Multicore optical fibers and methods of manufacturing the same

A multicore optical fiber with a reference section having a material defining a marked multicore glass optical fiber. The multicore fibers can be in groupings, for example, the groupings can be in the form of one of an optical fiber ribbon covered by a matrix, and a tight buffered cable. Fiber optic connectors can be assembled to the multicore optical fiber at either or both ends, and the colored portion can be associated with the optical fiber connector aligning the optical core elements with the optical connectors. The assembly can have at least one transceiver device with a transmit port and a receive port defining a two-way communication channel. Further aspects describe methods of manufacturing multicore fibers including application of curable coatings and reference sections.

BACKGROUND

Field

The present disclosure generally relates to optical fibers and, more specifically, to multicore optical fibers.

Technical Background

Optical fiber is the leading alternative to traditional materials used for data signal communication such as copper wiring. Optical fiber is now widely utilized in a variety of electronic devices and systems to facilitate the high-speed communication of voice, video, and data signals at high bandwidths. However, as the speed and bandwidth of the electronic systems increases, there is a corresponding need to increase the speed of optical interconnects which interconnect components of the system. One solution to increase the speed of optical interconnects is to increase the fiber density of the optical interconnects. However, increasing the number of individual fibers in an optical interconnect increases the overall size and cost of the optical interconnect. To avoid the increased fiber count, multicore optical fibers (“MCFs”) have been developed. MCFs contain optical core elements contained in a single fiber. The core elements are designed for, for example, the transmission and receiving of data, and can be arranged as transmit and receive (Tx/Rx) pairs. Such MCFs may be used in data networks to enable high speed Tx/Rx transmission of data between system components such as transceivers, processors, servers, and storage devices. For connection and termination in the networks, connectors are attached to the MCFs. For correct Tx/Rx optical transport and connections to be manufactured, it is important for the operators to know the orientation of the optical fibers when the connectors are terminated to the MCFs.

SUMMARY

According to embodiments of the present disclosure, a multicore optical fiber for use with, for example, at least one transceiver device, for example, an opto/electronic comprises optical core elements, the optical core elements comprising an array of at least two optical core elements contained within a common outer cladding, the common outer cladding being at least partially surrounded by a coating layer, the respective centers of the optical core elements being aligned along a first reference line and being capable of transmitting data, and the multicore optical fiber comprising at least one colored portion defining a marked multicore fiber. The colored portion can be selected from a UV light curable resin material and an ink material and combinations thereof, and the coating layer can include a color and the least one colored portion can include a relatively distinct color compared to the coating layer color. The colored portion can extend along the multicore optical fiber and can be in the form of one of a continuous line, an intermittent line, a ring, or combinations thereof. In addition, the colored portion can be one of a co-extruded layer adjacent the coating layer and a material applied to an outer surface of the coating layer and combinations thereof. The colored portion is disposed generally in alignment with the reference line, or it can be disposed in other positions, for example, generally above the reference line.

Marked multicore fibers can be arranged in groupings. For example, the groupings can be in the form of one of an optical fiber ribbon covered by a matrix, and a loosely disposed group of marked multicore optical fibers, and combinations thereof. Moreover, a cable jacket can surround at least one marked multicore optical fiber and at least one strength member. In addition, the marked multicore optical fiber can be part of an assembly comprising at least one opto/electronic transceiver system with at least one transmit port and at least one receive port defining at least one two-way communication channel moreover, at least one fiber optic connector can be assembled to the marked multicore optical fiber, and the colored portion can be associated with the optical fiber connector aligning the optical core elements indicating alignment of the optical elements with the optical connector.

Further embodiments describe methods of manufacturing multicore fibers and others aspects according to the foregoing. An exemplary method comprises the steps of translating an uncoated multicore optical fiber between an energy source and a detector, directing a beam of the energy source so that it at least partially impinges upon the multicore optical fiber causing an image to be detected by the detector, and the detector sending output to a controller, the controller determining the orientation of at least some of the core elements in the multicore optical fiber, and controlling a spinning or traction device and thereby adjusting the orientation of the multicore optical fiber in relation to its optical core elements and a coating die, passing the multicore optical fiber through the coating die and applying a material to the multicore optical fiber thus defining a coating portion, and applying a material in the form of a colored portion being visually distinct from the coating portion.

