Patent Publication Number: US-11036016-B2

Title: Ultra-small form factor receptacles for fiber optical connectors

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional (35 USC 120) of U.S. patent application Ser. No. 16/508,541 filed on Jul. 11, 2019, now U.S. Pat. No. 10,690,864, issued Jun. 23, 2020, titled “Ultra-Small Form Factor Receptacles For Fiber Optical Connectors”, which claims priority to U.S. Patent Application 62/696,710 filed on Jul. 11, 2018, titled “Ultra-Small Form Factor Receptacles For Fiber Optical Connectors”, and the above applications are incorporated by reference into this application. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates generally to ultra-small form factor receptacle for receiving optical connectors and used in fiber optic adapters and optical transceivers. 
     BACKGROUND 
     The prevalence of the Internet has led to unprecedented growth in communication networks. Consumer demand for service and increased competition has caused network providers to continuously find ways to improve quality of service while reducing cost. 
     Certain solutions have included deployment of high-density interconnect panels. High-density interconnect panels may be designed to consolidate the increasing volume of interconnections necessary to support the fast-growing networks into a compacted form factor, thereby increasing quality of service and decreasing costs such as floor space and support overhead. However, room for improvement in the area of data centers, specifically as it relates to fiber optic connections, still exists. For example, manufacturers of connectors and adapters are always looking to reduce the size of the devices, while increasing ease of deployment, robustness, and modifiability after deployment. In particular, more optical connectors may need to be accommodated in the same footprint previously used for a smaller number of connectors in order to provide backward compatibility with existing data center equipment. For example, one current footprint is known as the small form-factor pluggable transceiver footprint (SFP). This footprint currently accommodates two LC-type ferrule optical connections. However, it may be desirable to accommodate four optical connections (two duplex connections of transmit/receive) within the same footprint. Another current footprint is the quad small form-factor pluggable (QSFP) transceiver footprint. This footprint currently accommodates four LC-type ferrule optical connections. However, it may be desirable to accommodate eight optical connections of LC-type ferrules (four duplex connections of transmit/receive) within the same footprint. 
     In communication networks, such as data centers and switching networks, numerous interconnections between mating connectors may be compacted into high-density panels. Panel and connector producers may optimize for such high densities by shrinking the connector size and/or the spacing between adjacent connectors on the panel. While both approaches may be effective to increase the panel connector density, shrinking the connector size and/or spacing may also increase the support cost and diminish the quality of service. 
     In a high-density panel configuration, adjacent connectors and cable assemblies may obstruct access to the individual release mechanisms. Such physical obstructions may impede the ability of an operator to minimize the stresses applied to the cables and the connectors. For example, these stresses may be applied when the user reaches into a dense group of connectors and pushes aside surrounding optical fibers and connectors to access an individual connector release mechanism with his/her thumb and forefinger. Overstressing the cables and connectors may produce latent defects, compromise the integrity and/or reliability of the terminations, and potentially cause serious disruptions to network performance. 
     While an operator may attempt to use a tool, such as a screwdriver, to reach into a dense group of connectors and activate a release mechanism, adjacent cables and connectors may obstruct the operator&#39;s line of sight, making it difficult to guide the tool to the release mechanism without pushing aside the adjacent cables. Moreover, even when the operator has a clear line of sight, guiding the tool to the release mechanism may be a time-consuming process. Thus, using a tool may not be effective at reducing support time and increasing the quality of service. 
     SUMMARY OF THE INVENTION 
     An optical connector holding two or more LC-type optical ferrules is provided. The optical connector includes an outer body, an inner front body accommodating the two or more LC-type optical ferrules, ferrule springs for urging the optical ferrules towards a mating receptacle, and a back body for supporting the ferrule springs. The outer body and the inner front body are configured such that four LC-type optical ferrules are accommodated in a small form-factor pluggable (SFP) transceiver footprint or eight LC-type optical ferrules are accommodated in a quad small form-factor pluggable (QSFP) transceiver footprint. A mating receptacle (transceiver or adapter) includes a receptacle hook and a housing with an opening that accommodates the receptacle hook in a flexed position as the optical connector makes connection with the mating receptacle by introducing the receptacle hook into an optical receptacle hook recess. 
