Patent Publication Number: US-11650385-B2

Title: Optical module cages mounted for optimal density and cooling

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Ser. No. 63/145,184, entitled “Optical Module Cages With Optimized Density, Cooling, and Mounting”, filed Feb. 3, 2021, the disclosure of which is incorporated herein by reference in its entirety for all purposes. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to module cages that receive optical modules for electronic devices, e.g., in relation to communication networks. 
     BACKGROUND 
     Over the years, there has been an increase in the need for higher performance communications networks. To satisfy the increasing demand of bandwidth and speed, pluggable transceiver modules (optical modules) are being used on various network devices (e.g., switches, routers, etc.). The pluggable transceiver modules are used to convert electrical signals to optical signals or in general as the interface to a network element copper wire or optical fiber. Increased performance requirements have also led to an increase in energy use resulting in greater heat dissipation from the pluggable modules. 
     Pluggable optical modules (transceiver modules) come in many different form factors such as SFP (Small Form-Factor Pluggable), QSFP (Quad Small Form-Factor Pluggable), QSFP+, QSFP-DD (QSFP Double Density), OSFP (Octal Small Form-Factor Pluggable), and the like, and may support data rates up to 400 Gb/s, for example. Hosts for these pluggable modules include line cards or fixed designs that may be used on switches, routers, edge products, and other network devices. The optical modules may operate with heatsinks (e.g., integrated or riding heatsink) or without heatsinks. Single, double, and triple stack optical module cage configurations are typically connected to a printed circuit board with an opening for receiving an optical module positioned such that an optical module is inserted in a horizontal position. 
     As telecommunication systems speeds and power requirements increase, emission from the pluggable module increases along with a need for improved cooling. Also needed are increased density and flexibility in terms of pluggable configurations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  schematically depicts an optical module cage that secures to a face plate or front panel of the housing (chassis) of an electronic device in accordance with example embodiments described herein. 
         FIG.  1 B  schematically depicts the front panel of the housing for the electronic device including inner and outer panel portions in accordance with example embodiments described herein. 
         FIG.  1 C  schematically depicts an optical module cage as set forth in  FIG.  1 A  secured to the front panel of  FIG.  1 B . 
         FIGS.  2 A and  2 B  schematically depict a plurality of optical module cages in a 3×2 array and a 2×3 array arranged along a front panel of a housing for an electronic device in accordance with example embodiments described herein. 
         FIG.  3 A  schematically depicts optical module cages (e.g., arranged in an array such as depicted in  FIG.  2 A or  2 B ) including cables that connect with a circuit component (ASIC) of an electronic device. 
         FIG.  3 B  schematically depicts the plurality of optical module cages as depicted in  FIG.  2 A  directly connected to a printed circuit board (PCB). 
         FIG.  3 C  schematically depicts the plurality of optical module cages as depicted in  FIG.  2 A , where each cage is directly connected to a separate printed circuit board (PCB). 
         FIGS.  4 A and  4 B  depict a plurality of optical module cages connected with a front panel of a housing (chassis) of an electronic device in accordance with example embodiments described herein, where the outer or exterior surface of the front panel is depicted in  FIG.  4 A  (with an optical module installed within one of the cages) and the inner or interior surface of the front panel is depicted in  FIG.  4 B . 
         FIG.  4 C  depicts optical module cages and a portion of the front panel as shown in  FIG.  4 B , in which the optical module cages are separated from the front panel prior to installation with the front panel. 
         FIG.  4 D  depicts a portion of an optical module cage as shown in  FIG.  4 C  at its front end. 
         FIG.  4 E  depicts optical module cages and a portion of the front panel as shown in  FIG.  4 B , in which the optical module cages are connected with the front panel. 
         FIG.  5 A  depicts a front view of the front panel of a chassis or housing of an electronic device with optical module cages connected with the front panel and an optical module prior to insertion/installation within one of the cages. 
         FIG.  5 B  depicts a portion of a rear view of the front panel of  FIG.  5 A , and further showing structure comprising a snap-in edge connector including cables prior to connection/assembly with a rear end of an optical module cage in accordance with example embodiments described herein. 
         FIG.  5 C  depicts the view of  FIG.  5 B  in which the snap-in connector structure is connected with the rear end of the optical module cage. 
         FIG.  5 D  depicts cross-sectional views of a portion of an optical module cage and an edge connector coupled with the cage at its rear end. 
         FIG.  5 E  depicts an enlarged view of  FIG.  5 D  showing engaging structure between the rear end of the optical module cage and edge connector. 
         FIG.  6 A  depicts an isolated view in perspective of an optical module cage in accordance with example embodiments of the invention and in which the cage includes heat sink components (fins) disposed along opposing sides of the cage. 
         FIG.  6 B  depicts an exploded view in perspective of the optical module cage of  FIG.  6 A . 
         FIG.  7 A  depicts a view in perspective of a plurality of optical module cages including structural supports that connect between the cages prior to assembly in accordance with example embodiments described herein. 