Variations of the foregoing methods are included as embodiments of the disclosure. For example, the step of detecting the image of at least some of the core elements can include at least partial absorption of the energy by at least one dopant which is respectively part of the optical core elements, and the dopant can be, for example, a germanium dopant. Other dopants can be used in accordance with the disclosure which will potentially result in alternative absorption and transmittance characteristics. Alternatively, the step of energy absorption can cause fluorescence and the step of determining the orientation of at least some of the core elements can involve imaging of the fluorescence. In yet another alternative, the step of energy absorption can cause index of refraction differences and the step of detection of the image can thus be based upon interferometry.

As to the manufacturing line embodiments of the disclosure, determining the orientation of at least some of the core elements in the multicore optical fiber can include programming at least one characteristic absorption wavelength band of the dopant and cladding in an imaging system. In other embodiments, applying a material to the coating portion can include a colored portion visually distinct from the coating portion including one of co-extruding the colored portion and of applying an ink to the outer surface of the coating portion, and combinations thereof. In yet further embodiments of the disclosure, applying the colored portion can comprise one of forming the colored portion with one or more stripes, dashes, rings, or a series of rings and stripes thereon, and combinations thereof. As to exemplary groupings of marked multicore optical fibers, the manufacturing method can comprise translating at least two multicore optical fibers, aligning the colored portions respectively of the multicore optical fibers, coating the multicore optical fibers with a matrix material so they are contained in the matrix, curing the matrix material, and optionally applying a reference section to the matrix.

As alternative processes of the embodiments disclosed herein, translating the multicore optical fibers can include drawing an uncoated multicore optical fiber from a draw tower or supplying a multicore fiber with a colored portion from a reel. As to the draw tower alternative, the step of coating the multicore optical fiber can occur after cooling of the multicore optical fiber. Moreover, determining the core element orientation can occur prior to the coating application step and can include controlling the traction device prior to application of the coating. Furthermore, the steps of applying the colored portion can be one of various embodiments for example: directly applying the colored portion to the glass after a cooling step but prior to the coating application step, directly applying the colored portion to the coating after the coating step but before a curing step of the coating, directly applying the colored portion to the coating after a curing step of the coating, and combinations thereof.

Additional features and advantages of the embodiments described herein will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings. Moreover, it is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of multicore optical fibers, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like items. More specifically, one embodiment of a multicore optical fiber (“MCF”) generally comprises a common outer cladding formed from silica-based glass and having a cladding index of refraction. At least one optical core element, for example, a single mode core element or a multimode core element, or a combination of such elements, are disposed in the common outer cladding. The core element(s) are formed from, for example, silica-based glass with a higher index of refraction than the cladding. A center-to-center spacing between adjacent core elements is for example, greater than or equal to about 25 nm or less. Various embodiments of multicore optical fibers and methods for forming the same will be described in more detail herein with specific reference to the appended drawings. The term “multimode” as used herein refers to a core element which supports the propagation of multiple modes of light at the specified wavelength(s) of, for example, 850 nm to 1550 nm. Multicore fibers are made by exemplary processes disclosed in Corning Incorporated U.S. Pat. Nos. 6,539,151 and 6,154,594, both of which are respectively relied upon and incorporated by reference herein. The multicore fibers of the embodiments of the disclosure shown, for example inFIGS. 1, 2, and 11, are exemplary and include generally round outer shapes and round optical core elements14,15,16,17. However, the optical core elements can be other shapes such as rectangular, polygonal, flat, or elliptical as shown in US Patent Publication No. US 20130177273 A1, which is relied upon and incorporated by reference herein. In addition, forms of multicore fibers other than round, such as rectangular, hexagonal, partly flat and partly rounded forms, and multicore fibers made with a series of curved surfaces such as are as disclosed U.S. Ser. No. 13/485,192, which is relied upon and incorporated by reference herein, can be used with embodiments of the present disclosure.

