Patent Publication Number: US-2023141514-A1

Title: Passive Optical Couplers Having Passive Optical Activity Indicators and Methods of Operating the Same

Description:
RELATED APPLICATION 
     The present application is a continuation of U.S. patent application Ser. No. 17/524,361, filed on Nov. 11, 2021. U.S. patent application Ser. No. 17/524,361 is hereby incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     This disclosure relates generally to passive optical couplers, and, more particularly, to passive optical couplers having passive optical activity indicators and methods of operating the same. 
     BACKGROUND 
     A conventional passive optical network (PON) includes one or more optical line terminals (OLTs) at a central location connecting to one or more optical network terminals (ONTs) at respective customer premises. A PON is typically implemented using a point-to-multipoint topology in which a feeder optical fiber from an OLT serves multiple ONTs via respective distribution optical fibers. Typically, the feeder optical fiber is optically coupled to distribution optical fibers for respective ones of the ONTs in a fiber distribution hub (FDH) using an optical splitter and a bulkhead having a plurality of optical couplers. Over time, as distribution optical fibers are connected, disconnected, reconnected via different ports, etc. to a bulkhead, it may become increasingly difficult for a service technician to know which ports of a bulkhead are active, connected, provisioned, available for use, etc. Today, a service technician must disconnect, unplug, etc. an optical fiber and connect it to a light meter to determine whether the optical fiber is carrying an optical signal. Such a process may be time-consuming and may reduce technician efficiencies. Further, service technicians may erroneously attempt to repair a service by placing the optical fiber of a customer experiencing service disruptions into a working optical coupler, which was unknowingly providing service to a different customer. This may result in service disruptions. 
     Accordingly, there is a need for passive optical couplers that can provide an indication of the status of their ports. Moreover, there is a need for systems and methods for collecting information regarding optical connections in a PON. Furthermore, there is a need for systems and methods for mapping optical connections in a PON. 
     SUMMARY 
     In an example, a passive optical coupler for passively coupling first and second optical fibers includes: a housing including a first port configured to receive an end of a first optical fiber, and a second port configured to receive an end of a second optical fiber; and a passive optical activity indicator positioned at least partially within the housing, wherein a first portion of the passive optical activity indicator is exposed through the housing, and wherein the passive optical activity indicator is configured to passively illuminate in response to (i) first light propagating in the first optical fiber when the end of the first optical fiber is received in the first port, and (ii) second light propagating in the second optical fiber when the end of the second optical fiber is received in the second port. 
     In another example, a method includes inserting a first connector of a first optical fiber into a first port of a passive optical coupler, the passive optical coupler further including: a second port configured to receive a second connector of a second optical fiber to optically couple the second optical fiber to the first optical fiber; and a passive optical activity indicator positioned at least partially within the passive optical coupler and at least partially exposed, wherein the passive optical activity indicator is configured to passively illuminate in response to (i) first light propagating in the first optical fiber when the end of the first optical fiber is received in the first port, and (ii) second light propagating in the second optical fiber when the end of the second optical fiber is received in the second port. The method further includes: configuring a light source at an optical terminal to transmit light into an optical fiber; detecting light externally exposed by the first portion of the passive optical activity indicator; and determining whether the optical terminal is optically coupled to the passive optical coupler based on the detected light. 
     In yet another example, a bulkhead for an fiber distribution hub of a passive optical network includes a plurality of optical couplers. Each of the plurality of optical couplers including: a respective first port adapted to receive an end of a respective first optical fiber; a respective second port adapted receive an end of a respective second optical fiber; and a respective passive optical activity indicator constructed from a passive light transmissive material, wherein the passive optical activity indicator is configured to illuminate in response to (i) first light propagating in the first optical fiber when the end of the first optical fiber is received in the first port, and (ii) second light propagating in the second optical fiber when the end of the second optical fiber is received in the second port. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views, together with the detailed description below, are incorporated in and form part of the specification, and serve to further illustrate examples of concepts that include the claimed invention, and explain various principles and advantages of those examples. 
         FIG.  1    is a schematic diagram of an example system having an example passive optical network (PON) constructed in accordance with the disclosure. 
         FIG.  2 A  is a perspective view of an example passive optical coupler that may be used to implement the example passive optical couplers of  FIG.  1   , in accordance with the disclosure. 
         FIG.  2 B  is another perspective view of the example passive optical coupler of  FIG.  2 A , in accordance with the disclosure. 
         FIG.  2 C  is an end view of a first end the example passive optical coupler of  FIG.  2 A , in accordance with the disclosure. 
         FIG.  2 D  is a side view of the example passive optical coupler of  FIG.  2 A , in accordance with the disclosure. 
         FIG.  2 E  is a top view of the example passive optical coupler of  FIG.  2 A , in accordance with the disclosure. 
         FIG.  2 F  is a side cross-section view of the example passive optical coupler of  FIG.  2 A , in accordance with the disclosure. 
         FIG.  3    is a schematic diagram of an example optical terminal that may be used to implement the example optical line terminal and/or optical network terminals of  FIG.  1   , in accordance with the disclosure. 
         FIG.  4    is a schematic diagram of an example fiber distribution hub (FDH) that may be used to implement the example FDH of  FIG.  1   . 
         FIG.  5    is a flowchart representative of an example method for verifying an optical connection, in accordance with the disclosure. 
         FIG.  6    is a flowchart representative of an example method for configuring an optical connection, in accordance with the disclosure. 
         FIG.  7    is a flowchart representative of an example method for identifying an optical connection, in accordance with the disclosure. 
         FIG.  8    is a flowchart representative of an example method for mapping optical connections of an FDH, in accordance with the disclosure. 
         FIG.  9    is a block diagram of an example computing system that may be used to implement the various structures and methods for verifying optical connections, configuring optical connections, identifying optical connections and/or mapping connections of an FDH, in accordance with the disclosure. 
     
    
    
     Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of the present disclosure. 
     The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding examples of the present disclosure so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. 
     Although the figures show parts with clean lines and boundaries, some or all of these lines and/or boundaries may be idealized. In reality, the boundaries and/or lines may be unobservable, blended, and/or irregular. Use of terms such as up, down, top, bottom, side, end, front, back, etc. herein are used with reference to a currently considered or illustrated orientation. If they are considered with respect to another orientation, it should be understood that such terms must be correspondingly modified. 