         FIG.  7 B  depicts the view in perspective of  FIG.  7 A  and in which the structural supports assembled or connected with the cages. 
         FIGS.  7 C and  7 D  depict an enlarged view of a portion of an optical module cage and a structural support showing how the structural support connects with the cage in accordance with example embodiments described herein. 
         FIG.  8    depicts an example embodiment showing the operational temperature distribution of a vertically stacked arrangement of two optical modules disposed within corresponding cages. 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     Overview 
     In example embodiments, an apparatus comprises a housing for an electronic device includes a panel, where the panel includes a window. A cage includes a plurality of panels and a first end and a second end that opposes the first end. The cage further includes an opening at its first end and an enclosure disposed between the panels of the cage. Connecting structure is disposed at the first end of the cage, where the connecting structure secures the first end of the cage to the panel. The cage is suitably dimensioned to receive and retain a portion of an optical module within the enclosure when the optical module is inserted within the opening at the first end of the cage. 
     In other example embodiments, a cage comprises a plurality of panels that define an enclosure between the panels, a first end including an opening, a second end that opposes the first end, and connecting structure disposed at the first end of the cage, wherein the connecting structure secures the first end of the cage to a panel of a housing. The cage is suitably dimensioned to receive and retain a portion of an optical module within the enclosure when the optical module is inserted within the opening at the first end of the cage. 
     In further example embodiments, a method comprises providing a cage including a plurality of panels that define an enclosure between the panels, a first end including an opening, and a second end that opposes the first end, facilitating a connection, via connecting structure disposed at the first end of the cage, between the first end of the cage and a panel of a housing for an electronic device such that the cage extends from the first end to the second end in a cantilevered manner from the panel, and facilitating insertion of an optical module into the opening at the first and end into the enclosure of the cage such that the optical module engages with an edge connector disposed at the second end of the cage, wherein the edge connector includes engaging structure that enables an exchange of signals between the optical module and a circuit component within the housing. 
     Example Embodiments 
     Embodiments described herein provide an optical module cage mounting configuration that is independent of a printed circuit board mounting system. The embodiments provide one or more of improved density, cooling, mounting, or signal integrity. A modular optical module cage design described herein allows for multiple port configurations. The optical module cage may be designed for compatibility with various optical form factors including SFP, QSFP, OSFP, CFP, CFP2, CFP8, QSFP-DD, or any other current or future form factor. 
     As described herein, example embodiments provide an optical module cage (e.g., metal cage) that snaps into a face plate or front panel (faceplate) of a chassis or housing of an electronic device. Suitable types of electronic devices are any type of networking device (e.g., hubs, routers, switches, digital line cards, data storage devices and/or other computing devices) associated with communication networks. 
     In certain example embodiments described herein, the optical module cage does not need to interface directly or at all with a printed circuit board (PCB). The optical module cage may be mechanically fixed to a faceplate without PCB support. Power, ground, control, and data may be provided through interface with a snap-in direct attach cable system. Elimination of the PCB increases options for increased density, enhanced module to module spacing, or both increased density and enhanced module spacing. Improved airflow and density are provided by elimination of the PCB. 
     In certain embodiments, a snap-in cable system allows a plurality of cables in a pigtail configuration to be mounted to a circuit component, such as an ASIC (Application Specific Integrated Circuit) and/or to a PCB as an assembly. Connectors may then be snapped into the optical module cage or into an orthogonal connector frame to facilitate a suitable connection (e.g., switch fabric interconnect) between an optical module connected or installed within the optical module cage and the circuit component and/or PCB. The pigtails may be snapped into the optical module cage, which allows for the other end to be directly press-fit attached to circuit component and/or PCB via a suitable connection or engaging structure at the circuit component/PCB end (e.g., pin field and/or any other suitable contact members). This facilitates ease of connector changes and cabling changes based on module speed requirements, without any changes to the optical module cage assembly/front panel mounting system. The snap-in pigtail cable connector structure allows for lower cost connectors or other speed/style connectors to be used and easily mixed and matched in a system design. In addition, implementation of cables instead of direct connection with the PCB provides an improvement in SI (signal integrity) performance. In certain embodiments, the cabling may comprise graphene integrated copper. 
     In certain embodiments described herein, the optical module cage is mounted in a vertical orientation (plane), where the width or longer dimension of the opening of the optical module cage for receiving an optical module is positioned in a vertical orientation. This allows for an increased stack of mounting of the optical module cages, increased density, or greater spacing between optical modules. Increased spacing allows more room for cooling airflow, thereby making way for deployment of high power optical modules. 
