Abstract:
A fiber optic cable can comprise a jacket enclosing an internal space. A member extending lengthwise within the space can provide two or more compartments. Each compartment can house a respective bundle of optical fibers that are color coded for distinguishing the fibers of an individual bundle from one another. Different compartments can house different number of optical fibers. The compartments can comprise indicia for distinguishing the compartments and/or the bundles from one another. The member can be formed by extrusion and can have removable or detachable fins. With the extruded member in a relaxed state, the compartments can be closed. A series of dies can insert the bundles of optical fibers in the compartments. The dies can manipulate the member to open the compartments for bundle insertion. Once the bundles are inserted in the respective compartments, the dies can release the member so the compartments close on the bundles.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This patent application claims priority under 35 U.S.C. §119 to U.S. Provisional Patent Application No. 61/460,790, entitled “Color Coded Fiber Optic Cable” and filed Jan. 7, 2011, the entire contents of which are hereby incorporated herein by reference. This patent application is related to the patent application entitled “Method and System for Fabricating Communication Cable With Distinguishable Fiber Bundles,” filed on the same day as the present application, the entire contents of which are hereby incorporated herein by reference. 
    
    
     FIELD OF THE TECHNOLOGY 
     The present technology relates to fiber optic cables and more specifically to a cable that incorporates indicia for distinguishing like bundles of optical fibers from one another, for example to facilitate cable servicing or installation or in manufacturing of pre-terminated fiber optic assemblies. 
     BACKGROUND 
     Fiber optic cables include one or more optical fibers or other optical waveguides that conduct optical signals, for example carrying voice, data, video, or other information. Small diameter cabling benefits data centers and other highly populated cabling systems by increasing the number of links between equipment in limited space. Air and cooling specifications for communications equipment rooms and data centers with dense electronic systems are stringent; and, as transmission speeds become faster, cooling demands typically increase. Therefore, compact links between electronics are generally desired. For example, to enhance the number and density of information channels, certain fiber optic cables include multiple bundles of optical fibers, with each bundle comprising two or more optical fibers. 
     The term “bundle,” as used herein, generally refers to a group, set, collection, assemblage, arrangement or cluster of items that are together (typically gathered together), and “bundles” is the plural form of “bundle.” The terms “fiber optic bundle” and “bundle of optical fibers” are used herein interchangeably. The terms “fiber optic bundles” and “bundles of optical fibers” are used herein interchangeably. 
     Accommodating new industry standards (for example the IEEE 100 Gigabits per second (“Gps”) standard known as IEEE 802.3ba, released Jun. 17, 2010, covering 100 Gbs Ethernet) can involve multifiber connectors. Terminating or otherwise servicing cables that include multiple bundles of optical fibers typically entails distinguishing the bundles from one another. With many conventional technologies, differentiating the bundles involves labor intensive procedures like transmitting and receiving test signals or “ringing” the cable. Accordingly, improved technology is needed for distinguishing bundles of optical fibers of a cable from one another. Improved technology is further needed for making fiber optic cables that may incorporate a means for distinguishing bundles within the cable. A capability addressing such a need, or some related deficiency in the art, would promote fiber optic communications. 
     SUMMARY 
     For a fiber optic cable with two or more groups of visually indistinguishable optical fibers, the present technology supports distinguishing the groups from one another. 
     In one aspect of the present invention, a fiber optic cable can comprise multiple bundles of optical fibers. The bundles can have a common visual appearance, so that they are visually indistinguishable from one another to an unaided eye of an installer, a field service professional, or a technician. The fiber optic cable can comprise compartments, one for each bundle. For a two-bundle cable, one bundle can be located in one compartment, and another bundle can be located in a different compartment. For a multi-bundle cable having more than two bundles of optical fibers, bundles can be located in different compartments. The compartments can have indicia that distinguish the compartments and/or the bundles from one another. Accordingly, such an installer, field service professional, or technician can visually distinguish the bundles from one another. The indicia can comprise one or more colors, symbols, markings, signs, letters, numbers, digits, words, writings, alphanumeric symbols, codes, coatings, dyes, inks, prints, or messages, to mention a few representative examples without limitation. 
     The term “indicia,” as used herein, generally refers to indications or distinguishing markings or signs. 
     The discussion of fiber optic cables presented in this summary is for illustrative purposes only. Various aspects of the present invention may be more clearly understood and appreciated from a review of the following detailed description of the disclosed embodiments and by reference to the drawings and the claims that follow. Moreover, other aspects, systems, methods, features, advantages, and objects of the present invention will become apparent to one with ordinary skill in the art upon examination of the following drawings and detailed description. It is intended that all such aspects, systems, methods, features, advantages, and objects are to be included within this description, are to be within the scope of the present invention, and are to be protected by the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a cross sectional illustration of an exemplary fiber optic cable incorporating technology for distinguishing between bundles of optical fibers in accordance with certain embodiments of the present invention. 
         FIG. 1B  is a cross sectional cutaway illustration of a component of an exemplary fiber optic cable incorporating technology for distinguishing between bundles of optical fibers in accordance with certain embodiments of the present invention. 
         FIG. 1C  is an illustration of a cross sectional shape of a component of an exemplary fiber optic cable incorporating technology for distinguishing between bundles of optical fibers in accordance with certain embodiments of the present invention. 
