Abstract:
A device may include an input cable for receiving optical signals from a feeder cable, output cables for transmitting optical signals to a distribution cable, and a housing. The housing may include an optical splitter for splitting an input beam into a plurality of output beams, an input fiber segment for conveying the input beam from the input cable to the optical splitter, the input fiber segment excluding fiber loop slack, and output fiber segments for conveying the output beams from the optical splitter to the output cables using MT-APC connectors.

Description:
BACKGROUND INFORMATION 
     Many fiber distribution hub vendors offer preconfigured fiber distribution hubs with space to hold splitter modules of specific sizes. A splitter module is a component used within a fiber distribution hub to split an optical beam from an optical fiber (e.g., a fiber in a feeder cable from a service provider) into multiple optical beams, and output the split beams to multiple optical fibers (e.g., fibers that connect to cables that provide the service to consumers). Since a splitter module from one fiber distribution hub vendor may not fit in a fiber distribution hub from a different vendor, a purchaser may be compelled to procure both a fiber distribution hub and splitter modules from the same vendor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an exemplary optical network in which concepts described herein may be implemented; 
         FIG. 2  is a block diagram of a portion of an exemplary multiple dwelling unit complex; 
         FIG. 3  is a functional block diagram of an exemplary fiber distribution hub of  FIG. 2 ; 
         FIG. 4  illustrates an exemplary splitter module of  FIG. 3 ; 
         FIG. 5A  is a diagram of another exemplary splitter module of  FIG. 3 ; 
         FIG. 5B  is a diagram illustrating exemplary contents of a splitter container of  FIG. 5A ; 
         FIG. 6A  is a cross-sectional view of a splitter container of  FIG. 4  according to an exemplary implementation; 
         FIG. 6B  shows a perspective view of an optical splitter of  FIG. 6A ; and 
         FIG. 7  is a flowchart of an exemplary process that is associated with operation of the splitter module of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. 
     As described below, a small/compact splitter module that does not include optical fiber-loop slack may be constructed. Such small splitter modules may be used in a space-efficient indoor fiber distribution hub to save installation and optical fiber cabling cost (e.g., 40% savings in time/cost). In addition, splitter module designs with the smallest form factor may facilitate standardization of splitter module size, and may spur production of splitter modules that may be used in fiber distribution hubs from different vendors. 
       FIG. 1  shows an exemplary optical network  100  in which the concepts described herein may be implemented. As shown, optical network  100 , which may be sometimes referred to as a fiber-to-the-premises (FTTP) network, may include a central office  102 , a multiple dwelling unit complex  104 , a single dwelling unit complex  106 , and feeder optical fiber cables  108 . An actual optical network may include may include additional, fewer, or different dwelling complexes and components than optical network  100 . 
     Central office  102  may include a site that houses telecommunication equipment, including switches, optical line terminals, etc. Central office  102  may provide telecommunication services to subscribers, such as telephone service, access to the Internet, cable television programs, etc., via optical line terminals. 
     Multiple dwelling unit complex  104  may include apartments, condominiums, and/or other types of living units that are aggregated in a high-rise or another type of building. Single dwelling unit complex  106  may include attached town houses, single detached houses, condominiums, and/or other types of horizontally aggregated living units. 
     Feeder optical fiber cables  108  may include optical fiber cable bundles that interconnect multiple dwelling unit complex  104  and/or single dwelling unit complex  106  to optical line terminals in central office  102 . 
       FIG. 2  is a diagram of a portion of an exemplary multiple dwelling unit complex  104 . As shown, multiple dwelling unit complex  104  may include a floor/ceiling  202 , a wall  204 , a fiber distribution hub  206 , a distribution cable bundle  208 , a fiber distribution terminal  210 , a drop cable  212 , a optical network terminal  214 , and a living unit  216 . In  FIG. 2 , some components of multiple dwelling unit complex  104  are omitted for the sake of simplicity in illustration (e.g., stairs, doors, elevators, etc.). In addition, depending on the implementation, multiple dwelling unit complex  104  may include additional, fewer, or different components than those illustrated in  FIG. 2 . For example, in some implementations, fiber distribution terminal  210  may be connected to fiber distribution hub  206  through another component, such as a collector box that receives ribbon cables, and provides the ribbon cables connectivity to fiber distribution terminals. 