     An adapter or transceiver having one or more receptacles or ports configured to accept a low-profile, small form factor optical connector holding two or more LC-type optical ferrules is provided. A mating receptacle (transceiver or adapter) includes a transceiver alignment assembly for accepting, aligning and securing one or more connectors within a receptacle of transceiver. The transceiver housing has an opening that accommodates a connector hook in a flexed position as the optical connector makes connection therewith. At a first end, the transceiver alignment assembly is secured within a fiber optic stub holder comprising a top and bottom housing. At a second end, stub holder retains a plurality of fiber stubs that accept a plural plurality of fibers carrying a data signal. The stubs are aligned with alignment sleeve holder formed with transceiver alignment assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a prior art small form factor connector; 
         FIG. 2  is an exploded view of a transceiver housing with an array of receptacle hooks and fiber stub holders; 
         FIG. 3A  is an exploded view of  FIG. 2  prior to assembly of receptacle hooks and fiber stub holders and placement into transceiver bottom housing; 
         FIG. 3B  is a perspective view of bottom transceiver housing with array of receptacle hooks and fiber stub holders placed therein; 
         FIG. 4  a perspective view of a transceiver assembled according to an embodiment of the present invention; 
         FIG. 5A  is an exploded view of top and bottom housing portions of transceiver housing with components; 
         FIG. 5B  is an exploded view of transceiver housing without front body attached; 
         FIG. 5C  is a side view of fiber stub retained in fiber stub holder; 
         FIG. 6  is a cut-away view of fiber stub holder connected to transceiver electronic; 
         FIG. 7  is an array of fiber stub holders and adapter hooks to retain a fiber optic connector; 
         FIG. 8  is a perspective view of an alignment sleeve configured to be accepted as part of a fiber stub holder; 
         FIG. 9  is a perspective view of bottom housing of a two-piece fiber stub holder; 
         FIG. 10  is a perspective view of top housing of a two-piece fiber stub holder; 
         FIG. 11  is a perspective view of an alignment sleeve holder with a fiber stub inserted therein; 
         FIG. 12  is front, perspective view of a plurality of fiber stubs with a fiber stub holder; 
         FIG. 13  is an alignment sleeve holder with hooks or latches for securing within a one-piece fiber stub holder; 
         FIG. 14  is a perspective view of an one-piece fiber stub holder; 
         FIG. 15  is a perspective view of a fiber stub; 
         FIG. 16  is an exploded view of a fiber stub holder configured to accept an electrical shield plate; 
         FIG. 17  is a perspective view of an electrical shield and fiber stub retainer plate; 
         FIG. 18  is a perspective view of a one-piece fiber stub holder with latches to secure within an adapter housing; 
         FIG. 19  is a side view of  FIG. 17 ; 
         FIG. 20  is front view of fiber optic stub holder configured to be inserted into an adapter housing; 
         FIG. 21  is side view of an adapter housing; and 
         FIG. 22  is another embodiment of a fiber stub holder. 
     
    
    
     DETAILED DESCRIPTION 
     The following terms shall have, for the purposes of this application, the respective meanings set forth below. 
     A connector, as used herein, refers to a device and/or components thereof that connects a first module or cable to a second module or cable. The connector may be configured for fiber optic transmission or light signal transmission. The connector may be any suitable type now known or later developed, such as, for example, a ferrule connector (FC), a fiber distributed data interface (FDDI) connector, an LC connector, a mechanical transfer (MT) connector, a square connector (SC) connector, a CS connector, or a straight tip (ST) connector. The connector may generally be defined by a connector housing body. In some embodiments, the housing body may incorporate any or all of the components described herein. 