     Referring to the drawings,  FIGS.  1 A,  1 B and  1 C  schematically depict an optical module cage and its connection with the face plate or front panel of the chassis or housing of an electronic device (e.g., an electronic device for a networking/communications system). The optical module cages as described herein can be constructed of any suitably rigid materials (e.g., metals, hard plastic materials, etc.) that provide adequate support for optical modules and connection structure that engage with the cages as described herein. The panels that form the walls of the housing are also constructed of metal and/or any other suitable materials that provide sufficient structural support and protection for the optical module cages as well as components disposed within the housing. While not shown in some of the figures, it is understood that the housing of an electronic device has a generally rectangular shape and includes four sidewalls or side panels, including a front panel that includes windows or connection ports for connecting (e.g., via cables or other transmission lines) with other devices. The housing of the electronic device further includes a top wall or top panel and a bottom wall or bottom panel which, when combined with the side panels, provides an enclosure for one or more printed circuit boards (PCBs) mounted along an interior surface of one or more of the panels as well as electronic components (e.g., an ASIC) (e.g., components mounted and/or integrated with one or more of the PCBs) that perform the operations of the device. The front panel, rear panel, and side panels of the housing all extend between the top and bottom panels. 
     As shown in  FIG.  1 A , an apparatus includes an optical module cage and a panel of a chassis or housing of an electronic device (e.g., a front panel or face plate of the housing). In particular, an optical module cage  100  has a generally rectangular shape and includes panels  110  that extend a length of the cage and define sidewalls, a top wall and a bottom wall of the cage with a cavity or enclosure there between. The cage  100  is open at each of a first end or front end  112  and an opposing second end or rear end  114 , where the front end opening and rear end opening are each generally rectangular in shape. The cage  100  includes a plurality of flexible flanges  120  comprising thin plates that are located near the front end  112  and that extend transversely from each panel  110 . For simplification, airflow perforations are not shown in the cage or flange. However, it is noted that openings or perforations can be provided anywhere and in any configurations, sizes, patterns, etc. along any of the panels of the cage to facilitate cooling of an optical module inserted within the cage. 
     A front panel  150  for the housing of the electronic device is schematically depicted in  FIG.  1 B  and includes front plate or front wall  152  and a rear plate or rear wall  154 , where each of the front and rear walls includes a plurality of rectangular cut-outs or windows  160  that align with the windows  160  on the other plate so as to correspond when the two plates are brought together (as shown in  FIG.  1 C ). The windows  160  are further suitably dimensioned to receive and permit a portion of the optical module cage  100  including its front end  112  to extend through the front and rear walls  152 ,  154 . This structural configuration as depicted in  FIGS.  1 A- 1 C  facilitates a connection of the optical module cage  100  with the front panel  150  of the electronic device housing, where the flanges  120  of the cage are fit between the front wall  152  and the rear wall  154  so as to secure the cage  100  with the front panel  150  with a portion of the cage including the front end  112  extending beyond the front wall  152 . In this configuration shown in  FIG.  1 C , the front wall  152  defines an exterior surface of the front panel  150  through which a portion of the cage  100  including its front end  112  extends (thus permitting insertion of an optical module within the cage and connection with one or more circuit components within the housing of the device as described herein). 
     As shown in  FIGS.  1 B and  1 C , the front panel  150  of the electronic device housing can be configured so as to accommodate and support a plurality of optical module cages in any suitable grouping or array of cages in a stacked manner and/or a side-by-side manner. The term “stacked” as used herein refers to one optical module cage positioned in a location vertically above another cage, and the term “side-by-side” as used herein refers to two cages positioned horizontally adjacent to one another. It is to be understood that the terms above/below, upper/lower, top/bottom, horizontal/vertical, or front/rear as used herein are relative to the position of the cage in relation to the electronic housing and also cover other orientations of the cage. Thus, the terms are used only for ease of description and are not to be interpreted as limiting the arrangement of optical module cages. 
     For example,  FIG.  1 C  depicts a 2×1 arrangement of 2 cages (2 rows displaced from each other, each row including a single cage) along the front panel  150 . In the example embodiments of  FIGS.  2 A and  2 B , an arrangement of six optical cages are shown in which the front panel of the device housing can be constructed so as to accommodate such grouping of cages. In each of  FIGS.  2 A and  2 B , a chassis or housing including the front panel is depicted in phantom lines to show how the cages are arranged or aligned (horizontally and vertically) in relation to the alignment of the device housing. In  FIG.  2 A , the arrangement shows a 2×3 array of cages (i.e., 2 rows, each row including 3 cages). In  FIG.  2 B , the arrangement is rotated 90° to be a 3×2 array of cages (i.e., 3 rows, each row including 2 cages). In particular, the array of optical module cages depicted in  FIG.  2 A  is a horizontal arrangement in relation to the device housing, where the housing  180  includes a top panel  182 , a bottom panel  184  that opposes the top panel  182 , side panels  186  and  188  that oppose each other and extend between the top and bottom panels, a rear panel  189  that extends between the top and bottom panels, and a front panel  150 / 185  that opposes the rear panel and extends between the top and bottom panels. The cages  100  are disposed within windows of the front panel  150 / 185 . A lengthwise dimension of the rectangular opening at the front end  112  for each cage  100  generally corresponds or is parallel with the top panel  182  and the bottom panel  184  of the housing  180 . The array of optical module cages depicted in  FIG.  2 B  is a vertical arrangement in relation to the device housing, where the housing  190  includes a top panel  192 , a bottom panel  194  that opposes the top panel  192 , side panels  196  and  198  that oppose each other and extend between the top and bottom panels, a rear panel  199  that extends between the top and bottom panels, and a front panel  150 / 195  that opposes the rear panel and extends between the top and bottom panels. The cages  100  are disposed within windows of the front panel  150 / 195 . A lengthwise dimension of the rectangular opening at the front end  112  for each cage  100  transverses (e.g., is orthogonal with) the top panel  192  and the bottom panel  194  of the housing  190 . It is further noted that the front panel of the device housing can be constructed so as to receive any number of optical module cages in any arrangement (e.g., in a stacked or side-by-side arrangement, e.g., 2×1, 2×2, 2×3, etc.) as well as any orientations (horizontal or vertical) of the cages. 