         FIG. 2  is an illustration of an exemplary system for making a fiber optic cable that incorporates technology for distinguishing bundles of optical fibers in accordance with certain embodiments of the present invention. 
         FIGS. 3A and 3B  (collectively  FIG. 3 ) are illustrations of an exemplary opening die of a system for making a fiber optic cable that incorporates technology for distinguishing bundles of optical fibers in accordance with certain embodiments of the present invention. 
         FIG. 4A  is an illustration of an exemplary closing die of a system for making a fiber optic cable that incorporates technology for distinguishing bundles of optical fibers in accordance with certain embodiments of the present invention. 
         FIG. 4B  is an illustration of a cross sectional shape of a component of an exemplary fiber optic cable incorporating technology for distinguishing between bundles of optical fibers, wherein the component is closed in a relaxed state in connection with cable fabrication, in accordance with certain embodiments of the present invention. 
         FIG. 4C  is an illustration of a cross sectional shape of a component of an exemplary fiber optic cable incorporating technology for distinguishing between bundles of optical fibers, wherein the component is open in a stressed state in connection with cable fabrication, in accordance with certain embodiments of the present invention. 
         FIG. 5  is an illustration of an exemplary guide plate of a system for making a fiber optic cable that incorporates technology for distinguishing bundles of optical fibers in accordance with certain embodiments of the present invention. 
         FIG. 6  is a flowchart for an exemplary process for making a fiber optic cable that incorporates technology for distinguishing bundles of optical fibers in accordance with certain embodiments of the present invention. 
         FIG. 7A  is a cross sectional illustration of an exemplary fiber optic cable incorporating technology for distinguishing among bundles of optical fibers in accordance with certain embodiments of the present invention. 
         FIG. 7B  is a cross sectional illustration of a component of an exemplary fiber optic cable incorporating technology for distinguishing among bundles of optical fibers in accordance with certain embodiments of the present invention. 
         FIG. 8  is a cross sectional illustration of an exemplary fiber optic cable incorporating technology for distinguishing among bundles of optical fibers in accordance with certain embodiments of the present invention. 
     
    
    
     Many aspects of the invention can be better understood with reference to the above drawings. The elements and features shown in the drawings are not to scale, emphasis instead being placed upon clearly illustrating the principles of exemplary embodiments of the present invention. Moreover, certain dimensions may be exaggerated to help convey such principles visually. In the drawings, reference numerals designate like or corresponding, but not necessarily identical, elements throughout the several views. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     In accordance with certain exemplary embodiments of the present invention, a fiber optic cable can comprise two bundles of color-coded optical fibers or more than two bundles of optical fibers. One of skill in the art having benefit of this disclosure will appreciate that embodiments disclosed herein support more than two bundles and will further appreciate that the present disclosure teaches multiple cable embodiments that each comprises three, four, five, six, seven, eight, nine, ten, twenty, thirty, forty, etc. bundles of optical fibers. The optical fibers of the first bundle can have different colors, such that each of those fibers can be visually distinguished from one another. The optical fibers of the second bundle can have different colors, such that each of those fibers can be visually distinguished from one another. Each optical fiber in the first bundle can have a counterpart in the second bundle that has a common coloring. That is, each optical fiber in the first bundle can have a like colored, visually indistinguishable, optical fiber in the second bundle. The cable can comprise a separator that separates the two bundles, each in a different compartment. The two compartments can be color coded, to facilitate visually distinguishing the bundles, and thus the fibers, from one another. For example, the walls of the compartments can be colored differently, the separator can have one side colored different than the other side, and/or colored yarn or another visually distinguishable elongated item can be added to or integrated with one or both bundles or compartments. 
     The exterior jacket of the fiber optic cable can appear similar to conventional interconnect cables available on the market. In certain embodiments, the jacket is made from a low-smoke flame retardant material, for example polyvinyl chloride (“PVC”). The separator within the fiber optic cable can comprise a thin, formed barrier. The separator can likewise be made by extruding a low-smoke flame retardant material. In certain embodiments, the separator can comprise non-woven or woven textile or plastic tape or tapes. 
     Depending on the number of fiber bundles within the cable, the shape of the separator can vary. For cables with 24 fibers, the shape can be S-like, in order to create two opposing spaces for the fibers within the cable. In certain embodiments, the separator can be pinwheel shaped and may accommodate for than 24 fibers. 
     In certain embodiments the cable can comprise self-identifying groups. In a set of 12 optical fibers, the fibers can be grouped in four compartments, as such: first 4 fibers of first set (blue, orange, green, brown) in first compartment; 8 fibers of first set (slate, white, red, black, yellow, violet, rose, aqua) in second compartment; first 8 fibers of second set (blue, orange, green, brown, slate, white, red, black) in third compartment; last 4 fibers of second set (yellow, violet, rose, aqua) in fourth compartment. Because of the colors (first 4, last 8; first 8, last 4) in the groupings of fiber, they are identifiable sans indicia. 
     The optical fibers can be wrapped in flame-retardant polyester or aramid yarns, or similar materials. The separator can incorporate indicia for differentiating between or among bundles within the fiber optic cable. In certain embodiments, the indicia can comprise color, print, or another means of differentiation for the optical fibers in each compartment. For example, the separator can be colored or printed on one side to distinguish the first bundle, and not printed or colored, or have a different color, on the other side. The separator may also be a coextruded shape within the cable jacket, made of the same or different material than the jacket. The free space in the inside of the fiber optic cable can be empty for free fiber movement or filled with an appropriate type of yarn or filler material. 
