Patent Publication Number: US-10330869-B2

Title: Bayonet lock MPO connector

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/874,670, filed Oct. 5, 2015, which is a continuation-in-part application of U.S. patent application Ser. No. 14/790,077 filed on Jul. 2, 2015 both of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     The present disclosure relates generally to optical fiber connectors and systems, and specifically to MPO (Multi-fiber Push On) type optical fiber connectors having a compact design. 
     Fiber optics have become the standard cabling medium used by data centers to meet the growing needs for data volume, transmission speeds, and low losses. An optical fiber connector is a mechanical device disposed at an end of an optical fiber, and acts as a connector of optical paths, for example when optical fibers are joined to each other. An optical fiber connector may be coupled with an adapter to connect an optical fiber cable to other optical fiber cables or devices. An adapter generally includes a housing, or portion of a housing, having at least one port which is configured to receive and hold a connector to facilitate the optical connection of one connector to another connector or other device. 
     An MPO connector is a multi-fiber connector defined by industry standards. A conventional MPO connector has many constituent parts and a push/pull locking and unlocking mechanism, resulting in a relatively long connector design that wastes too much space, and which may not be sufficiently small for use in certain applications. Moreover, conventional MPO connectors are composed of many constituent parts, increasing the cost of materials and labor, as well as the complexity of assembly. Accordingly, there is a need for MPO type optical fiber connectors that have a more compact design than conventional MPO connectors. 
     SUMMARY 
     Embodiments disclosed herein address the aforementioned shortcomings of conventional MPO connectors by providing MPO connectors having a lock, such as a bayonet lock or a locking ring, and less constituent parts, resulting in a shorter length than conventional MPO connectors. For example, in one embodiment, an MPO connector may have a length less than about 37 mm. For example, the length of the MPO connector may be about 18.5 mm for a bare (non-reinforced) ribbon type fiber cable. By contrast, a conventional MPO connector typically has a length of about 37 mm. In another embodiment, the length of the MPO connector may be about 23.5 mm for a reinforced cable, prior to attachment of the reinforced cable and prior to addition of a strain relief. By contrast, a conventional MPO connector for a reinforced cable has a length of about 31 mm prior to attachment of the reinforced cable and prior to addition of a strain relief. 
     Other advantages of embodiments disclosed herein include lower cost of materials and assembly, and compatibility with conventional MPO adapters that are in use in various applications. Furthermore, various embodiments of MPO connectors disclosed herein are compatible with MPO type ferrule assemblies that are in use in various applications. Thus, various embodiments disclosed herein are backwards compatible with conventional MPO assemblies and adapters. 
     According to one aspect, there is disclosed a connector comprising a ferrule assembly, a housing coupled to the ferrule assembly and configured to couple to an adapter corresponding to the ferrule assembly, and a lock coupled to the housing and configured to rotate so as to lock and unlock the housing from said adapter. The ferrule assembly may be an MT/MPO ferrule assembly or an MPO ferrule assembly. The lock may be a ring configured to rotate about the housing. In some embodiments, the lock may be a bayonet lock. 
     In various embodiments, the connector may have a single housing. That is, the housing coupled to the ferrule assembly may be the only housing of said connector. The housing may include a front portion and a rear portion, and the front portion may be configured to receive the ferrule assembly. The lock may be coupled to the rear portion of the housing. In some embodiments, the housing may include a cylindrical portion. The cylindrical portion may be the rear portion of the housing. The bayonet lock may be disposed about the cylindrical portion. In some embodiments, the lock may include at least one flexing tab configured to snap into a respective groove of the housing so as to couple the lock to the housing. The housing may include a stop configured to limit rotation of the lock. 
     In some embodiments, the connector may further comprise a ferrule spring disposed within the housing. The housing may include at least one catch and the ferrule assembly may be secured to the housing between the ferrule spring and the at least one catch. The housing may comprise a plurality of inclined surfaces configured to facilitate coupling of the ferrule assembly to the housing. In some embodiments, the housing may include a plurality of slits configured to allow flexing of the housing. 
     In various embodiments, the housing may include at least one recess configured to receive a respective catch of an adapter. The lock may include at least one tab configured to cover the respective catch of said adapter disposed in the at least one recess of the housing when the lock is in a locked position. The at least one tab may be configured to uncover the respective catch of said adapter disposed in the at least one recess of the housing when the lock is in an unlocked position, to allow decoupling the housing from the adapter. 
     Various embodiments of connectors disclosed herein may have a length less than about 37 mm. Some embodiments may have a length less than or equal to about 18.5 mm. For example, one embodiment of a connector may have a length of about 18.5 mm. In various embodiments wherein the housing is coupled to an adapter, a portion of the connector protruding from said adapter may have a length less than about 26 mm. In some embodiments, the housing may be coupled to an adapter, and a portion of the connector protruding from said adapter may have a length less than or equal to about 7.5 mm. For example, the length of the portion of the connector protruding from an adapter coupled thereto may be about 7.5 mm. 
