Patent Publication Number: US-2018052295-A1

Title: Optical fiber distribution

Description:
BACKGROUND 
     Optical fibers can transmit data in the form of modulated light signals. The light signals efficiently propagate along the length of the optical fibers by a series of total internal reflections. Such optical transmission allows for transmission of data signals with very little loss of signal strength or integrity. By modulating optical signals across multiple wavelengths of light, a single optical fiber can transmit large amounts of data. However, optical fibers are relatively delicate. When subjected to excess physical strain or environmental damage, that ability of an optical fiber to efficiently transmit optical signals can be greatly diminished. 
     To avoid potential damage, optical fibers are often jacketed in protective sheaths to protect against exposure to environmental conditions. Such jacketing can also provide a level of protection against strain caused by kinking or over-bending. To further increase structural integrity, individually jacketed and unjacketed optical fibers are bundled together to create fiber-optic cables. Such fiber-optic cables are often used to transmit vast amounts of data in one-to-one, one-to-many and many-to-many communication systems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates an example optical fiber distribution assembly. 
         FIG. 1B  illustrates another example optical fiber distribution assembly. 
         FIG. 2A  depicts a detailed view of an example optical fiber distribution assembly that includes multiple optical fiber distribution nodes. 
         FIG. 2B  depicts a detailed view of another example optical fiber distribution assembly that includes multiple optical fiber distribution nodes having various shapes. 
         FIG. 3A  includes a series of cross-sectional views that depict an example construction of an optical fiber distribution node. 
         FIG. 3B  depicts a detailed view of internal components of an example optical fiber distribution node. 
         FIG. 4  is a flowchart of an example method for assembling an optical fiber distribution assembly. 
         FIG. 5A  is a schematic of an example many-to-many optical fiber distribution node. 
         FIG. 5B  depicts a simplified detail view of an example many-to-many optical fiber distribution node with strain relief elements. 
         FIG. 6  depicts an example stacked optical fiber distribution node with strain relief elements. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure describes devices and methods for distribution and alignment of optical fibers. For instance, various implementations of the present disclosure include an optical fiber distribution assembly for routing and aligning multiple optical fibers between various devices. Routing optical fibers between interconnected computing resource nodes and networking switches can be complicated. The convoluted physical routing, the density of fiber-optic connectors, the intricate sequencing of fiber couplings to the source and target devices, and other considerations all contribute to the complexity of implementing fiber-optic system topologies. Accordingly, optical fiber distribution assemblies described herein can be dimensioned and arranged to distribute and align optical fibers within a given computer system rack, row, or complex easily and cost effectively. 
     Various optical fiber distribution assemblies described herein can include features that decrease the cost and labor requirements involved in the manufacture of high density photonic routing connections. In addition, use of such optical fiber distribution assemblies can simplify the assembly of complex photonic communication topologies, such as in the installation of or upgrades to computing centers. In such implementations, the configuration and the optical fiber distribution assemblies can be custom built according to the intended installation. 
     In various example implementations, optical fiber distribution assemblies can include a source or input fiber-optic cable that includes a bundle of optical fibers. The input fiber-optic cable can include input ends of the optical fibers and a coupler for connecting each individual fiber within the bundle to a device, such as a photonic switching device. 
     At some point along its length, the fiber-optic cable can be coupled to an optical fiber distribution node. In various implementations, the optical fiber distribution node can include a housing assembly that can act as the structural support and/or framework for the node. The optical fiber distribution node housing assembly can include an input port through which the optical fibers can be threaded into the interior of the housing assembly. Once inside the housing assembly, the optical fibers can be grouped and routed to corresponding output ports in the housing assembly. As used herein, the terms “housing” and “housing assembly” can refer to any single or multiple part container or structure to which the fiber-optic cables can be coupled and through which the component optical fibers can be routed. 
