., a single ribbon 24) each including a plurality of multicore optical fibers 10 arranged in a side-by-side manner as described above.

[00149] Each cable connector 40 may include a ferrule 44 having one or more guide holes 46 and configured to support the plurality of optical fibers 10, a housing 48 having a cavity in which the ferrule 44 is received, and a connector body 50 configured to support the fiber optic cable 39 and retain the ferrule 44 within the housing 48. The ferrule 44 may be biased to a forward position within the housing 48 by a spring 52. The housing 48 and the connector body 50 may be coupled together, such as through a snap fit or the like, to capture the ferrule 44 within the housing 48. When the cable connector 40 is assembled as shown in Fig. 10, a front end 54 of the housing 48 may project beyond an end face 56 of the ferrule 44 to define a cavity 58. The cavity 58 may be configured to receive, for example, a ferrule from a mated optic component, such as a mated connector. The construction and interoperability between the various parts of connectors 40 are generally known to persons of ordinary skill in optical connectivity and thus will not described further herein. It should be understood that aspects of the disclosure are not limited to the particular shape, size, and configuration of the ferrule or housing shown and described herein but are applicable to a wide range of ferrule and housing configurations.

[00150] As best shown by Figs. 12 and 13, the multi-core optical fibers 10 may be arranged in the ferrule 44 so that they collectively define a pattern of cores 14 across the end face 56 of ferrule 44 which has mirror-image symmetry. In the exemplary embodiments depicted by Figs. 12 and 13, this symmetry is achieved by the multicore optical fiber or fibers 10 on one side of the ferrule 44 having one draw direction, and the multicore optical fiber or fibers 10 on the other side of the ferrule 44 having another draw direction opposite that of the one draw direction. That is, the multicore optical fiber or fibers 10 on the one side of the ferrule 44 are anti-parallel to the multicore optical fiber or fibers 10 on the other side of the ferrule 44. Additional anti-parallel arrangements of multicore optical fibers are described in detail below.

[00151] Fig. 14 depicts another exemplary fiber optic cable assembly 38 including a plurality of multicore optical fibers 10 (e.g., two multicore optical fibers 10 provided by the same fiber optic cable 39 or by two different fiber optic cables 39 - not shown) in a duplex arrangement. Each multicore optical fiber 10 includes a plurality of cores 14 (e.g., four cores in a 2x2 configuration) within a common cladding. Each end face 16 of each multicore optical fiber 10 is operatively coupled to a respective cable connector 40 including an alignment key 60. The connectors 40 are configured so that each core 14 can receive one or more optical signals from a port connector at one end of the multicore optical fiber 10 (generally referred to as the “A” end), and convey the one or more received optical signals to a port connector at the other end of the multicore optical fiber 10 (generally referred to as the “B” end). Accordingly, the fiber optic cable assembly 38 may be referred to as an A-to-B duplex patch cord.

[00152] The fiber optic cable assembly 38 has an outward appearance similar to a standard A-to-B duplex patch cord. However, unlike a standard A-to-B duplex patch cord that uses single core optical fibers, the fiber optic cable assembly 38 is configured to maintain the core polarity of each multicore optical fiber 10 to avoid routing optical signals to the wrong destination. Maintaining core polarity enables each transmitter/receiver channel from one transceiver to be operatively coupled to its respective receiver/transmitter channel in the other transceiver. To this end, and as described in more detail below, the connectors 40 at each end of the fiber optic cable assembly 38 and connectors of the transceiver are configured to have a commonly defined multicore connector interface 62.

[00153] The cable connectors 40 may be characterized in that the end face core patterns of the multicore optical fibers 10 are arranged to collectively define a pattern of cores 14 at the connector interface 62 which has mirrorimage symmetry, i.e., symmetry about an interface axis of symmetry 64. In the depicted embodiment, the interface axis of symmetry 64 is normal to a longitudinal axis 66 of the cable connector 40 and colinear with a key-axis 76 (Fig. 16). The longitudinal axis 66 of cable connector 40 may be normal to the connector interface 62 and pass through the geometric center of the connector interface 62. That is, the longitudinal axis 66 of the cable connector 40 may be generally centered in and orthogonal to the connector interface 62. The intersection of the longitudinal axis 66 and connector interface 62 may define a center point 67 on the connector interface 62 through which the interface axis of symmetry 64 passes. However, in alternative embodiments (such as described below), the interface axis of symmetry 64 may be, for example, orthogonal to the key-axis 76. Thus, embodiments are not limited to connectors in which the interface axis of symmetry 64 is aligned with the key-axis 76.

[00154] As will be described in more detail below, by virtue of the opposing draw directions and symmetric positioning of the end faces 16 with respect to the interface axis of symmetry 64, the connector core patterns in both port connectors and cable connectors 40 may have mirror-image symmetry about the interface axis of symmetry 64. As a result of this mirror-image symmetry, the connector core pattern is the same at each end of the multicore fiber optic cable assembly 38 (i.e., the “A” end has the same connector core pattern as the “B” end). This allows the connector core pattern of port connectors to be standardized to that of the cable connector 40 so that core polarity matches at both ends of multicore fiber optic cable assembly 38. Thus, exemplary multicore fiber optic cable assembly 38 is non-directional.

[00155] To provide an example of how a multicore A-to-B duplex patch cord can be directionally sensitive, Fig. 15 depicts an exemplary multicore A-to-B duplex patch cord 68 including two multicore optical fibers 10 each having the same draw direction. Each exemplary multicore optical fiber 10 includes four cores 14 in a 2x2 configuration and a marker 22. The patch cord 68 is terminated at each end by a cable connector 40, and is depicted as connecting a pair of exemplary transmit/receive port connectors 70 each corresponding to a respective network component, such as a transceiver (not shown). The cable connectors 40 and port connectors 70 include respective alignment keys 60 that ensure the connectors 40, 70 are connected in a predetermined orientation with respect to each other. Although the exemplary alignment keys 60 are depicted as being on the outer surface of the connectors 40, 70, it should be understood that other ways of ensuring consistent connection orientations may be used, such as connector markings, keyed shapes, or internal alignment keys.

Accordingly, aspects of the present disclosure are not limited to any particular type of connector keying, or the use of connectors having keys.

[00156] Due to the directionality of the multicore optical fibers 10, the connector core patterns are different at each end of the patch cord 68. The connector core pattern of a standardized port connector 70 can therefore only match one end of the patch cord 68. In the present example, the core polarity of the cable connector 40 on the A/B end of patch cord 68 matches that of the port connector 70 to which it is to be connected. That is, when mated, each core 14 of each multicore optical fiber 10 of cable connector 40 is aligned with a correspondingly numbered core 14 of the port connector 70.

[00157] In contrast, the core polarity of the cable connector 40 on the A7B’ end of patch cord 68 does not match that of the port connector 70 to which it is to be connected. Thus, when mated, each core 14 of each multicore optical fiber 10 in the cable connector 40 is aligned with a differently numbered core 14 of the port connector 70. Specifically, for each end face 16, core 1 in the cable connector 40 is aligned with core 2 in the port connector 70, core 2 in the cable connector 40 is aligned with core 1 in the port connector 70, core 3 in the cable connector 40 is aligned with core 4 in the port connector 70, and core 4 in the cable connector 40 is aligned with core 3 in the port connector 70. Accordingly, the connection on the right side of the figure is incorrect, as indicated by the “X” through each double-headed arrow.

[00158] Fig. 16 depicts another exemplary multicore A-to-B duplex patch cord 68 including two 2x2 multicore optical fibers 10 that have opposite draw directions, and which are terminated by cable connectors 40. Arranging multicore optical fibers 10 having the same core pattern asymmetry in an anti-parallel configuration provides mirror-image symmetry to the core pattern of connector 40. The cable connectors 40 are depicted as connecting a pair of exemplary transmit/receive port connectors 70. Each of the connectors 40, 70 has a key-axis 76 that bisects the connector 40, 70 and is aligned with (i.e. , passes through) the alignment key 60 thereof.

[00159] By virtue of the opposing draw directions and symmetric positioning of the end faces 16 with respect to the key-axis 76, the connector core patterns in both the cable connectors 40 and port connectors 70 have mirror-image symmetry about the key-axis 76. Thus, the key-axis 76 is colinear with the interface axis of symmetry 64 for the connector interface 62 of cable connectors 40 and port connectors 70. As a result of this mirror-image symmetry, the connector core pattern is the same at each end of the multicore A-to-B duplex patch cord 68 (i.e., the “A” end has the same connector core pattern as the “B” end). This allows the connector core pattern of the port connector 70 to be standardized to that of the cable connector 40 so that core polarity matches at both ends of the A-to-B duplex patch cord 68. Thus, exemplary multicore A-to-B duplex patch cord 68 is non-directional.

[00160] The connectors 40, 70 may be duplex LC, CS, SN, or MDC connectors, or any other suitable connector, consistent with general statements about this disclosure at the beginning of this Detailed Description section. The marker 22 may be oriented in other angles as long as the end faces 16 of the multicore optical fibers 10 are oriented to provide mirror-image symmetry of the connector core pattern about the key-axis 76. In practice, it may be desirable to standardize the orientation of the markers 22 with respect to the connector interface 62 to facilitate multi-vendor interoperability. For example, the markers 22 could be standardized as being oriented parallel to a key up direction. [00161] Fig. 17 depicts another exemplary multicore A-to-B duplex patch cord 68 including two 2x2 multicore optical fibers 10 in an anti-parallel configuration. The multicore optical fibers 10 are terminated by cable connectors 40, which are depicted as connecting a pair of exemplary transmit/receive port connectors 70. The connectors 40, 70 are configured so that the end faces 16 of multicore optical fibers 10 are centered on a plane that includes the key-axis 76 of the connector 40, 70 (i.e., a common plane including the key-axis 76 extends through the end faces 16).

