Patent Publication Number: US-11662269-B2

Title: Fiber-optic interconnection stabilization apparatus

Description:
PRIORITY 
     The present application is a Continuation of commonly assigned and U.S. patent application Ser. No. 15/996,136, filed Jun. 1, 2018, now U.S. Pat. No. 10,928,274 B2, which claims priority to U.S. Provisional Patent Application No. 62/641,173, entitled “Fiber-Optic Interconnection Stabilization Apparatus,” filed on Mar. 9, 2018, which are incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     Some network testing devices, especially those that measure and test insertion loss (IL), optical return loss (ORL), polarization dependent loss (PDL), and extinction ratio (ER), may be provided in single-box measurement platform. This network testing device will typically be preconfigured to include various modular testing components or cassettes. These may include a single output light source, standard connector adapters, one or more measurement elements, etc., within a single-bodied chassis. As a single testing unit, the network testing device may be able to handle most, if not all, measurement and testing determinations. For external sources not included in the network testing device, a fiber-optic cable (or jumper) may be used to connect the external source, or other modular system components to the network testing device. 
     In order to provide an interconnection between two modular testing components in the network testing device, a fiber-optic interconnect, for example, may be required to close a testing or measurement loop. However, a technical problem associated with such a configuration is that the fiber-topic interconnect is often exposed. This means the optical fiber may be affected by environmental elements, which in turn may lead to inaccurate measurements and readings by the network testing device. As a result, a fiber-optic interconnection stabilization apparatus may be needed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Features of the present disclosure are illustrated by way of example and not limited in the following Figure(s), in which like numerals indicate like elements, in which: 
         FIG.  1    illustrates a measurement system using a fiber-optic interconnect, according to an example; 
         FIG.  2    illustrates a measurement system using a fiber-optic interconnect stabilization apparatus, according to an example; 
         FIG.  3    illustrates a cross-section of a measurement system using a fiber-optic interconnect stabilization apparatus, according to an example; 
         FIGS.  4 A- 4 E  illustrate various views of a fiber-optic interconnection stabilization apparatus, according to an example; and 
         FIGS.  5 A- 5 C  illustrate various views of a fiber-optic interconnection stabilization apparatus, according to another example. 
     
    
    
     DETAILED DESCRIPTION 
     For simplicity and illustrative purposes, the present disclosure is described by referring mainly to examples and embodiments thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be readily apparent, however, that the present disclosure may be practiced without limitation to these specific details. In other instances, some methods and structures readily understood by one of ordinary skill in the art have not been described in detail so as not to unnecessarily obscure the present disclosure. As used herein, the terms “a” and “an” are intended to denote at least one of a particular element, the term “includes” means includes but not limited to, the term “including” means including but not limited to, and the term “based on” means based at least in part on. 
     Measuring and comparing optical return loss (ORL) in a network has become increasingly important in network provisioning and maintenance. There are two general techniques for measuring optical return loss (ORL): (1) time-domain measurements, and (2) optical-continuous-wave reflectometry (OCWR). Despite differences in sensitivity between these techniques and how equivalent measurements are obtained, both techniques may be widely used for measuring ORL. The newer time-domain techniques, however, have recently become more popular because of their ease of use, speed, and dynamic range and capabilities. 
     Optical loss return (ORL) is the ratio between the light launched into a device and the light reflected by a defined length or region. For ORL measurements, regardless of method (e.g., time-domain reflectometry (TDR), optical-continuous-wave reflectometry (OCWR), or other technique), length is an important factor and it may be defined differently for each type of measurement technique. Reflections and scattering of light within fiber may affect data transmission and performance. Therefore, ensuring fiber-optic integrity of an interconnect, for example, may be essential to more accurate and reliable network testing and measurements. 
     As described above, current measurement devices that measure and test insertion loss (IL), optical return loss (ORL), polarization dependent loss (PDL), extinction ratio (ER), and/or other optical signals in a network may be provided in single-box measurement system. As a result, these network devices that contain a plurality of modular components or cassettes may often need a fiber-optic interconnect to close a measurement loop in order to perform a measurement or other determination. Because such a fiber-optic interconnect may be a single-mode (SM) optical fiber that is exposed to various environmental conditions. These conditions may be mechanical (e.g., twisting, pulling, turning, kinking, etc.) or thermal, or may be based on proximity to other forms of interference. As a result of these external perturbations or fluctuations, measurements by the network testing device may not be as accurate or reliable as they could be with a more stabilized fiber-optic interconnect. Accordingly, a fiber-optic interconnection stabilization apparatus is described herein. 