     A “fiber optic cable” or an “optical cable” refers to a cable containing one or more optical fibers for conducting optical signals in beams of light. The optical fibers can be constructed from any suitable transparent material, including glass, fiberglass, and plastic. The cable can include a jacket or sheathing material surrounding the optical fibers. In addition, the cable can be connected to a connector on one end or on both ends of the cable. 
     Receptacle herein is not limited to port, opening, or channel. A receptacle can accept and releasably retain a connector  100  therein retained with a fiber stub holder, as described in the present invention. Fiber stub holder  330 ,  740  can be a molded one-piece (refer to  FIG. 3A ), or two-piece (refer to  FIG. 9 ,  FIG. 10 ). The fiber stub holder may be formed from plastic or metal. Metal stub holders can be deployed to reduce electro-magnetic field interference or EMI, or alternatively incorporate a metal shield as depicted in  FIG. 17 . 
       FIG. 1  depicts a small form-factor, low-profile micro-connector  100  that is inserted into receptacle front body  210  (refer to  FIG. 2 ) at a proximal end thereof that can accept a plurality of connectors  100  securely therein. Connector  100  contains one or more ferrules  106 . An outer housing  105  has alignment key  103  thereon to assist with inserting into receptacle  410  (e.g. proximal end of receptacle) with alignment slot  410   a  (refer to  FIG. 4 ). Slot  410   a  and alignment key  103  reduce receptacle overall height and width by removing wall structure normally found between connectors in a receptacle. A proximal end of connector  100  is defined as closer to ferrule  106 , and connector  100  further comprises ramp surface  101  formed as part of inner front body  102 . Ramp  101  engages corresponding hook tip ( 918   a ,  918   h ) formed as part of receptacle retainer assembly  700  (refer to  FIG. 7 ). 
       FIG. 2  depicts an exploded view of a two-piece press-fitted transceiver assembly configured to accept a plurality of connectors  100  secured by an array of receptacle hooks  220 . Receptacle hooks  220  each accept a corresponding fiber stub holder  230  configured on a distal side to accept a plurality of alignment sleeves  215 , and on a proximal side to accept the array of receptacle hooks  220 . Each alignment sleeve opening is configured to accept fiber stub  211   a  (refer to  FIG. 15 ). Referring to  FIG. 2 , each fiber stub  211   a  has one or more fibers  212  exiting from fiber array  213  that is in signal communication with a printed circuit board or PCB  214 . The transceiver is assembled in direction of arrow “A”. Receptacle front body  210  is placed over a front end of transceiver housing  280 , with the PCB  214 , fiber stubs  211 , and other components assembled and secured within transceiver housing  280 . 
       FIG. 3A  depicts transceiver bottom housing  380   b  with widthwise slots  380   d  configured to accept one-piece fiber stub holder  330  and array of receptacle hook  320  to form receptacle retainer assembly  700  ( FIG. 3B ) configured to retain one or more connectors  100  within transceiver housing  380 . Fiber stub holder  330  is assembled in direction of arrow “A 1 ”, then inserted into widthwise slot  380   d  according to arrow “A 2 ”, within bottom transceiver housing  380   b , as depicted in  FIG. 3B . 
       FIG. 4  depicts another embodiment of a transceiver housing with receptacle retainer assembly  700  therein. In this embodiment, fiber stub holder is two-piece. Receptacle front body  210  is configured to accept receptacle retainer assembly  700  comprising a two-piece fiber stub holder. Assembled transceiver comprises top housing  480   a  and bottom housing  480   b  that holds the following components. Housing  480  contains recess  480   c  that used with a removal tool (not shown) configured to remove transceiver ( FIG. 4 ) from a panel assembly (not shown). Front body  210  ( FIG. 2 ) contains opening  417  on one or both sides of housing that receives flexing of connector retention/adapter hooks  418  upon insertion of connector  100  into receptacle  410 . Receptacle retainer assembly latch  419  secures receptacle retainer assembly  700  to fiber stub holder  740  (refer to  FIGS. 9, 10 ), which comprises top housing  740   a  and bottom housing  740   b . Top housing  480   a  has lip  580   d  accepted into slot  580   e  to form transceiver housing  480 . 