[00162] The resulting connector core pattern of the connectors 40, 70 has mirror-image symmetry relative to a line of symmetry oriented orthogonally to the key-axis 76 and centered between the multicore optical fibers 10. This line of symmetry is colinear with a cross-axis 78 that bisects each connector 40, 70 along a plane perpendicular to the key-axis 76, and is thus orthogonal to the key-axis 76. Connectors having this type of coplanar arrangement between the optical fibers and alignment key include MDC and SN-type duplex connectors, which are described in the Quad Small Form Factor Pluggable Double Density Multi Source Agreement hardware specification revision 6.3 and the documents referred to therein. Accordingly, a duplex MDC or SN interface for an optical component, such as a breakout module, fan-in/fan-out module, or a transceiver, can be defined following the connector core patterns depicted in Fig. 17.

[00163] Configuring the multicore A-to-B duplex patch cord 68 so that the multicore optical fibers 10 have opposite draw directions and placing the end faces 16 within the connectors 40, 70 so that the connector core patterns have mirror-image symmetry about the cross-axis 78 results in each end of the multicore A-to-B duplex patch cord 68 having the same core polarity (i.e., the same connector core pattern). This, in turn, enables connections to port connectors 70 having a consistent configuration without concerns regarding the direction of the patch cord 68.

[00164] Fig. 18 depicts another exemplary multicore A-to-B duplex patch cord 68 including four 2x2 multicore optical fibers 10 in an anti-parallel configuration. At each end of the patch cord 68, the multicore optical fibers 10 are terminated in one of two cable connectors 40 (e.g., VSFF dual-ferrule connectors) that are ganged together to form a quadruplex cable connector. The patch cord 68 is depicted as connecting a pair of transmit/receive quadruplex port connectors each comprising a similarly ganged pair of port connectors 70. The connector core pattern of each quadruplex connector has mirror-image symmetry about an interface axis of symmetry 64 that bisects the quadruplex connector. The interface axis of symmetry 64 is considered as aligned with the alignment keys 60 of connectors 40, 70 (as opposed to orthogonal to or colinear with the alignment keys 60) because the interface axis of symmetry 64 is parallel to the key-axes 76 (not depicted) of the ganged connectors 40, 70. It may be noted that the quadruplex connectors also have essentially the same connector core pattern as would be formed by vertically stacking the cable and port connectors 70 depicted in Fig. 16. Advantageously, a quadruplex multicore fiber connector may provide an attractive solution for transceivers having eight lanes.

[00165] Fig. 19 depicts another exemplary multicore A-to-B duplex patch cord 68 including two 1x4 multicore optical fibers 10 in an anti-parallel configuration. At each end of the patch cord 68, the optical fibers 10 are terminated by a cable connector 40 which is depicted as connecting the patch cord 68 to exemplary transmit/receive port connectors 70. The connectors 40, 70 are configured to place each optical fiber 10 so that the cores 14 of the optical fibers 10 are aligned with the cross-axis 78 of the respective cable connector 40. The cores 14 of each multicore optical fiber 10 are thus colinearly aligned with the cores 14 of the other optical fiber 10 terminated by the same connector 40, 70. This core placement results in each connector core pattern having mirror-image symmetry about the key-axis 76 of the connector 40, 70 in question.

[00166] Fig. 20 depicts another exemplary multicore A-to-B duplex patch cord 68 including two 1 x4 multicore optical fibers 10 having an anti-parallel configuration. At each end of the patch cord 68, the optical fibers 10 are terminated by a cable connector 40 which is depicted as connecting the patch cord 68 to exemplary transmit/receive port connectors 70. The connectors 40, 70 are configured to place each optical fiber 10 so that the cores 14 thereof are parallel to the key-axis 76 of the respective connector 40, 70. This core placement results in each connector core pattern having mirror-image symmetry about the key-axis 76 of its connector 40, 70.

[00167] Fig. 21 depicts another exemplary multicore A-to-B duplex patch cord 68 including two 1 x4 multicore optical fibers 10 having an anti-parallel configuration. At each end of the patch cord 68, the optical fibers 10 are terminated by a cable connector 40 depicted as connecting the patch cord 68 to exemplary transmit/receive port connectors 70. The connectors 40, 70 are configured to place the end face 16 of each optical fiber 10 so that the cores 14 of the optical fibers 10 are aligned with the key-axis 76 of the respective cable connector 40. This core placement results in each connector core pattern having mirror-image symmetry about the key-axis 76 of its connector 40, 70. The optical fibers 10 are oriented within their respective connectors 40, 70 so that the connector core pattern also has mirror-image symmetry about the cross-axis 78 of the connector 40, 70.

[00168] The mirror-image symmetry of the end face core pattern of a multicore optical fiber having a 1*n core configuration may be utilized to provide more functions than other types of multicore optical fiber. For example, a 1x4 multicore optical fiber can be used directly for chip connectivity, thereby eliminating the need for fan-in/fan-out devices. However, relatively tight core spacing may cause the outer cores to be subject to higher attenuation as compared to other core configurations. Cross talk may also be higher than in 2x2 multicore optical fiber. Because 1xn multicore optical fibers can have end face core patterns with mirror-image symmetry, a single multicore optical fiber can provide two-way connectivity, and does not require end face core patterning that varies with fiber direction. By way of illustration, the following examples of multicore duplex patch cords including 1xn multicore optical fibers are depicted with an anti-parallel fiber layout. However, it should be recognized that due to the non-directional nature of 1 xn multicore optical fibers, the depicted designs may also be implemented using parallel multicore optical fiber configurations.

[00169] Occasionally, the receive/transmit polarity of a fiber optic link may need to be reversed. The need to reverse receive/transmit polarity may occur, for example, if the signals are being routed between equipment having different connector polarities. In these cases, A-to-A duplex patch cords, sometimes referred to as cross-over patch cords, may be used. The optical fibers in A-to-A duplex patch cords are “crossed” so that the optical fiber polarity is reversed by the cable. As described below, this crossing may disrupt core polarity when reversing optical fiber polarity in a multicore A-to-A duplex patch cord.

However, as described below, 1 xn multicore optical fibers may be used to avoid disrupting core polarity when reversing optical fiber polarity in a multicore A-to-A duplex patch cord.

[00170] Figs. 22-26 depict exemplary multicore A-to-A duplex patch cords 68 each corresponding to a respective multicore A-to-B duplex patch cord 68 depicted in Figs. 16, 17, and 19-21. The components of the A-to-A duplex patch cords 68 have the same configuration as those of their counterpart A-to-B duplex patch cords 68 except for cable connectors 40 and port connectors 70 on the reversed-polarity end thereof.

[00171] When the connector topologies of the A-to-B duplex patch cords 68 of Figs. 16 and 17 are adapted to the A-to-A duplex patch cords 68 of Figs. 22 and 23, core polarity is disrupted, as indicated by the “X” through the double-headed arrows. However, when the connector topologies of the A-to-B duplex patch cords 68 of Figs. 20-22 are adapted to the A-to-A duplex patch cords 68 of Figs. 24-26, core polarity is maintained. This ability to maintain core polarity in both the A-to-A duplex patch cords 68 and the A-to-B duplex patch cords 68 may be attributed to the core pattern of each individual optical fiber 10 having mirror-image symmetry about the direction of the key-axis 76 for each of the duplex patch cords 68. That is, the optical fibers 10 are oriented and positioned within each connector 40, 70 of the duplex patch cords 68 so that the core pattern of each optical fiber 10 has mirror-image symmetry about a line of symmetry parallel to the key-axis 76. Although the marker 22 provides an indication of the mirror-image reversal of the fiber end faces, the core patterns themselves are unchanged by this reversal. Thus, the configurations depicted by Figs. 19-21 and 24-26 support both straight-though and cross-over connectivity in duplex patch cords.

[00172] The 1x4 multicore optical fiber may be used, for example, with VSFF dual-ferrule connectors. The connector core pattern of the patch cords 68 depicted by Figs. 21 and 26 has mirror-image symmetry along both the key-axis 76 and cross-axis 78, which may be advantageous. The mirror image symmetry along the key-axis 76 of these patch cords 68 is due to the symmetric nature of the core pattern of each optical fiber 10. The mirror image symmetry along the cross-axis 78 is due to the anti-parallel configuration of the multicore optical fibers 10. [00173] The mirror-image symmetry along the cross-axis 78 of the patch cords 68 in Figs. 19 and 24 is due to the symmetric nature of the core pattern of each optical fiber 10, while the mirror-image symmetry along the key-axis 76 of these patch cords 68 is due to the anti-parallel configuration of the multicore optical fibers 10. In contrast, the mirror-image symmetry along the key-axis 76 of the patch cord 68 in Figs. 21 and 26 is due to the symmetric nature of the core pattern of each optical fiber 10, while the mirror-image symmetry along the cross-axis 78 of these patch cords 68 is due to the anti-parallel configuration of the multicore optical fibers 10.

[00174] Thus, a two-dimensional mirror-image symmetry can be achieved by combining these individual mirror image symmetries, e.g., by orienting the end faces 16 of the multicore optical fibers 10 in the connector interface 62 so that these mirror-image symmetries are orthogonal to each other. As a result, the cores 14 in the two multicore optical fibers 10 may be modified to switch fiber polarity by simply moving the alignment key 60 of connector 40 to the opposite side of the connector housing.

[00175] Fig. 27 depicts an exemplary multicore optical fiber loopback device 82. The connector interface 62 of loopback device 82 maintains a mirror-image symmetry between the core patterns of the end faces 16 about the key-axis 76. The loopback device 82 includes a single multicore optical fiber 10 having both end faces 16 terminated by the same connector 40. Loopback devices are commonly used for transceiver testing.

[00176] Fig. 28 depicts an exemplary structured multicore fiber optic cabling system 84 for interconnecting two sets of transceivers (not shown) through a trunk cable 86. The cabling system 84 includes a plurality of A-to-B duplex patch cords 68 that operatively couple fan-in/fan-out devices 88 to breakout modules 90 (e.g., breakout cassettes). The breakout modules 90 operatively couple one end of each A-to-B duplex patch cord 68 to the trunk cable 86. With a 4-core multicore optical fiber, a parallel single mode transceiver may only require a duplex interface. Alternatively, four Coarse Wavelength Division Multiplexing (CWDM) transceivers can share a single duplex interface. Advantageously, existing structured cabling hardware may be used to implement multicore optical fiber based connectivity. [00177] In an alternative embodiment, the breakout modules 90 and A-to-B duplex patch cords 68 may be replaced by breakout harnesses. As demonstrated by the cabling system 84 of Fig. 28, A-to-B duplex patch cords 68 are fundamental building blocks for many structured cabling systems. Without the two-way connectivity provided by the A-to-B duplex patch cords 68, the cabling system 84 would require two different types of duplex interfaces for transceivers and cassettes. The resulting duplex patch cord would therefore require a dedicated connector for each interface. This would be difficult to manage, resulting in increased component and maintenance costs.