     According to another aspect, there is disclosed a connector comprising a housing configured to receive a ferrule assembly, and to couple to an adapter corresponding to said ferrule assembly, and a lock coupled to the housing and configured to rotate around the housing so as to lock and unlock the housing from said adapter. The housing may be configured to receive an MT/MPO ferrule assembly or an MPO ferrule assembly, and to couple to an MPO adapter. The lock may be a bayonet lock. In some embodiments, the length of the connector may be less than or equal to about 18.5 mm. Various features described in conjunction with other embodiments may further be included in this embodiment. 
     According to another aspect, there is disclosed a connector comprising a ferrule assembly, a housing coupled to the ferrule assembly and configured to couple to an adapter corresponding to the ferrule assembly, a lock coupled to the housing and configured to rotate so as to lock and unlock the housing from said adapter, and an interface member coupled to the housing and having a stop configured to limit rotation of the lock. The ferrule assembly may be one of an MT/MPO ferrule assembly and an MPO ferrule assembly. The lock may be a ring configured to rotate about the housing. For example, the lock may be a bayonet lock. 
     In various embodiments comprising the interface member, the housing may be the only housing of said connector. The housing may include a rear portion and the bayonet lock may be disposed about the rear portion. In some embodiments, the lock may include at least one flexing tab configured to snap into a respective groove of the housing so as to couple the lock to the housing. The housing may include a front portion and a rear portion, the rear portion being configured to receive the ferrule assembly. The lock may also be coupled to the rear portion of the housing. 
     Some embodiments comprising the interface member may further comprise a ferrule spring disposed within the housing. The ferrule assembly may include a raised flange and the housing may include a corresponding ferrule flange stop, the ferrule assembly being secured to the housing between the ferrule spring and the ferrule flange stop. The housing may further comprise a plurality of inclined surfaces configured to facilitate coupling of the ferrule assembly to the housing. The housing may include at least one recess configured to receive a respective catch of the adapter. The lock may include at least one tab configured to cover the respective catch of said adapter disposed in at least one recess of the housing when the lock is in a locked position. At least one tab may be configured to uncover the respective catch of the adapter disposed in a recess of the housing when the lock is in an unlocked position, to allow decoupling the housing from the adapter. 
     Various embodiments may have a length less than about 32 mm. For example, the length may be less than or equal to about 18.5 mm. In some embodiments, the interface member may include a reinforcement portion configured to reinforce an optical fiber cable received by the interface member. These embodiments may have a length less than or equal to about 23.5 mm. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is an exploded view of a prior art MPO connector; 
         FIG. 2  is a perspective view of the assembled prior art MPO connector of  FIG. 1 ; 
         FIG. 3  is a top view of the prior art MPO connector of  FIG. 2 ; 
         FIG. 4  is a side view of the prior art MPO connector of  FIG. 2 ; 
         FIG. 5  is a cross-sectional view of the prior art MPO connector of  FIG. 2 ; 
         FIG. 6  is a perspective view of a prior art MPO adapter that is compatible with various embodiments of connectors according to aspects of the present disclosure; 
         FIG. 7  is a front view of the prior art MPO adapter of  FIG. 6 ; 
         FIG. 8  is a cross-sectional view of the prior art MPO adapter of  FIG. 6 ; 
         FIG. 9  is a perspective view showing the prior art MPO connector of  FIG. 2  being inserted into the prior art adapter of  FIG. 6 ; 
         FIG. 10  is a side view of the prior art MPO connector of  FIG. 2  coupled to the prior art adapter of  FIG. 6 ; 
         FIGS. 11A and 11B  are cross-sectional views of the prior art MPO connector and adapter of  FIG. 10  just before latching; 
         FIGS. 12A and 12B  are cross-sectional views of the coupled prior art MPO connector and adapter of  FIG. 11A  in a latched position; 
         FIG. 13  is a perspective view of the prior art MPO connector of  FIG. 2  coupled to an adapter disposed on a panel of adapters; 
         FIG. 14  is a perspective view of a plurality of prior art MPO connectors coupled to adapters on a high density panel, creating access issues; 
         FIG. 15  is an exploded view of one embodiment of a connector according to aspects of the present disclosure; 
         FIG. 16  is a perspective view showing an assembled form of the embodiment of the connector of  FIG. 15 , having a length of 18.5 mm according to aspects of the present disclosure; 
         FIG. 17  is a perspective view of the prior art MPO connector of  FIG. 2 , having a length of 37 mm in comparison with the embodiment of  FIG. 16  which has a length of 18.5 mm; 