       FIG. 5A  depicts an exploded view of transceiver top housing  280   a  and bottom housing  280   b . Between housing portions is an array of receptacle hooks  220 , in either side of alignment holder  950 . The hooks are configured to receive and secure connector  100 , at a proximal end thereof. At distal end of the retainer assembly is the array of fiber stubs  211 .  FIG. 5B  is a front view of  FIG. 5A  without front body  210 . Top housing  280   a  has a plurality of half or semi-circle cut-outs  287   a  and bottom housing  280   b  has corresponding cut-outs  287   b  that when the top and bottom housing are secured together, cut-outs are configured to retain the fiber stub  211  about fiber stub flange  911   a .  1  (refer to  FIG. 7 ).  FIG. 5C  depicts side view of fiber stub  211  secured within distal end of retainer assembly or fiber stub holder  230 . 
       FIG. 6  depicts PCB  714  in communication using fiber array  713  via optical fiber  712  formed as part of ferrule  106 . Ferrule  106  with fiber therein is inserted into a distal end of fiber stub holder  211   a  (refer to  FIG. 15 ). Top housing  740   a  and bottom housing  740   b  form housing  740  that secures array of fiber stub holders  211 . Referring to  FIG. 15 , fiber stub  211   a  can be retained in an unitary fiber stub holder  230  ( FIG. 16  and  FIG. 2 ). Referring to  FIG. 6 , each fiber stub holder  811   a  is in line with opposing connector hooks ( 718   d ,  718   h ) or may be called an adapter latch  718   a  that secures a data center or two fiber optical connector  100  between hooks  718   d  top hook and  718   h  bottom hook. Connector  100  is inserted into alignment sleeve holder at proximal end  950   a  (refer to  FIG. 7 ). Latch  719   a  secures fiber stub holder with alignment sleeve holder within front body  210  of transceiver housing  740 . 
       FIG. 7  depicts array alignment sleeve holder ( 950   a ,  950   d ) with opposing connector or adapter hook ( 918   a - 918   d ,  918   e - 918   h ) configured to accept connector  100 . Opposing hook pairs (( 918   a ,  918   h ), ( 918   b - 918   d ), ( 918   g - 918   e )) are lifted by ramp  101  and the opposing hook pair is secured within connector recess  104 . Fiber stub latches ( 919   a - 919   d ) have opposing latches (e.g.  919   e  opposes  919   d ), which secures the retained assembly into a transceiver front body or adapter housing  200  (refer to  FIG. 21 ), or to a fiber stub holder  230  (refer to  FIG. 20 ), which is then inserted into adapter housing  200 , with adapter latches  295  secured within corresponding adapter housing cut-out  275  (see  FIG. 20 ,  FIG. 21 ). Face  919   a .  1  of each fiber stub latch  919   a  is secured with recess  740   a .  1  (refer to  FIG. 10 ) of fiber stub holder top housing  740   a . The opposing latches are formed as part of main body  913  of the retainer receptacle assembly  700 . Assembly  700  is made up of individual retainer receptacle assembly units  700   a.    
       FIG. 8  depicts a front view of alignment sleeve holder  850  with opposing openings ( 850   a .  1 ,  850   a .  2 ) configured to accept data center connector  100 , the latter is formed as part of receptacle retainer assembly  700 . Alignment sleeve holder  850  has fiber stub latch  919   a  with face  919   a .  1  that engages fiber stub holder  740  to secure retainer to holder  740 .  FIG. 9  depicts bottom housing  740   b  of two-piece fiber stub holder  740  with opening  740   b .  1  that accepts latch  919   b  for securing alignment sleeve holder with bottom housing  740   b.    