[00178] Fig. 29 depicts another exemplary structured multicore fiber optic cabling system 84 including a multicore fiber optic cable assembly 38. Figs. 30-32 depict exemplary embodiments of a cable connector 40 for exemplary 2x2 and 1 x4 four-core multicore fibers that may be used with the cable assembly 38 of Fig. 29. The multicore fiber optic cable assembly 38 includes a plurality of multicore optical fibers 10, and is terminated at each end by a respective cable connector 40. Each cable connector 40 is configured to receive a matching port connector 70. Each of the connectors 40, 70 of Fig. 29 includes an alignment key 60. The cable connectors 40 are depicted in a “key-down” orientation in which the alignment key is not visible, while the port connectors 70 are depicted in a “key-up” orientation. It should be understood that the terms “key-up” and “key-down” are used herein to indicate connector orientation relative to another connector, and are thus somewhat arbitrary in terms of absolute position. The key-up orientation is generally indicated by an alignment key 60 that is on the top side of the connector 40 in front views and that is outward facing in top views. In contrast, the key-down orientation is generally indicated by an alignment key 60 that is on the bottom side of the connector in front views and that is hidden from view in top views. Connectors may be operatively coupled so that their alignment keys have the same orientation (e.g., both connectors in the key-up orientation or the key-down orientation) or so that their alignment keys have the opposite orientation (e.g., one connector in the key-up orientation and the other connector in the key-down orientation).

[00179] The structured multicore fiber optic cabling system 84 of Fig. 29 is depicted as using a TIA-568 method-B or other symmetric design in which the multicore fiber optic cable assembly 38 is a key-down to key-down array patch cord that uses key-up to key-down adaptors (not shown). The port connectors 70 may, for example, operatively couple the cable connectors 40 to breakout modules. These breakout modules may be operatively coupled to transceivers directly or using straight-through A-to-B duplex patch cords. The port connectors 70 may have the same configuration so that the components on both sides of the multicore fiber optic cable assembly 38 can be interchanged. [00180] The exemplary multicore fiber optic cable assembly 38 includes a plurality of multicore optical fibers 10 (e.g., 12 multicore optical fibers) arranged in a linear array that is orthogonal to a key-axis 76 of the connector 40. The key-axis 76 lies in a plane that bisects the connector 40 and is aligned with (i.e., passes through) an alignment key 60 thereof. As best shown by magnified views 92 of a portion of the connector 40, each multicore optical fiber 10 includes an end face 16, a plurality of cores 14 (e.g., four cores) within a common cladding, and a marker 22. The exemplary core configurations depicted include a 2x2 configuration (Fig. 30) and a 1x4 configuration (Figs. 31 and 32). However, other numbers of cores and configurations may be used. [00181] Using the 2x2 four-core multicore optical fiber of Fig. 30 as an example, each transmitter or receiver operatively coupled to the multicore optical fiber may support four channels. These channels may be numbered according to the core polarity, e.g., as illustrated in Fig. 30. Markers in multicore optical fibers may facilitate consistent mapping of core polarity across each connection, such that each transceiver channel is correctly connected. For purposes of clarity, a depiction similar to a Harvey Ball is used in Figs. 30-32 and some other figures herein to depict core polarity of 2x2 four core multicore optical fibers. This method of depiction locates core 1 in the fully covered quadrant and core 2 in the half covered quadrant, thereby uniquely defining the core polarity. Notice that when viewing from the opposite end of the multicore optical fiber, the polarity becomes the mirror-image of the other end face. Optimally, the multicore optical fiber core polarity is matched throughout each connection while managing the fiber polarity using the TIA-568 methods.

[00182] The exemplary 1xn multicore optical fibers 10 are depicted in one of two orientations. However other orientations may be used. Fig. 31 depicts the cores 14 in an orientation where they are colinear with the cross-axis 78 of the connector. The cross-axis alignment depicted by Fig. 31 may be advantageous for high density edge coupling of waveguides, and therefore preferred in a high-density transceiver interface, for example. Fig. 32 depicts the cores 14 in an orientation where they are parallel to the key-axis 76.

[00183] The axis of symmetry 64 of connector interface 62 may be normal to the longitudinal axis 66 of cable connector 40, and may be colinear with one of the key-axis 76 (as depicted in Figs. 30-32) or the cross-axis 78 of the connector. In non-angled connectors, the longitudinal axis 66 of cable connector 40 may be normal to the connector interface 62 and pass through the geometric center of the connector interface 62. That is, the longitudinal axis 66 of cable connector 40 may be generally centered in and orthogonal to the connector interface 62. In angled connectors, the longitudinal axis 66 may pass through the geometric center of the connector interface 62 at an angle corresponding to that of the connector, e.g., between 85 (90 - 5) and 75 (90 - 15) degrees.

[00184] It is contemplated that optical transceivers may be integrated into tiny integrated circuits, commonly referred to as “chiplets”. These chiplets may facilitate onboard optics or co-packaged optics, and are expected to support much higher bandwidths than existing pluggable optical transceivers. Transceiver chiplets are anticipated to have array multicore optical fiber interfaces similar to that of parallel single mode transceivers, with added channels in each core of the multicore optical fiber. Linear array multicore optical fiber core configurations may be advantageous for edge coupling to waveguides from transceiver chiplets. In particular, 1 *n multicore optical fiber may be a preferred solution for intra-building data center interconnects.

[00185] Figs. 31 and 32 depict two configurations of connector interface 62 that each provide mirror-image symmetry. In Fig. 31, the cores are colinearly aligned, which may be preferred for edge coupling to a waveguide of a transceiver chiplet. For multicore replacements of pre-terminated single-core fiber optic cabling systems, the configuration in Fig. 31 may be preferred because it supports chip edge coupling and the fiber orientations are the same for both key-up and key-down connectors. Patch cords may also be made that have the connector interface 62 of Fig. 31 at one end and the connector interface 62 of Fig. 32 at the other end.

[00186] The connectors depicted in Figs. 30-32 may be duplex LC, CS, SN, or MDC connectors, or any other suitable connector, consistent with general statements about this disclosure at the beginning of this Detailed Description section. The marker 22 may be oriented in other angles as long as the end faces 16 of the multicore optical fibers 10 are oriented so that the connector core pattern of connector interface 62 has mirror-image symmetry. In practice, it may be desirable to standardize the orientation of the markers 22 with respect to the connector interface 62 to facilitate multi-vendor interoperability. For example, the markers 22 could be standardized as being oriented parallel to a key-up direction.

[00187] Fig. 33 depicts another exemplary structured multicore fiber optic cabling system 84 including port connectors 70 operatively coupled by a multicore fiber optic cable assembly 38. The multicore fiber optic cable assembly 38 includes a plurality of multicore optical fibers 10 and cable connectors 40 that terminate each end thereof. The end faces 16 of multicore optical fibers 10 are arranged in a linear array that is orthogonal to the key-axis 76 of the connector 40, 70. Each of the multicore optical fibers 10 of multicore fiber optic cable assembly 38 has the same draw direction, and each of the end faces 16 has the same orientation. This results in the connector interfaces 62 of cabling system 84 having connector core patterns that lack mirror-image symmetry. The port connectors 70 and cable connectors 40 include respective alignment keys 60 that facilitate operatively coupling the connectors 40, 70 in a predetermined orientation with respect to each other as described above.

[00188] As described with respect to Fig. 15, due to the directionality of the multicore optical fibers 10, the connector core patterns are different at the front and back ends of the multicore fiber optic cable assembly 38 of Fig 33. The connector core pattern of a standardized port connector 70 can therefore only match one end of the multicore fiber optic cable assembly 38. In the present example, the core polarity of the cable connector 40 on the front end of multicore fiber optic cable assembly 38 (left side of Fig. 33) matches that of the port connector 70 to which it is to be connected. Thus, when coupled, each core 14 of each multicore optical fiber 10 of cable connector 40 is aligned with a correspondingly numbered core 14 of the port connector 70. In contrast, the core polarity of the back end cable connector 40 of multicore fiber optic cable assembly 38 does not match that of the port connector 70 to which it is to be connected. Thus, when coupled, each core 14 of each multicore optical fiber 10 in the back end cable connector 40 is aligned with a differently numbered core 14 of the port connector 70. Accordingly, the connection on the right side of the figure is incorrect, as indicated by the “X” through the double-headed arrow.

[00189] Fundamentally, the inability to maintain core polarity using the configuration depicted by Fig. 33 is caused by the one-way connectivity nature of a single multicore optical fiber. When all the fibers are placed parallel to each other in a fiber optic cable terminated with an array connector, the limitation of one-way connectivity remains. This is also evident when comparing the connector end face polarities on both ends of the multicore fiber optic cable assembly 38 of Fig. 33. Because the core polarities of the connector interfaces 62 are different at each end of the multicore fiber optic cable assembly 38, the cabling system 84 would require different connector interfaces 62 in the port connectors 70 at each end of the multicore fiber optic cable assembly 38. This requirement complicates network management and increases cost by requiring more part numbers.

[00190] To address the above core polarity problem, two-way multicore fiber optic trunk cables may be configured so that the multicore optical fibers 10 fibers are divided in two equal groups, with multicore optical fibers 10 within the same group having the same draw direction, and the multicore optical fibers 10 in different groups having opposite draw directions. This is referred to herein as a Type-B multicore fiber optic cable, examples of which and described in detail below.