         FIG. 18  is a side view of the connector of  FIG. 16  according to aspects of the present disclosure; 
         FIG. 19  is a front view of a bayonet lock according to aspects of the present disclosure; 
         FIG. 20  is an exploded view of the connector of  FIG. 16 , showing the housing and lock according to aspects of the present disclosure; 
         FIG. 21  is a side view of the housing of  FIG. 16 , showing a slit to allow flexing according to aspects of the present disclosure; 
         FIG. 22  is a top view of the housing of  FIG. 21 , showing a groove and a plurality of stops according to aspects of the present disclosure; 
         FIG. 23  is a front view of the housing of  FIG. 21  according to aspects of the present disclosure; 
         FIG. 24  is a cross-sectional view of the housing of  FIG. 21  being coupled to a ferrule assembly, showing a ferrule spring and a plurality of inclined surfaces of the housing according to aspects of the present disclosure; 
         FIG. 25A  is a front view of a lock in an unlocked position according to aspects of the present disclosure; 
         FIG. 25B  is a perspective view of the connector of  FIG. 16  in an unlocked position, showing a recess in the housing being uncovered by a tab of the lock in the unlocked position according to aspects of the present disclosure; 
         FIG. 26A  is a front view of the lock of  FIG. 25A  in a locked position according to aspects of the present disclosure; 
         FIG. 26B  is a perspective view of the connector of  FIG. 25B  in a locked position, showing a recess in the housing being covered by a tab of the lock in the locked position according to aspects of the present disclosure; 
         FIG. 27  is a perspective view of a locked connector coupled to an adapter positioned near a circuit board according to aspects of the present disclosure; 
         FIG. 28  is a perspective view of the connector of  FIG. 27  in an unlocked position and coupled to an adapter positioned near a circuit board according to aspects of the present disclosure; 
         FIGS. 29A and 29B  are perspective views of the connector of  FIG. 27  coupled to an adapter positioned near a circuit board, showing the use of tool for locking and unlocking the connector according to aspects of the present disclosure; 
         FIG. 30  is a perspective view of a connector coupled to an adapter in a high density panel, showing the use of a tool for axially locking and unlocking the connector according to aspects of the present disclosure; 
         FIG. 31  illustrates the assembled length of various embodiments according to aspects of the present disclosure, in comparison with the length of a conventional MPO connector; 
         FIG. 32  is an exploded view of one embodiment of a connector for non-reinforced cables according to aspects of the present disclosure; 
         FIGS. 33A and 33B  are various cross-sectional views of the embodiment shown in  FIG. 32  prior to complete assembly according to aspects of the present disclosure; 
         FIGS. 34A and 34B  are various cross-sectional views of the embodiment shown in  FIG. 32  after assembly according to aspects of the present disclosure; 
         FIG. 35  is an exploded view of one embodiment of a connector for reinforced cables according to aspects of the present disclosure; 
         FIGS. 36A and 36B  are various cross-sectional views of the embodiment shown in  FIG. 35  prior to complete assembly according to aspects of the present disclosure; and 
         FIGS. 37A and 37B  are various cross-sectional views of the embodiment shown in  FIG. 35  after assembly according to aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     As used herein, the term “optical fiber” is intended to apply to all types of single mode and multi-mode light waveguides, including one or more bare optical fibers, coated optical fibers, loose-tube optical fibers, tight-buffered optical fibers, ribbonized optical fibers, bend performance optical fibers, bend insensitive optical fibers, nanostructured optical fibers or any other expedient for transmitting light signals. A multi-fiber optic cable includes a plurality of the optical fibers. For connection of cables together or with other fiber optic devices, the terminal ends of a cable may include a connector. A connector may include a housing structure configured to interact with and connect with an adapter. 
     An MPO connector is a multi-fiber connector defined by industry standards. One brand of an MPO connector is an MPT connector. A conventional MPO connector has many constituent parts and a push/pull locking and unlocking mechanism, resulting in a relatively long connector, increased cost of materials and labor, as well as the complexity of assembly. 
       FIG. 1  shows an exploded view of a prior art MPO connector  100 . The connector  100  is an assembly having eight parts. The connector  100  includes a main body or inner housing  102 , a ferrule assembly  104 , a ferrule spring  106 , a spring retainer/pusher  108 , a strain relief, two outer housing springs  112  and  114 , and a sliding outer housing  116 . Conventional MPO connectors use multiple housing components, such as the inner housing and the outer housing of the connector  100 . 