     Referring to  FIG.  3 A , a pair of optical module cages  100  are schematically depicted, where each cage includes a module edge connector system  200  located at its rear end  114  and cables  250  that connect between the module edge connector system  200  and a circuit component  300  (e.g., an ASIC). When an optical module is fully inserted into the opening at the front end  112  of a cage  100 , the module includes engaging structure at its rear end that engages and connects with complementary engaging structure the module edge connector system  200  (e.g., engaging structure may utilize a via/pin combination and/or any other suitable connection mechanism to achieve a suitable connection) to facilitate transfer or exchange of signals (e.g., electrical signals, optical signals, or a combination of electrical and optical signals) between the optical module and the circuit component  300  via the edge connector system  200  and the cables  250 . 
     In other embodiments, such as shown in  FIGS.  3 B and  3 C , the optical module cages can connect directly, via a module edge connector system at the rear ends of the cages, to a circuit component (e.g., a pin field for an ASIC) or a PCB. Referring to  FIG.  3 B , all of the optical module cages  100  in a 2×3 array connect with a single PCB  350 . In the embodiment of  FIG.  3 C , each optical module cage  100  in the 2×3 array connect with an individual (separate) PCB  360 . While connection directly to a PCB is available utilizing the optical module cage connection structure (edge connector) as described herein (where the optical module cages connect directly to the front panel of the electronic device housing), such embodiments can result in reduced airflow around and through the cages due to their close alignment and connection with the PCB. A cable connection system, such as that depicted in  FIG.  3 A , facilitates a greater ability for airflow around the cages as well as the provision of heat sink structure or heat sink components on one or more sides of each cage as described in further detail herein. Utilization of a cable connection system also enables direct attachment of the cables with the module edge connector system as well as circuit components at a variety of different angles (e.g., at 90°, 180°, 45°, or 22° to 45°, thus providing more flexibility in arrangement of optical module cages as well as circuit components within the housing of the device. 
     In other example embodiments, the connection structure for the optical module cages is configured to connect with a front panel of the device housing that includes a single wall. Referring to  FIGS.  4 A and  4 B , an embodiment is depicted in which optical module cages  400  are connected to the front panel  450  of a chassis or housing of an electronic device. As described in further detail herein, each optical module cage  400  includes at its front end  412  flexible connecting structure that facilitates a connection of the cage at its front end within an opening or window  460  at the front panel  450 . Similar to the schematic depictions in  FIGS.  1 - 3   , each optical module cage  400  has a generally rectangular configuration and includes panels  410  that extend a length of the cage and define sidewalls, a top wall and a bottom wall of the cage with a cavity or enclosure there between, where each of a front end  412  and a rear end  414  of the cage includes an opening. The front end  412  of the cage, when connecting within an window  460  of the front panel  450 , extends beyond the exterior surface  452  of the front panel while the remaining portion of the cage extends beyond the interior surface  454  of the front panel such that the rear end  414  of the cage is floating or free of support (i.e., the cage extends from its front end to its second end in a cantilevered manner from the panel, with only the front end being connected to a panel of the housing). The interior of each cage  400  is further suitably dimensioned to receive and retain a portion of an optical module  500  that is inserted into the opening at the front end  412  of the cage. The opening at the rear end  414  of the cage  400  is configured to receive and couple with structure comprising an edge connector  470 , where the edge connector  470  includes an interior surface connector with suitable engaging structure that connects with complementary engaging structure at a rear end of an optical module inserted within the cage and an exterior surface that includes cables  475  that connect with a PCB or circuit component (e.g., an ASIC or other circuit component as schematically depicted in  FIG.  3 A ). As can be seen in the embodiment of  FIGS.  4 A and  4 B , the front panel  450  includes a plurality of apertures or perforations  455  that extend through the front panel and serve as air vents for the housing. 