     In accordance with certain exemplary embodiments of the present invention, data center cabling can support 12- or 24-fiber array connectorization. Fiber optic cables of very small diameter can be manufactured with separated bundles of colored optical fibers, without necessarily tubing the bundles. In accordance with certain exemplary embodiments of the present invention, a fiber optic cable complies with the IEEE 100 Gps standard known as IEEE 802.3ba, released Jun. 17, 2010, covering 100 Gbs Ethernet. 
     In accordance with certain exemplary embodiments of the present invention, a fiber optic cable can support connectorization of 24-fiber multi-fiber push on (“MPO”) style connectors, and can offer the added benefit of managing polarity via the connectors. The optical fibers of such a fiber optic cable can be loose rather than in ribbon form. In an exemplary tubing-free embodiment, a color-coded separator not only segregates two groups of twelve, but also enhances cable strength. 
     Cabling technology will now be discussed more fully hereinafter with reference to  FIGS. 1A-8 , which illustrate representative embodiments of the present invention.  FIGS. 1A ,  1 B, and  1 C (collectively  FIG. 1 ) describe certain embodiments in which an S-shaped member comprises indicia for distinguishing between two bundles of optical fibers.  FIGS. 2-6  describe a system and method for manufacturing the fiber optic cable that  FIG. 1  illustrates.  FIGS. 7A and 7B  (collectively  FIG. 7 ) and  FIG. 8  describe embodiments in which a cross- or pinwheel-shaped member comprises four compartments and indicia for distinguishing among bundles of optical fibers. 
     The invention can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those having ordinary skill in the art. Furthermore, all “examples” or “exemplary embodiments” given herein are intended to be non-limiting, and among others supported by representations of the present invention. 
     Turning now to  FIGS. 1A and 1B ,  FIG. 1A  illustrates in cross section a fiber optic cable  100  incorporating technology for distinguishing between bundles of optical fibers  105  ( 105   a  and  105   b ).  FIG. 1B  illustrates a component of the fiber optic cable  100  in cross sectional cutaway according to certain exemplary embodiments of the present invention. In one exemplary embodiment, the fiber optic cable  100  can be characterized as an optical fiber non-conductive plenum (“OFNP”) cable. 
     The jacket  115  of the fiber optic cable  100  forms an outer, cylindrical surface that provides environmental protection, including a moisture barrier, for the bundles of optical fibers  105 . The jacket  115  can further impart the fiber optic cable  100  with strength and structural integrity. In the illustrated embodiment, the jacket  115  can be characterized as a sheath or a casing. In one exemplary embodiment, the jacket  115  has a wall thickness of approximately 0.65 millimeters (“mm”)+/−0.005 mm. In one exemplary embodiment, the jacket  115  has an outer diameter of approximately 4.9 mm and an inner diameter of approximately 3.7 mm. However, the present technology is applicable to a wide variety of dimensions. 
     In certain exemplary embodiments, the jacket  115  is made from PVC with smoke and/or flame suppressing or retarding additives. The jacket  115  can have a polymer or polymeric composition, for example a fluoropolymer such as FEP, TFE, PTFE, PFA, etc.; or another polymer such as olefin, polyester, silicone, polypropylene, polyethylene, medium density polyethylene, or polyimide; or some other polymer or other material that provides acceptable strength, fire resistance, or abrasion and chemical properties as may be desirable for various applications. Certain exemplary embodiments comprise thermoplastic material while other embodiments can comprise thermosetting plastic. 
     Certain exemplary embodiments of the jacket  115  can be characterized as comprising polymeric material. The term “polymeric material,” as used herein, generally refers to a material that comprises one or more polymers. Accordingly, a jacket of polymeric material can comprise one or more polymers and one or more additional, non-polymer materials. 
     Strength fibers  145  located under the jacket  115  extend lengthwise to enhance strength of the fiber optic cable  100 . The strength fibers  145  may further provide a cushioning effect that mitigates contact between the bundles of optical fibers  105  and the jacket  145 , thereby improving signal quality. 
     In certain embodiments, the strength fibers  145  comprise yarns, threads, or filaments of aramid material or another material that strengthens the fiber optic cable  100 . In certain embodiments, the strength fibers  145  form a well defined ring when viewed in cross section as illustrated in  FIG. 1A . Alternatively, the strength fibers  145  can be substantially dispersed throughout the interior of the fiber optic cable  100 . In one exemplary embodiment, the strength fibers  145  are aramid yarns, 9×1420 denier. 
     In certain embodiments, the strength fibers  145  extend helically down the fiber optic cable  100 . In certain applications, orienting the strength fibers  145  along the fiber optic cable&#39;s longitudinal axis, rather than helically wound, avoids the strength fibers  145  constricting the bundles of optical fibers  105  when the fiber optic cable  100  is strained. 