     DETAILED DESCRIPTION 
     Disclosed examples of the disclosure provide a number of advantages over existing passive optical networks (PONs) that do not include the example passive optical couplers disclosed herein. For example, because active ports can be detected with disclosed examples, the occurrence of inadvertent disconnections of an active and currently working service can be reduced. Such inadvertent disconnections can result in a service call, which can cost a network provider hundreds of dollars. Moreover, by reducing inadvertent disconnections, customer satisfaction can be increased, at least because the customer isn&#39;t asked to factory reset their modem in an unfruitful and unnecessary attempt to restore service before initiating a service call. Such factory resets are frustrating to customers as they may require the customer to reconfigure their modem (e.g., the setup a WiFi network). Furthermore, the resources of a fiber distribution hub (FDH) can be conserved by, for example, allowing passive optical couplers that are not currently being used but are still connected to an unused distribution optical fiber to be identified and reassigned. Still further, the labor costs associated with provisioning and/or repairing a service to a customer can be reduced by the automatic ability to detect an active passive optical coupler for use in provisioning or repairing the service. Such problems may be exacerbated overtime by the inevitable development of a “rats nest” of cabling in an FDH due to numerous connections, re-connections, disconnections, etc. of optical fibers to passive optical couplers. Such conditions may make it extremely difficult to identify what is connected to what, what is active, what is inactive or unused, etc. 
     While examples of the disclosure are directed to using example passive optical activity indicators of example passive optical couplers of a fiber distribution hub (FDH) in a passive optical network (PON) to map optical connections of the FDH, persons of ordinary skill in the art will recognize that the disclosure may be used to map connections in other systems and/or network. For example, images of active port indicators may be taken and processed to determine a map of connections in active networks and/or systems. For example, images of a plurality of link activity indicators of an Ethernet switch/hub may be captured and processed to detect and map active/connected ports. For instance, activity of Ethernet devices may be controlled (e.g., by controlling a pattern of sending packets on a port), and images of an Ethernet switch may be used to identify which Ethernet devices are connected to which ports. 
     Reference will now be made in detail to non-limiting examples, some of which are illustrated in the accompanying drawings. 
     Example Passive Optical Network (PON) 
       FIG.  1    is a schematic diagram of an example system  100  including an example PON  101  constructed in accordance with the disclosure. The example PON  101  includes one or more optical line terminals (OLTs) (one of which is designated at reference numeral  102 ) at a central location (e.g., at a central office  104 ) connecting to one or more optical network terminals (ONTs) (two of which are designated at reference numerals  106 A and  106 B) at respective customer premises (two of which are designated at reference numerals  108 A and  108 B). The ONTs  106 A,  106 B may be located outside and/or inside the customer premises  108 A,  108 B. In some examples herein, an optical terminal refers to an OLT or an ONT. 
     The example PON  101  is implemented using a point-to-multipoint topology in which a feeder optical fiber  110  from the OLT  102  (sometimes called an F 1  optical fiber) serves the one or more ONTs  106 A,  106 B via respective distribution optical fibers  112 A,  1128  (sometimes called F 2  optical fibers). While in the illustrated example, there is one feeder optical fiber  110  feeding the distribution optical fibers  112 A,  1128  via a single optical splitter  114 , the PON  101  may include additional feeder optical fibers and optical splitters for a plurality of additional customer premises. Moreover, a PON may include a plurality of FDHs. 
     In the illustrated example, the feeder optical fiber  110  is optically coupled to the plurality ONTs  106 A,  106 B via an example 1-to-many optical splitter  114  disposed, located, implemented, etc. in an example FDH  116 . In some examples, the FDH  116  is located within a geographic area (e.g., a neighborhood) such that the customer premises  108 A,  108 B are close to the FDH  116 . 
     There may be multiple points along these paths where one optical fiber is connected to another optical fiber. For example, to provide for dynamic (e.g., changeable) connections, the example FDH  116  includes a distribution means having a plurality of coupling means for coupling optical fibers. In this example, this distribution means is a bulkhead  118  of the FDH  116 , and the couplings means are implemented by passive optical couplers (two of which are designated at reference numerals  120 A and  120 B) of the bulkhead  118 , but other structures are likewise appropriate. In the illustrated example, a plurality of optical fibers (two of which are designated at reference numerals  122 A and  122 B) from the optical splitter  114  are typically connected to respective first ports of the passive optical couplers  120 A,  120 B. In some examples, the optical fibers  122 A,  122 B are connected to the first ports of the passive optical couplers  120 A,  120 B on a backside of the bulkhead  118 , when looking into the FDH  116  from the front. The distribution optical fibers  112 A,  112 B are connected to respective second ports of the passive optical couplers  120 A,  102 B. In some examples, the distribution optical fibers  112 A,  112 B are connected to the second ports of the passive optical couplers  120 A,  120 B on a front side of the bulkhead  118 , when looking into the FDH  116  from the front. While in the illustrated example, there is a single bulkhead  118 , an FDH may have any number of bulkheads. Moreover, a bulkhead may provide for connecting optical fibers associated with more than one optical splitter. 
     In the illustrated example of  FIG.  1   , the passive optical couplers  120 A,  120 B are passive devices. That is, the example passive optical couplers  120 A,  120 B do not need, require, utilize, generate and/or otherwise use any form of electrical power. Instead, as will be discussed below, the passive optical couplers  120 A,  120 B include only passive components. 
     Over time, as distribution optical fibers  112 A,  112 B are connected to the bulkhead  118  (e.g., to provision a service to an ONT, to reconnect an ONT to a different coupler, etc.) and/or disconnected (e.g., to de-provision a service to an ONT, troubleshoot a service to an ONT, etc.), it may become increasingly difficult for a service technician working at the FDH  116  to know, determine, identify, detect, etc. which ports of the bulkhead  118  are active, connected, provisioned, available for use, etc. In some instances, grid maps for an FDH are managed manually and, thus, are often inaccurate and/or incomplete. Today, a service technician must disconnect, unplug, etc. an optical fiber and connect it to a light meter to determine whether the optical fiber is carrying an optical signal. 
     To provide one or more indications regarding the status of its ports, the example passive optical couplers  120 A,  120 B each include an indicating means for indicating port status. In this example, the indicating means is implemented by an example passive optical activity indicator  124 , but other structures are likewise appropriate. The example passive optical activity indicators  124  passively and externally expose a portion of the light propagating in one or both optical fibers connected to a respective passive optical coupler  120 A,  120 B. Thus, light exposed by a passive optical activity indicator  124  can be externally detected (e.g., visually, using a light meter, using a sensor, using an image sensor, etc.), and used to determine whether an optical fiber connected to a passive optical coupler  120 A,  120 B is actually carrying a propagating optical signal. 
     An example passive optical coupler  200  that may be used to implement the example passive optical couplers  120 A,  120 B are described below in connection with  FIGS.  2 A- 2 F . 
