Patent Publication Number: US-2019187382-A1

Title: Self-powered lighted dust caps for testing continuity; and methods

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is being filed on Aug. 2, 2017 as a PCT International Patent Application and claims the benefit of U.S. Patent Application Ser. No. 62/375,612, filed on Aug. 16, 2016, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to fiber optic cable networks. More specifically, the present disclosure relates to the components of passive optical networks and methods for deploying the same to test fiber optic continuity. 
     BACKGROUND 
     Passive optical networks are becoming prevalent in part because service providers want to deliver high bandwidth communication capabilities to customers. Passive optical networks are a desirable choice for delivering high-speed communication data because they may not employ active electronic devices, such as amplifiers and repeaters, between a central office and a subscriber termination. 
     When deploying indexing terminals, there is no easy way to continuously check for product and system continuity. If it is determined that there is no connectivity in the system, it can be hard to identify where the problem lies. Thus, it would be desirable to provide a method of ascertaining true connectivity while deploying indexing terminals in an optical system. 
     SUMMARY 
     A self-powered lighted dust cap used in an indexing system to verify connections and features thereof are described. One aspect of the present disclosure relates to a diagnostic method for testing continuity along an optical fiber. The method includes a step of mounting a dust cap to an optical port where the dust cap includes a self-generating light for testing an optical fiber line. The method further includes a step of activating the self-powered lighted dust cap to shine a light along the optical fiber line and determining whether the light is visible downstream of the optical fiber line. 
     Another aspect of the present disclosure relates to a diagnostic method for testing continuity along an optical fiber for a fiber indexing system. The fiber indexing system can include a plurality of indexing components daisy chained together. The plurality of indexing components can each have a first multi-fiber connection interface that defines a plurality of sequential fiber positions and a second multi-fiber connection interface that defines a plurality of sequential fiber positions. A plurality of indexing optical fibers can be connected between the first and second multi-fiber connection interfaces in an indexed configuration. The method includes the following steps: installing a first indexing component; mounting a dust cap to the first multi-fiber connection interface of the first indexing component, the dust cap including a self-powered light to test the plurality of indexing optical fibers in the fiber indexing system; activating the self-powered light of the dust cap to shine a light along the plurality of indexing optical fibers; installing a second indexing component such that the first and second multi-fiber connection interfaces of the first and second indexing components are optically coupled together; determining whether the light is visible at the first multi-fiber connection interface of the second indexing component in the fiber indexing system; installing a third indexing component such that the first and second multi-fiber connection interfaces of the second and third indexing components are optically coupled together; and determining whether the light is visible at the first multi-fiber connection interface of the third indexing component in the fiber indexing system. 
     A further aspect of the present disclosure relates to a dust cap for an optical fiber connector in an optical system. The dust cap can be adapted to cover an end of the optical fiber connector. The dust cap includes a self-generating light source for testing connections in the optical system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an example distributed optical network including indexing terminals daisy-chained together; 
         FIG. 2  is a schematic diagram of an example indexing terminal suitable for use in the distributed optical network of  FIG. 1 ; 
         FIG. 3  is a schematic diagram of an example telecommunications cable distribution architecture in accordance with principles of the present disclosure; 
         FIG. 4  is a schematic of an example indexing component shown in the telecommunications cable distribution architecture of  FIG. 3  depicting a self-powered lighted dust cap; 
         FIG. 5  is a schematic of a fiber indexing system in accordance with the principles of the present disclosure; and 
         FIG. 6  is an enlarged view of a portion of the fiber indexing system shown in  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the exemplary aspects of the present disclosure that are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like structure. 