     The selection of the groups of optical fibers and the position of the corresponding output port can be based on the location or intended location of at least one target device. For example, optical fibers that are to be routed to devices located on one side of the housing can exit through an output port disposed on a corresponding side of the housing, while optical fibers to be routed to devices located on another side of the housing can exit through another output port disposed on another corresponding side of the housing. 
     The interior of the housing can include elements for limiting the curvature of the optical fibers to help avoid breakage or loss in transmission efficiency. For example, once the optical fibers are routed within the interior cavity of the housing, the interior can be flooded with a potting material, such as an epoxy or resin that will set to immobilize and stabilize the positions of the optical fibers. 
     Optical fibers exiting the housing can be routed directly to corresponding target devices. In other example implementations, the optical fibers exiting one or more of the output ports can be bundled into intermediate or secondary fiber-optic cables. Those secondary fiber-optic cables can be then coupled to intermediate or secondary optical fiber distribution nodes to further distribute the optical fibers to devices disposed close to those nodes. 
     To further illustrate aspects and features of the present disclosure, various example implementations are described in additional detail in reference to the figures. For instance,  FIG. 1A  depicts a schematic of an example optical fiber distribution assembly  100 . In the example shown, the optical fiber distribution assembly  100  can couple device  101  to multiple devices  130 . For example, device  101  can be a source device, such as a photonic switch, that can transmit and/or receive photonic data signals to or from select devices  130  through corresponding component optical fibers  120  of fiber-optic cable  103 . Devices  130  can also include photonic transmission and receiving capabilities. Accordingly, the optical fiber distribution assembly  100  can be used to route photonic signals between devices  130  and device  101  through the corresponding optical fibers  120 . 
     In configurations like the example optical fiber distribution assembly  100 , the fiber-optic cable  103  can be coupled to a photonic connection on device  101 . To couple the fiber-optic cable  103  to device  101 , at least some of the component optical fibers  120  can be coupled to a faceplate connector on device  101 . The faceplate connector can couple corresponding optical signals from optical or photonic transmitters, receivers, or transceivers to component optical fibers  120 . 
     As described herein, the fiber-optic cable  103  can include a bundle of multiple optical fibers  120  and other component structural and protective elements that give support and protection to the optical fibers. In one implementation, multiple optical fibers  120  can be protected by bundling them together loosely in sheath or jacket. In other examples, multiple optical fibers can be protected by arranging them on a plastic ribbon in groups (e.g., groups of 12), which can then be over-molded or covered with another plastic ribbon. In other examples, the optical fibers  120  can be protected by wrapping the fibers or molding a plastic jacket over the fibers. 
     In some implementations, the fiber-optic cable  103  can include a central core that provides tensile strength to the cable and an outer jacket that protects the internal components (e.g., optical fibers  120 ) of the cable. As described herein, each individual optical fiber  120  can be left bare or individually jacketed in a corresponding protective coating or jacket. The central core, the outer jacket, and/or the individual jackets of the optical fibers  120  can all work together to provide stiffness to the fiber-optic cable  103  to prevent kinks or drastic changes in curvature to prevent the optical fibers  120  from being strained or broken. Excess strain or breakage can reduce or destroy the ability of each individual optical fiber from being able to transmit a viable photonic signal. 
     The fiber-optic cable  103  can be coupled to the optical fiber distribution node  110  at the input port  111 . The coupling of the fiber-optic cable  130  to the input port  111  can include inserting the fiber-optic cable  103  into an opening in the housing of the optical fiber distribution node  110 . As such, the individual jacketed or unjacketed optical fibers  120  can be routed into the interior volume of the housing. Groups of the individual jacketed and/or unjacketed optical fibers  120  can be routed to a corresponding output port  112 . 