     Mapping of Optical Connections 
     In some examples, an optical terminal (e.g., the OLT  102  and/or the ONTs  106 A,  106 B) includes a light transmitting means for selectively multiplexing, injecting, transmitting, etc. indication light into an optical fiber according to a particular pattern. In this example, the light transmitting means is implemented by a light source to transmit light according to a pattern, and/or an optical multiplexer (e.g., see  FIG.  3   ), but other structures are likewise appropriate. When the pattern with which an optical terminal transmits indication light is unique to the optical terminal, then light exposed by the passive optical indicator  124  can be used to uniquely identify an optical terminal connected (e.g., optically coupled) to a passive optical coupler  120 A,  120 B. Moreover, when two optical terminals are connected via a passive optical coupler  120 A,  120 B and each transmit indication light according to a respective unique pattern, then light exposed by the passive optical indicator  124  can be used to identify whether neither, one, or both of the optical terminals are actually connected (e.g., optically coupled) to the passive optical coupler  120 A,  120 B. In some examples, an optical terminal selectively transmits indication light into an optical fiber in response to a received control signal. 
     In some examples, the indication light transmitted into an optical fiber is in addition to or instead of other light propagating in the optical fiber associated with providing a service to an ONT. The indication light may be transmitted by multiplexing first light having a first wavelength associated with providing the communication service with second light having a different second wavelength associated with providing an activity indication. Light exposed by the passive optical indicator  124  associated with the second wavelength may be used to determine and/or identify whether an optical terminal is coupled to a passive optical coupler  120 A,  120 B. In some examples, a device (e.g., an image sensor) used to detect light emitted by a passive optical activity indicator  124  is tuned, adjusted, configured, etc. to detect light having the second wavelength and to block light having the first wavelength. 
     In some examples, the indication light transmitted into an optical fiber is at a wavelength visible to a person and blinks at a rate that can be perceived by the person such that the person can visually look at a passive optical activity indicator  124  and determine whether a passive optical coupler  120 A,  120 B is connected to a particular optical terminal. In some examples, indication light is simultaneously transmitted into an optical fiber by two different optical terminals using a wavelength visible to a person and with intertwined blink patterns such that a person can determine that both optical terminals are connected to a passive optical coupler  120 A,  120 B when the light exposed by a passive optical activity indicator  124  is substantially steady. In such examples, when the passive optical activity indicator  124  blinks, the person can visually determine that only one of the optical terminals is connected to the passive optical coupler  120 A,  120 B. Moreover, if the optical terminals blink their indication light at different rates (e.g., one slow and one fast), then the rate of blinking may be visually detected by the person and used to identify which optical terminal is connected to the passive optical coupler  120 A,  120 B. 
     In some examples, the pattern by which indication light is transmitted into an optical fiber is based on a unique identifier (e.g., a device identifier, a serial number, a MAC address, etc.). That is, the transmitted indication light can convey an encoded identifier. For example, whether indication light is active or inactive during each of a plurality of time periods can be determined based on the value of a respective bit of an encoded identifier. In such examples, the encoded identifier may include a preamble that can be used to identify, detect, etc. the start of an encoded identifier in transmitted indication light. 
     In some examples, an optical terminal (e.g., the OLT  102  and/or the ONTs  106 A,  106 B) transmits indication light into an optical fiber in response to control signals received from a computing device. For example, control signals may be received from a computing device  126  (e.g., a laptop, a computer, a tablet, a mobile phone, etc.) associated with a service technician. In some examples, the device  126  controls an optical terminal via the PON  101 , via a network  128  such as the Internet or a private network, and/or by direct interaction with the optical terminal (e.g., via a hotspot provided by the optical terminal, a service port of the optical terminal, etc.). Additionally and/or alternatively, control signals may be received from a server  130  that is used to manage the PON  101  via the PON  101 , the network  128 , etc. 
     To collect, obtain, etc. information representing optical connections of the FDH  116 , the example FDH  116  includes an imaging means for capturing images of the bulkhead  118 . In this example, the imaging means is implemented by one or more image sensors, imaging devices, cameras, etc.  132 , but other structures are likewise appropriate. The image sensor  132  captures images of the passive optical activity indicators  124  of the bulkhead  118  falling within a field of view  134  of the image sensor  132 . As discussed below in connection with  FIG.  4   , the image sensor  132  may be mounted on a door of the FDH  116  such that the image sensor  132  is opposite the bulkhead  118  when the door is closed. In such examples, the image sensor  132  may be close to the bulkhead  118  when the door is closed. Accordingly, more than one image sensor  132  may be required to capture images of all of the passive optical activity indicators  124  of the bulkhead  118 . In some examples, the image sensor(s)  132  are configured to capture images a frame rate that exceeds (e.g., at least twice) the rate at which light sources change their transmitted indication light. As discussed below in connection with  FIG.  9   , the image sensor(s)  132  may be associated with a computing device  136  that includes, among other things, a processing means for controlling the image sensor(s)  132 , a storage means for storing images captured by the image sensor(s)  132 , and a communicating means for communicating, providing, etc. stored image to another computing device (e.g., the computing devices  126 ,  130 ). When indication light is transmitted into an optical fiber by multiplexing first light having a first wavelength associated with providing a communication service with second light having a different second wavelength associated with providing an activity indication, the image sensor(s)  132  may be configured to sense light at the second wavelength and to filter out light at the first wavelength 
     To map optical connections of the FDH  116 , the example system  100  includes a computing means for processing image data of the images captured of the bulkhead  118  for determining which of the plurality of passive optical couplers  120 A,  120 B are receiving optical signals on one or more of their ports. In this example, the computing means is a processor platform such as the server  130 , but other structures are likewise appropriate. As will be described in more detail below in connection with the flowchart  800  of  FIG.  8   , the server  130  may configure one or more optical terminals (e.g., the OLT  102  and/or the ONTs  106 A,  106 B) of the PON  101  to transmit indication light into respective optical fibers, control the FDH  116  (e.g., the image sensor(s)  132  via the computing device  136 ) to capture one or more images of the bulkhead  118  of the FDH  116 , and process image data for the images to determine which passive optical activity indicators  124  are emitting light and the pattern(s) of emitted light. Based on these, or other, determinations, the server  130  may identify which passive optical couplers  120 A,  120 B are connected to which optical terminals. In some examples, the server  130  uses the identifications to fill in one or more entries of an electronic grid map  138  of the FDH  116  that represents the connections of particular optical terminals to particular ports of particular passive optical couplers  120 A,  120 B. 