     Ceiling/floor  202  and wall  204  may partition space within multiple dwelling unit complex  104  into multiple living units. Fiber distribution hub  206  may include an enclosure (e.g., a plastic or metal cabinet) to receive feeder optical fiber cables  108 , split an optical signal on an optical fiber within optical fiber cables  108  into multiple optical signals, convey the split optical signals to fiber distribution cables, collect the fiber distribution cables into distribution cable bundle  208 , and provide distribution cable bundle  208 . 
     Distribution cable bundle  208  may include riser cables that carry optical fibers from fiber distribution hub  206  to fiber distribution terminal  210 . In some implementations, distribution cable bundle  208  may be tapered as it is routed vertically through multiple dwelling unit complex  104  and as fiber distribution cables are branched from distribution cable bundle  208  to feed into one or more of fiber distribution terminal  210 . Fiber distribution terminal  210  may include an enclosure to receive a fiber distribution cable from distribution cable bundle  208 . 
     Drop cable  212  may include optical fiber that carries an optical signal from a fiber distribution cable in fiber distribution terminal  210  to optical network terminal  214 . Typically, drop cable  212  may be installed in a raceway that is placed along the ceiling of a hallway, in a conduit, in a duct, etc. 
     Optical network terminal  214 , which may also be called optical network unit  214 , may receive optical signals via drop cable  212  and convert the received optical signals into electrical signals that are further processed or carried over, for example, copper wires to one or more living units. In some implementations, optical network terminal  214  may be placed within a living unit, and devices that use services offered by central office  102  may be directly connected to optical network terminal  214 . 
     Living unit  216  may include a partitioned space that a tenant or an owner of the living unit  216  may occupy. Living unit  216  may house devices that are attached directly or indirectly, via copper wires, to optical network terminal  214  to receive services that central office  102  provides. 
       FIG. 3  is a functional block diagram of fiber distribution hub  206 . As shown, fiber distribution hub  206  may include splitter modules  302 - 1  through  302 - 6  (herein individually and collectively referred to as splitter modules  302  and splitter module  302 , respectively), splitter output parking unit  304 , and splitter-to-distribution fiber connection matrix  306 . Depending on the implementation, fiber distribution hub  206  may include additional, fewer, or different functional components than those illustrated in  FIG. 3 . For example, in some implementations, fiber distribution hub  206  may not include splitter output parking unit  304 . 
     Splitter module  302  may include an assembly of an optical splitter and optical fiber cables. Splitter module  302  may receive an optical signal over an input cable, split the beam into multiple optical signals, and transmit the multiple optical signals via ribbon cables that are connected to the optical splitter. 
     In  FIG. 3 , an input cable of splitter module  302  may be attached to a fiber cable from feeder optical fiber cables  108 . In one implementation, feeder optical fiber cables  108  may enter fiber distribution hub  206  from the bottom or lower portion, be routed about fiber distribution hub  206 , and provide an optical fiber cable that is mated to an input cable of splitter module  302  via connectors and an adaptor. 
     Splitter output parking unit  304  may include slots in which ribbon cables from splitter modules  302  may be parked until the ribbon cables are attached to fiber distribution cables to provide signal pathways to the living units in multiple dwelling unit complex  104 . 
     Splitter-to-distribution fiber connection matrix  306  may include a mechanism (e.g., fiber optic patch panel) to hold adaptors via which connectors at ends of ribbon cables from splitter modules  302  and connectors at fiber distribution cable ends are adjoined. 