     Referring to  FIGS.  4 C,  4 D and  4 E  (and also  FIG.  6 A ), each optical module cage  400  includes connecting structure  420  at its front end  412  that facilitates a connection between the cage and the front panel  450  within a corresponding window  460 . The connecting structure comprises a row of flexible front flanges or front fingers  422  disposed along and extending transversely from each panel  410  at the front end  412  and also a row of flexible rear flanges or rear fingers  424  disposed directly behind the row of front fingers  422  (i.e., between the front fingers  422  and the rear end  414  of the cage  400 ) and also along and extending transversely from each panel  410 . The front fingers  422  can have a slightly angled profile and a sufficient flexibility that allows the front flanges to slightly flex or bend when the front end  412  of the optical module cage  400  is inserted through an window  460  (e.g., at the interior surface  454 ) of the front panel  450 . Each cage  400  secures to the front panel  450  at a corresponding window  460  with the row of front fingers  422  extending slightly beyond and engaging with the exterior surface  452  while the row of rear fingers  424  extend slightly beyond and engage with the interior surface  454 . This allows for a snap-in type of securing connection between each optical module cage  400  at its front end  412  and the front panel  450  of the device housing, with the rear end  414  of the cage floating such that the cage is cantilevered in relation to the front panel (i.e., the cage is secured to the housing only at the front panel). 
     The front fingers  422  and the rear fingers  424  can be constructed of any suitable materials meeting EMC/EMI (electromagnetic interference/electromagnetic compatibility) compliance for the device and its environment of use. It is noted that any other suitable connection structure can also be provided at the front end of each optical module cage to facilitate securing of the cage to the front panel of the device housing. For example, in an alternative example embodiment, one or more cages can be connected with the front panel via flanges and threaded fasteners (e.g., screws). 
     An optical module  500  is depicted in  FIG.  5 A  prior to insertion/installation within the enclosure of a cage  400  at its front end  412 . As previously noted herein, the optical module can have any suitable optical form factor that corresponds with the cage and cable connector structure couple with the cage, including, without limitation, form factors such as SFP, QSFP, OSFP, CFP, CFP2, CFP8, QSFP-DD. The optical module  500  has a generally rectangular shape that corresponds with the cage enclosure and includes a front end  512  that can include a handle  520  or any other suitable structure that facilitates ease of insertion and removal of the module from the cage. A rear end  514  of the optical module  500  is inserted into the opening at the cage front end  412 . The module rear end  514  includes engaging structure that connects with the interior surface engaging structure of the edge connector  470  coupled with the cage  400  at its rear end  414  to facilitate transfer or exchange of signals (e.g., electrical signals, optical signals, or a combination of electrical and optical signals) between the optical module  500  and the edge connector  470  (where the edge connector  470  transfers such signals, via cables  475 , to one or more circuit components and/or a PCB within the device housing). 
     Referring to  FIGS.  5 B,  5 C,  5 D and  5 E , the edge connector  470  with cables  475  can be constructed so as to include locking or mechanical connection structure at a forward end  472  of the edge connector, where the connection structure at the forward end  472  corresponds with complementary connection structure at the rear end  414  of the cage  400 . The rear end  474  of the end connector  470  includes the cables  475  extending therefrom and which extend to connect with one or more circuit components and/or PCBs within the device housing. The forward end  472  of the edge connector  470  includes suitable engaging structure that facilitate a connection with complementary engaging structure at the rear end  514  of the optical module  500  to enable transfer of signals (optical and/or electrical signals) therebetween. 
     In an example embodiment, the connection structure at the corresponding ends of the edge connector and the cage facilitates a frictional locking connection or a snap-tight locking engagement in which one or more tabs of the connection structure for the edge connector engage and lock with complementary grooves or notches at the rear end of the cage. As best shown in  FIG.  5 E  (an enlarged cross-sectional view at the rear end  414  of the cage), the forward end  472  of the edge connector  470  includes a flexure arm  480  that is cantilevered from the main body of the edge connector. The flexure arm  480  includes a forward aligned tab  482  and a rearward aligned raised member or stop member  484  (located at the terminal, free end of the flexure arm). The top wall or panel  410  of the cage  400  includes a groove, notch or slot  415  near the rear end  414  of the cage that is suitably aligned and dimensioned to receive the tab  482  of the flexure arm  480  when the edge connector  470  is inserted into the opening at the rear end  414 . Upon full insertion of a portion of the edge connector  470  including its forward end  472  into the opening of the cage  400  at its rear end  414 , the flexure arm  480  is slightly depressed allowing tab  482  to slide and fit within the slot  415  of the top wall or panel  410  of the cage and stop member  484  abuts a portion of the rear end  414  of the cage thus achieving the snap-tight locking engagement and preventing further inward movement as well as outward movement of the edge connector in relation to the cage. Release of the locking engagement and removal of the edge connector  470  from the cage  400  is also easily facilitated by pressing the flexure arm  480  (e.g., via the stop member  484  exposed at the rear end  414  of the cage) so as to release the tab  482  from its locking engagement with the slot  415  and allowing the edge connector to be removed from the cage. As further shown in  FIGS.  5 D and  5 E , the edge connector  470  includes a pair of flexure arms  480  that correspond with top wall and bottom walls or opposing panels  410  of the cage  400  (each of which includes a corresponding groove or slot  415 ), where operation of each flexure arm operates in the same or similar manner to provide a releasable snap-tight locking engagement with the cage. 