     The example electronic grid map  138  may be a table that contains a plurality of rows for respective ones of the passive optical couplers  120 A,  120 B, with each row including, possibly among other entries, an entry to identify the passive optical coupler  120 A,  120 B (e.g., coordinates of the location of the passive optical coupler  120 A,  120 B on the bulkhead  118 ), an entry to indicate whether and/or which feeder optical fiber  110  is connected to the passive optical coupler  120 A,  120 B, and an entry to indicate whether and/or which distribution optical fiber  112 A,  112 B is connected to the passive optical coupler  120 A,  120 B. In some examples, the electronic grid map  138  is accessible by a service technician via a user interface provided by either or both of the computing devices  126 ,  130 . The electronic grip map  138  may be stored on any storage means. In this example, the storage means in any number and/or type(s) of computer-readable storage medium, disk or device, such as memory  904  and/or database  910  of  FIG.  9   , but other structures are likewise appropriate. 
     Example Passive Optical Coupler 
       FIG.  2 A  is a perspective view of an example passive optical coupler  200  that may be used to implement the example passive optical couplers  120 A,  120 B of  FIG.  1   , in accordance with the disclosure.  FIG.  2 B  is another perspective view of the example passive optical coupler  200 .  FIG.  2 C  is an end view of an end the example passive optical coupler  200 .  FIG.  2 D  is a side view of the example passive optical coupler  200 .  FIG.  2 E  is a top view of the example passive optical coupler  200 .  FIG.  2 F  is a side cross-section view of the example passive optical coupler  200  taken along line  2 F- 2 F of  FIG.  2 A . 
     The example passive optical coupler  200  of  FIGS.  2 A- 2 F  includes a housing  205  in which two receiving means are defined on opposite ends of the housing  205 . In this example, the receiving means are ports, openings, receptacles, female connectors, etc.  210  and  215  defined in the housing  205  and configured, adapted, etc. for receiving and securing connectors at ends of respective optical fibers, but other structures are likewise appropriate. In some examples, the ports  210 ,  215  are configured to receive SC fiber optic connectors. 
     In the illustrated example, the optical fibers, when their respective connectors are received in the ports  210 ,  215 , are optical coupled by an indicating means. In this example, the indicating means is a pane  220  of passive optical material disposed at least partially within the housing  205  and generally in the middle of the housing  205  between the ports  210 ,  215 , but other structures are likewise appropriate. The pane  220  may be used to implement the example passive optical activity indicators  124  of  FIG.  1   . When connectors of the optical fibers are received in respective ports  210 ,  215 , ends of the optical fibers come into optical contact with respective sides, surfaces or planes of the pane  220 , and become optically coupled thereby. 
     At least a portion of light propagating in one or both of the optical fibers will propagate between the optical fibers via the pane  220 . An additional portion of light propagating in one or both of the optical fibers will propagate through and/or within the pane  220  and be emitted out of the optical coupler  200  through an opening  225  defined in the housing  205 . In some examples, only one decibel (1 dB) of optical loss is introduced between the optical fibers by the example pane  220 . In some examples, the pane  220  includes an angled surface (not shown) to direct light in the pane  220  through the opening  225 . An example angle is 45 degrees. 
     In the illustrated example, the ports  210 ,  215  of the passive optical coupler  200  may have a respective ferrule  230 ,  235  to position and secure optical ends of the optical fibers within the passive optical coupler  200  relative to the pane  220  to provide a stable optical coupling. 
     As shown, the passive optical coupler  200  may include mounting means for securing the passive optical coupler  200  to a bulkhead (e.g., the bulkhead  118 ). In this example, the mounting means includes one or more tabs  240  with mounting holes  245 , and/or one or more spring tabs  250 , but other structures are likewise appropriate. In the illustrated example, the passive optical coupler  200  is configured to be mounted front-to-back to the face of a bulkhead with the opening  225  and pane  220  exposed frontward from the bulkhead. The port  215  may face backwards from the face of the bulkhead to receive an optical fiber from a splitter (e.g., the splitter  114 ), and the port  210  may face forward from the face of the bulkhead to receive a distribution optical fiber (e.g., one of the distribution optical fibers  112 A,  112 B). In some examples, the passive optical coupler  200  may be secured to the face of the bulkhead with screws, bolts, etc. through the openings  245  in the tabs  240  into or through the face of the bulkhead. Additionally and/or alternatively, the spring tabs  250  may be used to secure the face of the bulkhead between the spring tabs  250  and the tabs  240 . 
     While an example method of exposing a portion of a passive optical activity indicator (e.g., the pane  220 ) is illustrated in  FIGS.  2 A- 2 F , persons of ordinary skill in the art will recognize that other methods of exposing a portion of a passive optical activity indicator may be used. For example, an edge or end of the pane  220  may be exposed through the housing  205 , an end of the pane  220  may extend through and beyond a surface of the housing  205 , etc. 
     Example Optical Terminal 
       FIG.  3    is a schematic diagram of an example optical terminal  300  that may be used to implement at least a portion of the example OLT  102  and/or the example ONTs  106 A,  106 B. To send data to and/or receive data from a customer&#39;s equipment, the example optical terminal  300  includes any number and/or type(s) interface transceivers  305 . Example interface transceivers  305  include an Ethernet transceiver, a WiFi transceiver, a telephone service interface, etc. 
     To convert between optical signals propagating on an optical fiber  310  and digital signals for and/or from the interface transceiver(s)  305 , the example optical terminal  300  includes any type of optical-to-electrical (O/E) converter  315 . 
     To generate indication light  320  for detection at a passive optical activity indicator, the example optical terminal  300  includes an example light source  325 . The example light source  325  selectively generates the indication light  320  responsive to control signals from a controller  330 . The light source  325  may be configured to generate indication light  320  according to a prescribed pattern. Example patterns include, as described above, a blinking rate and duty cycle, an encoding with a unique identifier, etc. In some examples, a wavelength associated with the indication light  320  is selected to be different from a wavelength associated with providing a service via the  0 /E converter  315  and the interface transceiver(s)  305 . 
     Control of the light source  325  by the controller  330  may be responsive to control signals received from another device such as a laptop, a computer, a mobile phone, etc. associated with a service technician (e.g., the computing device  126 ), a server used to manage a PON (e.g., the server  130 ), etc. The signals may be received, for example, via a PON (e.g., via the optical fiber  310 ), via a network such as the Internet or a private network, via direct interaction with the optical terminal (e.g., via a hotspot provided by the optical terminal, a service port of the optical terminal, etc.), etc. 
     An example optical multiplexer  335  multiplexes the indication light  320  onto to the optical fiber  310  together with service light  340  associated with providing a service via the  0 /E converter  315  and the interface transceiver(s)  305 . 