FIG. 1depicts a MCF component10with optical core elements, for example, core elements14,15,16, and17contained within a common outer cladding11that is covered by a coating system12comprising a primary coating12aand a secondary coating12bdefining a coating system12. Coating system12comprises at least one first reference section which comprises, a UV light curable resin which is formed of, for example, a first colored material18. Core elements14,15,16,17are generally aligned along their respective centers along a line “L1”. The optical core elements14,15,16,17can be arranged in a row as shown, for example, inFIGS. 1, 2, and 10. The common outer cladding11comprises a silica-based glass having a cladding index of refraction. In one embodiment, optical core elements14and15are designed to communicate data, for example, to transmit data (Tx), and core elements16and17are designed to communicate data, for example, to receive data (Rx) (FIG. 11). A fiber optic connector can be attached to MCF component10and would connect to, for example, an opto/electronic transceiver device (FIGS. 11 and 12). The connector is keyed to align core elements14and15with the device, such as Vertical Cavity Surface Emitting Laser transmitters for Tx purposes, and core elements16and17are to be aligned with optical/electronic receiver devices for Rx purposes (FIG. 13). As stated above, MCF components10can have two or more single mode core elements, two or more multimode core elements, or a combination of single mode and multimode core elements disposed in common outer cladding11.

The operator is to align the core elements14,15,16,17to the connectors at each end of the cable using at least one second reference section. The second reference section comprises, for example, a second colored material forming a colored portion22(FIG. 2) comprising a UV light curable resin. With further reference toFIG. 2, MCF component10includes at least one coating layer, for example, a layer21,22formed of, for example, at least one ink color material as a part of coating system12defining a marked MCF20. For example, the coating layer includes a coating portion21comprising an optical fiber color such as blue or red, and at least one adjacent colored portion22comprising a relatively distinct color such as black or white. In exemplary embodiments, colored portion22is disposed in alignment with exemplary line L1, for example, and colored portion22can take the form of a continuous or intermittent stripe or line of constant or varying width. In other exemplary embodiments described herein, colored portion22, is disposed in relation to the first reference section, for example, colored portion18. Colored portion22is adjacent to coating portion21in the sense that, for example, colored portion22is applied to the surface of, or is alternatively co-extruded with, coating portion21, as is further described below. The color distinction between portions20and21is observable, during a connector attachment process, by an operator with or without specialized equipment such as optical magnification or illumination equipment. As an alternative to co-extrusion, at least one colored portion22can be applied, in an adjacent sense, integrally with the thickness of coating21, or applied to a surface of the coating layer with one or more applicators36(FIGS. 3-4) for example printing devices, for example, ink jet style printers. An applicator can form, for example, a continuous or intermittent line with dots and dashes and combinations thereof. In exemplary embodiments, the applicator can be located between a coating die and a UV-light curing device as further described below (FIG. 4).

In further exemplary embodiments, colored portion22can be aligned with an axis of the core elements as shown with reference to exemplary line L2(FIG. 10) above core elements14,15,16,17, for example, at an angle of about 90 degrees relative to line L1. The location and composition of colored portion22, and additional colored portions22, can be added as desired, and can be disposed at various locations relative to, for example, the center of marked MCF20to facilitate the operator's requirements as needed. In other words, the reference sections can be placed at various radial locations, for example, a marked MCF20can have at least one colored portion18aligned with line L2(FIG. 10) and at least one colored portion22aligned with line L1(FIG. 2), or both colored portions18,22can be aligned with line L2(FIG. 10). The angular precision of colored portion22relative to exemplary lines L1and L2can be adjusted depending on the requirements for the application in which it is used. In general, for the purposes of orienting marked MCF20with a connector or to identify the top of a fiber in production (FIGS. 11-13), in an exemplary embodiment, the angular accuracy can be on the order of, for example, +/−1 degree of arc.