       FIG. 4  illustrates splitter module  302  according to one exemplary implementation. As shown, splitter module  302  may include a connector  402 , an input cable  404 , a splitter container  406 , ribbon cables  408 - 1  through  408 - 3  (herein collectively and individually referred to as ribbon cables  408  and ribbon cables  408 , respectively), and connectors  410 - 1  through  410 - 3  (herein collectively and individually referred to as connectors  410  and connector  410 , respectively). Depending on the implementation, splitter module  302  may include additional, fewer, or different components (e.g., additional ribbon cables  408 , connectors  410 , etc.) than those illustrated in  FIG. 4 . 
     Connector  402  may include a component to encase a fiber end such that the fiber is axially aligned with the optical signaling path in another component to which connector  402  is coupled (e.g., a optical fiber cable, a waveguide, etc.). Examples of connector  402  may include a subscriber connector (SC), SC-angle polished connector (SC-APC), etc. In some implementations, such as in APC connectors, a ferrule (e.g., a ceramic holder for the optical fiber end) and the fiber end are polished at an angle to reduce internal reflection of the optical signal where the optical fiber is coupled to the other component. 
     Input cable  404  may encase an optical fiber segment that extends from connector  402  to an optical splitter housed in splitter container  406 . In some implementations, input cable  404  may have a fiber that has a functional bend radius of less than or equal to 10 millimeters (mm). Splitter container  406  may contain splitter components that split an optical signal from input cable  404  into multiple optical signals and output the multiple optical signals via ribbon cables  408 . 
     Ribbon cable  408  may encase one or more optical fiber segments that extend from the optical splitter housed in splitter container  406  to connectors  410 . Each ribbon cable  408  may encase multiple optical fiber segments. For example, in one implementation, ribbon cables  408 - 1 ,  408 - 2 , and  408 - 3  may encase 12, 12, and 8 optical fibers, respectively. 
     Connector  410  may include a component to encase fiber ends such that the fibers are axially aligned with the optical signaling paths in a component to which connector  410  couples (e.g., a ribbon cable). Examples of connector  410  may include a mechanical transfer-APC (MT-APC). Such a connector may be mated to another connector attached to a distribution cable running to one of the floors in multiple dwelling unit complex  104 . Depending on the number of cable drops per floor, connector  410  may be implemented as 4-fiber, 8-fiber, or 12-fiber MT-APC connector. The 4-fiber, 8-fiber, or 12-fiber MT-APC may allow, respectively, 4, 8, and 12 cables to be dropped on a floor in a single distribution cable run. A connector  410  that is not attached a distribution cable may be parked at splitter output parking unit  304 . 
     In splitter module  302 , splitter container  406  may not include optical fiber-loop slack. Consequently, splitter module  302  may be constructed to be smaller than a splitter module that includes optical fiber loop slack (e.g., 70% smaller). Input cable  404  and ribbon cables are located on the back and front sides of splitter container  406 , and therefore, when splitter container  406  is placed inside fiber distribution hub  206 , splitter input/outputs may be accessible from the front and back of fiber distribution hub  206 . 
       FIG. 5A  shows one implementation of a splitter module  502  that includes optical fiber loop slack. As shown, splitter module  502  may include components that correspond to each of the components illustrated in  FIG. 4 . In  FIG. 5A , components that correspond to those in  FIG. 4  are labeled with the same numbers, but with an apostrophe. The components illustrated in  FIG. 5A  may operate similarly as the corresponding components described with respect to  FIG. 4 . 
     In contrast to splitter module  302  in  FIG. 4 , splitter module  502  may include splitter container  406 ′ that is larger than splitter container  406 , as splitter container  406 ′ includes fiber loop slack. In addition, whereas each of ribbon cables  408  shown in  FIG. 4  encases multiple optical fibers, each of output fiber cables  408 ′ in  FIG. 5A  encases a single optical fiber. 
       FIG. 5B  is a diagram that illustrates exemplary contents of splitter container  406 ′. As shown, splitter container  406 ′ may include an optical splitter  504  and fiber loop slack  506 . In an actual implementation, splitter container  406 ′ may include additional or different components than those illustrated in  FIG. 5B . 