     Example Fiber Distribution Hub (FDH) 
       FIG.  4    is a diagram of an example FDH  400  that may be used to implement the example FDH  116  of  FIG.  1   . The example FDH  400  includes a cabinet  405  that may be mounted to, for example, a concrete pad. The FDH  400  includes a door  410  for selectively opening and closing the FDH  400 . The door  410  may include a lock for securing the FDH  400  from tampering by unauthorized persons. 
     As shown, the example FDH  400  includes the example bulkhead  118  of  FIG.  1    including the plurality of passive optical couplers  120 A,  120 B each having a respective passive optical activity indicator  124 . As described above, the passive optical couplers  120 A,  120 B are mounted front-to-back to a face of the bulkhead  118  such that a port  415  of each passive optical coupler  120 A,  120 B (e.g., the example port  210  of  FIGS.  2 A- 2 E ) is exposed frontward from the bulkhead  118  to receive a distribution optical fiber. 
     The example FDH  400  includes the example computing device  136  of  FIG.  1    and one or more image sensors  132 . In the example of  FIG.  4   , the image sensor(s)  132  are mounted to the door  410  of the FDH  400  such that, when the door  410  is closed, fields of view  420  of the image sensors  132  include one or more of the passive optical activity indicators  124 , as shown. In general, the number of image sensors  132  depends on the dimensions of the FDH  410 , and the dimensions of the fields of view  420  of the image sensor(s)  132 . In some examples, the fields of view  420  overlap to accommodate the routing of optical fibers in front of the passive optical couplers  120 A,  120 B that may sometimes block a view of a particular passive optical activity indicator  140  by a particular image sensor  132 . 
     To detect whether the door  410  of the FDH  400  is closed, the example FDH  400  may include a relay  425  configured to trip, for example, when the door  410  is closed. In such examples, the computing device  136  may, responsive to the relay  425 , cause the image sensors  132  to capture one or more images of the passive optical activity indicators  124  of the bulkhead  118 , and store the captured images for subsequent conveyance to another computing device such as the server  130 . 
     As shown, the FDH  400  may include any number and/or type(s) of cable rails  430  for managing the orderly routing of optical fibers within the cabinet  405 . 
     Example Method of Verifying an Optical Connection 
       FIG.  5    is a flowchart  500  representative of an example method for verifying the connection of an optical terminal to an FDH (e.g., one of the example FDHs  116 ,  400 ). The example method of  FIG.  5    may be carried out by, for example, a service technician during the connection of an optical terminal to an FDH. 
     The example flowchart  500  begins with the identification of an optical fiber connected at a first end to an optical terminal (e.g., one of the ONTs  106 A,  106 B) (block  505 ), and the coupling of what is believed to be a second end of the optical fiber to a passive optical coupler in an FDH (block  510 ). A light source of the optical terminal is configured to transmit indication light into the optical fiber, for example, according to a prescribed pattern (block  515 ). Light is detected (e.g., visually, using a light meter, etc.) at the passive optical activity indicator of the passive optical coupler (block  520 ). If indication light is detected (block  525 ), the coupling of the optical terminal to the passive optical coupler is confirmed and control exits from the example flowchart  500 . 
     If indication light is not detected (block  525 ), troubleshooting of the coupling of the optical terminal to the passive optical coupler may be performed (block  530 ), and control may return to block  520  to detect light. 
     Example Method of Provisioning an Optical Connection 
       FIG.  6    is a flowchart  600  representative of an example method for provisioning an ONT to an FDH (e.g., one of the example FDHs  116 ,  400 ). The example method of  FIG.  6    may be carried out by, for example, a service technician during the provisioning and/or repair of a service for a customer. 
     The example flowchart  600  begins with configuring a light source at an OLT to transmit indication light into an optical fiber, for example, according to a prescribed pattern (block  605 ). A first passive optical coupler is selected or identified (e.g., based on a grid map of the FDH to determine to which passive optical coupler a customer is supposedly connected to and/or is supposed to be connected to) (block  610 ). Light is detected (e.g., visually, using a light meter, etc.) at the passive optical activity indicator of the passive optical coupler (block  615 ). If indication light is detected (block  620 ), the coupling of the OLT to the passive optical coupler is confirmed. If indication light is not detected (block  620 ), then control returns to block  610  to identify another passive optical coupler (block  610 ). The process of blocks  610 - 620  may be repeated until a passive optical coupler actively coupled to the OLT is identified. 
     If the passive optical coupler is (supposedly) connected to the customer&#39;s ONT (e.g., based on a distribution optical fiber being connected to the passive optical coupler) (block  625 ), a light source at the customer&#39;s ONT is configured to transmit indication light into an optical fiber, for example, according to a prescribed pattern (block  630 ). Light is detected (e.g., visually, using a light meter, etc.) at the passive optical activity indicator of the passive optical coupler (block  635 ). If indication light is detected (block  640 ), the coupling of the OLT to the customer&#39;s ONT via the passive optical coupler is confirmed, and control exits from the example flowchart  500 . 
     If indication light is not detected (block  640 ), troubleshooting of the coupling of the customer&#39;s ONT to the passive optical coupler may be performed (block  645 ) and control may return to block  635  to detect light. 
     Returning to block  625 , if the passive optical coupler is not connected to the customer&#39;s ONT (e.g., based on a distribution optical fiber not being connected to the passive optical coupler) (block  625 ), then a distribution optical fiber (supposedly) associated with the customer&#39;s ONT is identified and coupled to the passive optical coupler (block  650 ), and control proceeds to block  630  to verify the connection. 
     Example Method of Identifying an Optical Connection 
       FIG.  7    is a flowchart  700  representative of an example method for identifying a passive optical coupler coupled to an optical terminal. The example method of  FIG.  7    may be carried out by, for example, a service technician during the provisioning and/or repair of a service for a customer. Additionally and/or alternatively, the method of  FIG.  7    may be performed by a computing device to automatically identify associations of optical terminals and passive optical couplers. 
     The example flowchart  700  begins with a light source at an optical terminal being configured to transmit indication light into an optical fiber, for example, according to a prescribed pattern (block  705 ). A first passive optical coupler is selected or identified (e.g., based on a grid map of the FDH to determine to which optical terminal is supposedly connected to and/or is supposed to be connected to) (block  710 ). Light is detected (e.g., visually, using a light meter, etc.) at the passive optical activity indicator of the passive optical coupler (block  715 ). If indication light is detected (block  720 ), the coupling of the optical terminal to the passive optical coupler is confirmed and the optical terminal may be associated with the passive optical coupler in, for example, the example electronic grid map  138  of  FIG.  1   . 