FIG. 3depicts an exemplary glass optical fiber manufacturing process70such that the first reference section, for example, colored portion18is disposed on the optical fiber during the fiber drawing process forming a MCF component10. A draw tower for making multicore optical fiber includes a furnace72for heating a glass preform71having a multicore fiber construction, a diameter monitor73, and a cooling system74for cooling an uncoated multicore fiber75from a high furnace temperature to a lower temperature to allow application of, for example, UV curable acrylate coatings to protect the glass fiber from damage. Once the uncoated multicore fiber75, containing core elements14,15,16,17surrounded by clad11is cooled, coating system12is applied by a coating system77a, and is cured by exposure to appropriate energy, for example, respective UV light sources. Coating system77acomprises two stages, a first stage applying primary coating12afollowed by curing, and a second stage applying secondary coating12bfollowed by curing, thereby defining coating system12. In exemplary embodiments, both coatings comprise a UV curable acrylate mixture of monomers, oligomers, photoinitiators, and additives, and the mixtures are cured at respective curing stations. One such exemplary curing station78ais shown inFIG. 3. Relevant exemplary diameters for MCF component10include: cladding11at 125 μm, primary coating12aat 190 μm, and secondary coating12bat 245 μm which is the diameter of the coated multicore fiber such as MCF component10. Optionally, where extra diameter sizes are desired, the manufacturing line can include equipment applying a translucent or transparent coating portion21with a coating system77bwhich is cured by a single stage UV light station78b. The coated multicore optical fiber is pulled by tractor80in the general direction of arrow81. An optical fiber spin device79can be located below the coating curing unit78b. The fiber spin device has rotational elements engaging the fiber to allow twisting of the optical fiber back and forth.

Detection of core elements14,15,16,17is accomplished by monitoring their positions prior to applying the acrylate coatings to the multicore optical fiber. More specifically, prior to application of the coatings, an imaging and control system76,76a,76bprovides an energy beam source76emitting an energy beam of a wavelength “W”. The beam impinges on uncoated multicore fiber75and the beam is imaged by imaging device76a, the output thereof is sent to controller76bwhich outputs a control signal to fiber spin device79and an applicator36as shown and described with reference toFIG. 4. Controller76bis operative to control applicator36for control of application of the colored portion18. Fiber rotational alignment is accomplished by fiber spin device79as described above which, rather than imparting a random twist, is driven by controller76bto control angular alignment of the multicore optical fiber.

Colored portion18can be applied in a variety of locations to allow for variations in desired shapes and radial positions relative to the core elements. To further illustrate, colored portion18, as described with reference to applicator36(FIG. 4), can be applied in various stations along the manufacturing line70(FIG. 3) and still be controlled by controller76b. In other words, applicator36can apply the material comprising the first reference material, for example, colored portion18, onto a wet secondary coating12bat position82abetween coating system77aand curing station78a, onto a cured secondary coating12bat position82bbetween curing station78aand coating system77b, or by co-extrusion with secondary coating12b. Completion of the foregoing addition of colored portion18produces a MCF component10(FIG. 1).

Manufacturing considerations play a role in electing whether to run MCF component10to stock on a reel and adding a coating21and colored portion22with a separate process (FIG. 4), or to optionally add coating21and with a second reference for example a colored portion22with respect to the additional thickness process described above (FIG. 3). For example, in the optional process, colored portion22can be added to MCF component10by locating applicator36so that it applies the reference section onto a wet secondary coating comprising coating21at position82c(FIG. 3) between coating system77band curing station78b, or onto a cured secondary coating comprising coating21at position82dafter curing station78b. Combinations of the foregoing can be implemented as well, for example, where multiple applicators36are used in selected positions82a-82drespectively.