     Optical splitter  504  may include a component to receive input cable  404 ′ and provide multiple output cables  408 ′, which, in one implementation, may include jacketed 1.6-3 mm fiber cables that are terminated with SC-APC connectors. Optical splitter  504  may split an optical signal received via input cable  404 ′ into multiple optical signals and output the multiple optical signals via output cables  408 ′. Optical splitter  504  may be small compared to the overall size of splitter container  406 ′, whose size may be governed by fiber loop slack  506 . 
     Fiber loop slack  506  may include a portion of input cable  404 ′ that is wound into one or more loops before input cable  404 ′ enters optical splitter  504 . In addition, fiber loop slack  506  may include a portion of output cables  408 ′ that are wound into one or more loops before output cables  408 ′ exit splitter container  406 ′. In  FIG. 5B , only one output cable is illustrated as exiting optical splitter container  406 ′. The size of fiber loop slack  506  may depend on the type of optical fibers in input cable  404 ′ and output cables  408 ′. 
     Typically, splitter container  406 ′ may include fiber loop slack  506  for a number of reasons. For example, if optical splitter  504  is located close to an optical signal source (e.g., laser), in terms of relative distance that the optical signal travels from the source to optical splitter  504 , the optical signal at optical splitter  504  may be distorted. Including fiber loop slack  506  may increase the distance between the source and optical splitter  504 , and therefore, may eliminate the distortion. 
     In another example, if optical splitter  504  is located in an outdoor fiber distribution hub, optical splitter  504  may be exposed to climate changes. At low or high temperatures, input cable  404 ′ and/or output cable  408 ′ may contract/expand relative to the encased optical fiber(s). In such instances, without fiber loop slack  506 , the encased optical fibers may bend at various points on input and output cables  404 ′ and  408 ′. 
     In yet another example, a technician who is troubleshooting fiber distribution hub  206  that contains splitter module  302  may accidentally yank or pull on input cable  404 ′ or output cables  408 ′. In such instances, without fiber loop slack  506  to absorb excess strain, connections between waveguides within optical splitter  504  and the optical fibers in input/output cables  404 ′/ 408 ′ may weaken or break. 
     Unlike splitter module  502 , however, because splitter module  302  may be used in a fiber distribution hub  206  that is not exposed to significant climate changes/outside elements and is distant from a signal source, splitter container  406  in splitter module  302  may exclude fiber loop slack. Consequently, splitter module  302  may be constructed smaller than splitter module  502  (e.g., smaller by 70%). 
       FIG. 6A  is a cross-sectional view of splitter container  406  according to an exemplary implementation that excludes fiber loop slack. As shown, splitter container  406  may include a fan-out unit  602 , N-fiber ribbon cables  604 , an optical splitter  606 , an input cable  608 , and a fan-out unit  610 . Depending on the implementation, splitter container  406  may include additional, fewer, or different components than those illustrated in  FIG. 6A . For example, in one implementation, splitter container  406  may include fan-out unit  602  or fan-out unit  610  that partly protrudes from splitter container  406 . 
     Fan-out unit  602  may include a component that receives N-fiber ribbon cables  604 , regroups/connects optical fibers in N-fiber ribbon cables  604  to optical fibers in ribbon cables  408 , and provides ribbon cables  408 . For example, in one implementation, fan-out unit  602  may receive 8 of 4-fiber ribbon cables, and regroups optical fibers in two 12-fiber ribbon cables (e.g., ribbon cable  408 - 1  and ribbon cable  408 - 2 ) and one 8-fiber ribbon cable (e.g., ribbon cable  408 - 3 ). 
     Each of N-fiber ribbon cables  604  may encase N optical fiber segments. 