     If indication light is not detected (block  720 ), control returns to block  710  to identify another passive optical coupler. 
     Example Method of Mapping Optical Connections of an FDH 
       FIG.  8    is a flowchart  800  representative of an example method for automatically mapping optical connections in an FDH (e.g., one of the FDHs  116 ,  400 ). The method of  FIG.  8    may be performed by a computing device such as the example server  130 . 
     The example flowchart  800  begins with a computing device configuring light sources associated with one or more optical terminals to transmit indication light into respective optical fibers according to respective patterns (block  805 ). At block  810 , one or more image sensors of the FDH are configured to capture one or more images of a bulkhead of the FDH (block  810 ). 
     The one or more images are accessed (block  815 ). For example, the FDH can communicate the images to the computing device via a network. 
     A passive optical coupler is selected (block  820 ), and one or more of the captured images that include the selected passive optical coupler are processed to determine whether any light is being exposed by the passive optical activity indicator of the selected passive optical coupler (block  825 ). If light is detected (block  830 ), then the computing device processes the one or more of the captured images that include the selected passive optical coupler to identify a first light source of a first optical terminal that is transmitting light according to a detected pattern of light (block  835 ), and identify a second light source of a second optical terminal that is transmitting light according to a detected pattern of light (block  840 ). The computing device updates an electronic grid map of the FDH to associate the first and second optical terminals with the passive optical coupler (block  845 ). 
     If there are more passive optical couplers to process (block  850 ), control returns to block  820  to select a next passive optical coupler. 
     Returning to block  830 , if no indication light is detected (block  830 ), control proceeds to block  850  to determine if there are more passive optical couplers to process. 
     Example Processing Platform 
       FIG.  9    is a block diagram representative of an example logic circuit capable of implementing, for example, one or more components of the example server  130 , an optical terminal (e.g., any of the OLT  102 , the ONTs  106 A,  106 B and/or the optical terminal  300 ), and/or the example computing system  136 . The example logic circuit of  FIG.  9    is a processing platform  900  capable of executing instructions to, for example, implement operations of the example methods described herein, as may be represented by the flowcharts of the drawings that accompany this description. Other example logic circuits capable of, for example, implementing operations of the example methods described herein include a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a programmable logic device (PLD), and a field programmable logic device (FPLD). The processing platform  900  may be, for example, a server, a computer, a workstation, a laptop, a mobile device (e.g., a cell phone, a smart phone, a tablet such as an IPAD™), or any other type of computing device or system. 
     The example processing platform  900  of  FIG.  9    includes one or more processors  902 , memory  904 , one or more network interfaces  906 , one or more input/output (I/O) interfaces  908 , and/or one or more databases  910 , all of which are interconnected via an address/data bus  912 . 
     The processor  902  of the illustrated example is hardware, and may be a semiconductor based (e.g., silicon based) device. The processor  902  may be, for example, one or more programmable microprocessors, controllers, digital signal processors (DSP), graphics processing units (GPU) and/or any suitable type of programmable processor capable of executing instructions to, for example, implement operations of the example methods described herein. Additionally and/or alternatively, the processor  902  may be a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), etc. that implements operations of the example methods described herein without executing instructions. 
     The memory  904  is accessible by the processor  902  (e.g., via a memory controller). The example processor  902  interacts with the memory  904  to obtain, for example, machine-readable instructions stored in the memory  904  corresponding to, for example, the operations represented by the flowcharts of this disclosure. The example processor  902  may also interact with the memory  904  to store data, such as data formed or used during execution of machine-readable instructions. Example memory  904  includes any number and/or type(s) of volatile or non-volatile, non-transitory, machine-readable storage medium, devices or disks, such as a semiconductor memory, magnetically readable memory, optically readable memory, a hard disk drive (HDD), a solid-state drive (SSD), a read-only memory (ROM), a random-access memory (RAM), a redundant array of independent disks (RAID) system, a cache, flash memory, or any other storage medium, device or disk in which information may be stored for any duration (e.g., permanently, for an extended time period, for a brief instance, for temporarily buffering, for caching of the information, etc.). Additionally and/or alternatively, machine-readable instructions corresponding to the example operations described herein may be stored on one or more volatile or non-volatile, non-transitory, machine-readable removable storage media (e.g., a compact disc (CD), digital versatile disk (DVD), Blu-ray disk, removable flash memory, etc.) that may be coupled to the processing platform  900  to provide access to the machine-readable instructions stored thereon. 
     The example processing platform  900  of  FIG.  9    includes one or more communication interfaces such as, for example, the one or more network interfaces  906 , and/or the one or more input/output (I/O) interfaces  908 . The communication interface(s) enable the processing platform  900  of  FIG.  9    to communicate with, for example, another device, system, etc. (e.g., the OLT  102 , the ONTs  106 A,  106 B, the computing device  136 , the sever  130 , the computing device  126 , etc.), datastore, database, and/or any other machine. 
     The example processing platform  900  of  FIG.  9    includes the network interface(s)  906  to enable communication with other machines (e.g., the OLT  102 , the ONTs  106 A,  106 B, the computing device  136 , the sever  130 , the computing device  126 , etc.) via, for example, one or more networks such as the PON  101  and/or the network  128 . The example network interface(s)  906  may be used to implement the example interface transceiver(s)  305 . The example network interface  906  includes any suitable type of communication interface(s) (e.g., wired and/or wireless interfaces) configured to operate in accordance with any suitable communication protocol(s). Example network interfaces  906  include a TCP/IP interface, a WiFi™ transceiver (e.g., according to the IEEE 802.11x family of standards), an Ethernet transceiver, a cellular transceiver, a satellite transceiver, an asynchronous transfer mode (ATM) transceiver, a digital subscriber line (DSL) modem, a coaxial cable modem, a dialup modem, or any other suitable interface based on any other suitable communication protocols or standards. 
     The example, processing platform  900  of  FIG.  9    includes the input/output (I/O) interface(s)  908  (e.g., a Bluetooth® interface, a near-field communication (NFC) interface, a universal serial bus (USB) interface, a serial interface, an infrared interface, a PCI express interface, etc.) to enable the processor  902  to communicate with peripheral I/O devices and/or other communication systems. For example, the I/O interface(s)  908  may be used to control and receive image data from the image sensor(s)  132 , control a light source  325 , enable receipt of user input (e.g., from a touch screen, a keyboard, a navigation device such as mouse, touch pad, joystick or trackball, a microphone, a button, etc.) and communication of output data (e.g., visual indicators, instructions, data, images, etc.) to the user (e.g., via a display, a speaker, a printer, a communication interface, an antenna, etc.). The I/O interface(s)  908  typically include a graphics driver card, graphics driver chip and/or graphics driver processor to drive a display when a display is present. 