[00191] Fig. 34 depicts another exemplary structured multicore fiber optic cabling system 84 including port connectors 70 operatively coupled by a multicore fiber optic cable assembly 38. The exemplary cable assembly 38 of Fig. 34 includes a plurality of multicore optical fibers 10, and is terminated at each end by a respective cable connector 40. The multicore optical fibers 10 of cable assembly 38 are arranged so that the optical fibers 10 having end faces 16 on one side of the interface axis of symmetry 64 have one draw direction, and the optical fibers 10 having end faces 16 on the other side of the interface axis of symmetry 64 have the other draw direction, as indicated by the orientations of the end faces 16.

[00192] The anti-parallel configuration of the multicore optical fibers 10 of the cable assembly 38 of Fig. 34 enables the connector core patterns to have mirror-image symmetry. This mirror-image symmetry results in core patterns being the same at each end of the cable assembly 38. The connector core pattern of a standardized port connector 70 can therefore match both ends of the cable assembly 38. Thus, the core polarity of the cable connector 40 at each end of cable assembly 38 matches that of the respective port connector 70 to which it is to be connected. Accordingly, when coupled, each core 14 of each multicore optical fiber 10 of each cable connector 40 is aligned with a correspondingly numbered core 14 of its respective port connector 70.

[00193] To demonstrate that the cabling system 84 of Fig. 34 is insensitive to the direction thereof, Fig. 35 depicts the cabling system 84 of Fig. 34 with the cable assembly 38 running in the opposite direction as compared to Fig. 34. As can be seen, both optical fiber polarity and core polarity are preserved. Thus, the ends of cable assembly 38 can be flipped with no change in either the core or fiber polarities. As can be seen from the orientations of the multicore optical fiber markers relative to the connector key positions in the key-up and key-down connectors, the port connectors 70 and cable connectors 40 have the same connector interface 62 configuration on both ends of the cable assembly 38. This standardization reduces the number of different part numbers and allows the cable assembly 38 to be installed in any direction. The depicted structured multicore optical fiber cabling configuration thus preserves the benefits of single core structured cabling systems while keeping consistent core polarities across each of the multicore optical fibers.

[00194] Fig. 36 depicts a portion of another exemplary structured multicore fiber optic cabling system 84. The cabling system 84 of Fig. 36 includes a breakout module 90 (e.g., a breakout cassette) and a plurality of multicore A-to-B duplex patch cords 68. The breakout module 90 includes a trunk connector 100 (e.g., an MPO connector) having a key-up orientation. The trunk connector 100 is operatively coupled to a plurality of branch connectors 98 (e.g., six branch connectors) by paired multicore optical fibers 10 having a duplex configuration. In the depicted embodiment, the end faces 16 of the multicore optical fibers 10 are arranged in the connector interface 62 so that the end faces 16 of the multicore optical fibers 10 having one draw direction are on one side of the axis of symmetry 64, and the end faces 16 of the multicore optical fibers 10 having the other draw direction are on the other side of the axis of symmetry 64. Each branch connector 98 is operatively coupled to one multicore optical fiber 10 from one side of the axis of symmetry 64, and one multicore optical fiber 10 from the other side of the axis of symmetry 64. The multicore optical fibers 10 may be selected for coupling to the same branch connector 98 based on their position relative to the axis of symmetry 64. For example, by selecting multicore optical fibers 10 having end faces that are the same distance from the axis of symmetry 64.

[00195] Each branch connector 98 is shown as being operatively coupled to a respective port connector 70 (e.g., a transceiver connector or branch connector of another breakout device) by a respective duplex patch cord 68. Each duplex patch cord 68 includes a plurality of multicore optical fibers 10 (e.g., two multicore optical fibers) terminated by front and back cable connectors 40. The trunk connector 100, and each of the branch connectors 98, cable connectors 40, and port connectors 70 includes a connector interface 62 having a connector core pattern with mirror-image symmetry about the interface axis of symmetry 64.

[00196] Because both the duplex patch cords 68 and trunk connector 100 are core polarity invariant, the cabling system 84 supports many of the same configurations used for structured single core fiber optic cabling systems. Thus, trunk cable assemblies can, for example, be connected to a breakout cassette on one end and a breakout harness on the other end. The exemplary trunk connector 100 supports a total of 12 multicore optical fibers 10, with two multicore optical fibers 10 (e.g., a transmit optical fiber and a receive optical fiber) being operatively coupled to each branch connector 98. However, embodiments are not limited to any particular number of multicore optical fibers or connectors.

[00197] Fig. 37 depicts an alternative embodiment of the structured multicore fiber optic cabling system 84 of Fig. 36 in which the multicore optical fibers 10 are arranged so that the optical fibers 10 have alternating draw directions at the trunk connector 100. This type of arrangement results in a connector core pattern having a mirror-image symmetry that may enable less complex routing of the multicore optical fibers 10 for the breakout module 90 (e.g., a Type-A multicore optical fiber MPO breakout cassette) as compared to the embodiment depicted by Fig. 36. For example, each branch connector 98 may be operatively coupled to a pair of multicore optical fibers 10 having adjacent end faces 16 at the connector interface 62 of trunk connector 100.

[00198] Fig. 38 depicts another exemplary structured multicore fiber optic cabling system 84 that provides multicore optical fiber duplex connectivity with cross-connect structured cabling. The cabling system 84 of Fig. 38 includes a plurality of two-way multicore fiber optic cable assemblies 38 (e.g., two trunk cables) each including a plurality of multicore optical fibers 10 (e.g., 12 multicore optical fibers) terminated by cable connectors 40 in a key-down orientation. One cable connector 40 of each cable assembly 38 (on the left side of Fig. 38) is operatively coupled to a trunk connector 100 of a respective breakout module 90a (e.g., a fan-in/fan-out module) in a key-up orientation. Each cable connector 40 of breakout module 90a is shown as being operatively coupled to a respective port connector 70, e.g., a transceiver port connector. [00199] Another cable connector 40 of each cable assembly 38 (on the right side of Fig. 38) is operatively coupled to a trunk connector 100 of another breakout module 90b (e.g., a breakout cassette) in a key-up orientation. The breakout module 90b includes a trunk connector 100 in the key-up position and that is operatively coupled to a plurality of branch connectors 98 (e.g., six branch connectors) by paired multicore optical fibers 10 having a duplex configuration. The branch connectors 98 of one breakout module 90a are operatively coupled to the branch connectors of the other breakout module 90b by multicore duplex patch cords 68 in a cross-connect configuration. This results in a cross connected structured cabling system 84 with multicore optical fiber duplex connectivity. The structured cabling system 84 of Fig. 38 shows that a duplex cross connect structured cabling configuration is possible using two-way multicore fiber optic cable assemblies (e.g., trunk cables terminated with MPO connectors) and multicore duplex patch cords.

[00200] Fig. 39 depicts another exemplary structured multicore fiber optic cabling system 84 that includes a two-way multicore fiber optic cable assembly 38a (e.g., a trunk cable) in a key-down orientation. Each connector 40 of cable assembly 38a is operatively coupled to a key-down port connector 70 by a two-way multicore fiber optic cable assembly 38b (e.g., an inter-connect patch cord). The port connector 70 may be, for example, associated with a breakout module 90, such as an array fan-in/fan-out device. Each cable assembly 38b includes a plurality of multicore optical fibers 10 terminated by a cable connector 40 in a key-up orientation. This results in parallel connectivity between network node connectors, i.e. , RX1 is operatively coupled to TX1, RX2 is operatively coupled to TX2, etc. Fig. 39 demonstrates that two key-up to key-up multicore optical fiber patch cords terminated in MPO connectors having the core polarities depicted in Fig. 34 can provide parallel connectivity while maintaining consistent core polarities.

[00201] Figs. 40A and 40B depict another exemplary structured multicore fiber optic cabling system 84 including a two-way multicore fiber optic cable assembly 38 in a key-down orientation. Each cable connector 40 of the fiber optic cable assembly 38 includes a plurality of end faces 16 (e.g., 24 end faces) arranged in two linear arrays each having an equal number of end faces 16 (e.g., 12 end faces). The resulting two-row core pattern is essentially two core patterns of the cable connector 40 depicted in Fig. 34 stacked in a parallel arrangement. This configuration of end faces 16 preserves mirror-image symmetry about the interface axis of symmetry 64 of cable connector 40. Each cable connector 40 may be coupled to a key-up port connector 70 having a reciprocal arrangement of end faces 16, and the fiber row sequence changes between key-up and key-down connectors. The structured multicore fiber optic cabling system of Figs. 40A and 40B may be scalable to MPO cable connectors having multiple rows, and illustrates the use of two-row 24-fiber MPO connectors for both trunk cables and breakout modules. Breakout modules may be similarly wired according to the transceiver pattern.

[00202] Figs. 41 A and 41 B depict another exemplary structured multicore fiber optic cabling system 84 including a two-way multicore fiber optic cable assembly 38 in a key-up orientation suitable for use with VSFF array connectors. Each cable connector 40 of the fiber optic cable assembly 38 includes a plurality of end faces 16 (e.g., 12 end faces) arranged in a linear array. This configuration of end faces 16 preserves mirror-image symmetry about the interface axis of symmetry 64 of cable connector 40. Each cable connector 40 may be coupled to a key-up port connector 70 having a reciprocal arrangement of end faces 16, such as a VSFF array connector. The structured multicore fiber optic cabling system 84 of Figs. 41 A and 41 B provides a TIA-568 method-B equivalent for column connectors. The fiber sequence of the fiber optic cable assembly 38 is flipped in the right cable connector 40, which enables the core polarities to align between both ends of the cable assembly 38. The port connectors 70 also have the same core polarities, which are complementary to the polarities of the cable connector 40. If the ferrule has two columns of fibers, or two column connectors are grouped together to form a two-column connector, the cable configuration of Figs. 41 A and 41 B may be scaled to define multi-column connectors.