     The present disclosure generally relates to an installation methodology that allows for testing true connectivity in at least a portion of an indexing system while deploying indexing terminals. The present disclosure describes a diagnostic method of using a self-generating (e.g., self-powered) lighted dust cap that emits light in an optical system to test continuity of optical fiber lines in the optical system. In one example, the self-generating lighted dust cap is described with reference to  FIG. 4  in an indexing system. The self-generating lighted dust cap can be utilized to check true connectivity or continuity in the indexing system as will be disclosed in more detail herein. It will be appreciated that the self-generating lighted dust cap can be applicable to any type of optical system where it is desired to test true connectivity. An example fiber indexing system and method for deploying a fiber optic network architecture is shown in U.S. Pat. No. 9,348,096, the disclosure of which is hereby incorporated herein by reference. 
     An example fiber indexing system can be described with reference to  FIGS. 1-3 . 
       FIG. 1  illustrates an example optical network  10  being deployed in accordance with the principles of the present disclosure. The example optical network  10  includes a central office  12  and at least one fiber distribution hub  14 . While only a single hub  14  is shown in  FIG. 1 , it will be understood that optical networks  10  typically include multiple hubs. At least one feeder cable  16  extends from the central office  12  to each distribution hub  14 . At the distribution hub  14 , optical fiber carried by the feeder cable  16  are split onto optical fibers of one or more distribution cables  18 . At least one distribution cable  18  extends from the distribution hub  14  towards subscriber premises  20 . 
     In accordance with some aspects, the optical network  10  is a distributed optical network in which optical signals may be split at a splitting location disposed between the distribution hub  14  and the individual subscriber premises  20  as will be disclosed in more detail herein. In such systems, individual optical fibers may be broken out from the distribution cable  18  at geographic intervals and routed to the splitting locations. In various implementations, the splitting locations may be positioned at telephone poles, strands, and/or hand holes. From the splitting locations, the split optical signals are carried by drop cables to the individual subscriber premises  20 . 
     In some implementations, the individual optical fibers are broken out from the distribution cable  18  at indexing terminals  22 . Each indexing terminal  22  receives a distribution cable  18  having two or more optical fibers. In some implementations, the distribution cable  18  is a stub cable that extends outwardly from the indexing terminal  22 . In other implementations, the indexing terminal  22  receives a connectorized end of the distribution cable  18 . In certain implementations, each indexing terminal  22  separates one of the optical fibers from other optical fibers  24  (see  FIG. 2 ) of the distribution cable  18 . The separated optical fiber  24  is routed to a first port  26  of the indexing terminal  22  and the other optical fibers  28  are routed to a second port  30  of the indexing terminal  22  (e.g., see  FIG. 2 ). A dead indexing optical fiber corresponding to an inactive fiber position P 12 ′ may also be routed from the second port  30  such that the dead indexing optical fiber may be optically connected to a reverse drop fiber  21  at a reverse drop location  23 . 
     In the example shown in  FIG. 1 , a first distribution cable  18 A is routed from the distribution hub  14  to a mounting structure (e.g., telephone pole)  32 A at which the indexing terminal  22  is mounted. A second distribution cable  18 B extends from the indexing terminal  22  at the first mounting structure  32 A to another indexing terminal mounted at a second mounting structure  32 B. In the distributed network  10  shown in  FIG. 1 , indexing terminals  22  are mounted to eight poles  32 A- 32 H. These indexing terminals  22  are daisy-chained together using distribution cables  18 A- 18 H as will be described in more detail herein. In other implementations, however, distributed networks may include a greater or lesser number of indexing terminals  22 . 
       FIG. 2  illustrates an example indexing terminal  22  suitable for use in the distributed optical network  10  of  FIG. 1 . The indexing terminal  22  includes a housing  34  that defines the first port  26  and the second port  30 . In the example shown, the stub distribution cable  18  extends outwardly from the indexing terminal housing  22 . The stub distribution cable  18  includes multiple optical fibers that are connectorized at an end opposite the indexing terminal housing  34 . In the example shown, the stub distribution cable  18  includes twelve optical fibers. In other implementations, however, the stub distribution cable  18  may include a greater or lesser number of optical fibers (e.g., four, six, eight, ten, sixteen, twenty-four, seventy-two, etc.). 