     It is noted that the snap-tight releasable locking engagement between the edge connector and the cage as depicted in  FIGS.  5 B- 5 E  is an example embodiment and the optical module cage system and apparatus as described herein are not limited to such embodiment (i.e., other structural configurations that facilitate a suitable engagement between cage and edge connector may also be implemented). Providing a releasable locking engagement between the optical module cage at its rear end and the edge connector facilitates ease of changing the edge connector based upon different modules being inserted within the cages. 
     The connection of optical module cages with the front panel (or any other wall or panel) of the chassis or housing of an electronic device facilitates orientations of the cages in any configurations (e.g., horizontal or vertical) and arrays along the housing panel. For example, as noted herein and as shown schematically in  FIG.  2 B , the cages can be vertically oriented along a front panel of the device housing (i.e., where each cage is oriented along the front panel such that the rectangular opening at its front end has a lengthwise dimension that is transverse the top and bottom walls or panels of the device housing), and this can allow for a larger number and/or density of cages while also permitting adequate airflow (for cooling purposes) along the panels at each side of the cages. Such configurations of cages can also allow for heat sink components to be provided along two or more panels (i.e., along two or more sides) of one or more cages in an array. 
     For example, referring to  FIGS.  6 A and  6 B , an optical module cage  400  is depicted in isolation (exploded view in  FIG.  6 B ) where heat sink components are provided along two opposing panels  410  of the cage. In particular, each heat sink component comprises a base plate  605  that secures to a panel  410  of the cage  400 , where a plurality of cooling fins  610  that extend transversely from the base plate  605 . The base plate and cooling fins can comprise a metal and/or other material having suitable heat transfer properties (e.g., aluminum or copper) that facilitate transfer of heat generated by an optical module within the cage so as to adequately cool and prevent undesirable heating of the optical module during use. Each heat sink component further includes a clamp member or clip  620  that affixes the base plate  605  to a corresponding panel  410  of the cage  400 . This configuration allows for the placement of heat sinks including cooling fins along at least two sides or panels of the optical module cage. In some embodiments, heat sink structure including cooling fins (e.g., of the type depicted in  FIGS.  6 A and  6 B ) can be provided along any number of sides or panels (e.g., along one panel, along two panels, along three or even all four panels) of the optical module cage to enhance heat transfer and cooling of the cage and optical module disposed within the cage. 
     The connecting structure  420  of the cages  400  provides an adequate connection and support of optical cages with the front panel (or any other panel) of the device housing in any arrangements and arrays, in which the front ends of the cages are connected to the panel while the opposing or rear end of each cage is floating or free (i.e., not connected to any support structure). In addition, further structural support for the cages can also be provided utilizing bridging spacers comprising support columns or support posts extending between cages in the same row and/or in neighboring rows in an array of cages. Referring to  FIGS.  7 A,  7 B,  7 C and  7 D , interconnecting spacers or spacing structure  700  is provided that connects support columns or support posts between cages in an array. Support columns or support posts  710  are provided that extend between and connect with closely neighboring cages  400  from different rows. In addition, the spacing structure  700  includes support columns or support posts  720  that extend between and connect with consecutively aligned cages in the same row. 
     For example, in a 2×2 array of cages as shown in  FIG.  7 A  (2 rows of cages, with 2 cages in each row), a support post  710  extends from a panel  410  of each cage  400  in the first row to a panel  410  of a cage  400  in the second row that is directly aligned with the cage in the first row. The support post  710  includes a foot  715  at each of its lengthwise ends. Each foot  715  includes a pair of base rails  716  extending outward from the foot end and a central rail  718  disposed between the base rails  716 . Each cage  400  includes a track member  750  disposed along one or more panels  410  at a location near the rear end  414 , where the track member  750  comprises a pair of flanges spaced a small distance from each other and extending transversely from the panel  410  at an angle toward the other flange so as to define a narrow track therebetween for receipt of the central rail  718  of the support post  710 . As shown in  FIGS.  7 C and  7 D , the support post  710  is guided along the facing panels  410  of the two aligned cages  400  in the first and second rows such that the central rail  718  slides within the track defined between the flanges of the track member  750 , thus connecting the end of the support post  710  to the panel  410  of each of the two aligned cages  400  in rows 1 and 2. The support posts  720  and cages  400  include the same or similar structure that facilitates a bridging connection between the two cages consecutively aligned in the first row and between the two cages consecutively aligned in the second row. 
     Thus, the spacers or support posts can be easily aligned and slid or snap-fit into place for providing bridging interconnections between optical module cages located in the same row as well as in different rows. The spacers/support posts can be formed of metal, plastic and/or any other suitably rigid material that provides support and stability for the cages. While the embodiments in the drawings show only a single support post connecting each pair of neighboring cages together at or near the rear end (i.e., free or floating end) of each cage, it is noted that any number of support posts (e.g., one, two or more) can be provided along the same facing sides or panels of two or more aligned and closely neighboring cages to enhance support and stability of the cages in addition to the connection at their front ends with the front panel of the device housing. In addition, the spacers/support posts can have any other suitable geometries and/or any suitable mechanical connection structure that facilitates a bridging contact and connection between neighboring cages in the same row and also in separate, consecutively aligned rows. The spacers/support posts can further be shaped to minimize airflow impact around the cages. 