[00203] Figs. 42A and 42B depict another exemplary structured multicore fiber optic cabling system 84 including a two-way multicore fiber optic cable assembly 38 in a key-up orientation suitable for use with MPO multi-fiber connectors. Each cable connector 40 of cable assembly 38 includes a plurality of end faces 16 (e.g., 24 end faces) arranged in two linear arrays each having an equal number of end faces 16 (e.g., 12 end faces) parallelly aligned with the key-axis of cable connector 40. The resulting two-column end face pattern may have one linear array designated for transmitters and the other linear array designated for receivers. Configuring the multicore optical fibers 10 associated with one array as anti-parallel to those associated with the other array produces a mirror-image symmetry about an interface axis of symmetry 64 which is colinear with the key-axis. The resulting connector core pattern is similar to that which would be produced by stacking a plurality of the connector interfaces 62 of Fig. 14 along their key axes. Each cable connector 40 may be coupled to an up-key port connector 70 having a reciprocal arrangement of end faces 16. A transceiver polarity flip is achieved which is similar to that of a duplex A-to-B patch cord.

[00204] Figs. 43A and 43B depict another exemplary structured multicore fiber optic cabling system 84 suitable for use with VSFF array connectors having connector fiber polarities based on TIA-568 Method-A. In TIA-568 method-A, the trunk cable is terminated in key-up to key-down configuration and reverse fiber polarity duplex patch cords are used at one side of the trunk cable. Here, the structured multicore fiber optic cabling system 84 includes a two-way multicore fiber optic cable assembly 38 having one cable connector 40 in the key-up orientation and the other cable connector 40 in the key-down orientation. Each cable connector 40 of cable assembly 38 includes a plurality of end faces 16 (e.g., 12 end faces) arranged in a linear array generally orthogonal to the key-axis of the cable connector 40. The multicore optical fibers 10 of multicore fiber optic cable assembly 38 have alternating draw directions, and may be referred to as a Type-A multicore optical fiber ribbon.

[00205] The resulting connector core pattern has mirror-image symmetry about an interface axis of symmetry 64 that is colinear with the key-axis of its respective connector. Each cable connector 40 may be coupled to a port connector 70 having a reciprocal arrangement of end faces 16. One of the port connectors 70 (e.g., the right side port connector) may have a cross-connect configuration that swaps the positions of the multicore optical fibers in each duplex (transmit and receive) pair.

[00206] The connector core pattern of each connector interface 62 in Figs. 43A and 43B has horizontal mirror-image symmetry, and core polarities are preserved through the link. Each interface includes one key-up and one key-down connector. However, the port connectors 70 at each end of the multicore fiber optic cable assembly 38 have different key orientations. Thus, they match to a specific end of the multicore fiber optic cable assembly 38. The structured multicore fiber optic cabling system 84 of Figs. 43A and 43B also requires two types of duplex patch cords. Accordingly, structured multicore fiber optic cabling systems based on TIA-568 Method-B may be preferred over those based on TIA-586 Method-A. A breakout module 90 suitable for use with the structured multicore fiber optic cabling system 84 of Figs. 43A-43B is depicted in Fig. 37. The other side of this breakout module 90 may use a reverse fiber polarity A-to-A type duplex patch cord.

[00207] Figs. 44A and 44B depict another exemplary structured multicore fiber optic cabling system 84 suitable for use with a multicore fiber optic trunk cable based on TIA-568 Method-A. The cabling system 84 includes a two-way multicore fiber optic cable assembly 38 including a plurality of multicore optical fibers each having the same draw direction, one cable connector 40 having a key-up orientation, and another cable connector 40 having a key-down orientation. Each cable connector 40 of cable assembly 38 includes a plurality of end faces 16 (e.g., 12 end faces) arranged in a linear array generally orthogonal to the key-axis 76 of the cable connector 40.

[00208] Unlike the multicore fiber optic cable assembly 38 depicted by Figs. 43A and 43B, each multicore optical fiber 10 of two-way multicore fiber optic cable assembly 38 has the same draw direction. Thus, the core patterns of the connector interfaces 62 of connectors 40, 70 do not have mirror-image symmetry. Each cable connector 40 may be coupled to a port connector 70 having a reciprocal arrangement of end faces 16. One of the port connectors 70 (e.g., the right side port connector 70) may have a cross-connect configuration that swaps the positions of the multicore optical fibers in each duplex pair (transmit and receive) thereof. Figs. 44A and 44B show that while a parallel multicore optical fiber ribbon can be used for TIA-568 method-A solution, it may be limited to use in cabling systems with one-way connectivity to preserve the core polarities.

[00209] Figs. 45A and 45B depict another exemplary structured multicore fiber optic cabling system 84 based on TIA-586 Method-C in which the trunk cable has pair-wise flipped optical fibers to change the fiber polarity. Due to the symmetry limitation, the connector polarities at both ends of the Type-A direction managed multicore optical fiber ribbon do not match. This limitation may be overcome by using a 1 xn connector interface 62 such as depicted in Fig. 32. Fiber core polarities can also be preserved by using a Type-B direction managed multicore optical fiber ribbon. However, the benefits of using direction managed multicore optical fiber ribbon may be diminished by the need to use a specific array connector to match to each end of the trunk cable. Figs. 45A and 45B show that while a parallel multicore optical fiber ribbon can be used for TIA-586 Method-C solution, it may be limited to use in cabling systems with one-way connectivity to preserve the core polarities.

[00210] Embodiments of the disclosure include the features of pre-terminated single core fiber optic cabling systems while preserving the multicore optical fiber core polarities throughout the entire link. In comparing TIA-586 Type-B, Type-A, and Type-C trunk cable solutions, a direction managed Type-B multicore optical fiber trunk typically has the lowest number of parts with the most error-proof connectivity and highest flexibility because both the trunk and duplex patch cords are direction-insensitive.

[00211] There are many variations in the embodiments within the spirit of this invention. The transceivers in the figures can be multiple channel transceivers or the interfaces of fan-in/fan-out devices. The “key-up” and “key-down” positions can be swapped with the same results. The multicore optical fiber core polarity can take different orientations, as long as the mirror symmetry is satisfied. Because of the significant number of variations, standardizing one scheme may help create an interoperable ecosystem.

[00212] The multicore optical fibers may also have other numbers of cores and different core configurations. For example, 8-core optical fibers may be suitable for a next generation 8-lane parallel single mode transceivers. Multicore optical fibers with different numbers of cores may also be used for combining the fibers from Coarse Wavelength Division Multiplexing (CWDM) transceivers. Thus, the use of anti-parallel multicore optical fiber with properly oriented mirror-image symmetry in duplex core patterns may be applied to any type of duplex connector.

[00213] It should be further understood that many different core patterns and configurations of multicore optical fibers may be used to produce a connector having a connector core pattern with mirror-image symmetry. Moreover, although the exemplary connectors described above are generally depicted as having 1x2, 2x2, 1x12, and 2x12 connectors for purposes of clarity, aspects of the present disclosure are not limited to this configuration. For example, connectors may be expanded vertically by stacking arrangements of multicore optical fibers similar to those depicted herein, or horizontally by ganging arrangements of multicore optical fibers similar to those depicted herein.

[00214] Typically, fiber optic ribbons, cables, and/or connectors having mirror-image symmetry will have an even number of multicore optical fibers. However, an odd number of multicore optical fibers may be used if the core pattern of a center fiber itself has mirror-image symmetry. Although the above examples are connectors having between two and twenty four multicore optical fibers, there is no specific limit to the number of multicore optical fibers that can be assembled into a cable assembly. The multicore optical fibers may also have different numbers of cores and cores arranged in different patterns than shown. For example, cores may be arranged in patterns that have radial symmetry or that lack radial symmetry. Reference cores may be indicated by a marker embedded in the multicore optical fiber, or may be indicated by being in an off normal position.

[00215] Advantageously, the cost of manufacturing cable assemblies having multicore optical fibers with mirror-image symmetry should not be significantly higher than for conventional fiber optic cable assemblies that have single core optical fibers. The same manufacturing processes may be used to make the cable assemblies despite the different optical fibers (i.e. , multicore instead of single core). To form the desired pattern of anti-parallel multicore optical fibers, the end face of the multicore optical fiber on each fiber reel may be inspected to determine the draw direction, e.g., by observing the orientation of the core patterns.

[00216] While the present disclosure has been illustrated by the description of specific embodiments thereof, and while the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features discussed herein may be used alone or in any combination within and between the various embodiments. Additional advantages and modifications will readily appear to those skilled in the art. The present disclosure in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope of the present disclosure.

Claims

What is claimed is:

1. A fiber optic ribbon including a first end and a second end, comprising: a first multicore optical fiber having a first core pattern and a first draw direction; and a second multicore optical fiber having a second core pattern that is the same as the first core pattern and a second draw direction that is opposite the first draw direction; wherein the first multicore optical fiber and the second multicore optical fiber are arranged relative to each other in the fiber optic ribbon so that the first core pattern has a mirror-image symmetry with the second core pattern at both the first end and the second end of the fiber optic ribbon.

2. The fiber optic ribbon of claim 1 , wherein the first multicore optical fiber and the second multicore optical fiber are arranged in an anti-parallel configuration.

3. The fiber optic ribbon of claim 1 or 2, wherein: the first multicore optical fiber and the second multicore optical fiber are part of a plurality of multicore optical fibers consisting of a first number of multicore optical fibers with the first core pattern and the first draw direction, and a second number of multicore optical fibers with the second core pattern and the second draw direction, and the first number of multicore optical fibers is equal to the second number of multicore optical fibers.

4. The fiber optic ribbon of claim 3, wherein: the mirror-image symmetry at both the first end and the second end of the fiber optic ribbon is about an axis of symmetry of the fiber optic ribbon at the respective end, there is a third number of the plurality of multicore optical fibers with the first draw direction on one side of the axis of symmetry, there is a fourth number of the plurality of multicore optical fibers with the second draw direction on the other side of the axis of symmetry, and the third number of the plurality of multicore optical fibers is equal to the fourth number of the plurality of multicore optical fibers.

5. The fiber optic ribbon of claim 4, wherein the plurality of multicore optical fibers is arranged so that the draw direction of equally-sized subunits of multicore optical fibers alternates between the first draw direction and the second draw direction.

6. The fiber optic ribbon of claim 5, wherein each subunit of the multicore optical fibers includes at least one multicore optical fiber and not more than the first number of multicore optical fibers.