     In certain implementations, the optical fibers of the stub distribution cable  18  extend from first ends to a second ends. The first ends of the fibers are connectorized at a multi-fiber connector  36  (e.g., an MPO-type connector). In the example shown, the first ends of the fibers are connectorized at a ruggedized multi-fiber connector (e.g., an HMFOC-connector). As the terms are used herein, ruggedized optical connectors and ruggedized optical adapters are configured to mate together to form an environmental seal. Some non-limiting example ruggedized optical connector interfaces suitable for use with an indexing terminal  22  are disclosed in U.S. Pat. Nos. 7,744,288, 7,762,726, 7,744,286, 7,942,590, and 7,959,361, the disclosures of which are hereby incorporated herein by reference. 
     The connector  36  indexes the first end of each optical fiber at a particular position relative to the other fibers. In the example shown, the connector  36  indexes each of the twelve optical fibers into one of twelve positions P 1 -P 12 . The second port  30  has the same number of fiber positions as the connector  36 . In the example shown, the second port  30  has twelve fiber positions P 1 ′-P 12 ′ that correspond with the fiber positions P 1 -P 12  of the connector  36 . 
     In one example, a first one  24  of the optical fibers has a first end located at the first position P 1  of the connector  36 . The second end of the first optical fiber  24  is separated out from the rest of the optical fibers  28  within the indexing terminal housing  34  and routed to the first port  26  at which optical signals carried by the first optical fiber  24  may be accessed. In some implementations, the first port  26  defines a female port at which an optical fiber plug may be mated to the first optical fiber  24 . In certain implementations, the first port  26  includes a ruggedized (i.e., hardened) optical adapter configured to receive a ruggedized optical connector (e.g., an HMFOC). 
     The remaining optical fibers  28  are routed to the second port  30 . At least one of the fiber positions P 1 ′-P 12 ′ does not receive an optical fiber  28  since at least one optical fiber  24  is diverted to the first port  26 . However, the second port  30  indexes the received optical fibers  28  so that a first position P 1 ′ at the second port  30  that corresponds with the first position P 1  of the connector  36  does receive one of the optical fibers  28 . In accordance with aspects of the disclosure, when the indexing terminals  22  are daisy-chained together as shown in  FIG. 1 , the optical fiber  24  diverted to the first port  26  will be pulled from the same position P 1 -P 12 . Also, the remaining fibers  28  will be cabled so that the corresponding position P 1 ′-P 12 ′ at the second port  30  will receive one of the optical fibers  28  if any are available. 
     In the example shown, the separated optical fiber  24  is located at an end of the row/strip of fibers. Accordingly, the optical fibers  28  are cabled within the indexing terminal housing  34  to divert the second end of each optical fiber  28  over one indexed position P 1 ′-P 12 ′ compared to the first end. For example, a fiber  28  having a first end at position Pn of the connector  36  would have a second end at position P(n−1)′ at the second port  30 . In the example shown, the optical fiber  28  having a first end at the second position P 2  of the connector  36  will have a second end disposed at the first position P 1 ′ of the second port  30 . Likewise, the optical fiber  28  having a first end at disposed the third position P 3  of the connector  36  will have a second end disposed at the second position P 2 ′ of the second port  30 . The optical fiber  28  having a first end at the twelfth position P 12  of the connector  36  will have a second end disposed at the eleventh position P 11 ′ of the second port  30 . The twelfth position P 12 ′ of the second port  30  will not receive an optical fiber. In other implementations, the optical fiber at any of the positions P 1 -P 12  may be separated out from the rest as long as each indexing terminal separates out a fiber from the same position. It will be appreciated that the second end of each optical fiber  28  can be diverted over more than one indexed position P 1 ′-P 12 ′ compared to the first end in a repeated pattern. 