As to detection and tracking of core elements14,15,16,17in the process described above (FIG. 3), a first method involves the detection of the partial or complete absence of light by detector76a. For example, light at wavelength(s) W impinges onto uncoated fiber75and can pass or be absorbed by the germanium dopant which is part of the core elements. The measurement by detector76acan be done by optical imaging of a wavelength(s) of light that is highly absorbed by the germanium, causing a shadow or absence of such wavelength(s). With reference toFIG. 7, which shows transmission percent (axis Y) as a function of wavelength W measured in nanometers (axis X), germanium doped glass has a strong absorption of light at wavelengths shorter than approximately 270 nm as shown by curve C1. By comparison, strong absorption in silica glass SiO2 starts at significantly shorter wavelengths as shown by curve C2(reference for example Applied Optics Vol. 23, No. 24, 15 Dec. 1984), in other words, the silica absorption becomes appreciable at wavelengths shorter than approximately 180 nm. Zone S, generally disposed between wavelength W1of about 180 nm and wavelength W2of about 270 nm, represents an exemplary spectral region for detecting Germania doped optical core elements disposed in a transparent cladding of uncoated multicore fiber75.

Thus, shadowing measurements by the imaging control system76,76a,76bof the shadowing effects of the germania-doped cores14,15,16,17embedded within the silica cladding11are in generally in zone S at wavelengths W1, W2of between about 180 nm and 270 nm respectively. The transmittance, as a function of wavelength band W1,W2, and as associated with zone S, is in a range of about 80-90%. However, other transmissivities can be attained by adjusting the wavelength(s) used, for example, comprising a zone R (FIG. 7), having a wavelength of about W1and a relatively higher wavelength of about 300 nm resulting in a transmittance range of about 70-80% through uncoated multicore fiber75. Thus a minimum wavelength W1of about 180 nm can be employed with embodiments of the present disclosure. A number of commercially available light sources76are available in the exemplary wavelength range W1,W2, including lasers at 266, 257 and 244 nm. Non-laser light sources are also available, for example, which operate (at least partially) in the W1,W2region include Deuterium bulb (190-400 nm), Xenon (220-visible), and LED 240 nm, and available from Ocean Optics Inc.

At relatively short wavelengths, the germanium-doped cores can be caused to fluoresce and then be detected by imaging system76,76a,76b. This is possible as germanium-doped optical fibers and preforms can fluoresce at wavelength(s) W near 420 nm when excited by UV radiation at a wavelength below 350 nm, as discussed in “Ultraviolet-excited fluorescence in optical fibers and preforms”, Herman M. Presby, Applied Optics, Vol. 20, Issue 4, pp. 701-706 (1981). Both the absorption and fluorescence methods described above use ultraviolet light that will be largely absorbed by conventional fiber optic coatings so it is best to do these two measurements without any coatings in the optical path.

Thus light source76, detector76a, and controller76b, operating as an imaging system, are to be adjusted to detect and react to the light absorption or fluorescent characteristics of the dopant associated with the optical core elements, as in this exemplary embodiment, the germanium dopant. As another alternative, light can be transmitted laterally through the uncoated fiber75and the index of refraction differences can be detected, again, through interferometry or commercially available imaging techniques. In all of the methods, a characteristic absorption band, for example, between wavelengths W1,W2is to be programmed into and detected by the imaging system76,76a,76bthrough uncoated multicore fiber75.

To further illustrate,FIGS. 5 and 6illustrate exemplary core element measurement orientations at a position after cooling station74(FIG. 3).FIG. 5depicts light source76directing an energy beam such as light beam “W” comprising one or more detection wavelength(s) based on the known or characteristic absorption band, for example zones S and R, with wavelength boundaries W1,W2based on the relevant dopant of core elements14,15,16,17, for example, germanium, and cladding11(FIG. 7). Beam W transits cladding11between, for example, one or more rows of core elements14,15,16,17and shadowing of the detection wavelength(s) is detected by detector76a(FIG. 5). For example, detection of the maximum amplitude of detection wavelength of beam W received by detector76a, as the rotation of uncoated fiber75varies by control of fiber spin device79, indicates that beam W is generally parallel to the at least one row of core elements14,15,16,17, as is the case with line L1(FIGS. 1-2). On the other hand,FIG. 6depicts source76directing beam W toward outer cladding11, but the detection wavelength(s) W largely impinges upon, and is partially or wholly absorbed by, the dopant of core elements14,15,16,17. Consequently, the detection wavelength(s) W may not be detected by detector76a, or is otherwise at a minimum amplitude in the imaging system, as rotation of the uncoated fiber75varies, indicating that beam W is generally perpendicular to the at least one row of core elements, as is the case when the beam is essentially parallel to line L2(FIG. 10).