     In certain embodiments, the strength fibers  145  are water-swellable, for example water swellable yarn comprising particles of super absorbent material that cling to yarn filaments. The term “water-swellable yarn,” as used herein, generally refers to a yarn that comprises a super absorbent polymer, with the term encompassing yarn in which super absorbent polymer clings to a yarn surface. Yarn may comprise one or more threads, filaments, cords, ropes, fibrous materials, fibers, strands, or similar structures that may include manmade or natural materials. In certain exemplary embodiments, the particles of super absorbent material cling without any adhesives, binders, cured materials, or wetted surfaces. The superabsorbent material chemically reacts with water, when present. However, in certain exemplary embodiments, the superabsorbent material is insoluble (or essentially insoluble) in water. 
     In one exemplary embodiment, the superabsorbent material comprises sodium polyacrylate powder. The term “super absorbent polymer” or “SAP,” as used herein, generally refers to a material that can absorb or otherwise capture at least 50 times its weight in water (including without limitation liquid and vapor forms of water) or a liquid. Polyacrylonitrile starch graft polymer, saponified polyacrylonitrile starch graft polymer, polyacrylamide, and sodium polyacrylate are examples of SAP; however, this is not an exhaustive list. Typically, SAP swells or may assume a gelatinous state in the presence of water, thereby absorbing the water. SAP materials may have a granular or powder form, may be beads, or may have a variety of shapes. Many SAP materials can absorb 100 times their weight in water. 
     In certain exemplary embodiments, the strength fibers  145  are replaced by or augmented with a film or tape of fire resistant material, such as the materials sold by DuPont under the identifiers KAPTON and NOMEX. 
     In addition to strength fibers  145 , the illustrated fiber optic cable  100  comprises a flexible member  125  that extends lengthwise along the axis of the cable  100 . In the illustrated embodiment, the flexible member  125  is S-shaped when viewed in cross section. That is, the flexible member  125  has a form generally resembling the letter “S” when viewed in cross section. 
     The flexible member  125  provides two compartments  107  ( 107   a  and  107   b ), each containing one of the bundles of optical fibers  105 . In various embodiments, the compartments  107  can comprise cavities, chambers, enclosures, slots, cells, pockets, nooks, and so forth, to mention a few representative examples without limitation. 
     The term “compartment,” as used herein, generally refers to a space, region, or area that has been dedicated, sectioned off, or partitioned, separated, or divided with respect to a larger space, region, or area. 
     The flexible member  125  can be characterized as a separator, an organizer, a partition, a sectioning member, and/or a divider. In the illustrated embodiment, the flexible member  125  curls over, curls around, and extends partially around the bundle of optical fibers  105   a  and the bundle of optical fibers  105   b . The flexible member  125  can be characterized as forming, producing, providing, defining, framing, and/or creating the compartments  107 . 
     As shown in  FIG. 1B , the flexible member  125  comprises two surfaces  127   a  and  127   b . The surface  127   a  faces and adjoins the compartment  107   a  and the bundle of optical fibers  105   a  that is in that compartment  107   a . The surface  127   b  faces and adjoins the compartment  107   b  and the bundle of optical fibers  105   b  that is in that compartment  107   b.    
     At least one of the surfaces  127   a  and  127   b  comprises indicia for distinguishing the compartments  107   a  and  107   b  and the associated bundles of optical fibers  107   a  and  107   b . In the illustrated embodiment, the indicia comprises different colors. For example, the surface  127   a  can be violet, while the surface  127   b  can be black. In various embodiments, the different colors can be violet, purple, blue, green, yellow, gold, pink, red, black, white, gray, or silver, to mention a few representative possibilities without limitation. In certain embodiments, one of the surfaces  127   a  and  127   b  is colored while the other surface  127   a  and  127   b  is the color of the base material of the flexible member  125 . In certain embodiments, the indicia comprises a distinguishing pattern of colors, for example a blue background with red stripes. In various embodiments, the indicia can comprise symbols, markings, signs, letters, numbers, digits, words, writings, alphanumeric symbols, codes, coatings, stripes, patterns, dyes, inks, prints, messages, or some other appropriate means for distinguishing the bundles of optical fibers  105   a  and  105   b  from one another.  FIG. 1B  illustrates one representative example where the words “BUNDLE ONE”  128   a  AND “BUNDLE TWO”  128   b  are respectively printed on the surfaces  127   a  and  127   b  as distinguishing markings. 
     In certain embodiments, each bundle of optical fibers  105  uses a common color coding scheme to support visual fiber-to-fiber differentiation within a single bundle  105 . With such a color coding scenario, the bundles  105  can be visually indistinguishable yet differentiated by the indicia on one or more of the surfaces  127   a  and  127   b.    
     In certain embodiments, the bundles of optical fibers  105  are disposed randomly and loosely in the compartments  107 . In certain embodiments, each bundle of optical fibers  105  is organized, for example in one or more linear arrays or “ribbons.” In certain embodiments, each bundle of optical fibers  105  comprises multiple ribbons of optical fibers  105  stacked on top of one another. 
     The illustrated number of optical fibers in each bundle of optical fibers  105  and the illustrated configuration are intended to be exemplary rather than limiting. The optical fibers may be bound to one another in units of twelve, or may alternatively be loose and relatively unstructured. 
     The bundles of optical fiber  105  can be single mode fiber or some other optical waveguide that carries communications data. In various exemplary embodiments, the bundles of optical fibers  105  can be single mode or multimode and can have a composition based on glass, glassy, or silica material. Alternatively, the bundles of optical fibers  105  can incorporate plastic material as an optical transmission medium. 