     Such a cabling configuration enables the indexing terminals to be daisy-chained together using identical components while always delivering the next fiber in line to the first port  26 . For example, in  FIG. 1 , the stub distribution cable  18 B of the second indexing terminal  22  mounted to the second pole  32 B may be routed to and plugged into the second port  30  of the first indexing terminal  22  mounted to the first pole  32 A. The stub distribution cable  18 A of the first indexing terminal  22  may be routed to the distribution hub  14  to receive split optical signals from the feeder cable  16 . Accordingly, the split optical signals carried by the first optical fiber  24  of the first stub distribution cable  18 A are routed to the first port  26  of the first indexing terminal  22 . The split optical signals carried by the remaining optical fibers  28  of the first stub distribution cable  18 A are routed to positions P 1 ′-P 11 ′ of the second port  30  of the first indexing terminal  22 . 
     At the second port  30 , the second optical fiber  28  of the first stub cable  18 A is mated with the first optical fiber  24  of the second stub cable  18 B. The first optical fiber  24  of the second stub cable  18 B is routed to the first port  26  of the second indexing terminal. Accordingly, the split optical signals carried by the second optical fiber  28  of the first stub cable  18 A propagate to the first optical fiber  24  of the second stub cable  18 B and are accessible at the second port  30  of the second indexing terminal  22 . Likewise, the split optical signals carried by the sixth optical fiber  28  of the first stub cable  18 A propagate to the fifth optical fiber  24  of the second stub cable  18 B, the fourth optical fiber  28  of the third stub cable  18 C, the third optical fiber  28  of the fourth stub cable  18 D, the second optical fiber  28  of the fifth stub cable  18 E, and the first optical fiber  24  of the sixth stub cable  18 F and are accessible at the second port  30  of the sixth indexing terminal  22 . 
     In alternative implementations, the distribution cable  18  is not a stub cable and the indexing terminal housing  38  defines an input port (e.g., an HMFOC port) configured to receive a second connectorized end of the distribution cable  18 . In such implementations, internal cabling between the input port and the second port  30  is implemented as described above. Accordingly, the optical fiber coupled to a first position at the input port is routed to the first port  26  and the optical fiber coupled to a second position at the input port is routed to a first position at the second port  30 . In such implementations, each distribution cables  18  would include twelve optical fibers that are connectorized at both ends. The first end of each distribution cable  18  would mate with the input port of one indexing terminal. The second end of each distribution cable  18  would mate with the second port  30  of another indexing terminal. 
     Referring to  FIG. 3 , an example telecommunications cable distribution architecture  40  is shown. The telecommunications cable distribution architecture  40  can include a plurality of indexing components  42 . Each one of the plurality of indexing components  42  can include a first multi-fiber connection interface  44  defining a plurality of sequential fiber positions and a second multi-fiber connection interface  46  defining a plurality of sequential fiber positions. 
     The telecommunications cable distribution architecture  40  further includes a plurality of indexing optical fibers  48  connected between the first and second multi-fiber connection interfaces  44 ,  46  in an indexed configuration. A feeder distribution cable  62  (e.g., main cable) may be associated at one end with a central office  64 . The cable  62  may have on the order of 12 to 48 fibers; however, alternative implementations may include fewer or more fibers. The cable  62  shown has 12 fibers that each have an end associated with the central office  64 . The central office  64  may connect a number of end subscribers  20  (e.g., end users). In certain examples, the central office  64  may also connect to a larger network such as the Internet (not shown) and a public switched telephone network (PSTN). The various lines of the network can be aerial or housed within underground conduits. 
     In certain examples, forward drop fibers  50  may be routed from the first multi-fiber connection interfaces  44  of indexing components  42  in the architecture  40  to forward drop locations  52  where they are connected into adapter ports  53 . In certain examples, a second connector (not shown) may be plugged or connected into the adapter ports  53  and routed to the individual subscriber premises  20 . 
     The plurality of indexing components  42  can be daisy chained together end-to-end in an upstream to downstream direction as shown by arrow A with first multi-fiber connection interfaces  44  of each indexing component  42  being positioned upstream from its corresponding second multi-fiber connection interface  46 . The first and second multi-fiber connection interfaces  44 ,  46  of adjacent indexing components  42  in the daisy chain can be optically coupled together. 