     A perspective view of the assembled prior art MPO connector of  FIG. 1  is shown in  FIG. 2 . The ferrule assembly  104  disposed within the inner housing  102 , which is further disposed within the outer housing  116 , and coupled to the strain relief  110 . In the assembled form shown in  FIG. 2 , the connector  100  has an overall length of about 37 mm.  FIG. 3  is a top view of the prior art MPO connector  100  of  FIG. 2 .  FIG. 4  is a side view of the prior art MPO connector  100  of  FIG. 2 . 
       FIG. 5  shows a cross-sectional view of the prior art MPO connector  100 , along section A-A shown in  FIG. 4 .  FIG. 5  further shows the outer springs  112  and  114 , configured to allow sliding of the outer housing  116 . The inner housing  102  includes recesses  118  and  120  for engaging with the catches of an adapter. 
     A perspective view of a prior art MPO adapter  600  is shown in  FIG. 6 . The adapter includes an adapter housing  602 , and adapter catches  604  and  606 .  FIG. 7  is a front view of the prior art MPO adapter of  FIG. 6 , showing the catches  604  and  606 .  FIG. 8  is a cross-sectional view of the prior art MPO adapter  600  along section X-X of  FIG. 7 , showing the catches  604  and  606 , and a channel  608  configured to receive at least a portion of a ferrule assembly within the housing  602 . 
     The prior art MPO connector  100  may be inserted into the adapter  600  by pushing the strain relief  110 , as shown in  FIG. 9 . Conventional MPO connectors, such as the connector  100 , use both the strain relief and the sliding outer housing for latching to and unlatching from the adapter  600 . Specifically, the MPO connector  100  is pushed using the strain relief  110  to latch the connector into the adapter and the outer housing  116  is pulled or retracted to unlatch the connector from the adapter. These components, as well as the many constituent parts of the MPO adapter as shown in  FIG. 1  are necessary for locking and unlocking the MPO connector and the adapter. Moreover, the design of a conventional MPO connector dictates that these components be arranged adjacent to one another, thereby resulting in a relatively long length of the conventional MPO connector. For example, the length of the connector  100  is about 37 mm. 
     A side view of the prior art MPO connector  100  coupled to the adapter  600  is shown in  FIG. 10 .  FIGS. 11A and 11B  show cross-sectional views of the MPO connector  100  and the adapter  600  along Section X-X shown in  FIG. 10 , just prior to latching.  FIG. 11B  shows a zoomed portion enclosed within the circle  1100  of  FIG. 11A . Specifically,  FIG. 11B  shows an MPO adapter catch  604  within the housing  602  of the MPO adapter  600 , and a recess  118  of the connector  100  just prior to latching. As the MPO connector  100  travels into the MPO adapter  600 , the catches of the adapter, including catch  604 , flex outward. With the catches opened, the catches push back the outer sliding housing  116  which is spring loaded, and engage the recesses, including recess  118 , of the MPO connector  100 . 
       FIGS. 12A and 12B  show cross-sectional views of the MPO connector  100  and the adapter  600  along Section X-X shown in  FIG. 10 , after latching.  FIG. 12B  shows a zoomed portion enclosed within the circle  1200  of  FIG. 12A . Specifically,  FIG. 12B  shows that the MPO adapter catch  604  within the housing  602  of the MPO adapter  600  has engaged the recess  118  of the connector  100 . The sliding outer housing  116  has been pushed forward by the springs  112  and  114  as shown in  FIG. 12A . 
     Connectors may need to couple to adapters placed in high density panels. For example,  FIG. 13  shows the MPO connector  100  coupled to the adapter  600  disposed in a panel  1300  having a plurality of MPO adapters. The connector  100  has a multi-fiber ribbon  1302 . The MPO adapter  100  is inserted into the adapter  600  by pushing in while holding the strain relief  110  by hand. The MPO connector  100  is removed from the panel adapter  600  by pulling back the sliding outer housing  116  by hand.  FIG. 14  shows additional conventional MPO connectors  1400  coupled to adapters  1402  on the high density panel  1300 , creating problems for access to any MPO connector located in the middle of the MPO adapter field. Reaching into the middle of the field of adapters to remove an MPO connector is impossible to accomplish by hand without damage or disruption to adjacent MPO connectors and delicate ribbon fibers  1404 . 
     Aspects of the present disclosure are directed to addressing the shortcomings of the conventional MPO connectors described in relation with  FIGS. 1 to 14 . Various embodiments disclosed herein provide connectors that are shorter than the conventional connectors and have less components, thereby being both cost efficient and capable of use in tight spaces. Moreover, various embodiments may be compatible with existing adapters, such as the MPO adapters described in relation with  FIGS. 6 to 8 . 