     While the illustrated cable embodiment can be characterized as buffer tube free, other embodiments, may incorporate buffer tubes. The term “buffer tube,” as used herein, generally refers to a tube within a cable for containing one or more optical fibers and for providing such optical fibers annular space for lateral movement. When a fiber optic cable is bent, optical fibers in a buffer tube of the cable may shift toward one side of the buffer tube, for example. 
     In certain exemplary embodiments, the flexible member  125  is made from PVC with smoke and/or flame suppressing or retarding additives. The flexible member  125  can have a polymer or polymeric composition, for example a fluoropolymer such as FEP, TFE, PTFE, PFA, etc.; or another polymer such as olefin, polyester, silicone, polypropylene, polyethylene, medium density polyethylene, or polyimide; or some other polymer or other material that provides acceptable strength, fire resistance, or abrasion and chemical properties as may be desirable for various applications. Certain exemplary embodiments comprise thermoplastic material while other embodiments can comprise thermosetting plastic. 
     In certain exemplary embodiments, the flexible member  125  comprises an inorganic material, such as glass fiber. In certain exemplary embodiments, the flexible member  125  comprises an organic material. In certain exemplary embodiments, the flexible member  125  comprises a polymeric material. In certain exemplary embodiments, the flexible member  125  comprises aramid fibers. In certain exemplary embodiments, the flexible member  125  comprises natural fiber, such as cotton, wool, animal fiber, sisal, hemp, or plant fiber, to mention a few representative examples. 
     Turning now to  FIG. 1C , this figure illustrates a cross sectional shape of a component of a fiber optic cable incorporating technology for distinguishing between bundles of optical fibers according to certain exemplary embodiments of the present invention. More specifically,  FIG. 1C  illustrates a cross sectional shape for a flexible member  126  that provides an alternative geometric form relative to the flexible member  125  illustrated in  FIGS. 1A and 1B  and discussed above. 
     The flexible member  126 , which typically incorporates bundle distinguishing technology as discussed above, is S-shaped. In this embodiment, the top and the bottom of the “S” are relatively flat so that they may deviate in form from the interior surface of the jacket  115  (see  FIG. 1 ). The outer profile of the flexible member  126  can be viewed as square with rounded corners. 
     Turning now to  FIGS. 2 ,  3 ,  4 , and  5 , these figures describe exemplary tooling for fabricating an embodiment of the fiber optic cable  100  as illustrated in  FIG. 1  and discussed above.  FIG. 2  illustrates an exemplary system  200  for making a fiber optic cable that incorporates technology for distinguishing bundles of optical fibers according to certain exemplary embodiments of the present invention.  FIGS. 3 ,  4 A, and  5  respectively illustrate an opening die  230 , a closing die  240 , and a guide plate  250  of the system  100  according to certain exemplary embodiments of the present invention.  FIGS. 4B and 4C  respectively illustrate cross sectional profiles of the flexible member  125  closed in a relaxed state  125 A and open in a stressed state  125 B in connection with cable fabrication according to certain exemplary embodiments of the present invention. 
     Referring to  FIG. 2 , the two bundles of optical fibers  105   a  and  105   b  and the flexible member  125  feed into the system  200  from the right as separate elements, are integrated as they flow though the system  200 , and emerge on the left as an integrated unit. In certain embodiments, the bundles of optical fibers  105   a  and  105   b  and the flexible member  125  may feed in the opposite direction. That is the bundles of optical fibers  105   a  and  105   b  and the flexible member  125  can enter from the left and exit on the right. 
     As illustrated in  FIG. 5 , each guide plate  250  comprises a center hole  540  through which the flexible member  125  passes and two lateral holes  550 , one for the bundle of optical fibers  105   a , and one for the bundle of optical fibers  105   b . In certain embodiments, the center hole  540  is oval or oblong, while in other embodiments, the center hole  540  can be square with rounded corners or substantially circular. As discussed in further detail below, the guide plates  250  can rotate in connection with creating twist or providing excess fiber length. 
     As illustrated in  FIG. 3 , the opening die  230  has an entry side  350  facing the guide plates  250  (upstream) and an exit side  351  facing the closing die  240  (downstream). From the entry side  350 , the flexible member  125  passes through the hole  320  that has a shape substantially matching the flexible member  125 , in this case S-shaped. 
     While S-shaped, relative to the flexible member  125 , the shape of the hole  320  of the opening die  230  is stretched or somewhat flattened. That is, the S shape has been opened to facilitate placement of the bundles of optical fibers  105   a  and  105   b  into the compartments  107   a  and  107   b . Prior to entering the hole  320 , the flexible member  125  is in a relaxed state  125 A as illustrated in  FIG. 4B . The hole  320  applies forces to the flexible member  125  to place the flexible member  125  in an open or stressed state  125 B as illustrated in  FIG. 4C . Thus, the hole  320  can be viewed as spreading, distorting, reconfiguring, or reorienting the flexible member  125 . When the flexible member exits the hole  320 , the flexible member  125  springs back to the relaxed state  125 , and the compartments  107   a  and  107   b  close. 
     The hole  320  is enlarged relative to the flexible member  125  to facilitate transmission of the S-shaped member while maintaining the flexible member  125  in a specified orientation. Thus, the flexible member  125  has a level of play within the hole  320  to avoid binding. 