     In  FIG. 3 , a mechanical coupling  58  is schematically shown to indicate the coupling of the first and second multi-fiber connection interfaces  44 ,  46  of adjacent indexing components  42  in the daisy chain. 
     In some examples, reverse drop fibers  54  may also be routed from the second multi-fiber connection interfaces  46  of the indexing components  42  in the architecture  40  to reverse drop locations  56  where they can be connected into adapter ports  57 . 
     Referring to  FIG. 4 , a schematic of an example indexing component  42  is shown. A dust cap (e.g., device)  66  can be configured to mount onto a ruggedized optical connector (e.g., an HMFOC) or a ruggedized (i.e., hardened) optical adapter, although alternatives are possible. In certain examples, the dust cap  66  can be mounted onto a single fiber connector. 
     The dust cap  66  can be mounted onto the indexing component  42  at the second multi-fiber connection interface  46 . In one example, the dust cap  66  can be secured to the indexing component  42  by a threaded connection. For example, the dust cap  66  can have internal threads (not shown) that mate with external threads (not shown) of the indexing component  42  to secure the dust cap  66  on the indexing component  42 . 
     In the example shown, the dust cap  66  includes a self-generating light source  68  (e.g., self-powered light source) to emit light through the optical fibers sequentially positioned in the indexing component  42 . In one example, the self-generating light source  68  can be a light emitting diode (LED), although alternatives are possible. For example, the dust cap  66  may include self-generating laser light source. 
     The dust cap  66  may include a battery holder  70  (e.g., clip) for securing a battery  72  therein for powering the self-generating light source  68 . The dust cap  66  may include a printed circuit board assembly  74  (PCBA) to mechanically support and electrically connect the self-generating light source  68 , although alternatives are possible. The PCBA  74  is shown positioned between the battery holder  70  and the self-generating light source  68 . 
     The dust cap  66  generates its own light such that when connected to the indexing component  42 , light is pushed through a HMFOC or single connector to test the fiber optic lines for true connectivity. In  FIG. 4 , the dust cap  66  shines self-emitting or self-generating light through positions P 2 -P 4  of the indexing component  42  to test the indexing optical fibers  48  for true connectivity. 
     Referring to  FIG. 5 , a schematic of an example fiber indexing system  76  is depicted. The fiber indexing system  76  shows an example method of installation of the indexing components  42 . When deploying the indexing components  42 , the components  42  are deployed from the downstream end where an installer would work backwards towards the central office  64 . Typically in a fiber indexing system, testing of fiber optic lines for true continuity occurs after the installation process. Thus, if there is an issue with continuity, trouble shooting is required to determine where the issue lies in the system. If an indexing terminal needs replacing, the terminals already deployed would be taken down. 
     In the depicted fiber indexing system  76 , the dust cap  66  can be mounted at a tail end of the fiber indexing system  76  having a plurality of the indexing components  42  daisy chained together, although alternatives are possible. For example, the dust cap  66  can be mounted over any one of the indexing components  42  individually. In other examples, the dust cap  66  can be mounted onto a single fiber for testing purposes. For example, the dust cap  66  can be mounted onto the forward drop fibers  50  or reverse drop fibers  54  to test for true continuity. 
     Referring to  FIG. 6 , an enlarged view of a portion of the fiber indexing system  76  shown in  FIG. 5  is shown. The dust cap  66  is arranged and configured to mount onto the second multi-fiber connection interface  46  of the downstream-most indexing component  42 A. The self-generating light source of the dust cap  66  passes through the indexing optical fibers  48  of the indexing component  42 A to test for true continuity along the plurality of sequential fiber positions P 1 -P 12 . Accordingly, verification of light on the HMFOC connector can be provided for the downstream-most indexing component  42 A in the fiber indexing system  76 . As depicted, the forward drop fibers  50  and the reverse drop fibers  54  progressively dropped in the fiber indexing system  76  are no longer visible through the dust cap  66 . However, it will be appreciated that the dust cap  66  can be arranged and configured to mount separately onto the forward and reverse drop fibers  50 ,  54  to test for true continuity or connection. In certain examples, the dust cap  66  can be mounted onto an optical port for testing true continuity of an optical fiber line. 