Detector76awill output the imaging information in either exemplary case (FIGS. 5 and 6) to controller76b. Controller76bcontains a programmable device such as a computer or microprocessor, and it will be programmed to, as one output control signal, adjust fiber spin device79to control the orientation of the multifiber fiber core with respect to the core element position as imaged, for example, as by rotation of the multifiber core to allow maximum detection wavelength values to impinge on detector76a. In other words, in the example shown inFIG. 5, controller76bwill control fiber spin device79so that the core elements14,15,16,17will be essentially parallel to beam W and line L2whereby colored portion18will be applied by applicator36to the top of the multicore fiber (FIGS. 1, 2, and 10). Alternatively, as mentioned above, applicator36can be integrated into coloring die77a, being a co-extrusion die, thereby co-extruding colored portion18with secondary coating12b. Colored portion18can be coextruded comprising a stripe of UV curable ink material(s) of essentially the same thickness as coating system12. In addition, applicator36can be mounted to be moved to different axial or radial locations relative to MCF component10. Multiple applicators36can be used so that, rather than a single line or dashed stripe being formed, a radial ring of ink can be applied to coating system12and combinations thereof. Moreover, the multicore fiber can have a series of stripes, dashes, rings, or a series of rings and stripes on its outer surface of various or similar colors and combinations thereof.

As discussed above, MCF component10may be made on draw line70, reeled, and sent to inventory in the factory. However, to further illustrate and describe the alternative process which takes as an input a MCF component10and produces a marked MCF20, reference is made toFIG. 4which depicts an exemplary manufacturing process including a marking line30. Marking line30is moving product generally in the direction of arrow “A”. Marking line30contains a scanning camera system31,32detecting energy such as visible wavelength light which light is reflecting from the surface of MCF component10. Camera system31,32thus detects colored portion18on the surface of MCF component10. This information is transmitted to controller34for tracking the orientation of the core elements in MCF component10. Exemplary controller, scanning cameras, and applicators are disclosed in U.S. Pat. Nos. 6,293,081, 5,904,037, and 5,729,966 of Corning Cable Systems which are relied upon and incorporated by reference herein.

To further explain the process, a caterpuller is a traction device with moving belts, having potentially variable speeds, arranged to frictionally engage an elongate article such as a fiber, cable, or cable components, and to draw or force the article in a generally rectilinear direction, for example, drawing an article off of a reel and propelling it toward an extrusion die. With reference toFIG. 4, a caterpuller33contains upper and lower drive belts33aand33brespectively. Upper drive belt33ahas a rotational drive that moves MCF component10through the process, and lower drive belt33bhas a lateral drive which causes MCF component10to roll or twist between belts33a,33b. Controller34adjusts the dispositions of caterpuller33based on inputs from detectors31,32such that the orientation of MCF component10, based on detection of colored portion18, is established and maintained in relation to core elements14,15,16,17. As such, MCF component10passes through a coloring die35that applies a UV curable layer defining coating portion21, for example, which can be translucent, transparent, or of a first color such as white, red, or orange. At least one applicator36applies a second material to coating portion21in the form of a stripe, dashed line, or combination thereof defining colored portion22, which is to be visually distinct from coating portion21, and thus portion22can be a second color for example, black or blue. The coating portion21and colored portion22are cured by a UV-light source37to produce a marked MCF20. Colored portion22defines a reference section for an operator's connector termination purposes, and, in this embodiment, the colored portion comprises a color that is, to an operator's observation, visually distinct from coating portion21.