     Each of the bundles of optical fibers  105   a  and  105   b  passes through one of the holes  310 . The holes  310  move the flowing bundles of optical fibers  105   a  and  105   b  into the respective compartments  107   a  and  107   b  of the flexible member  125  to provide the general configuration illustrated in  FIG. 1A  and discussed above. To move the bundles of optical fibers  105   a  and  105   b  into position, the axis of each of the holes  320  is tilted relative to the flat surface or face of the opening die  230 . The tilting hole axes translate the flowing bundles of optical fibers  105   a  and  105   b  into their respective compartments  107   a  and  107   b . The holes  310  also neck down to facilitate bundle translation and to avoid bundle damage. That is, each of the holes  310  has a larger diameter on the entry side  350  of the opening die  230  than on the closing side  351  of the opening die  230 . 
     As the flexible member  125  and bundles of optical fibers  105   a  and  105   b  exit the opening die  230 , the flexible member  125  springs back from the flattened state caused by the elongate form of the hole  320  and returns to a relaxed state as shown in  FIGS. 1A and 1B  and in  FIG. 4B . Accordingly, the flexible member  125  embraces, captures, and retains the bundles of optical fibers  105   a  and  105   b . As illustrated in  FIG. 4A , the closing die  240  has a single hole  440  through which the integrated unit of the flexible member  125  and the two bundles of optical fibers  105   a  and  105   b  passes. 
     As discussed further below, in certain exemplary embodiments, twisting motion of tooling within the system  200  produces a helical oscillation of that integrated unit. 
     The strength fibers  145  are disposed around that integrated unit, which can be characterized as a cable core, and the jacket  115  is extruded applied over the result to form the fiber optic cable  100  as illustrated in  FIG. 1  and discussed above. 
     Turning now to  FIG. 6 , this figure illustrates a flowchart for a process  600  for making a fiber optic cable  100  that incorporates technology for distinguishing bundles of optical fibers  105  according to certain exemplary embodiments of the present invention.  FIG. 6  will be discussed with exemplary reference to the foregoing figures and embodiments, without limitation. 
     At step  605  of process  600 , which is entitled Manufacture Fiber Optic Cable, an extruder forms the flexible member  605 , typically in a continuous process. In certain embodiments, bundle distinguishing colors can be applied to the flexible member  605  after the flexible member  605  exits the extruder, or alternatively by applying a layer of colored thermoplastic within the extruder tip. 
     At step  610  of process  600 , the flexible member  125  and the bundles of optical fibers  105   a  and  105   b  flow or feed into a tool, such as the system  200  illustrated in  FIG. 2  and discussed above. In certain embodiments, bundle distinguishing colors or writing is applied to the flexible member  125  before, at, or after entry in the tool. In certain exemplary embodiments, fiber tension is between about 50 and 300 grams, with payoff tension in a range of 100 to 5000 grams, for example. 
     At step  615 , the tool applies rotation to create excess fiber length and/or to mitigate fiber stress in the finished fiber optic cable  100 . 
     In certain exemplary embodiments, each guide plate  250  (which is a type of tool in and of itself) rotates based on machine settings entered for overall twist lay and number of turns. The guide plates  250  can rotate individually but in synchronization. The rotation can comprise “SZ” oscillation, whereby fibers coil helically clockwise for a specified cable length, counterclockwise for another specified cable length, clockwise for another specified cable length, and so forth. Typical lay length can be in a range of 400 millimeters (mm) to 1600 mm, with the number of turns in a range of 1 to 10 for example. 
     In certain exemplary embodiments, helical rotation of the bundles of optical fibers  105   a  and  105   b  and the flexible member  125  is substantially constant along the cable length. Typical lay length can be in a range of 400 to 1600 mm, for example. 
     In certain exemplary embodiments, the tool operates without applying any intended rotation or oscillation to the bundles of optical fibers  105   a  and  105   b  and the flexible member  125 . 
     At step  620 , the tool opens the compartments  107   a  and  107   b  of the flexible member  125 . As discussed above with reference to  FIGS. 3A ,  3 B,  4 A,  4 B, and  4 C the opening die  230 , which is a tool in and of itself, can receive the flexible member  125  in a closed or relaxed state  125 A and apply forces to the flexible member  125  to distort the flexible member  125  into an open or stressed state  125 C. Accordingly, the compartments  107   a  and  107   b  are open and configured for receiving the bundles of optical fibers  105   a  and  105   b.    
     At step  625 , the tool feeds the bundles of optical fibers  105   a  and  105   b  into the opened compartments  107   a  and  107   b . As discussed above, the opening die  230  can comprise holes  310  that are oriented for translating the bundles of optical fibers  105   a  and  105   b  into the opened compartments  107   a  and  107   b.    
     At step  630 , the flexible member  125  and the bundles of optical fibers  105   a  and  105   b  exit the opening die  230  and are received by the closing die  240 , passing through the hole  440 . Accordingly, the stress and force applied by the opening die  230  are relieved, reduced, and/or eliminated. In response, the flexible member  125  springs back to the closed or relaxed state  125 B as illustrated in  FIG. 4B , and the compartments  107   a  and  107   b  close on the bundles of optical fibers  105   a  and  105   b . Accordingly, the flexible member  125  captures the bundles of optical fibers  105   a  and  105   b , providing a cable core as illustrated in  FIG. 1A . 