     The embodiments described herein facilitate a frictional or snap-in/snap-tight attachment or connection of optical module cages to a wall or panel (e.g., front panel) of the chassis or housing of an electronic device, where the cages can be suitably spaced from each other in any selected type of array that achieves a space saving for the housing, including space saving along the PCB within the housing (since the cages are not connected with and/or supported by the PCB). The configuration of the edge connector, also which can be frictionally or snap-in/snap-tight connected with the cages and can include cabling, also enable a space saving for components within the housing (e.g., since the cables can facilitate connections at a variety of different angles between optical modules housed within the cages and circuit components within the housing). 
     The ease with which cages, as well as optical modules within the cages, can be inserted/assembled and removed/disassembled, provides a modular design that facilitates ease of replacement or reconfiguration of device components within a housing. For example, in some embodiments, optical modules and their corresponding cages can be removed from the front plate and replaced by other components, such as a front replaceable fan tray that can improve air flow and cooling of the PCB, ASIC and/or one or more other circuit components within the device housing. This can facilitate non-heated air (e.g., air from the ambient environment directly surrounding the housing instead of air flowing around optical modules) to flow directly to the ASIC or other component within the housing. 
     In conventional optical module cage configurations, the optical modules and cages are oriented horizontally in relation to the housing. In this conventional configuration, it is typically very difficult to stack several modules without experiencing a negative impact on operational temperatures for the modules and/or for other components within the device housing. In contrast, and as described herein (e.g., with reference to  FIG.  2 B ), an array of cages and optical modules can be arranged vertically in relation to the housing, which facilitates an increase in port density (e.g., as up to about 20% for a 1 RU form factor, where number of ports can be increased from 32 to 38) with minimal thermal impact and while maintaining operational temperatures for the device within tolerance levels. 
     The vertical orientation of cages and modules also facilitates greater flexibility in the face plate/front panel design, allowing for slanted or angled panel designs without the requirement of modified heatsink fin designs for the cages. The connection configurations for the cages with the front panel further allow for enhanced airflow rates around the cages and a resultant reduction in optical module temperatures even at lower air flow approach velocities around the cages during device operations. 
     As shown in  FIG.  8   , an example embodiment shows the operational temperature distribution of a vertically stacked arrangement of two optical modules disposed within two cages  400 . The data provided in  FIG.  8    shows that the temperature distribution is about the same for both modules in the vertically stacked cages  400  (i.e., almost no skewness between the two vertically stacked modules). In contrast, in a conventional horizontal design, temperatures may different by more than 10° C. between two consecutive horizontally aligned modules. 
     Thus, the embodiments described herein provide an optical module cage mounting configuration that are modular in design and can be independent of a printed circuit board mounting system. The cages and their connections with a panel of the electronic device housing enable improved density, cooling, mounting, and/or signal integrity for a variety of applications. 
     Optical module cages described herein may be located within a line card, fabric card, or other modular card or fixed design. The embodiments operate in the context of a data communications network including multiple network devices. The network may include any number of network devices in communication via any number of nodes (e.g., routers, switches, gateways, controllers, access points, or other network devices), which facilitate passage of data within the network. The network devices may communicate over or be in communication with one or more networks (e.g., local area network (LAN), metropolitan area network (MAN), wide area network (WAN), virtual private network (VPN) (e.g., Ethernet virtual private network (EVPN), layer 2 virtual private network (L2VPN)), virtual local area network (VLAN), wireless network, enterprise network, corporate network, data center, Internet of Things (IoT), Internet, intranet, or any other network). The network may include any number or arrangement of network communications devices (e.g., switches, access points, routers, or other devices operable to route (switch, forward) data communications). 
     The optical modules are coupled to electronic components, which may be operable to interface telecommunication lines (e.g., copper wire, optical fibers) in a telecommunications network. The network device may be configured to perform one or more operations and receive any number or type of pluggable transceiver modules configured for transmitting and receiving signals, and may be configured for operation in any type of chassis or network device (e.g., router, switch, gateway, controller, edge device, access device, aggregation device, core node, intermediate node, or other network device). 
     The network device may be a programmable machine that may be implemented in hardware, software, or any combination thereof. The network device includes one or more processor, memory, and network interfaces. Memory may be a volatile memory or non-volatile storage, which stores various applications, operating systems, modules, and data for execution and use by the processor. Logic may be encoded in one or more tangible media for execution by the processor. For example, the processor may execute codes stored in a computer-readable medium such as memory. The computer-readable medium may be, for example, electronic (e.g., RAM (random access memory), ROM (read-only memory), EPROM (erasable programmable read-only memory)), magnetic, optical (e.g., CD, DVD), electromagnetic, semiconductor technology, or any other suitable medium. The network device may include any number of processors. In one example, the computer-readable medium comprises a non-transitory computer-readable medium. The network interfaces may comprise any number of interfaces (line cards, ports) for receiving data or transmitting data to other devices. The network interfaces may be configured to transmit or receive data using a variety of different communication protocols. The interfaces may include mechanical, electrical, and signaling circuitry for communicating data over physical links coupled to the network. The network device may further include any suitable combination of hardware, software, processors, devices, components, or elements operable to facilitate the capabilities described herein. 