7. The fiber optic ribbon of claim 6, wherein: the fiber optic ribbon has a longitudinal axis at each end normal to a cross section of the fiber optic ribbon, each longitudinal axis passes through a geometric center of the cross section of the fiber optic ribbon, and each axis of symmetry is normal to the longitudinal axis of the respective end of the fiber optic ribbon.

8. The fiber optic ribbon of any of claims 1-7, wherein the fiber optic ribbon has an even number of the multicore optical fibers.

9. The fiber optic ribbon of any of claims 1-8, wherein each of the first core pattern and the second core pattern includes a reference core indicated by one or more of a mark-based asymmetry or a position-based asymmetry.

10. The fiber optic ribbon of claim 9, wherein both the first core pattern and the second core pattern follow a predetermined naming convention that uniquely identifies each core of the respective core pattern based on a position of the core relative to the respective reference core.

11. A fiber optic cable assembly including a first end and a second end, comprising: a first multicore optical fiber having a first core pattern and a first draw direction; a second multicore optical fiber having a second core pattern that is the same as the first core pattern and a second draw direction that is opposite the first draw direction; a first connector defining the first end of the optical cable assembly, wherein a first end of the first multicore optical fiber and a first end of the second multicore optical fiber are each secured to the first connector; and a second connector defining the second end of the optical cable assembly, wherein a second end of the first multicore optical fiber and a second end of the second multicore optical fiber are each secured to the second connector; wherein the first multicore optical fiber and the second multicore optical fiber are arranged relative to each other in each of the first connector and the second connector so that the first core pattern has a mirror-image symmetry with the second core pattern at both the first end and the second end of the optical cable assembly.

12. A method of making a fiber optic ribbon including a first end and a second end, comprising: providing a first multicore optical fiber having a first core pattern in a first draw direction; providing a second multicore optical fiber having a second core pattern that is the same as the first core pattern in a second draw direction that is opposite the first draw direction; and arranging the first multicore optical fiber and the second multicore optical fiber relative to each other in the fiber optic ribbon so that the first core pattern has a mirror-image symmetry with the second core pattern at both the first end of the fiber optic ribbon and the second end of the fiber optic ribbon.

13. The method of claim 12, wherein arranging the first multicore optical fiber and the second multicore optical fiber relative to each other so that the first core pattern has the mirror-image symmetry with the second core pattern includes arranging the first multicore optical fiber and the second multicore optical fiber in an anti-parallel arrangement.

14. The method of claim 12 or 13, wherein: the first multicore optical fiber and the second multicore optical fiber are provided as part of a plurality of multicore optical fibers consisting of a first number of multicore optical fibers having the first draw direction and a second number of multicore optical fibers having the second draw direction, and the first number of multicore optical fibers is equal to the second number of multicore optical fibers.

15. The method of claim 14, wherein the fiber optic ribbon includes an axis of symmetry, and further comprising: arranging a third number of the plurality of multicore optical fibers with the first draw direction on one side of the axis of symmetry, and arranging a fourth number of the plurality of multicore optical fibers with the second draw direction on the other side of the axis of symmetry, wherein the third number of the plurality of multicore optical fibers is equal to the fourth number of the plurality of multicore optical fibers.

16. The method of claim 15, further comprising: arranging the plurality of multicore optical fibers so that the draw direction of equally-sized subunits of the multicore optical fibers alternates between the first draw direction and the second draw direction.

17. The method of claim 16, wherein each subunit of the multicore optical fibers includes at least one multicore optical fiber and not more than the first number of multicore optical fibers.

18. The method of any of claims 12-17, wherein the first multicore optical fiber is provided from a first reel of multicore optical fiber wound in the first draw direction; and the second multicore optical fiber is provided from a second reel of multicore optical fiber wound in the second draw direction.

19. The method of claim 18, further comprising: winding a length of multicore optical fiber from a third reel onto the second reel, wherein the third reel of multicore optical fiber is wound in the first draw direction.

20. The method of any of claims 12-19, further comprising: identifying a reference core in each of the first core pattern and the second core pattern by providing one or more of a mark-based asymmetry or a position based asymmetry to the core pattern.

21. A method of making a fiber optic cable assembly including a first end and a second end, comprising: providing a first multicore optical fiber having a first core pattern and a first draw direction; providing a second multicore optical fiber having a second core pattern that is the same as the first core pattern and a second draw direction that is opposite the first draw direction; securing a first connector to a first end of the first multicore optical fiber and a first end of the second multicore optical fiber to define the first end of the fiber optic cable assembly; and securing a second connector to a second end of the first multicore optical fiber and a second end of the second multicore optical fiber to define the second end of the fiber optic cable assembly, wherein the first multicore optical fiber and the second multicore optical fiber are arranged relative to each other in each of the first connector and the second connector so that the first core pattern has a mirror-image symmetry with the second core pattern at both the first end and the second end of the optical cable assembly.

22. A fiber optic cable assembly, comprising: a first connector defining a first end of the fiber optic cable assembly and including a first connector interface having a first interface axis of symmetry; a second connector defining a second end of the fiber optic cable assembly and including a second connector interface having a second interface axis of symmetry; a first multicore optical fiber including a first front end face having a front end face core pattern and a first back end face having a back end face core pattern that is a mirror-image of the front end face core pattern; and a second multicore optical fiber including a second front end face having the front end face core pattern and a second back end face having the back end face core pattern, wherein: the first connector is configured so that the first front end face of the first multicore optical fiber and the second back end face of the second multicore optical fiber are placed in the first connector interface to define, at least in part, a first connector core pattern having mirror-image symmetry about the first interface axis of symmetry, and the second connector is configured so that the first back end face of the first multicore optical fiber and the second front end face of the second multicore optical fiber are each placed in the second connector interface to define, at least in part, a second connector core pattern having mirror-image symmetry about the second interface axis of symmetry; wherein the first connector core pattern and the second connector core pattern are the same.

23. The fiber optic cable assembly of claim 22, wherein: the first connector includes a first alignment key that defines an orientation of the first connector, and the second connector includes a second alignment key that defines the orientation of the second connector.

24. The fiber optic cable assembly of claim 23, wherein: the first connector interface includes a first key-axis that is aligned with the first alignment key, the second connector interface includes a second key-axis that is aligned with the second alignment key, the first interface axis of symmetry is parallel to the first key-axis, and the second interface axis of symmetry is parallel to the second key-axis.

25. The fiber optic cable assembly of claim 23, wherein: the first connector interface includes a first key-axis that is aligned with the first alignment key, the second connector interface includes a second key-axis that is aligned with the second alignment key, the first interface axis of symmetry is orthogonal to the first key-axis, and the second interface axis of symmetry is orthogonal to the second key-axis.

26. The fiber optic cable assembly of any of claims 22-25, wherein: the front end face core pattern has mirror-image symmetry about a fiber axis of symmetry in each of the first front end face and the second front end face, and the back end face core pattern has mirror-image symmetry about the fiber axis of symmetry in each of the first back end face and the second back end face.

27. The fiber optic cable assembly of claim 26, wherein: the first interface axis of symmetry divides the first connector interface into a first side and a second side thereof, the second interface axis of symmetry divides the second connector interface into a first side and a second side thereof, the first side of the first connector interface has the same position relative to the first interface axis of symmetry as the first side of the second connector interface has relative to the second interface axis of symmetry, the second side of the first connector interface has the same position relative to the first interface axis of symmetry as the second side of the second connector interface has relative to the second interface axis of symmetry, the first front end face of the first multicore optical fiber is on the first side of the first connector interface, the second back end face of the second multicore optical fiber is on the second side of the first connector interface, the first back end face of the first multicore optical fiber is on the second side of the second connector interface, and the second front end face of the second multicore optical fiber is on the first side of the second connector interface.

28. The fiber optic cable assembly of claim 26, wherein: the first interface axis of symmetry divides the first connector interface into a first side and a second side thereof, the second interface axis of symmetry divides the second connector interface into a first side and a second side thereof, the first side of the first connector interface has the same position relative to the first interface axis of symmetry as the first side of the second connector interface has relative to the second interface axis of symmetry, the second side of the first connector interface has the same position relative to the first interface axis of symmetry as the second side of the second connector interface has relative to the second interface axis of symmetry, the first front end face of the first multicore optical fiber is on the first side of the first connector interface, the second back end face of the second multicore optical fiber is on the second side of the first connector interface, the first back end face of the first multicore optical fiber is on the first side of the second connector interface, and the second front end face of the second multicore optical fiber is on the second side of the second connector interface.

29. The fiber optic cable assembly of any of claims 26-28, wherein: the fiber axis of symmetry of each of the first front end face and the second back end face is orthogonal to the first interface axis of symmetry, and the fiber axis of symmetry of each of the first back end face and the second front end face is orthogonal to the second interface axis of symmetry.

30. The fiber optic cable assembly of any of claims 26-28, wherein: the fiber axis of symmetry of each of the first front end face and the second back end face is parallel to the first interface axis of symmetry, and the fiber axis of symmetry of each of the first back end face and the second front end face is parallel to the second interface axis of symmetry.

31. A method of making a fiber optic cable assembly, comprising: providing a first multicore optical fiber including a first front end and a first back end, the first front end including a first front end face having a front end face core pattern, and the first back end including a first back end face having a back end face core pattern that is a mirror image of the front end face core pattern; providing a second multicore optical fiber including a second front end and a second back end, the second front end including a second front end face having the front end face core pattern and the second back end including a second back end face having the back end face core pattern; coupling the first front end of the first multicore optical fiber and the second back end of the second multicore optical fiber to a first connector, the first connector including a first connector interface having a first interface axis of symmetry; coupling the first back end of the first multicore optical fiber and the second front end of the second multicore optical fiber to a second connector, the second connector including a second connector interface having a second interface axis of symmetry; placing the first front end face of the first multicore optical fiber and the second back end face of the second multicore optical fiber in the first connector interface to define, at least in part, a first connector core pattern having mirrorimage symmetry about the first interface axis of symmetry; and placing the first back end face of the first multicore optical fiber and the second front end face of the second multicore optical fiber in the second connector interface to define, at least in part, a second connector core pattern having mirror-image symmetry about the second interface axis of symmetry, wherein the first connector core pattern and the second connector core pattern are the same.