     As shown in  FIG. 1A , the group or output port  112  associated with a particular optical fiber  120  can be based on the physical location or configuration of the corresponding target device  130 . For example, the output port  112  shown on the top of the housing of the optical fiber distribution node  110  can route the corresponding optical fibers  120  to the corresponding devices  130  in the upper portion of the array of devices. The output ports  112  shown on the right-hand side of the housing of the optical fiber distribution node  110  can route the corresponding optical fibers  120  to the corresponding devices  130  in the middle portion of the array of devices. Finally, the output port  112  shown on the bottom of the housing of the optical fiber distribution node can route the corresponding optical fibers  120  to corresponding devices  130  in the lower portion of the array of devices. In various implementations, the length of the individual optical fibers  120  can be dimensioned according to the placement of the target devices  130  relative to the optical fiber distribution node  110 . For example, the length of optical fibers  120  going to the devices  130  at the ends of the array can be longer than the length of the optical fibers  120  routed to devices  130  in the middle of the array. 
       FIG. 1B  illustrates an example optical fiber distribution assembly  101  that includes multiple optical fiber distribution nodes  110 . In such implementations, groups of optical fibers can exit the initial or subsequent optical fiber distribution nodes  110  through the corresponding output ports  112  and be bundled into intermediate or secondary fiber-optic cables  105 . For example, multiple racks of server computers can be associated or equipped with a corresponding optical fiber distribution node  110 . The length of the fiber-optic cables  103  and intermediate fiber-optic cables  105  can be dimensioned to span the distances between the racks. The individual optical fibers  120  exiting the output port  112  of the associated optical fiber distribution node  110  can then be routed and coupled to the target devices  130  (e.g., server computers, photonic switches, routers, etc.) in that rack. Accordingly, each of the initial and subsequent optical fiber distribution nodes  110  route the component optical fibers  112  to corresponding locations associated with the corresponding optical fiber distribution node  110 . In such implementations, the length of the individual optical fibers  120  exposed outside of a fiber-optic cables  103  or  105  can be reduced to help avoid potential damage. 
       FIG. 2A  depicts a detailed view of a portion of an example optical fiber distribution assembly  200  that includes multiple optical fiber distribution nodes  110 . In the view of the optical fiber distribution assembly  200  of  FIG. 2A , the optical fiber distribution nodes  110  are shown as being open (e.g., with no top cover) to show the routing of the individual optical fibers  120  within the housings. 
     In the example shown, a bundle of optical fibers  120  are coupled from a source device  101  to an initial optical fiber distribution node  110  through an input fiber-optic cable  103 . In implementations like the one depicted in  FIG. 2A , the input ports  111  and output ports  112  of the optical fiber distribution nodes  110  can include stress relief elements. The stress relief elements can include structures or fasteners that can prevent the input fiber-optic cable  103  and intermediate fiber-optic cables  105  from being pulled from their respective optical fiber distribution nodes  110 . The stress relief elements can also limit the curvature of the fiber-optic cables  103  and  105  as well as the component optical fibers  120  when subjected to forces oblique to the housings. 
     Inside the housings of the optical fiber distribution nodes  110 , the individual optical fibers  120  are grouped and routed to a corresponding output ports  112  such that the curvature of the optical fibers  120  is not less than a threshold radius. The threshold radius of curvature for the optical fibers  120  can be based on the optical characteristics of the component optical material(s) and the diameter or thickness of the optical fiber  120 . The curvature of the optical fibers  120  within the housings of the optical fiber distribution nodes  110  can be controlled by the relative placement and angle of the input and output ports  111  and  112  and/or the dimensions and/or shape of the optical fiber distribution nodes  110 . For example, output ports  112  disposed at 90 degrees relative to the input ports  111  can maintain a curvature of the optical fibers  120  greater than the threshold radius by placing them far enough apart from one another. 