       FIG. 10  depicts top housing  740   a  of two-piece fiber stub holder  740 . Opening  740   a .  1  accepts fiber stub latch  919   a  to secure alignment sleeve holder  850  within top housing  740   a . To form fiber stub housing  740 , post  740   c  is received within press-fit opening  740   d , and likewise post  740   e  is received within press-fit opening in top housing  740   a , as shown by dotted lines. 
       FIG. 11  depicts fiber stub  811   b  inserted into a corresponding alignment sleeve holder opening  950   a , and further secured with flange  811   b . l inside fiber stub top housing  740   a . Latch  919   a  is secured behind stop face  741  of fiber stub holder  740 . Upon insertion of connector  100  into receptacle along center line (C.L.), hook  918   a  (as well as opposing hook  918   h ) are pushed into gap  980   a  (and  980   b  not shown) until connector  100  is fully inserted into the receptacle over alignment sleeve  950   a . Optical fiber  912  interconnects connector  100  with PCB  714 . 
       FIG. 12  depicts a rear view of a fully assembled fiber stub holder  740  with a plurality of fiber stubs ( 911   a - 911   h ) at a second end with optical fiber  912   a  therethrough, and receptacle retainer assembly  700  at a first end. Latch  919   a  is secured up against surface  741  of an opening within fiber stub holder  740 . 
       FIG. 13  depicts alignment sleeve holder  850  prior to insertion (along direction of arrows “I”) into a one-piece fiber stub holder  740 . Openings  740   a .  1  and  740   b .  1  accept fiber stub latches ( 919   a ,  919   b ) to secure alignment sleeve holder within fiber stub holder  740 .  FIG. 14  depicts fiber stub holder  740  as one-piece, with top opening  740   a .  1  and bottom opening  740   b .  1  as described above.  FIG. 15  depicts fiber stub  211   a  with flange  211   a .  1 . Flange  211   a .  1  is retained within fiber stub holder  740  to secure fiber stub  211   a  therein, or is secured to shield plate  205  described below. 
       FIG. 16  depicts an exploded view of another embodiment of retainer assembly secured within a transceiver housing. The assembly depicts array of adapter hook  220  each opposing hook pair with an alignment sleeve  215  between the opposing hook pair. Hooks  220  are secured along dotted arrow to latch post  230   a  in Step  1 . In Step  2 , alignment sleeves  215  are placed over corresponding fiber stub  211 , which is then inserted into an alignment sleeve opening in Step  3 . In Step  4 , electrical interference shield or metal shield  205  is inserted onto posts  150  at distal side of fiber stub holder  230  (refer to  FIG. 19  and  FIG. 22 ).  FIG. 17  depicts metal shield  205  with openings  140  to receive posts  150  formed at a distal end of fiber stub holder  230 . Fiber stub openings  255  receive fiber stub  211  ( FIG. 16 ). The metal shield protects an optical light signal from the electromagnetic energy of the transceiver electronics PCB  714 . 
       FIG. 18  depicts another one-piece embodiment of fiber stub holder  230  with adapter housing latch  295  position on a distal end, with an opposing latch (refer to  FIG. 19 ). A plurality of latches  295 , as depicted in  FIG. 20  also, are secured within adapter housing cut-out or opening  275  (refer to  FIG. 21 ) to secure fiber stub holder  230  therein.  FIG. 22  depicts a side view of another embodiment of fiber stub holder  230 . Adapter housing latches  295  form a channel for securing the fiber stub holder within a receiver housing. 
     In the above detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify components, unless context dictates otherwise. For example,  211  or  811  is generally a fiber stub holder while  211   a  is one of a plurality of fiber stub holders. 
     It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (for example, bodies of the appended claims) are generally intended as “open” terms (for example, 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,” et cetera). 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. 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” (for example, “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.