       FIG.  1    illustrates a measurement system  100  using a fiber-optic interconnect, according to an example. In an example, the measurement system  100  may be an ORL measurement system. Although examples described herein are generally directed to an ORL measurement system, it should be appreciated that the ORL measurement system  100  may also be used for measuring insertion loss (IL), optical return loss (ORL), polarization dependent loss (PDL), extinction ratio (ER), and/or run other optical signals or measurements. As depicted, the ORL measurement system  100  may be a single-box platform. In an example, the ORL measurement system  100  may include a chassis  102  containing a display  104  for a unified application. In an example, the ORL measurement system  100  may include a plurality of modular components. These modular components may be provided in cassette form (or other suitable form), which may be inserted into the chassis  102 . In an example, the ORL measurement system  100  may include Cassette  1   106   a  and Cassette  2   106   b . It should be appreciated that while only two cassettes  106   a  and  106   b  or modular components are shown, there may be more or less depending on chassis size or other predetermined configurations. In  FIG.  1   , Cassette  1   106   a  may be a single output light source (e.g., MSRC, MTLG, etc.), and Cassette  2   106   b  may be a measurement module family (e.g., single mode (SM): IL/RL (return loss), multimode (MM): IL/RL, etc.). Other various configurations may also be provided. 
     Cassette  1   106   a  and Cassette  2   106   b , in this example, may include a variety of input/output ports and/or adapters. These may be for connecting power, cables, wires, or other inputs/outputs. In some examples, the ORL measurement system  100  may have at least an Ethernet connection to connect to other computing devices  108 , such as a reporting tool or other system. Other various ports, adapters, connections may also be provided. Also as shown in  FIG.  1   , Cassette  2   106   b  may include ports or adapter to a fiber-optic cable (or jumper), which may be used to connect the ORL measurement system  100  to an external source. In an example, this external source may be a device under test (DUT)  110  or other network component in which measurements are to be measured and taken. 
     As shown in  FIG.  1   , Cassette  1  and Cassette  2  may be connected by a fiber-optic interconnect  112 , which may be another fiber-optic cable. The fiber-optic interconnect  112  may be exposed to external conditions. These conditions may cause fluctuations and perturbations that may be mechanical, thermal, or other environment condition that may adversely affect potential measurements by the ORL measurement system  100 . As described above, it may be important for an optical signal to be as stable as possible, especially for ORL measurements that involve parameters of IL and polarization stability. Therefore, as shown in  FIG.  1   , the fiber-optic interconnect  112  may be encased in a fiber-optic interconnect stabilization apparatus  200 , which will be described in greater detail below. 
     In some examples, the interconnect  112  may be a polarization-maintaining (PM) optical fiber. A PM fiber may be a single-mode optical fiber in which linearly polarized light maintains a linear polarization during propagation. In other words, a PM fiber may allow light to exit with little or no cross-coupling of optical power between two polarization modes. A PM fiber may work to stabilize polarization fluctuations and may be helpful to preserve polarization where that is important. In some situations, a PM fiber may provide adequate stabilization since some sources in the modular components may not be properly aligned to polarization axes of a fiber. 
     In some examples, the interconnect  112  may be a single-mode (SM) optical fiber. An SM fiber may be more sensitive to polarization fluctuations, and in certain cases where use of PM fiber is precluded, steps may be taken to minimize polarization fluctuations. Since an SM fiber may be more affected by external factors, stabilization may help minimize polarization issues. In other examples, such as a vibrating or mechanically noisy environment, a fiber resting on a bench, for instance, may be more easily jostled or disturbed. In this scenario, the fiber may be encapsulated and to remove it from direct contact with the bench, ultimately isolating it from mechanical disturbances. 
       FIG.  2    illustrates a measurement system  100  using a fiber-optic interconnect stabilization apparatus  200 , according to an example. An SM fiber may be used as the fiber-optic interconnect for the modular components of the ORL measurement system  100 . A fiber-optic interconnection stabilization apparatus  200  may be used to encase the fiber-optic interconnect and reduce at least some adverse external conditions and influences, while maintaining its core function of connecting two intermodular measurement components or cassettes (e.g.,  106   a  and  106   b ). 