       FIG. 15  shows one embodiment of a connector  1500  according to aspects of the present disclosure. The connector  1500  includes an MPO ferrule assembly  1502 , a ferrule spring  1504 , a main body or housing  1506  and a lock  1508 . Connectors disclosed herein may include less components compared to conventional MPO connectors. For example, the connector  1500  includes four components, less than the eight components of known MPO connectors as shown in  FIG. 1 . In various embodiments, a connector may include an MPO connector or an MT/MPO connector. For example, the ferrule may be an MT ferrule, whereas the ferrule assembly may be an MPO ferrule assembly. Although the ferrule assembly  1502  shown in  FIG. 15  is a male ferrule assembly, various embodiments disclosed herein may include a female ferrule assembly. 
     In one embodiment, the housing may include a front portion and a rear portion. The rear portion may be cylindrically shaped. For example, as shown in  FIG. 15 , the housing  1506  includes a front portion  1510  and a cylindrical rear portion  1512 . The housing  1506  may be configured to receive the ferrule assembly  1502  from the front portion  1510  of the housing. This is in contrast with the conventional MPO connectors, where the ferrule is received from the rear portion of the inner housing. For example, in  FIG. 1 , the inner housing  102  is configured to receive the ferrule assembly  104  from the rear portion of the inner housing. An advantage of receiving the ferrule assembly through the front of the housing is that it allows the rear portion of the housing to accommodate a single locking and unlocking mechanism for the connector. Another advantage is the use of less components in the connector. 
     The housing  1506  is configured to receive both the ferrule spring  1504  and the ferrule assembly  1502  through the front portion  1510 . The ferrule spring  1504  and the ferrule assembly may be common parts used in conventional MPO connectors. In other embodiments, the ferrule assembly or the ferrule spring may be new or different types than those used in conventional connectors. 
     Moreover, in one embodiment, as shown in  FIG. 15 , the cylindrical portion  1512  of the housing  1506  may be configured to couple to the lock  1508 . The lock may be configured to rotate about the housing so as to lock and unlock the housing from an adapter corresponding to the ferrule assembly  1502 . In this embodiment, the lock  1508  is a bayonet lock. In other embodiments, the lock may be of another type. In one embodiment, the lock may be a ring coupled to the housing by any other coupling means and configured to rotate about the housing so as to lock and unlock the housing from an adapter. 
     As shown in  FIG. 15 , the bayonet lock  1508  may be configured to couple to the cylindrical portion of the housing  1506 . The housing  1506 , and specifically the cylindrical portion  1512  in this embodiment, may have at least one groove  1514  and at least one stop  1516 . Further, the lock  1508  may include at least one flexing tab  1518  configured to snap into the groove  1514  so as to couple the lock to the housing  1506 . The stop  1516  may be disposed on the housing  1506  so as to limit rotation of the lock  1508 . 
     Various coupling mechanisms may be provided for coupling the connector to an adapter. For example, in one embodiment as shown in  FIG. 15 , the housing  1506  may have at least one recess  1520  configured to receive a respective catch of an adapter so as to couple the connector  1500  to the adapter. Moreover, the housing  1506  may have at least one slit  1522  to allow flexing of the housing. In some embodiments, as shown, the lock  1508  may also have at least one tab  1524  positioned so as to allow covering a respective recess  1520  of the housing, as well as a respective adapter catch, when the lock  1508  is in a locked position. 
     An assembled form of the connector  1500  is shown in  FIG. 16 . The length of the assembled MPO connector  1500  is about 18.5 mm. By contrast, as shown in  FIG. 17 , the prior art MPO connector  100  has a length of about 37 mm. Embodiments disclosed herein allow shorter length MPO connectors, for example, by using a single housing and a rotating mechanism that requires twisting to latch and unlatch. By contrast, conventional MPO connectors use multiple housing components and a sliding mechanism to latch and unlatch. 
       FIG. 18  is a side view of the connector  1500 , showing the housing  1506  having a slit  1522  and a recess  1520  covered by the tab  1524  of the lock  1508  disposed around the rear cylindrical portion  1512 . The ferrule assembly  1502  is coupled to the housing  1506 . 
     In some embodiments of connectors disclosed herein, bayonet type locks may be provided.  FIG. 19  is a front view of the bayonet lock  1508 , showing two flexing tabs  1518  configured to snap into respective grooves of the housing. In some embodiments, the lock  1508  may have recesses  1900  configured to limit rotation of the lock in conjunction with stops disposed on the housing, such as the stop  1516  shown in  FIG. 15 . In some embodiments, the lock  1508  may also have recesses  1902  configured to receive a tool to facilitate rotation of the lock, especially when the connector is coupled to an adapter in a high density adapter panel. The arrows on the lock  1508  indicate lock and unlock directions. 