     When installing additional indexing components  42 B,  42 C,  42 D, progressively backwards from the downstream end, the self-generating light source  68  of the dust cap  66  emits light that continues to pass through the indexing optical fibers  48  of the indexing component  42 A to the next indexing component  42 B that is installed in the network. Such a configuration allows for verification of continuity or connections throughout the “daisy chaining” process of installing indexing components  42 C,  42 D etc. It will be appreciated that the dust cap  66  may be utilized in a fiber indexing system that is deployed in a direction from the upstream end to the downstream end. 
     While we show the dust cap  66  utilized in a fiber indexing system, the dust cap  66  may also be applicable in any type of optical system having a port or connector where testing true continuity is desirable. 
     In one example, the dust cap  66  can be designed to remain on the indexing component  42  and the battery is allowed to run dead. Leaving the dust cap  66  on eliminates the need for a technician to come back to the terminal to remove the dust cap  66 . It will be appreciated that verification of light on the connector end can take place in the field prior to deploying each terminal, on a spool or in a coiled state. 
     Another aspect of the present disclosure relates to a diagnostic method for testing continuity along an optical fiber. The method includes a step of mounting a dust cap  66  to an optical port. The dust cap  66  can include the self-generating light source  68  for testing an optical fiber line. The method can further include a step of activating the self-generating light source  68  of the dust cap  66  to shine a light along the optical fiber line. The method includes a step of determining whether the light is visible downstream of the optical fiber line. 
     The present disclosure further relates to a diagnostic method for testing continuity along an optical fiber for the fiber indexing system  76 . The fiber indexing system  76  includes the plurality of indexing components  42  daisy chained together. The plurality of indexing components  42  can each have the first multi-fiber connection interface  44  that defines a plurality of sequential fiber positions and the second multi-fiber connection interface  46  that defines a plurality of sequential fiber positions. A plurality of indexing optical fibers  48  can be connected between the first and second multi-fiber connection interfaces  44 ,  46  in an indexed configuration. 
     The method includes the steps of: 1) installing the first indexing component  42 A; 2) mounting the dust cap  66  to the first multi-fiber connection interface  44  of the first indexing component  42 A where the dust cap  66  includes the self-generating light source  68  to test the plurality of indexing optical fibers  48  in the fiber indexing system  76 ; 3) activating the self-generating light source  68  of the dust cap  66  to shine a light along the plurality of indexing optical fibers  48 ; 4) installing a second indexing component  42 B such that the first and second multi-fiber connection interfaces  44 ,  46  of the first and second indexing components  42 A,  42 B are optically coupled together; 5) determining whether the light is visible at the first multi-fiber connection interface  44  of the second indexing component  42 B in the fiber indexing system  76 ; 6) installing a third indexing component  42 C such that the first and second multi-fiber connection interfaces  44 ,  46  of the second and third indexing components  42 B,  42 C are optically coupled together; and 7) determining whether the light is visible at the first multi-fiber connection interface  44  of the third indexing component  42 C in the fiber indexing system  76 . 
     The present disclosure also relates to the dust cap  66  for an optical fiber connector in an optical system. The dust cap  66  can be adapted to cover an end of the optical fiber connector. The dust cap  66  includes a self-generating light source  68  for testing connections in the optical system. 
     The principles, techniques, and features described herein can be applied in a variety of systems, and there is no requirement that all of the advantageous features identified be incorporated in an assembly, system or component to obtain some benefit according to the present disclosure. 
     From the forgoing detailed description, it will be evident that modifications and variations can be made without departing from the spirit and scope of the disclosure.