32. The method of claim 31 , further comprising: providing a first alignment key to the first connector that defines an orientation of the first connector, and providing a second alignment key to the second connector that defines the orientation of the second connector.

33. The method of claim 32, further comprising: defining a first key-axis of the first connector interface that is aligned with the first alignment key; and defining a second key-axis of the second connector interface that is aligned with the second alignment key, wherein the first interface axis of symmetry is parallel to the first key-axis, and the second interface axis of symmetry is parallel to the second key axis.

34. The method of claim 32, further comprising: defining a first key-axis of the first connector interface that is aligned with the first alignment key; and defining a second key-axis of the second connector interface that is aligned with the second alignment key, wherein the first interface axis of symmetry is orthogonal to the first key-axis, and the second interface axis of symmetry is orthogonal to the second key axis.

35. The method of any of claims 31-34, further comprising: configuring the first and second multicore optical fibers so that the front end face core pattern has mirror-image symmetry about a fiber axis of symmetry in each of the first front end face and the second front end face, and the back end face core pattern has mirror-image symmetry about the fiber axis of symmetry in each of the first back end face and the second back end face.

36. The method of claim 35, wherein the first interface axis of symmetry divides the first connector interface into a first side and a second side thereof, the second interface axis of symmetry divides the second connector interface into a first side and a second side thereof, the first side of the first connector interface has the same position relative to the first interface axis of symmetry as the first side of the second connector interface has relative to the second interface axis of symmetry, the second side of the first connector interface has the same position relative to the first interface axis of symmetry as the second side of the second connector interface has relative to the second interface axis of symmetry, and further comprising: placing the first front end face of the first multicore optical fiber in the first connector interface so that the first front end face is on the first side of the first connector interface, placing the second back end face of the second multicore optical fiber in the first connector interface so that the second back end face is on the second side of the first connector interface, placing the first back end face of the first multicore optical fiber in the second connector interface so that the first back end face is on the second side of the second connector interface, and placing the second front end face of the second multicore optical fiber in the second connector interface so that the second front end face is on the first side of the second connector interface.

37. The method of claim 35, wherein the first interface axis of symmetry divides the first connector interface into a first side and a second side thereof, the second interface axis of symmetry divides the second connector interface into a first side and a second side thereof, the first side of the first connector interface has the same position relative to the first interface axis of symmetry as the first side of the second connector interface has relative to the second interface axis of symmetry, the second side of the first connector interface has the same position relative to the first interface axis of symmetry as the second side of the second connector interface has relative to the second interface axis of symmetry, and further comprising: placing the first front end face of the first multicore optical fiber in the first connector interface so that the first front end face is on the first side of the first connector interface, placing the second back end face of the second multicore optical fiber in the first connector interface so that the second back end face is on the second side of the first connector interface, placing the first back end face of the first multicore optical fiber in the second connector interface so that the first back end face is on the first side of the second connector interface, and placing the second front end face of the second multicore optical fiber in the second connector interface so that the second front end face is on the second side of the second connector interface.

38. The method of any of claims 35-37, further comprising: placing each of the first front end face and the second back end face in the first connector interface so that the fiber axis of symmetry of each of the first front end face and the second back end face is orthogonal to the first interface axis of symmetry, and placing each of the first back end face and the second front end face in the second connector interface so that the fiber axis of symmetry of each of the first back end face and the second front end face is orthogonal to the second interface axis of symmetry.

39. The method of any of claims 35-37, further comprising: placing each of the first front end face and the second back end face in the first connector interface so that the fiber axis of symmetry of each of the first front end face and the second back end face is parallel to the first interface axis of symmetry, and placing each of the first back end face and the second front end face in the second connector interface so that the fiber axis of symmetry of each of the first back end face and the second front end face is parallel to the second interface axis of symmetry.

40. A fiber optic connector, comprising: a connector interface including an interface axis of symmetry; a front end face of a first multicore optical fiber including a front end face core pattern; and a back end face of a second multicore optical fiber including a back end face core pattern that is a mirror image of the front end face core pattern, wherein: the front end face of the first multicore optical fiber and the back end face of the second multicore optical fiber are placed in the connector interface so that the front end face and the second back end face define, at least in part, a connector core pattern having mirror-image symmetry about the interface axis of symmetry.

41. The fiber optic connector of claim 40, wherein: the front end face core pattern has mirror-image symmetry about a fiber axis of symmetry of the front end face, and the back end face core pattern has mirror-image symmetry about the fiber axis of symmetry of the back end face.

42. A structured multicore fiber optic cabling system, comprising: one or more multicore fiber optic cable assemblies each including: a first cable connector including a first cable connector interface, a second cable connector including a second cable connector interface, and a first plurality of multicore optical fibers each including a first end face having a first end face core pattern and a second end face having a second end face core pattern that is a mirror-image of the first end face core pattern, the first plurality of multicore optical fibers configured so that a first half thereof has a first draw direction and a second half thereof has a second draw direction opposite the first draw direction, wherein the first cable connector is configured so that the first end face of each multicore optical fiber having the first draw direction and the second end face of each multicore optical fiber having the second draw direction is placed in the first cable connector interface to define a first connector core pattern having a first mirror-image symmetry, and wherein the second cable connector is configured so that the first end face of each multicore optical fiber having the second draw direction and the second end face of each multicore optical fiber having the first draw direction is placed in the second cable connector interface to define the first connector core pattern; and a plurality of network components each including a port connector having a port connector interface including a plurality of end faces with a first half thereof having the first end face core pattern and a second half thereof having the second end face core pattern, each end face of the plurality end faces being placed in the port connector interface to define the first connector core pattern, wherein core polarity is preserved between a first port connector of a first network component of the plurality of network components and a second port connector of a second network component of the plurality of network components: when the first cable connector of a first multicore fiber optic cable assembly of the one or more multicore fiber optic cable assemblies is operatively coupled to the first port connector, and the second cable connector of the first multicore fiber optic cable assembly is operatively coupled to the second port connector, and when the first cable connector of the first multicore fiber optic cable assembly is operatively coupled to the second port connector, and the second cable connector of the first multicore fiber optic cable assembly is operatively coupled to the first port connector.

43. The structured multicore fiber optic cabling system of claim 42, wherein: the first cable connector includes a first cable alignment key having a first placement relative to the first connector core pattern of the first cable connector, and the second cable connector includes a second cable alignment key having the first placement relative to the first connector core pattern of the second cable connector.

44. The structured multicore fiber optic cabling system of claim 43, wherein: the first port connector includes a first port alignment key having a second placement relative to the first connector core pattern of the first port connector, the second port connector includes a second port alignment key having the second placement relative to the first connector core pattern of the second port connector, the second placement relative to the first connector core pattern is opposite the first placement relative to the first connector core pattern, each cable connector and each port connector includes a key-axis that lies in a plane which bisects the respective connector and is aligned with the cable alignment key or port alignment key of the respective connector, in each cable connector interface and each port connector interface, the first and second end faces of the first plurality of multicore optical fibers are aligned in one or more arrays that are orthogonal to the key-axis of the respective connector, and the core polarity is preserved between the first port connector of the first network component and the second port connector of the second network component when each of a first cable alignment key orientation and a second cable alignment key orientation is opposite that of a first port alignment key orientation or a second port alignment key orientation to which the respective first and second cable connector is operatively coupled.

45. The structured multicore fiber optic cabling system of claim 43, wherein: the first port connector includes a first port alignment key having the first placement relative to the first connector core pattern of the first port connector, the second port connector includes a second port alignment key having the first placement relative to the first connector core pattern of the second port connector, each cable connector and each port connector includes a key-axis that lies in a plane which bisects the respective connector and is aligned with the cable alignment key or the port alignment key of the respective connector, in each cable connector interface and each port connector interface, the first and second end faces of the first plurality of multicore optical fibers are aligned in one or more arrays that are parallel to the key-axis of the respective connector, and the core polarity is preserved between the first port connector of the first network component and the second port connector of the second network component when each of a first cable alignment key orientation and a second cable alignment key orientation is the same as a first port alignment key orientation or a second port alignment key orientation to which the respective first and second cable connector is operatively coupled.

46. The structured multicore fiber optic cabling system of claim 45, wherein the first and second end faces of the first plurality of multicore optical fibers are aligned in one array that is parallel to the key-axis of the respective connector, and the first mirror-image symmetry of the first connector core pattern of each connector is about an axis of symmetry that is orthogonal to the key-axis.

47. The structured multicore fiber optic cabling system of claim 45, wherein the first and second end faces of the first plurality of multicore optical fibers are aligned in an even number of two or more arrays that are parallel to the key-axis of the respective connector, and the first mirror-image symmetry of the first connector core pattern of each connector is about an axis of symmetry that is parallel to the key-axis.

48. The structured multicore fiber optic cabling system of any of claims 42-47, wherein the first and second end faces of the first plurality of multicore optical fibers are arranged in at least two linear arrays, and each linear array of end faces includes 4, 8, 12, or 16 end faces.

49. The structured multicore fiber optic cabling system of any of claims 42-48, wherein the first port connector of each of the first and second network components is a trunk connector, and at least one of the first and second network components is one of a plurality of breakout modules, each breakout module of the plurality of breakout modules including: the trunk connector having the first connector core pattern, a second plurality of multicore optical fibers each including the first end face and the second end face, the second plurality of multicore optical fibers configured so that a first half thereof has the first draw direction and a second half thereof has the second draw direction, and a plurality of branch connectors each including a branch connector interface and being operatively coupled to the trunk connector by a respective multicore optical fiber from each of the first and second halves of the second plurality of multicore optical fibers, wherein each branch connector is configured so that the second end face of the multicore optical fiber having the first draw direction and the first end

-SO- face of the multicore optical fiber having the second draw direction is placed in the branch connector interface to define a second connector core pattern having a second mirror-image symmetry.