     In some examples, the processing platform  900  also includes, or is otherwise communicatively coupled to, a database  910  or other data storage mechanism (one or more of a HDD, optical storage drive, solid state storage device, CD, CD-ROM, DVD, Blu-ray disk, RAID, etc.). In the illustrated example, the database  910  may store the example electronic grid map  138 . 
     ADDITIONAL CONSIDERATIONS 
     The above description refers to a block diagram of the accompanying drawings. Alternative implementations of the example represented by the block diagram includes one or more additional or alternative elements, processes and/or devices. Additionally or alternatively, one or more of the example blocks of the diagram may be combined, divided, re-arranged or omitted. Components represented by the blocks of the diagram are implemented by hardware, software, firmware, and/or any combination of hardware, software and/or firmware. In some examples, at least one of the components represented by the blocks is implemented by a logic circuit. As used herein, the term “logic circuit” is expressly defined as a physical device including at least one hardware component configured (e.g., via operation in accordance with a predetermined configuration and/or via execution of stored machine-readable instructions) to control one or more machines and/or perform operations of one or more machines. Examples of a logic circuit include one or more processors, one or more coprocessors, one or more microprocessors, one or more controllers, one or more digital signal processors (DSPs), one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more microcontroller units (MCUs), one or more hardware accelerators, one or more special-purpose computer chips, and one or more system-on-a-chip (SoC) devices. Some example logic circuits, such as ASICs or FPGAs, are specifically configured hardware for performing operations (e.g., one or more of the operations described herein and represented by the flowcharts of this disclosure, if such are present). Some example logic circuits are hardware that executes machine-readable instructions to perform operations (e.g., one or more of the operations described herein and represented by the flowcharts of this disclosure, if such are present). Some example logic circuits include a combination of specifically configured hardware and hardware that executes machine-readable instructions. The above description refers to various operations described herein and flowcharts that may be appended hereto to illustrate the flow of those operations. Any such flowcharts are representative of example methods disclosed herein. In some examples, the methods represented by the flowcharts implement the apparatus represented by the block diagrams. Alternative implementations of example methods disclosed herein may include additional or alternative operations. Further, operations of alternative implementations of the methods disclosed herein may combined, divided, re-arranged or omitted. In some examples, the operations described herein are implemented by machine-readable instructions (e.g., software and/or firmware) stored on a medium (e.g., a tangible machine-readable medium) for execution by one or more logic circuits (e.g., processor(s)). In some examples, the operations described herein are implemented by one or more configurations of one or more specifically designed logic circuits (e.g., ASIC(s)). In some examples the operations described herein are implemented by a combination of specifically designed logic circuit(s) and machine-readable instructions stored on a medium (e.g., a tangible machine-readable medium) for execution by logic circuit(s). 
     As used herein, each of the terms “tangible machine-readable medium,” “non-transitory machine-readable medium” and “machine-readable storage device” is expressly defined as a storage medium (e.g., a platter of a hard disk drive, a digital versatile disc, a compact disc, flash memory, read-only memory, random-access memory, etc.) on which machine-readable instructions (e.g., program code in the form of, for example, software and/or firmware) are stored for any suitable duration of time (e.g., permanently, for an extended period of time (e.g., while a program associated with the machine-readable instructions is executing), and/or a short period of time (e.g., while the machine-readable instructions are cached and/or during a buffering process)). Further, as used herein, each of the terms “tangible machine-readable medium,” “non-transitory machine-readable medium” and “machine-readable storage device” is expressly defined to exclude propagating signals. That is, as used in any claim of this patent, none of the terms “tangible machine-readable medium,” “non-transitory machine-readable medium,” and “machine-readable storage device” can be read to be implemented by a propagating signal. 
     In the foregoing specification, specific examples have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the disclosure as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the disclosure. Additionally, the described examples should not be interpreted as mutually exclusive, and should instead be understood as potentially combinable if such combinations are permissive in any way. In other words, any feature disclosed in any of the aforementioned examples may be included in any of the other aforementioned examples. 
     The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The claimed invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued. 
     Moreover in this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” “has”, “having,” “includes”, “including,” “contains”, “containing” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, has, includes, contains a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “comprises . . . a”, “has . . . a”, “includes . . . a”, “contains . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises, has, includes, contains the element. The terms “a” and “an” are defined as one or more unless explicitly stated otherwise herein. The terms “substantially”, “essentially”, “approximately”, “about” or any other version thereof, are defined as being close to as understood by one of ordinary skill in the art, and in one non-limiting example the term is defined to be within 10%, in another example within 5%, in another example within 1% and in another example within 0.5%. The term “coupled” as used herein is defined as connected, although not necessarily directly and not necessarily mechanically. A device or structure that is “configured” in a certain way is configured in at least that way, but may also be configured in ways that are not listed. 
     Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, “A, B or C” refers to any combination or subset of A, B, C such as (1) A alone, (2) B alone, (3) C alone, (4) A with B, (5) A with C, (6) B with C, and (7) A with B and with C. As used herein, the phrase “at least one of A and B” is intended to refer to any combination or subset of A and B such as (1) at least one A, (2) at least one B, and (3) at least one A and at least one B. Similarly, the phrase “at least one of A or B” is intended to refer to any combination or subset of A and B such as (1) at least one A, (2) at least one B, and (3) at least one A and at least one B. 
     The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various examples for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed examples require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may lie in less than all features of a single disclosed example. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter. 
     Use of “a” or “an” are employed to describe elements and components of the examples herein. This is done merely for convenience and to give a general sense of the description. This description, and the claims that follow, should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise. A device or structure that is “configured” in a certain way is configured in at least that way, but may also be configured in ways that are not listed. 
     Further, as used herein, the expressions “in communication,” “coupled” and “connected,” including variations thereof, encompasses direct communication and/or indirect communication through one or more intermediary components, and does not require direct mechanical or physical (e.g., wired) communication and/or constant communication, but rather additionally includes selective communication at periodic intervals, scheduled intervals, aperiodic intervals, and/or one-time events. The examples are not limited in this context. 
     Further still, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, “A, B or C” refers to any combination or subset of A, B, C such as (1) A alone, (2) B alone, (3) C alone, (4) A with B, (5) A with C, (6) B with C, and (7) A with B and with C. As used herein, the phrase “at least one of A and B” is intended to refer to any combination or subset of A and B such as (1) at least one A, (2) at least one B, and (3) at least one A and at least one B. Similarly, the phrase “at least one of A or B” is intended to refer to any combination or subset of A and B such as (1) at least one A, (2) at least one B, and (3) at least one A and at least one B. 