     At step  635 , a yarn server serves yarns around the flexible member  125  and the captured bundles of optical fibers  105   a  and  105   b . In an exemplary embodiment, two to eighteen yarns are applied with a tension range of 100 to 300 grams, for example. Lay length can be in a range of 100 to 400 mm, for example. Helically, counter-helically, or longitudinally served yarns can be utilized. 
     At step  640 , the jacket  115  is extruded over the yarns to form the finished fiber optic cable  100 , as illustrated in  FIG. 1 . 
     Since in certain embodiments, the flexible member  125  may be made of a material that melts at the same or lower temperature of the extruder head, techniques can be employed to prevent breakout upon startup of jacket extrusion. In certain exemplary embodiments, startup of jacketing extrusion proceeds with an aramid tie that secures the bundles of optical fibers  105  and the flexible member  125  to one another and to a start line. The core of the cable to be manufactured can be tied to a pull cord or previously made cable&#39;s tail, to facilitate rapid run set up. Due to a potential low melt temperature of the flexible member  125 , the aramid yarns can be fed through the extrusion crosshead and tied onto the pull rope or cable beyond the extruder crosshead. The bundles of optical fibers  105  and the flexible member  125  can then be secured to the aramid yarns via tape, glue or other attachment mechanism. The extruder can then be started and the take up activated. This technique can help avoid breaks of the flexible member  125  during jacket extrusion. 
     Process  100  can iterate from step  640  to step  605  or  610  for continuous or semi-continuous process flow, for example. 
     Turning now to  FIG. 7 ,  FIG. 7A  illustrates in cross section a fiber optic cable  700  incorporating technology for distinguishing among bundles of optical fibers  105  ( 105   a ,  105   b ,  105   c , and  105   d ), and  FIG. 7B  illustrates a component of the fiber optic cable  700  in cross section according to certain exemplary embodiments of the present invention. In the illustrated embodiment, that component is a flexible member  735  that extends lengthwise along a longitudinal axis  750  of the fiber optic cable  700 . 
     In the embodiment of  FIG. 7 , the illustrated flexible member  735  comprises four fins  731 ,  732 ,  733 ,  734  that form four compartments  107   a ,  107   b ,  107   c ,  107   d  for four bundles of optical fibers  105   a ,  105   b ,  105   c ,  105   d . Various forms of the flexible member  735  can comprise fewer or more fins. For example, certain embodiments can comprise two, three, five, six, seven, eight, nine, ten, or more than ten fins. In one exemplary embodiment, each of the fins  731 ,  732 ,  733 ,  734  has a thickness in a range of about 0.35 mm to about 0.6 mm, for example 0.52 mm. The flexible member  735  provides one example of a pinwheel shaped cross section. 
     The term “fin,” as used herein, generally refers to an elongate strip or ribbon of material having one edge running or extending along a surface of a substrate or member or base and another edge raised with respect to or projecting from the surface; and, as used herein, the term “fin” is broad enough to cover an element or feature resembling a fin of a fish, a thin projection or ridge that extends lengthwise, and a feature that resembles a fin of a heat sink. 
     Various embodiments of the fiber optic cable  700  can have fewer or more compartments  107  than the illustrated number and/or few or more bundles of optical fibers  105  than the illustrated number. For example, certain embodiments can comprise two, three, five, six, seven, eight, nine, ten, or more than ten bundles of optical fibers  105 . Certain embodiments can comprise two, three, five, six, seven, eight, nine, ten, or more than ten compartments  107 . 
     As illustrated, the fiber optic cable  700  has a common number of compartments  107 , bundles of optical fibers  105 , and fins  731 ,  732 ,  733 ,  734 . However, many other configurations are supported. 
     Certain embodiments of the fiber optic cable  700  have more fins  731 ,  732 ,  733 ,  734  than bundles of optical fibers  105 . Certain embodiments of the fiber optic cable  700  have more bundles of optical fibers  105  than fins  731 ,  732 ,  733 ,  734 . 
     Certain embodiments of the fiber optic cable  700  have more fins  731 ,  732 ,  733 ,  734  than compartments  107 . Certain embodiments of the fiber optic cable  700  have more compartments  107  than fins  731 ,  732 ,  733 ,  734 . 
     Certain embodiments of the fiber optic cable  700  have more compartments  107  than bundles of optical fibers  105 . Certain embodiments of the fiber optic cable  700  have more bundles of optical fibers  105  than compartments  107 . 
     In the illustrated embodiment, each fin  731 ,  732 ,  733 ,  734  curls to extend laterally or circumferentially over, forming a respective compartment  107   a ,  107   b ,  107   c ,  107   d , each of which houses a respective bundle of optical fibers  105   a ,  105   b ,  105   c ,  105   d . As discussed above, the bundles of optical fibers  105   a ,  105   b ,  105   c ,  105   d  can be visually indistinguishable from one another. Further, the compartments  107   a ,  107   b ,  107   c ,  107   d  can have indistinguishable sizes and shapes. Accordingly, in an exemplary embodiment, a person looking at the fiber optic cable  725  with unaided eye may find the bundles of optical fibers  105   a ,  105   b ,  105   c ,  105   d  indistinguishable based on size and shape of the flexible member  725  and based on the bundles  105   a ,  105   b ,  105   c ,  105   d  themselves. As discussed in further detail below, the flexible member  725  comprises indicia distinguishing the bundles of optical fibers  105   a ,  105   b ,  105   c ,  105   d.    