50. The structured multicore fiber optic cabling system of claim 49, wherein the plurality of breakout modules includes a third breakout module and a fourth breakout module, the one or more multicore fiber optic cable assemblies includes a second multicore fiber optic cable assembly, and the structured multicore fiber optic cabling system further comprises: a plurality of multicore duplex patch cords, each multicore duplex patch cord including: a first multicore optical fiber including the first end face having the first end face core pattern and the second end face having the second end face core pattern, a second multicore optical fiber including the first end face having the first end face core pattern and the second end face having the second end face core pattern, a first patch cord connector defining a first end of the multicore duplex patch cord and including a first patch cord connector interface, wherein the first end face of the first multicore optical fiber and the second end face of the second multicore optical fiber are placed in the first patch cord connector interface to define the second connector core pattern, and a second patch cord connector defining a second end of the multicore duplex patch cord and including a second patch cord connector interface, wherein the second end face of the first multicore optical fiber and the first end face of the second multicore optical fiber are placed in the first patch cord connector interface to define the second connector core pattern, wherein the trunk connector of the third network component is operatively coupled to the trunk connector of the fourth network component by the second multicore fiber optic cable assembly, and each of the branch connectors of the second network component is operatively coupled to a respective branch connector of the third network component to define a cross-connection between the first network component and the fourth network component.

51. The structured multicore fiber optic cabling system of claim 49, further comprising: a third network component including one or more transceivers each having a high-density transceiver interface; and one or more multicore duplex patch cords, each multicore duplex patch cord including: a first multicore optical fiber including the first end face having the first end face core pattern and the second end face having the second end face core pattern, a second multicore optical fiber including the first end face having the first end face core pattern and the second end face having the second end face core pattern, a first patch cord connector defining a first end of the multicore duplex patch cord, the first patch cord connector including a patch cord alignment key defining a key-axis and a first patch cord connector interface having a cross-axis orthogonal to the key-axis, a second patch cord connector defining a second end of the multicore duplex patch cord, the second patch cord connector including the patch cord alignment key defining the key-axis and a second patch cord connector interface having the cross-axis orthogonal to the key-axis, wherein each of the first and second end face core patterns includes a plurality of cores arranged in a linear array of cores, the first end face of the first multicore optical fiber and the second end face of the second multicore optical fiber are placed in the first patch cord connector interface so that each linear array of cores is aligned with the cross-axis of the first patch cord connector and to define the second connector core pattern having the second mirror-image symmetry, and the second end face of the first multicore optical fiber and the first end face of the second multicore optical fiber are placed in the second patch cord connector interface so that each linear array of cores is aligned with the cross-axis of the second patch cord connector and to define the second connector core pattern having the second mirror-image symmetry, wherein the second network component is one of the plurality of breakout modules, each branch connector of the second network component includes a branch alignment key defining the key-axis of the branch connector, and the branch connector interface has the cross-axis orthogonal to the keyaxis and the second connector core pattern, the high-density transceiver interface includes a transceiver connector having a transceiver alignment key defining the key-axis of the transceiver connector, and a transceiver connector interface having the cross-axis orthogonal to the key-axis and the second connector core pattern, and each transceiver connector is operatively coupled to a respective branch connector by a respective multicore duplex patch cord of the one or more multicore duplex patch cords with a same key orientation.

52. The structured multicore fiber optic cabling system of claim 42, wherein: the first cable connector includes a first cable alignment key having a first placement relative to the first connector core pattern of the first cable connector, and the second cable connector includes a second cable alignment key having a second placement relative to the first connector core pattern of the second cable connector that is opposite the first placement relative to the first connector core pattern.

53. The structured multicore fiber optic cabling system of claim 52, wherein: the first port connector includes a first port alignment key having the second placement relative to the first connector core pattern of the first port connector, the second port connector includes a second port alignment key having the first placement relative to the first connector core pattern of the second port connector, and the core polarity is preserved between the first port connector of the first network component and the second port connector of the second network component when each of first and second cable alignment key orientations is the opposite of the first or second port alignment key orientation to which the respective first and second cable connector is operatively coupled.

54. A breakout module for a structured multicore fiber optic cabling system, comprising: a plurality of multicore optical fibers each including a first end face having a first end face core pattern and a second end face having a second end face core pattern that is a mirror-image of the first end face core pattern, the plurality of multicore optical fibers being configured so that a first half thereof has a first draw direction and a second half thereof has a second draw direction opposite the first draw direction, a trunk connector including a trunk connector interface configured so that the first end face of each multicore optical fiber having the first draw direction and the second end face of each multicore optical fiber having the second draw direction is placed in the trunk connector interface to define a first connector core pattern having a first mirror-image symmetry; and a plurality of branch connectors each including a branch connector interface and being operatively coupled to the trunk connector by a respective multicore optical fiber from each of the first and second halves of the plurality of multicore optical fibers, wherein each branch connector is configured so that the second end face of the multicore optical fiber having the first draw direction and the first end face of the multicore optical fiber having the second draw direction is placed in the branch connector interface to define a second connector core pattern having a second mirror-image symmetry.

55. The breakout module of claim 54, wherein: the first mirror-image symmetry is about an axis of symmetry of the trunk connector interface, the first and second end faces of the plurality of multicore optical fibers are arranged in a linear array orthogonal to the axis of symmetry in the trunk connector interface such that each first end face is on one side of the axis of symmetry, and each second end face is on the other side of the axis of symmetry, and each of the branch connectors is operatively coupled to a respective pair of multicore optical fibers associated with first and second end faces on each side of, and the same distance from, the axis of symmetry.

56. The breakout module of claim 54, wherein: the first mirror-image symmetry is about an axis of symmetry of the trunk connector interface, the end faces of the trunk connector are arranged in a linear array orthogonal to the axis of symmetry such that the first end faces alternate with the second end faces, and each of the branch connectors is operatively coupled to a pair of multicore optical fibers having adjacent end faces at the trunk connector interface of the trunk connector.

57. A method of making a structured multicore fiber optic cabling system, comprising: providing a first cable connector including a first cable connector interface; providing second cable connector including a second cable connector interface; providing a first plurality of multicore optical fibers each including a first end face having a first end face core pattern and a second end face having a second end face core pattern that is a mirror-image of the first end face core pattern; arranging the first plurality of multicore optical fibers so that a first half thereof has a first draw direction, and a second half thereof has a second draw direction opposite the first draw direction; placing the first end face of each multicore optical fiber having the first draw direction and the second end face of each multicore optical fiber having the second draw direction in the first cable connector interface to define a first connector core pattern having a first mirror-image symmetry; placing the first end face of each multicore optical fiber having the second draw direction and the second end face of each multicore optical fiber having the first draw direction in the second cable connector interface to define the first connector core pattern; providing a plurality of network components each including a port connector having a port connector interface including a plurality of end faces with a first half thereof having the first end face core pattern and second half thereof having the second end face core pattern; placing each end face of the plurality of end faces in the port connector interface to define the first connector core pattern; operatively coupling one of the first cable connector or the second cable connector to a first port connector of a first network component of the plurality of network components; and operatively coupling the other of the first cable connector or the second cable connector to a second port connector of a second network component of the plurality of network components, wherein core polarity is preserved between the first network component and the second network component regardless of whether the first cable connector or the second cable connector is operatively coupled to the first port connector.

58. The method of claim 57, further comprising: placing a first cable alignment key on the first cable connector at a first placement relative to the first connector core pattern of the first cable connector; placing a second cable alignment key on the second cable connector at the first placement relative to the first connector core pattern of the second cable connector; placing a first port alignment key on the first port connector at a second placement relative to the first connector core pattern of the first port connector; placing a second port alignment key on the second port connector at the second placement relative to the first connector core pattern of the second port connector; and aligning, in each cable connector interface and each port connector interface, the first and second end faces of the first plurality of multicore optical fibers in one or more arrays that are orthogonal to a key-axis of the respective connector, wherein the second placement relative to the first connector core pattern is opposite the first placement relative to the first connector core pattern, the key-axis of each connector lies in a plane that bisects the respective connector and is aligned with the cable alignment key or the port alignment key of the respective connector, and the core polarity is preserved between the first and second network components when the first and second port connectors are operatively coupled to each other through the first and second cable connectors and each of the first and second cable alignment key orientations are opposite the respective first or second port alignment key to which they are operatively coupled.

59. The method of claim 57, further comprising: placing a first cable alignment key on the first cable connector at a first placement relative to the first connector core pattern of the first cable connector; placing a second cable alignment key on the second cable connector at the first placement relative to the first connector core pattern of the second cable connector; placing a first port alignment key on the first port connector at a second placement relative to the first connector core pattern of the first port connector; placing a second port alignment key on the second port connector at the second placement relative to the first connector core pattern of the second port connector; and aligning, in each cable connector interface and each port connector interface, the first and second end faces of the first plurality of multicore optical fibers in one or more arrays that are parallel to a key-axis of the respective connector, wherein the key-axis of each cable connector and each port connector lies in a plane which bisects the respective connector and is aligned with the cable alignment key or the port alignment key of the respective connector, and the core polarity is preserved between the first and second network components when the first and second port connectors are operatively coupled to each other through the first and second cable connectors and each of the first and second cable alignment key orientations are opposite the respective first or second port alignment key to which they are operatively coupled.

60. The method of any of claims 57-59, wherein the first port connector of each of the first and second network components is a trunk connector having the first connector core pattern, at least one of the first and second network components is one of a plurality of breakout modules, and further comprising: providing each breakout module with a second plurality of multicore optical fibers each including the first end face and the second end face; configuring the second plurality of multicore optical fibers so that a first half thereof has the first draw direction and a second half thereof has the second draw direction; providing each breakout module with a plurality of branch connectors each including a branch connector interface; operatively coupling each branch connector to the trunk connector by a respective multicore optical fiber from each of the first and second halves of the second plurality of multicore optical fibers; and placing the second end face of the multicore optical fiber having the first draw direction and the first end face of the multicore optical fiber having the second draw direction in the branch connector to define a second connector core pattern having a second mirror-image symmetry in the branch connector interface.

61. The method of claim 57, further comprising: placing a first cable alignment key on the first cable connector in a first placement relative to the first connector core pattern of the first cable connector, and placing a second cable alignment key on the second cable connector in a second placement relative to the first connector core pattern of the second cable connector that is opposite the first placement relative to the first connector core pattern.