     Thus, an example embodiment of an apparatus comprises a housing including a panel, where the panel includes a window, and a cage including a plurality of panels and a first end and a second end that opposes the first end, the cage including an opening at its first end and an enclosure disposed between the panels of the cage. The apparatus further comprises connecting structure disposed at the first end of the cage, where the connecting structure secures the first end of the cage to the panel. The cage is suitably dimensioned to receive and retain a portion of an optical module within the enclosure when the optical module is inserted within the opening at the first end of the cage. 
     The cage can extend from the first end to the second end in a cantilevered manner from the panel. 
     The apparatus can further comprise an edge connector disposed at the second end of the cage, where the edge connector includes engaging structure that enables an exchange of signals between the optical module and a circuit component within the housing. The edge connector can be releasably connected with the second end of the cage via a frictional locking connection. 
     The edge connector can directly connect with the circuit component disposed on a printed circuit board (PCB). The apparatus can also comprise a plurality of cables connected with edge connector, where the cables are dimensioned to extend to and connect with the circuit component within the housing to enable the exchange of signals between the optical module and the circuit component. 
     The housing can include a top panel, a bottom panel opposing the top panel, and a front panel extending between the top panel and the bottom panel, the front panel including a plurality of windows arranged in an array along the front panel. The apparatus can also further comprise a plurality of cages, each cage including a first end and a second end and an opening at the first end, where connecting structure disposed at the first end of each cage secures the first end of each cage to the panel at a corresponding one of the plurality of windows. A lengthwise dimension of the opening at the first end of each cage can be oriented vertically such that the lengthwise dimension is transverse an orientation of each of the top panel and the bottom panel. 
     The apparatus can further comprise at least one support post that extends and provides a bridging connection between at least two cages secured to the front panel. The at least one support post can comprise a plurality of support posts, the plurality of support posts including a first support post that connects a first cage secured to the front panel with a second cage secured to the front panel, where the first and second cages are located at windows arranged in a first row of windows along the panel, and a second support post that connects the first cage with a third cage secured to the front panel, where the third cage is located at a window arranged along a second row of windows that is displaced from the first row of windows. 
     The apparatus can further comprise a plurality of heat sink components coupled with the cage, each heat sink component comprising a plurality of cooling fins extending transversely from at least two panels of the cage. 
     An electronic device can comprise the apparatus as described herein, where the panel comprises a front panel for the housing. 
     In other example embodiments, a cage comprises a plurality of panels that define an enclosure between the panels, a first end including an opening, a second end that opposes the first end, and connecting structure disposed at the first end of the cage, where the connecting structure secures the first end of the cage to a panel of a housing. The cage can be suitably dimensioned to receive and retain a portion of an optical module within the enclosure when the optical module is inserted within the opening at the first end of the cage. 
     The cage can further comprise an edge connector disposed at the second end of the cage, where the edge connector includes engaging structure that enables an exchange of signals between the optical module and a circuit component within the housing. 
     The cage can also further comprise a plurality of cables connected with edge connector, where the cables are dimensioned to extend to and connect with the circuit component within the housing to enable the exchange of signals between the optical module and the circuit component. 
     In further example embodiments, a method comprises providing a cage including a plurality of panels that define an enclosure between the panels, a first end including an opening, and a second end that opposes the first end, facilitating a connection, via connecting structure disposed at the first end of the cage, between the first end of the cage and a panel of a housing for an electronic device such that the cage extends from the first end to the second end in a cantilevered manner from the panel, and facilitating insertion of an optical module into the opening at the first and end into the enclosure of the cage such that the optical module engages with an edge connector disposed at the second end of the cage, where the edge connector includes engaging structure that enables an exchange of signals between the optical module and a circuit component within the housing. 
     The method can further comprise facilitating a direct connection between the edge connector and the circuit component within the housing. The method can also further comprise providing cables that connect with the edge connector and are dimensioned to extend to and connect with the circuit component within the housing to enable the exchange of signals between the optical module and the circuit component. 
     In the method, the housing can include a top panel, a bottom panel opposing the top panel, and a front panel extending between the top panel and the bottom panel, the front panel including a plurality of windows arranged in an array along the front panel. The method can further comprise facilitating connection of a plurality of cages, each cage including a first end and a second end and an opening at the first end, with the front panel, where each cage connects at the first end of each cage to the panel at a corresponding one of the plurality of windows. A lengthwise dimension of the opening at the first end of each cage can be oriented vertically such that each cage connects with the front panel and the lengthwise dimension of each cage is transverse an orientation of each of the top panel and the bottom panel. 
     The above description is intended by way of example only. The descriptions of the various embodiments have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.