       FIG. 20  shows an exploded view of the connector  1500  including the housing  1506  and the bayonet lock  1508 . The arrow indicates the direction of assembly of the lock with the housing. The housing  1506  may include slits  1522  and recesses  1520  on either side of the housing. The housing  1506  may also have stops  1516  on either side of the housing, and grooves  1514  at the top and bottom of the housing, disposed around the cylindrical portion  1512  so as to couple the lock  1508  to the housing. The stops  1516  are bumps on each side of the housing  1506 , and configured to fit into recesses  1900  inside the bayonet lock  1508  to limit rotation and provide stops at the locked and unlocked positions of the bayonet lock. 
     As shown in  FIG. 20 , in some embodiments, the lock  1508  may have two flexing tabs  1518  arranged in positions corresponding to that of the two grooves  1514  of the housing  1506 , and configured to engage the grooves to couple the lock to the housing. The lock  1508  may also have recesses  1900  configured to engage the stops  1516  to limit rotation of the lock. Moreover, the lock  1508  may have recesses  1902  configured to receive a portion of a tool to rotate the lock. Finally, the lock  1508  may have two tabs  1524  on either side of the lock, positioned to correspond to the locations of the recesses  1520  of the housing  1506  to allow covering the recesses and respective catches of an adapter coupled to the connector  1500 . In other embodiments, the lock may be configured to include a different number or arrangement of flexing tabs, recesses for stops, recesses for a locking and unlocking tool, and tabs to facilitate coupling and decoupling the connector to and from an adapter. 
       FIG. 21  is a side view of the housing  1506 , showing the slit  1522 , the recess  1520 , the stop  1516  and the two grooves  1514 . In this embodiment, the housing is symmetrical, such that the other side of the housing is identical to the side shown in  FIG. 21 . However, in other embodiments, the housing need not be symmetrical, and various features discloses herein may be arranged in different configurations.  FIG. 22  shows a top view of the housing  1506 , showing the top groove  1514  and a two stops  1516  on the sides of the housing, specifically positioned on the cylindrical portion  1512  that is configured to couple with a lock. 
       FIGS. 23 and 24  illustrate one embodiment of the interior of the housing  1506 .  FIG. 23  shows a front view through the housing  1506 , illustrating one embodiment wherein the housing includes inclined surfaces  2300  within the housing.  FIG. 24  also shows the inclined surfaces  2300  configured to facilitate coupling of the ferrule assembly  1502  to the housing  1506 . The cross-sectional view of the housing in  FIG. 24  also shows that the housing may accommodate the ferrule spring  1504  disposed within the housing, and may also include a plurality of catches  2400  configured to engage the ferrule assembly  1502 . The ferrule assembly  1502  may be inserted into the housing  1506  through a front portion  1510  of the housing. The ferrule assembly  1502  may include a plurality of corners  2402  which engage the catches  2400 . Thus, the ferrule assembly  1502  may be secured to the housing  1506  between the ferrule spring  1504  and the catches  2400 . 
     The bayonet lock  1508  is shown in an unlocked position in  FIG. 25A , and in a locked position in  FIG. 26A . During operation of one embodiment, the connector is pushed by the bayonet lock into an adapter, following by a 1/12 th  rotational twist to latch and lock the connector to the adapter. The reverse is done to unlatch and unlock the connector from the adapter. In some embodiments, the lock may be configured so as to make a clicking noise and/or provide another form of feedback to the user when twisting the lock. This will allow the user to more conveniently recognize the switch between locked and unlocked states of the connector. In one embodiment, when the bayonet lock  1508  is in an unlocked position, as shown in  FIG. 25B , the recesses  1520  of the housing may be uncovered. On the other hand, when the bayonet lock  1508  is in a locked position, as shown in  FIG. 26B , the tabs  1524  of the lock may cover the recesses  1520  of the housing, as well as the catches of the adapter coupled to the recesses. 
     The connector  1500  may be coupled to an adapter positioned on a panel or inside a device or module, or close to a circuit board. For example,  FIG. 27  shows the connector  1500  having a ribbon fiber  2700 . Ribbon fibers may be delicate, requiring careful handling. For example, as shown in  FIG. 27 , the connector  1500  is coupled to an adapter  2702  positioned near a circuit board  2704 . The compact size and shorter length of the connector  1500  requires less space inside a device or module, a benefit when positioned to circuit boards. The connector  1500  is shown to be in a locked position in  FIG. 27 . The same connector  1500  is shown in an unlocked position in  FIG. 28 . The bayonet lock  1508  is shown to be twisted relative to the locked position in  FIG. 27 . In one embodiment, when the connector is coupled to an adapter as shown for example in  FIGS. 27 and 28 , the portion of the connector protruding from the adapter may have a length less than or equal to about 7.5 mm. In other embodiments, the length of the protruding portion may be less than that of a conventional connector, e.g. less than about 26 mm. 