     Optical splitter  606  may include a component (e.g., a planar lightwave circuit (PLC) chip) to split an optical signal on input cable  608  into a predetermined number of optical signals (e.g., 8, 16, 32, 64, etc. signals) and route the split signals into optical fibers that feed into N-fiber ribbon cables  604 . 
     Input cable  608  may encase an optical fiber segment. Fan-out unit  610  may include a component that receives input cable  404 , and routes/connects the optical fiber in input cable  404  to input cable  608 . 
     In the above, fan-out units  602  and  610  may also affix or hold ribbon cables  408  and input cable  404 , respectively, to splitter container  406  such that pulling at ribbon cables  408  or input cable  404  does not easily damage or detach optical fibers in ribbon cables  408 /input cable  404  from optical splitter  606 . This may aid in eliminating a need for fiber loop slack  506  to protect optical splitter  606 . 
     In such implementations, fan-out units  602  and  610  may use epoxy to hold ribbon cables  408  and input cable  408 , respectively. 
     As further shown in  FIG. 6A , optical splitter  606  may include a stress absorbing unit  612 , N-fiber ribbon cable segments  614 , a fiber array  616 , adhesive  618 , a substrate  620 , adhesive  622 , a fiber array  624 , an input cable segment  626 , a stress absorbing unit  628 , and a splitter housing  630 . Some of these components may be spatially arranged as illustrated in  FIG. 6B , which shows a perspective view of optical splitter  606 . In other implementations, optical splitter  606  may include additional, fewer, or different components than the ones illustrates in  FIG. 6A . and/or  6 B. 
     Stress absorbing unit  612  may include a component through which N-fiber ribbon cables  604  from splitter housing  630  are guided toward fan-out unit  602 . Stress absorbing unit  612  may be securely attached to or integrally formed with splitter housing  630 , and may include material that protects N-fiber ribbon cables  604  against bending at angles that may break or damage the optical fiber segments encased in N-fiber ribbon cables  604 . In some implementations, optical splitter  606  may not include stress absorbing unit  612 . 
     N-fiber ribbon cable segments  614  may include portions of N-fiber ribbon cables  604 , and may extend from an inner wall of splitter housing  630  to fiber array  616 . Fiber array  616  may include a component that aligns each of optical fibers in N-fiber ribbon cable segments  614  to waveguides constructed in substrate  620 . V-grooves that are formed in fiber array  616  may precisely position the optical fibers, which are fitted within the V-grooves, to meet the waveguides such that optical signals from the waveguides may propagate to the optical fibers in N-fiber ribbon cable segments  614 . 
     Adhesive  618  may affix/fuse fiber array  616  to substrate  620 . Substrate  620  may include waveguides that extend from fiber array  624  to fiber array  616 . Depending on the implementation, the waveguides may split an optical signal from the optical fiber in input cable segment  626  into, for example, 8, 16, 32, 64, etc., optical signals that exit substrate  620  through optical fibers in N-fiber ribbon cable segments  614 . Adhesive  622  may affix/fuse fiber array  624  to substrate  620 . 
     Fiber array  624  may include a component that aligns the optical fiber in input cable segment  626  to waveguides constructed in substrate  620 . A V-groove that is formed in fiber array  624  may precisely position the optical fiber, which is fitted within the V-groove, to meet the waveguides such that optical signals from the optical fiber in input cable segment  626  may propagate to the waveguides. Input cable segment  626  may include a portion of input cable  608 , and may extend from fiber array  624  to an inner wall of splitter housing  630 . 
     Stress absorbing unit  628  may include a component through which input cable  608  from splitter housing  630  is guided toward fan-out  610 . Stress absorbing unit  628  may be securely attached to or integrally formed with splitter housing  630 , and may protect input fiber  608  from bending at angles that may break or damage the optical fiber segment encased in input cable  608 . In some implementations, splitter container  406  may not include stressing absorbing unit  628 . 
     Splitter housing  630  may protect components  614 - 626  contained within splitter housing  630  from outside forces/elements and secure components  614 - 626  in proper locations. 