In further exemplary embodiments, one or more marked MCF20can be constrained relative to a further layer of material such as an optical fiber ribbon matrix (FIG. 8) or a tight buffered cable jacket (FIG. 10). In such a case, an optional reference section can be added comprising a groove, dent, or colored portion, such as colored portion52(FIG. 8) and colored portion23a(FIG. 10), and which colored portion in each case is generally aligned with a respective colored portion22.

More specifically, groupings of MCFs20can be formed as a first example in the form of ribbon cable50(FIG. 8) with marked MCFs20aligned within the ribbon. Marked MCFs20are bonded together with a matrix material51, for example, a UV-light curable acrylate matrix. Colored portions22of each marked MCF20in optical fiber ribbon50can be generally aligned, for example, toward the same direction or side of the ribbon, such as toward the side of colored portion52. Alternatively, the colored portions22can be aligned in different directions within the same optical ribbon, for example, MCFs20that are to be utilized by an operator as transmit data (Tx) can be aligned toward one side of the optical fiber ribbon, and MCFs20that are to be utilized by an operator to receive data (Rx) can be aligned toward a different direction. Alignment variations, for example, can be set according to an angle α of about 45 from line L1or L2(FIG. 8).

Optical fiber ribbon50can be connectorized with multi-fiber connectors, for example, commercially available push on MPO or MTP® fiber optic connectors. As an alternative toFIG. 8, optical core elements can be arranged in a column format so that the optical core elements are generally aligned with line L2rather than line L1. An entire column of fiber will enable each fiber to be connected in the same orientation to transceivers on both the proximal and distal sides of the fiber ribbon. On a row by row basis, such as an optical ribbon50, a twist of the ribbon will arrange the optical fiber cores, and for a multicore fiber having columns and rows of optical core elements, a shuffle with a left to right mirror image transposition arrangement of the cores would maintain the optical core elements on the correct orientation at both ends.

FIG. 9shows an exemplary optical fiber ribbon manufacturing line60moving product generally in direction “B” with marked MCFs20having colored portions22generally aligned. This means the colored portions are within 0-45 degrees of each other relative to the top center of the optical fiber as angle α illustrates inFIG. 8. Process60has a series of fiber pay-off assemblies61, for example, four to six assemblies61, each supplying the aligned MCFs20into a coating die66which coats the marked MCFs20with matrix material51. The number of fiber pay-off assemblies61is determined by the number of marked MCFs20desired for the optical ribbon50being manufactured. For example, a 4-fiber ribbon would have four pay-offs61, and a 12-fiber ribbon would have twelve pay-offs61. Pay-off assemblies61each comprise a reel assembly that allows its marked MCF20to pay off under controlled tension. Scanning cameras64are positioned to observe marked MCFs20to determine the orientation of the colored section22and provide a feedback control signal65to a drive motor63that rotates the respective reel assemblies62to control the orientation of MCFs20. Matrix material51is in turn cured by a UV-light source67to produce optical fiber ribbon50with MCFs20having colored portions22, which as described above, can be aligned according to the same or different angles.

As described above, one or more marked MCF20scan be constrained relative to a further layer of material such as a tight buffered cable jacket (FIG. 10). In such a case, an optional reference section can be added comprising a groove, dent, or colored portion, such as colored portion23a(FIG. 10). Similar to the process of making optical fiber ribbon50, scanning cameras can be used to detect colored portion22and then an extrusion die would extrude a tight buffered cable jacket onto coating portion21, and another applicator36would apply the colored portion23a.