       FIG.  3    illustrates a cross-section of a measurement system  100  using a fiber-optic interconnection stabilization apparatus  200 , according to an example. As shown in  FIG.  3   , a fiber-optic interconnection stabilization apparatus  200  may be used to effectively form a “rigid jumper” to form a closed measurement loop. The rigid jumper may be the fiber-optic interconnect stabilization apparatus that encases the fiber-optic interconnect cable that connects Cassette  1   106   a  and Cassette  2   106   b . It should be appreciated that a DUT  110  (e.g., SM PCT/MORL) may be connected to the ORL measurement system  100  by other fiber-optic cables or jumpers, as shown. It should be appreciated that  FIG.  3    may provide one exemplary configuration. Other various configurations and uses of the fiber-optic interconnection stabilization apparatus  200  and/or the DUT  110  may also be provided and are not intended to be limited by what is shown in  FIG.  3   . 
       FIGS.  4 A- 4 E  illustrate various views of a fiber-optic interconnection stabilization apparatus  200 , according to an example.  FIG.  4 A  depicts an isometric view of a fiber-optic interconnection stabilization apparatus.  FIG.  4 B  depicts a side view of a fiber-optic interconnection stabilization apparatus. In the side view, the fiber-optic interconnection stabilization apparatus may have a particular thickness or height (H) (e.g., 10 mm). As shown, the fiber-optic interconnection stabilization apparatus may have a main body  402  with an enclosure to contain a fiber-optic interconnect  112  in an organized way. The fiber-optic interconnection stabilization apparatus  200  may have an open configuration and a closed configuration. In order to have two such configurations, the fiber-optic interconnection stabilization apparatus  200  may have the capability to be opened and closed via mechanical, magnetic, electrical, or other feature. In an example, the main body may have two mating portions, e.g., a top portion  404  and a bottom portion  406 . The top portion  404  and bottom portion  406  may be mechanically attached to enclose the fiber-optic interconnect  112 . In one example, the top portion  404  and the bottom portion  406  of the main body  402  may be fully separated. In another example, the top portion  404  and the bottom portion  406  of the main body  402  may be attached at a joint (not shown). For example, there may be a hinge and a latch which may be used to open and close the main body  402 , such as a clamshell design. In other examples, the top portion  404  and the bottom portion  406  of the main body  402  may be attached using epoxy or other similar materials. Other various configurations may also be provided. 
     In some examples, the main body  402  of the fiber-optic interconnection stabilization apparatus  200  may also include two openings  408 . These openings may be configured to allow connecting ends  410  of the fiber-optic interconnect  112  to be fitted in the main body  402 , such that when the fiber-optic interconnection stabilization apparatus  200  is in a closed configuration, the entire fiber-optic interconnection stabilization apparatus  200 , together with the optical-fiber interconnect fitted within, becomes a rigid jumper rather than just a loosely dangling optical cable. 
       FIG.  4 C  depicts a top cross-section view of a fiber-optic interconnection stabilization apparatus  200 . In this example, the fiber-optic interconnection stabilization apparatus  200  may be shown to have an SM fiber coiled in the enclosure of the main body  402 . In one example, the interior of the main body may have a molded area  412  in the shape of a cylinder around which the fiber may be coiled. Other various designs may be provided to ensure organization or stabilization of the fiber within the main body  402 . As shown, the fiber-optic interconnection stabilization apparatus  200  may have two openings  408  fitted to receive connecting ends  410  of a fiber-optic interconnect, such as an SM fiber. It should be appreciated that each opening  408  may have an axial gap  414  that is designed to fit each connecting end  410  of the fiber-optic interconnect  112  to help retain the connecting ends of the fiber and ensure stabilization of the fiber. 
     It should be appreciated that in the event the connecting end  210  does not fit exactly within the opening  408 , various fittings or materials may be provided. For example, if a connecting end  410  is too small for the opening  408 , an attachment  416  may be provided to ensure a stable fit. It should be appreciated that attachment  416  may come in a variety of sizes, shapes, and/or materials. In another example, if there is too much space in the enclosure  411  which allows the fiber  112  to move excessively, a padding (not shown) material may be inserted in the enclosure  411  to provide a more secure fit. Again, the padding may come in a variety of sizes, shapes, and/or materials. These and other various stabilization options may also be provided to ensure the fiber  112  is securely fitted within the main body  402  of the fiber-optic interconnection stabilization apparatus  200 . 