     Moreover, in the foregoing specification and the attached drawings, specific examples have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made in view of aspects of this disclosure without departing from the scope of the disclosure as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications made in view of aspects of this disclosure are intended to be included within the scope of present teachings. Numerous alternative examples could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims. By way of example, and not limitation, the disclosure herein contemplates at least the following examples: 
     1. A passive optical coupler for passively coupling first and second optical fibers, the passive optical coupler comprising: 
     a housing including:
         a first port configured to receive an end of a first optical fiber, and   a second port configured to receive an end of a second optical fiber; and       

     a passive optical activity indicator positioned at least partially within the housing, wherein a first portion of the passive optical activity indicator is exposed through the housing, and wherein the passive optical activity indicator is configured to passively illuminate in response to (i) first light propagating in the first optical fiber when the end of the first optical fiber is received in the first port, and (ii) second light propagating in the second optical fiber when the end of the second optical fiber is received in the second port. 
     2. The passive optical coupler of example 1, wherein the passive optical activity indicator is configured to passively optically couple the end of the first optical fiber to the end of the second optical fiber. 
     3. The passive optical coupler of example 1, wherein the passive optical activity indicator comprises a flat pane of optical material, wherein a first portion of a first side of the pane of the optical material is exposed through a hole in the housing, wherein the end of the first optical fiber is optically coupled with a second portion of the first side of the pane of optical material when the end of the first fiber optical fiber is received in the first port, and wherein the second optical fiber is optically coupled with a portion of a second side of the pane of optical material when the end of the second optical fiber is received in the second port. 
     4. The passive optical coupler of example 3, wherein a plane of the flat pane of optical material is positioned substantially perpendicular to an axis of the first and second optical fibers when received in the respective first and second ports. 
     5. The passive optical coupler of example 1, wherein the passive optical activity indicator is positioned at a midpoint of the passive optical coupler between the first port and the second port. 
     6. The passive optical coupler of example 1, wherein the first port and the second port are configured to receive SC fiber optic connectors. 
     7. The passive optical coupler of example 1, wherein the passive optical coupler is a portion of a bulkhead of a fiber distribution hub. 
     8. A method comprising: 
     inserting a first connector of a first optical fiber into a first port of a passive optical coupler, the passive optical coupler further including:
         a second port configured to receive a second connector of a second optical fiber to optically couple the second optical fiber to the first optical fiber, and   a passive optical activity indicator positioned at least partially within the passive optical coupler and at least partially exposed, wherein the passive optical activity indicator is configured to passively illuminate in response to (i) first light propagating in the first optical fiber when the end of the first optical fiber is received in the first port, and (ii) second light propagating in the second optical fiber when the end of the second optical fiber is received in the second port;       

     configuring a light source at an optical terminal to transmit light into an optical fiber; 
     detecting light externally exposed by the first portion of the passive optical activity indicator; and 
     determining whether the optical terminal is optically coupled to the passive optical coupler based on the detected light. 
     9. The method of example 8, wherein determining whether the optical terminal is optically coupled to the passive optical coupler based on the detected light includes determining whether the detected light changes according to a changing pattern of light associated with the light source. 
     10. The method of example 8, wherein configuring the light source to transmit light includes configuring the light source to encode a unique identifier in the transmitted light. 
     11. The method of example 8, further comprising, when the optical terminal is determined to be optical coupled to the passive optical coupler based on the detected light, inserting the second connector of the second optical fiber associated with a second optical terminal that is to be coupled to the passive optical coupler into the second port. 
     12. The method of example 11, further comprising: 
     configuring a second light source at the second optical terminal to transmit light; 
     detecting further light externally exposed by the passive optical activity indicator; and 
     confirming the second optical terminal is optically coupled to the passive optical coupler based on the further detected light. 
     13. The method of example 12, wherein confirming the second optical terminal is optically coupled to the passive optical coupler based on the further detected light includes determining whether the detected further light changes according to a second changing pattern of light associated with the second light source. 
     14. The method of example 10, further comprising: 
     inserting the second connector of the second optical fiber into the second port; 
     configuring a second light source at a second optical terminal to transmit light into an optical fiber; 
     detecting further light externally exposed by the passive optical activity indicator; and 
     determining whether the second optical terminal is optically coupled to the passive optical coupler based on the further detected light. 
     15. The method of example 14, wherein configuring the light source to transmit light includes configuring the light source to change its transmitted light according to a first pattern, and wherein configuring the second light source to transmit light includes configuring the second light source to change its transmitted light according to a second pattern. 
     16. The method of example 15, further comprising selecting the first pattern and the second pattern such that an illumination of the passive optical activity indicator is substantially steady when the light source is coupled to the first optical fiber and the second light source is coupled to the second optical fiber. 
     17. The method of example 15, further comprising selecting the first pattern and the second pattern such that an illumination of the passive optical activity indicator blinks when only one of the light source and the second light source is coupled to their respective optical fiber. 
     18. The method of example 8, wherein configuring the light source to transmit light comprises configuring the light source to multiplex first light having a first wavelength associated with providing a communication service with second light having a different second wavelength. 
     19. The method of example 8, wherein detecting light externally exposed by the first portion of the passive optical activity indicator comprises at least one of detecting light visually, or detecting light using a meter. 
     20. A bulkhead for an fiber distribution hub of a passive optical network, the bulkhead comprising: 
     a plurality of optical couplers, each of the plurality of optical couplers comprising:
         a respective first port adapted to receive an end of a respective first optical fiber;   a respective second port adapted receive an end of a respective second optical fiber; and   a respective passive optical activity indicator constructed from a passive light transmissive material, wherein the passive optical activity indicator is configured to illuminate in response to (i) first light propagating in the first optical fiber when the end of the first optical fiber is received in the first port, and (ii) second light propagating in the second optical fiber when the end of the second optical fiber is received in the second port.       

     Additionally, the benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. 
     Finally, any references, including, but not limited to, publications, patent applications, and patents cited herein are hereby incorporated in their entirety by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
     The patent claims at the end of this patent application are not intended to be construed under 35 U.S.C. § 112(f) unless traditional means-plus-function language is expressly recited, such as “means for” or “step for” language being explicitly recited in the claim(s). The systems and methods described herein are directed to an improvement to computer functionality, and improve the functioning of conventional computers. 
     Although certain example methods, apparatus and articles of manufacture have been disclosed herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the claims of this patent.