The foregoing embodiments allow for a single transceiver design to be used on both ends of marked MCF20, and it also allows operators assembling the parts to use the same termination procedure on either end of marked MCF20. For example, a proximal transceiver (not shown) may have two transmit ports T1and T2and two receive ports R1and R2. As viewed from the end of the transceiver, the ports would be arranged from left to right for example as T1, T2, R2, R1(FIG. 11). The outer two ports T1,R1define a two-way communication channel1and the inner two ports T2,R2define a two-way communication channel2. Marked MCF20with colored portion22positioned up in the proximate transceiver would place core element14in communication with a transmitter T1, core element15in communication with transmitter T2, core element16in communication with receiver R2, and core element17in communication with receiver R1. The distal end of the multicore fiber would be placed into the distal transceiver in the same orientation with colored portion22oriented in an up position which would align core element14with receiver R1and core element17with transmitter T1. Thus the signal from transmitter T1in the proximal transceiver will go to receiver R1in the distal transceiver via core element14. Likewise, the signal from transmitter T1in the distal transceiver will go to receiver R1in the proximal transceiver over core element17. When attaching a connector to marked MCF20, the connector is assembled with colored portion22toward the top of the connector on both ends of the fiber, which will ensure that the cores14,15,16,17are aligned with the correct ports.

To further illustrate, reference line L2is on a line of symmetry of marked MCF20that does not intersect any core elements, and optical core elements on the left hand side of line L2(FIG. 10) of marked MCF20, for example core elements14and15, have essentially a corresponding mirror image of core elements on the right side of line L2, for example, core elements16and17. In an exemplary embodiment, when the cable is in a loop of a 180 degree bend, as in a factory termination procedure, and as shown inFIG. 11, core elements14and15define a pair of corresponding core elements and core elements16and17also define a pair of corresponding core elements. Core elements14and15are above line L2and are disposed for optical communication with transmitters at the proximal end of the cable “P”. At a distal end of the cable “D”, core elements14,15are below line L2for optical communication with receivers. Similarly, core elements16and17are disposed at distal end D of marked MCF20above line L2for optical communication with transmitters, and they are below line L2for optical communication with receivers at the proximal end P of marked MCF20. In other words, each core element14,15,16,17is to be connected at each end P and D, for example, to respective optical connectors, which are in turn associated with transceivers. To accomplish the correct connections on both sides, for example, the same transceiver design can be used on both ends, and the operator is to make sure the at least one colored portion22is positioned indicating alignment of the optical elements with the optical connector. The relative positions of the transmitter and receiver do not need to be inverted thus simplifying the design and deployment of the transceivers. For example, colored portion22aligned with line L2is at the top at both ends of the fiber/cable and is to be aligned with a connector for termination.

As a further illustration, Marked MCF20can interface with connector portions25a,25bhaving respective angled polished ends20a,20bas shown inFIG. 12. Angular polished ends20a,20bare oriented relative to cores14,15,16,17in a way that the polished ends can be arranged for connection on either end P,D with devices such as connectors, a mid-span connector26, or transceivers. Line L2is generally in the plane of the angularly polished surfaces20a,20b, and line L1is aligned with the optical core elements14,15,16,17and transits the angled polish plane but is generally transverse to the plane of the angled polish. Line L1will form an angle relative to the angularly polished surface generally equal to the angle of the polish. The polish angle being, for example, an angle of about 8-9 degrees relative to line L1. Both ends P,D of marked MCF20can be prepared by the process of flock polishing. An exemplary flock polishing technique is described in U.S. Pat. No. 6,106,368 of Corning Cables Systems which is relied upon and incorporated herein by reference. For orientation of mating connector parts, the optical connector includes a key27(FIG. 13). In an exemplary embodiment, colored portion22is aligned with key27along the same axis, and line L2is generally aligned with key27as well. The disposition of key27is at an angle β relative to the optical core elements and line L1(FIG. 13), and angle β can be in the range of about 45 degrees to about 90 degrees. Colored portion18can be aligned with colored portion22(FIG. 10) or radially offset therefrom (FIG. 2). Both ends of marked MCF20can be attached to a respective fiber optic connecter, as described above, defining a jumper cable assembly, or only one end can be attached to a connector thereby defining a pigtail cable assembly. As described above, colored portions18and22can be in the non-aligned positions with respect to each other (FIG. 2) and during connectorization. In alternative embodiments, colored portion22will be on a first side of the proximal termination side, and on the opposing side of the distal termination side, and with colored portion18on the top in (FIG. 12), and coating21should be transparent or translucent so that colored portion18is observable therethrough.