     The example optical fiber distribution assembly  200  shown in  FIG. 2A  can be specific to a particular installation. For example, the source device  101  may be at a location at a particular distance from the installation of a rack of photonic communication devices  130 . In such implementations, the fiber-optic cable  103  of a particular length that can include medium or long haul characteristics that help avoid damage to the component optical fibers  120 . The first optical fiber distribution node  110  (e.g., the optical fiber distribution node to which the incoming fiber-optic cable  103  is coupled), can split the component optical fibers  120  into two groups. One group of optical fibers  120  can be routed to a first set of secondary optical fiber distribution nodes  110 , while the other group can be routed to a second set a secondary optical fiber distribution node  110 . In  FIG. 2A , only one set of secondary optical fiber distribution nodes  110  are illustrated. 
     The length of the secondary fiber-optic cables  105  can be based the distance or position of corresponding target devices  130  relative to the initial optical fiber distribution node  110 . For each location of target devices  130 , a corresponding group of optical fibers  120  can be routed to a corresponding output port  112 . The individual optical fibers  120  can then be routed externally to the target devices  130 . Optical fibers  120  not intended to be coupled to target devices  130  local to a particular optical fiber distribution node  110 , can be routed to another corresponding output port  112  and bundled in another secondary fiber-optic cable  105  and routed to subsequent optical fiber distribution nodes  110 . Accordingly, individual optical fibers  120  can be peeled off and routed to a corresponding output port  112  in successive optical fiber distribution nodes  110 . 
       FIG. 2B  illustrates that the shape and dimensions of the optical fiber distribution nodes, as well as the relative placement of the component input and output ports  111  and  112  can vary. In the particular example optical fiber distribution assembly  201  shown in  FIG. 2B , the two secondary optical fiber distribution nodes  210  include a cylindrical or spherical housings. In such implementations, the output ports  112  can be disposed anywhere in the housing of the distribution nodes  210 . As in other examples, the input ports  111  and output ports  112  can include stress relief elements. 
       FIG. 3A  depicts cross-sectional views of an example optical fiber distribution node  110  in various states of assembly. In view  301 , one part of the housing  114  (e.g., the bottom portion) is shown in cross-section. The part of the housing  114  can include coupling elements  115  for connecting the corresponding coupling elements  113  of ports  111  and  112 . In the example shown, the coupling elements include corresponding C-shaped elements that can nest within one another. The fiber-optic cable  103  can be threaded through the port  111 . In the example shown, the port  111  includes a cone shaped curvature restricting element made of a flexible material (e.g., plastic, rubber, or the like). 
     Between the input port  111  and the output port  112 , the jacket of the fiber-optic cable  130  and/or each individual optical fiber  120  can be removed. For example, individual optical fibers  120  can be bare or jacketed in individual protective coatings or sheaths. As described herein, the optical fibers  120  can be routed to a corresponding output port  112 . Beginning in the interior volume of the optical fiber distribution node  110 , the interior of the stress relief element of the output port  112 , or the exterior of the output port  112 , the various individual optical fibers  120  can be re-bundled into a secondary or intermediate fiber-optic cable  105 . While only one output port  112  is depicted in the various views of  FIG. 3A , the optical fiber distribution node  110  can include multiple output ports  112 . 
     Once all of the individual optical fibers  120  are routed to the corresponding output ports  112 , a corresponding cover element, part  116 , of the housing can be coupled to the input port  111 , the output ports  112 , and/or the bottom  114  to create an interior volume, thus enclosing the individual optical fibers  120  in the optical fiber distribution node  110 , as shown in view  303 . For example, part  116  can be a top or a lid that can be joined with the bottom housing  114  to create an enclosure around the optical fibers  120  and further engage the input port  111  and output ports  112  at the corresponding coupling elements  117  and  118 . In various implementations, part  116  can be adhesively joined, welded (e.g., heat or ultrasonic welding), clipped, screwed, or otherwise fastened or attached to part  114  and/or ports  111  and  112 . In some implementations, part  116  and part  114  can include features that snap together. In the particular example shown, part  116  of the housing can include an access port or opening  121 . 