       FIG.  4 D  depicts a top view of a fiber-optic interconnection stabilization apparatus  200  having exemplary dimensions. As shown, the fiber-optic interconnection stabilization apparatus  200 , together with the encased fiber, may have a length (L) of 71.5 mm and a width (VV) of 55.0 mm, such that the connecting ends  410  of the protruding fiber-optic interconnect  112  may be 41.0 mm apart (X), which may be what is needed to close the measurement loop of the ORL measurement system. While specific dimensions are shown, it should be appreciated that other dimensions, lengths, and sizes may be provided depending on other needs of the measurement system or other implementations of the apparatus. Furthermore, it should be appreciated that while examples described herein are directed to depictions of two ports being used to connect two cassettes, other various may be provided as well. For instance, a fiber-optic interconnection stabilization apparatus  200  may be used in configurations with more than two ports interconnecting more than two cassettes as well. 
       FIG.  4 E  depicts a cross-section view A-A of the fiber-optic interconnection stabilization apparatus  200  shown in  FIG.  4 D . In  FIG.  4 E , the fiber-optic interconnection stabilization apparatus  200  may include a translation gap  416 , a rotation gap  418 , a u-shape bracket  420  to control rotation and/or translation. It should be appreciated that these configurations and designs may allow compatibility to different types of interconnects or connecting ends, as well as offer some flexibility of movement for the fiber-optic interconnection stabilization apparatus in the event the connecting ends of the fiber may not always line up with the ports of Cassette  1  and Cassette  2 . 
     It should be appreciated that the fiber-optic interconnection stabilization apparatus  200 , as described herein, may be made of various materials. In an example, the fiber-optic interconnection stabilization apparatus  200  may be made of metal (e.g., aluminum, etc.). A metallic material may allow a thermal mass associated with it. This may stabilize, integrate, and otherwise lessen thermal fluctuations as normally felt by an enclosed fiber. It should be appreciated that other materials for the fiber-optic interconnection stabilization apparatus  200  may also be provided, such as rubber, plastic, glass, carbon fiber, or other composites. Whatever materials are used, it should be appreciated that the fiber-optic interconnection stabilization apparatus  200  has some mechanical rigidity. As described herein, rigidity may help provide stability against polarization fluctuations caused by movement for non-PM fibers. 
     It should be appreciated that other configurations for a fiber-optic interconnection stabilization apparatus  200  may be provided.  FIGS.  5 A- 5 C  illustrate various views of a fiber-optic interconnection stabilization apparatus  200 , according to another example. In this case, the fiber-optic interconnection stabilization apparatus  200  may include a floating connector design. For example, the connecting ends may be fitted within the opening of the fiber-optic interconnection stabilization apparatus yet have some space or freedom to move sideways. Such movement may or may not include angular movement. In some examples, use of viscoelastic plastic, or other material, may be used to smooth out such spacing and minimize freedom of movement. 
     In some examples, a specific clocking angle may be provided for the fiber-optic interconnection stabilization apparatus on the connector. Alternatively or additionally, some ability to adapt the spacing for inter-cassette positional and angular tolerances may also be provided. These configurations may balance rigidity with flexibility (e.g., strict sagittal angular tol on the connector keying, but allow some flexibility in lateral displacement and azimuthal/elevation angles) that ultimately results in a fiber-optic interconnection stabilization apparatus  200  that may be more universally used for inter-cassette connections (or other connections) in various types of ORL measurement systems. 
     Ultimately, a fiber-optic interconnection stabilization apparatus  200  as described herein may stabilize a fiber-optic interconnect cable from mechanical, thermal, or other environmental stresses that affect ORL measurements. Thus, the fiber-optic interconnection stabilization apparatus  200  maximizes stability and provides improved IL/PDL/RL measurements by an ORL measurement system  100 . 
     What has been described and illustrated herein are examples of the disclosure along with some variations. The terms, descriptions, and figures used herein are set forth by way of illustration only and are not meant as limitations. Many variations are possible within the scope of the disclosure, which is intended to be defined by the following claims—and their equivalents—in which all terms are meant in their broadest reasonable sense unless otherwise indicated.