     Various embodiments of connectors disclosed herein may be configured to allow locking and unlocking using tools.  FIG. 29A  shows a tool  2900 , such as a wrench, in an unlocked position of the connector  1500 , and  FIG. 29B  shows the same tool moved to a locked position, thereby locking the connector to the adapter  2702 . 
     In some embodiments where adapters are positioned in high density panels or delicate spaces, locking or unlocking using a tool positioned in a transverse plane of the connector, as shown in  FIGS. 29A and 29B , may not be feasible. In such cases, a tool, such as tool  3000  shown in  FIG. 30 , positioned along the longitudinal axial direction of the connector  1500  may allow access to the high density panel  3002  having a plurality of adapters  3004  arranged in close proximity. Accordingly, the connector may be configured with recesses  1902 , as shown and described for example in relation with  FIG. 19 . The recesses  1902  may be configured to receive respective keys  3006  of the tool  3000 , thereby allowing convenient manipulation of the connector  1500 , even in high density spaces. 
       FIG. 31  illustrates the lengths of various embodiments of assembled connectors in comparison with the length of a conventional MPO connector  3100 . Connector  3102  is one embodiment of a connector for non-reinforced (bare) optical fiber cables. The connector  3102  is configured according to features described herein, such as the embodiment described in relation with  FIG. 15 . As shown, in one example, the length of the connector  3102  is about 18.5 mm. Connector  3104  is another embodiment of a connector for reinforced optical fiber cables. The connector  3104  may be configured to include one or more features of connectors for bare cables, and may further include additional components, such as a reinforcing portion  3106 . As shown, in one example, the length of the connector  3104  is about 23.5 mm prior to attachment to the optical fiber cable, and prior to addition of a strain relief. By contrast, connector  3100  is a conventional MPO connector for a reinforced cable, having a length of 32 mm prior to attachment to the optical fiber cable, and prior to addition of a strain relief. Various embodiments of connectors for reinforced cables disclosed herein have an assembled length less than that of a conventional connector, that is less than about 32 mm. 
       FIG. 32  illustrates one embodiment of a connector  3200  for a bare non-reinforced optical fiber cable. The connector  3200  includes a housing  3202  having a front portion  3204  and a rear portion  3206 . The housing  3202  is configured to receive a ferrule assembly  3208  from the rear portion  3206 . The ferrule assembly includes a ferrule  3210  and an alignment member  3212 . The housing  3202  is further be configured to receive the ferrule spring  3214  from the rear portion  3206 . In embodiments wherein the housing is configured to receive the ferrule assembly from the rear portion rather than the front portion, the connector may further include a separate interface member  3216  for the lock  3218 , as shown in  FIG. 32 . The rear portion  3206  of the housing  3202  is configured to couple with the interface member  3216 . The interface member  3216  includes a stop  3220 , similar to the stop  1516  described in relation with  FIG. 15 . The interface member  3216  is configured to receive an optical fiber cable. The rear portion  3206  of the housing  3202  also includes a groove  3222 , similar to groove  1514  described in relation with  FIG. 15 . The same features of the lock  1508  in  FIG. 15  may also be included in the lock  3218 , including flexing tabs  3224  configured to engage the grooves  3222 , and the tabs  3226 . 
       FIG. 33A  shows a partially assembled view of the connector  3200 , including a top view of the housing  3202 , and a top view of the ferrule assembly  3208  coupled to the interface member  3216 , the spring  3214 , and further coupled to the lock  3218 . As shown, the ferrule assembly  3208  is configured to include a raised flange  3300 .  FIG. 33B  shows a cross-sectional view of  FIG. 33A  along section X-X.  FIG. 33B  also shows the raised flange  3300 . The housing  3202  includes a corresponding ferrule flange stop  3302  to facilitate proper fitting of the ferrule within the housing  3202 . 
       FIG. 34A  shows the assembled connector  3200  of  FIGS. 32, 33A and 33B . The connector  3200  may be configured to have an assembled length less than about 32 mm, for example, an assembled length of about 18.5 mm or less as shown in  FIG. 31 .  FIG. 34B  shows a cross-sectional view of the connector  3200  of  FIG. 34A  along section X-X.  FIG. 34B  further shows the raised flange  3300  of the ferrule assembly  3208 , and the corresponding ferrule flange stop  3302  of the housing  3202 . Further,  FIG. 34B  shows that the flexing tab  3224  of the bayonet lock  3218  has engaged the groove  3222  of the housing  3202  so as to hold the assembly together. 