     As shown in view  305 , a potting material  119  can be injected through access port  121  into the volume between part  116  and  114 . The rate of injection can be controlled so as to reduce the possibility of the flow of the potting material  119  disturbing or displacing the optical fibers  120 . The potting material  119  can include any adhesive, resin, epoxy, silicone, or the like, that can be injected into the interior volume of the optical fiber distribution node  110  as a liquid or gel and cured to form a solid or semi-solid around the individual optical fibers  120 . In some implementations, the potting material  119  can include an ultraviolet (UV) light curable material or other fast-setting material. Accordingly, potting material  119  be cured using ultraviolet (UV) light or otherwise induced to set quickly to increase the speed of assembly in high volume production. 
       FIG. 3B  depicts a top cross-sectional view of an example optical fiber distribution node  110  according to various implementations of the present disclosure. In view  307 , the optical fiber distribution node  110  is shown without the potting material  119 . View  307  also depicts elements  123 . Elements  123  can be included in the bottom part  114  or the top part or cover element  116  of the housing of the optical fiber distribution node  110 . In some implementations, elements  123  can include fill ports that can provide access for injecting potting material  119 . Such fill ports can be used in a manufacturing environment or in the field for filling the volume of the optical fiber distribution node  110  with potting material  119  at pressures low enough to avoid damaging or kinking the optical fibers  120 . In other implementations, the elements  123  can include standoff elements. Such standoff elements can include cylindrical or other structurally shaped elements that can span the volume between the bottom part  114  and the top part  116  to prevent the housing from being crushed or compressed. 
     View  309  depicts a top cross-sectional view of the example optical fiber distribution node  110  similar to that in view  307  but with the potting material  119  in place and encasing the optical fibers  120 . 
       FIG. 4  is a flowchart of an example method  400  for assembling an optical fiber distribution node  110 , according to various implementations of the present disclosure. The method can begin at box  411 , in which the optical fibers  120  of a particular fiber-optic cable  103  are routed through the input port  111  in the housing of an optical fiber distribution node  110 . As described herein, the housing may be a portion of the housing that makes up the exterior and or structure of the optical fiber distribution node  110  such that the interior is open and accessible to a user. For example, the housing may be the bottom portion  114  of the distribution node  110 . 
     With ends of the individual optical fibers  120  introduced into the interior of the housing, the optical fibers  120  can be separated into groups at box  413 . At box  415 , the groups of optical fibers  120  can be routed to the corresponding output ports  112  of the optical fiber distribution node  110 . 
     The creation of the groups can be based on the location of the intended target devices  130  relative to the intended placement of the resulting optical fiber distribution node  110 . For example, a particular optical fiber distribution node may include at least one output port  112  that will end up being installed at or near a particular rack of server computers. Each of the optical fibers intended to be coupled to those server computers can be grouped and routed to that corresponding output port  112 . 
     Grouping the optical fibers  120  can be achieved by illuminating the input end of those optical fibers  120  with a particular wavelength of light while other optical fibers  120  within the input fiber-optic cable  103  remain dark or are illuminated with a different wavelength of light. In some implementations the wavelengths of light used to illuminate a group of optical fibers can include any wavelength in the visual spectrum. For example, the wavelengths of light can include red, green, blue, white, or other colors of light that are easily distinguishable from one another. Accordingly, the optical fibers  120  can be sorted using the color of light being emitted from the output end of the optical fibers. As such, colored light coded optical fibers  120  can be associated with and routed to a particular port. 
     The color coding can include both visible light (e.g., wavelengths clearly visible to human users) and invisible light (e.g., wavelength detectable by non-human sensors). In some implementations, the illumination can include an optical signal to confirm proper routing and fiber integrity. While routing the optical fibers  120 , care can be taken to route the optical fibers  120  so as to reduce the curvature of the optical fibers  120  to avoid excess strain or breakage. 