     The fin  731  provides the compartment  107   a  for the bundle of optical fibers  105   a . The fin  732  provides the compartment  107   b  for the bundle of optical fibers  105   b . The fin  733  provides the compartment  107   c  for the bundle of optical fibers  105   c . The fin  734  provides the compartment  107   d  for the bundle of optical fibers  105   d.    
     The flexible member  725  comprises indicia distinguishing at least one of the bundles of optical fibers  105  from another one of the bundles of optical fibers  105 . In certain embodiments, the flexible member  725  can comprise indicia distinguishing the bundle of optical fibers  105   a  from the bundle of optical fibers  105   b  without distinguishing other bundles of optical fibers  105   c ,  105   d . In certain embodiments, the flexible member  725  comprises indicia distinguishes all of the bundles of optical fibers  105   a ,  105   b ,  105   c ,  105   d  from one another. 
     In certain exemplary embodiments, the indicia comprises different colors applied to the surfaces  731   a ,  731   b ,  732   a ,  732   b ,  733   a ,  733   b ,  734   a ,  734   b . In certain embodiments, each of those surfaces  731   a ,  731   b ,  732   a ,  732   b ,  733   a ,  733   b ,  734   a ,  734   b  has a different color. In one exemplary embodiments, the surfaces  731   b  and  734   a  are blue, the surfaces  731   a  and  732   b  are red, the surfaces  732   a  and  733   b  are green, and the surfaces  733   a  and  734   b  are orange. 
     In various embodiments, indicia on one or more of the surfaces  731   a ,  731   b ,  732   a ,  732   b ,  733   a ,  733   b ,  734   a ,  734   b  comprises one or more symbols, markings, signs, letters, numbers, digits, words, writings, alphanumeric symbols, codes, coatings, stripes, patterns, dyes, inks, prints, or messages. Accordingly, a person can visually distinguish otherwise indistinguishable bundles of optical fibers  105 . 
     In certain embodiments, the fins  731  and  733  are substantially thicker than the fins  732  and  734 . In such embodiments, the compartment  107   a  may house eight optical fibers, the compartment  107   b  may house four optical fibers, the compartment  107   c  may house four optical fibers, and the compartment  107   d  may house eight optical fibers, for example. 
     In certain embodiments, the fins  732  and  734  can be notched at the base to facilitate technician breakaway. In this manner a technician can readily remove a terminal section of the fins  732  and  734  to consolidate the four groups of fibers into two groups for connectorization. In certain embodiment, the fins  732  and  734  can comprise perforations that aid removal of distal fin sections during field connectorization. 
     In certain embodiments, the flexible member  725  comprises a stabilizing element, such as a yarn, glass reinforced plastic strength member, optical fiber, or copper wire, that extends lengthwise along the central axis of the flexible member  725 . Such an element can provide structural support and/or carry signals. 
     In certain embodiments, each fin  731 ,  732 ,  733 ,  734  extends radially and then has two circumferential projections, one extending clockwise and one extending counter clockwise. The projections of adjacent fins may overlap, be separated by a gap, or abut and touch one another. Such overlaps or gaps can facilitate opening and closing the compartments. 
     As discussed above with reference to the fiber optic cable  100  illustrated in  FIG. 1 , the fiber optic cable  700  can comprise strength fibers  145  and a jacket  115 . In one exemplary embodiment, the jacket  115  of the fiber optic cable  700  has an outer diameter of about 6.0 mm and an inner diameter of about 4.7 mm. In one exemplary embodiment, the jacket  115  of the fiber optic cable  700  has a wall thickness of about 0.65 mm. 
     Turning now to  FIG. 8 , this figure illustrates in cross section a fiber optic cable  800  incorporating technology for distinguishing among bundles of optical fibers according to certain exemplary embodiments of the present invention. As compared to the embodiment illustrated in  FIGS. 7A and 7B  and discussed above, the fiber optic cable  800  of  FIG. 8  comprises two strength members  805 , one in the compartment  107   b  and another in the compartment  107   d . In certain embodiments, the fiber optic cable  800  further comprises bundle distinguishing technology, such as embodiments of the indicia disclosed above. The strength members  805  can mitigate stress on the bundles of optical fibers  105   a  and  105   b.    
     In certain embodiments, the strength members  805  comprise glass reinforced plastic members or rods or rigid strength members. In certain embodiments, the strength members comprise aramid fibers or yarns. 
     Technology has been described for distinguishing between or among bundles of optical fibers within a fiber optic cable. From the description, it will be appreciated that an embodiment of the present invention overcomes the limitations of the prior art. Those skilled in the art will appreciate that the present invention is not limited to any specifically discussed application or implementation and that the embodiments described herein are illustrative and not restrictive. From the description of the exemplary embodiments, equivalents of the elements shown therein will suggest themselves to those skilled in the art, and ways of constructing other embodiments of the present invention will appear to practitioners of the art. Therefore, the scope of the present invention is to be limited only by the claims that follow.