       FIG. 35  illustrates one embodiment of a connector  3500  for a reinforced optical fiber cable. The connector  3500  includes a housing  3502  having a front portion  3504  and a rear portion  3506 . The housing  3502  is configured to receive a ferrule assembly  3508  from the rear portion  3506 . The ferrule assembly  3508  includes a ferrule  3510  and an alignment member  3512 . The housing  3502  is further be configured to receive the ferrule spring  3514  from the rear portion  3506 . In embodiments wherein the housing is configured to receive the ferrule assembly from the rear portion rather than the front portion of the housing, the connector may further include a separate interface member  3516  for the lock  3518 , as shown in  FIG. 35 . The rear portion  3506  of the housing  3502  is configured to couple with the interface member  3516 . The interface member  3516  includes a stop  3520 , similar to the stop  1516  described in relation with  FIG. 15 . The interface member  3516  is configured to receive an optical fiber cable. The interface member  3516  further includes a reinforcement portion  3530  so as to reinforce the optical fiber cable coupled to the connector  3500 . The rear portion  3506  of the housing  3502  includes a groove  3522 , similar to groove  1514  described in relation with  FIG. 15 . The same features of the lock  1508  in  FIG. 15  may also be included in the lock  3518 , including flexing tabs  3524  configured to engage the grooves  3522 , and the tabs  3526 . 
       FIG. 36A  shows a partially assembled view of the connector  3500 , including a top view of the housing  3502 , and a top view of the ferrule assembly  3508  coupled to the interface member  3516  having a reinforcement portion  3530 , the spring  3514 , and further coupled to the lock  3518 . As shown, the ferrule assembly  3508  is configured to include a raised flange  3600 .  FIG. 36B  shows a cross-sectional view of  FIG. 36A  along section X-X.  FIG. 36B  also shows the raised flange  3600 . The housing  3502  includes a corresponding ferrule flange stop  3602  to facilitate proper fitting of the ferrule within the housing  3502 . 
       FIG. 37A  shows the assembled connector  3500  of  FIGS. 35, 36A and 36B . The connector  3500  may be configured to have an assembled length less than about 32 mm, for example, an assembled length of about 23.5 mm or less as shown in  FIG. 31 . This assembled length is prior to addition of a strain relief.  FIG. 37B  shows a cross-sectional view of the connector  3500  of  FIG. 37A  along section X-X.  FIG. 37B  further shows the raised flange  3600  of the ferrule assembly  3508 , and the corresponding ferrule flange stop  3602  of the housing  3502 . Further,  FIG. 37B  shows that the flexing tab  3524  of the bayonet lock  3518  has engaged the groove  3522  of the housing  3502  so as to hold the assembly together. Various embodiments of connectors disclosed herein may further include a strain relief. 
     Various embodiments disclosed herein are compatible with known MPO adapters, and may also be configured for compatibility with new types of adapters. The adapters may be configured to be fastened to a chassis, bulkhead, panel, or any type of enclosure structure. Various embodiments may be configured with alternative types of coupling mechanisms than those described herein, for coupling the connectors to the adapters, for coupling the ferrule assemblies to the housing or for coupling the lock to the housing. Coupling mechanisms may include, for example, a threaded configuration, or a clip-type attachment. 
     Assembly of connectors disclosed herein may be simpler than that of conventional MT/MPO connectors, at least due to the reduced number of components and the shorter length of the connectors. Manufacturing costs can be reduced as fewer different parts need to be designed, tooled and constructed, and inventories of parts can also be minimized. 
     In external applications wherein the adapters and connectors may be exposed to weather, particularly rain or moisture in general, the connectors may be configured as ingress protection (IP) connectors that are waterproof. A standard for such connectors may be an OVDA connector. For weatherproof or waterproof installations, the connectors may include protective housings and seals to inhibit water penetration, and may include different levels of ‘ingress protection’ depending on the environment to which they will be exposed. 
     Various parts, components or configurations described with respect to any one embodiment above may also be adapted to any others of the embodiments provided. 
     This disclosure is not limited to the particular systems, devices and methods described, as these may vary. The terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope. 
     In the above detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be used, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein. 
     The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds, compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. 
     As used in this document, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art. Nothing in this disclosure is to be construed as an admission that the embodiments described in this disclosure are not entitled to antedate such disclosure by virtue of prior invention. As used in this document, the term “comprising” means “including, but not limited to.” 
     While various compositions, methods, and devices are described in terms of “comprising” various components or steps (interpreted as meaning “including, but not limited to”), the compositions, methods, and devices can also “consist essentially of” or “consist of” the various components and steps, and such terminology should be interpreted as defining essentially closed-member groups. 
     With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. 
     It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.” 
     In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group. 
     As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” and the like include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, a group having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells, and so forth. 
     Various of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art, each of which is also intended to be encompassed by the disclosed embodiments.