     In some implementations of method  400 , the optical fiber distribution node  110  can be closed by coupling the bottom part of the housing  114  with a top part  116  (e.g., a cover element). With the top part  116  in place, the housing of the optical fiber distribution node  110  can secure strain relief elements at ports  111  and/or  112 . In some implementations, a potting material  119  can be injected through an opening in the housing, such as openings  121  or fill port element  123 , into the interior volume of the optical fiber distribution node  110  to stabilize the optical fibers  120  therein. 
     In various implementations, the routing of the optical fibers and assembly of the optical fiber distribution nodes  110  can be sufficiently simple to allow on-site construction of the optical fiber distribution assemblies in the field. Accordingly, optical fiber distribution assemblies can be constructed in the field as needed to facilitate installations of large optical fiber communication topologies. As such, various implementations of the present disclosure allow for low-cost on-site manufacture of custom optical fiber distribution assemblies. Custom optical fiber distribution assemblies can reduce costs and more efficiently use optical fibers and fiber-optic cable than other methods used to create photonic communication connections. 
       FIG. 5A  depicts a schematic of an example many-to-many optical fiber distribution node  510 , according to implementations of the present disclosure. As shown, the optical fiber distribution node  510  can include ports  112  for receiving corresponding fiber-optic cables  105  that can each include one or more component optical fibers  120 . Each of the fiber-optic cables  105  can be dedicated to a particular corresponding device  130 . The ports  112  can simultaneously be an input port and an output port. For example, any device  130  can be communicatively coupled to any and all other devices  130  through corresponding optical fibers  120  routed through the optical fiber distribution node  510 . Accordingly, each of the fiber-optic cables  105  and/or the component optical fibers  120  (not shown in  FIG. 5A ) can carry photonic signals in both directions (e.g., each port  112 , fiber-optic cable  105 , and optical fiber  120  can be bidirectional). 
       FIG. 5B  illustrates a simplified internal view of an example many-to-many optical fiber distribution node  510 , according to various implementations of the present disclosure. For clarity, only the optical fiber connections between one port  112  and other ports  112  are shown. Accordingly, the optical fibers  120  can represent the output connections from the one port  112  to all other ports  112 , or, alternatively, the input connections from all ports  112  to the one port  112 . Each of the ports  112  can be connected to all other ports  112  by a corresponding optical fibers  120 , similar to configuration shown. 
     As shown, the housing of the distribution node  510  can include coupling elements for receiving and coupling to ports  112  that include stress relief elements. The individual component optical fibers  120  of an input fiber-optic cable  105  can be routed to the corresponding output ports  112 . The interior volume of the distribution node  510  can also be stabilized using a potting material, such as a potting material  119  described herein. 
     The many-to-many optical fiber distribution node  510  can be stacked on additional many-to-many optical fiber distribution nodes  510  to create a high density many-to-many optical fiber distribution node, such as the many-to-many optical fiber distribution node  600  illustrated in  FIG. 6 . For example, if each port  112  and  111  included 100 optical fibers, then 1600 optical fibers would cross in the interior of the fiber-optic distribution node  510 . To reduce the complexity of any one particular optical fiber distribution node  510  in the stack  600 , each of the optical fiber distribution nodes  510  can include a subset of the optical fiber  120  connections. The reduction of the number of optical fibers  120  in any one particular optical fiber distribution node  510  can simplify the manufacturing process and produce good yield without specialized manufacturing equipment. 
     In some implementations, routing of the optical fibers  120  in the fiber-optic distribution node  510  can be laid out on a wiring harness loom with little modification. Accordingly, implementations of the present disclosure can provide methods and optical fiber distribution assemblies that allow for routing optical fibers with reduced requirement for precise optical fiber placement. As such, the speed of manufacturing such assemblies can be increased and the cost decreased. 
     These and other variations, modifications, additions, and improvements may fall within the scope of the appended claims(s). As used in the description herein and throughout the claims that follow, “a”, “an”, and “the” includes plural references unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the elements of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or elements are mutually exclusive.