     In some implementations, additional stress absorbing units may be fixedly placed outside of splitter container  406 . about ribbon cables  408  and input cable  404 . to provide additional support for ribbon cables  408  and input cable  404  against external forces (e.g., a tug/pull). 
       FIG. 7  is a flow diagram of an exemplary process  700  that is associated with operation of splitter module  302 . Process  700  may start when splitter module  302  receives an optical signal from a feeder optical fiber cable (block  702 ). For example, splitter module  302  may receive the optical signal from one of feeder optical fiber cables  108  ( FIG. 1 ) via a connector, such as a SC-APC connector. 
     An input cable may route the optical signal to a splitter container of the splitter module (block  704 ). For example, input cable  404  may route the optical signal to splitter container  406 . 
     An input fan-out unit may route the optical signal into the splitter container (block  706 ). For example, fan-out unit  610  may receive input cable  404  and route/connect input cable  404  to input cable  608 . Consequently, the optical signal may be routed into splitter container  606 . 
     An input cable segment may route the optical signal from the input fan-out unit to an optical splitter in the splitter container (block  708 ). For example, input cable  608  may convey the optical signal from fan-out unit  610  to optical splitter  606 . Input cable  608 , as illustrated in  FIG. 6A , may not include fiber loop slack. 
     The optical splitter may split the optical signal into multiple optical signals (block  710 ). For example, in  FIG. 6A , the optical signal may enter optical splitter  606  via input cable  608 . Input cable  608  may be connected to fiber array  624  that aligns the optical fiber in input cable  608  to waveguides in substrate  620 . The waveguides may split the optical signal into multiple optical signals and output the multiple optical signals to optical fibers in ribbon cable segments  614 . The optical fibers in ribbon cable segments  614  may be aligned to the waveguides by fiber array  616 . 
     Ribbon cables may route the multiple optical signals from the optical splitter to an output fan-out unit (block  712 ). For example, ribbon cables  604  and ribbon cable segments  614  may convey the multiple optical signals to output fan-out unit  602 . 
     The fan-out unit may route the optical signals through the fan-out unit to ribbon cables (block  714 ). For example, in one implementation, fan-out unit  602  may receive optical signals from eight 4-fiber ribbon cable segments (e.g., ribbon cables  604 ) and output optical signals via two 12-fiber ribbon cables (e.g., ribbon cables  408 - 1  and  408 - 2 ) and one 8-fiber ribbon cable (e.g., ribbon cable  408 - 3 ). 
     The ribbon cables may route the optical signals to connectors (block  716 ). For example, two 12-fiber ribbon cables and one 8-fiber ribbon cable (e.g., ribbon cables  408 - 1 ,  408 - 2 , and  408 - 3 ) may route the optical signals to connectors  410  (e.g., 12, 8, or 4 fiber MT-APC connectors). 
     The connectors may output the optical signals to distribution cables (block  718 ). For example, connectors  410  may output the optical signals to the distribution cables in distribution cable bundle  208 . Connectors  410  may be mated, via adaptors, to connectors that are attached to distribution cables bundle  208 . 
     The above describes process  700  associated with splitter module  302 . As indicated in the preceding, optical splitter module  302  does not include an optical fiber loop slack. Such small splitter modules may be used in a space-efficient indoor fiber distribution hub, to save installation and optical fiber cabling cost (e.g., 40% savings in time/cost). In addition, splitter module designs with the smallest form factor may facilitate standardization of splitter module size, and may spur production of splitter modules that may be used in fiber distribution hubs from different vendors. 
     In the preceding specification, various preferred embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense. 
     For example, while a series of blocks have been described with regard to the process illustrated in  FIG. 7 , the order of the blocks may be modified in other implementations. In addition, non-dependent blocks may represent blocks that can be performed in parallel. 
     No element, block, or instruction used in the present application should be construed as critical or essential to the implementations described herein unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items. Where only one item is intended, the term “one” or similar language is used. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.