Patent Publication Number: US-2023161118-A1

Title: Stackable optical ferrule and connector using same

Description:
TECHNICAL FIELD 
     This disclosure relates generally to optical connector assemblies and methods related to optical connector assemblies. 
     BACKGROUND 
     Optical connectors can be used for optical communications in a variety of applications including telecommunications networks, local area networks, data center links, and internal links in computer devices. There is interest in extending optical communication to applications inside smaller consumer electronic appliances such as laptops and even cell phones. Expanded optical beams may be used in connectors for these systems to provide an optical connection that is less sensitive to dust and other forms of contamination and so that alignment tolerances may be relaxed. Generally, an expanded beam is a beam that is larger in diameter than the core of an associated optical waveguide (usually an optical fiber). The connector is generally considered an expanded beam connector if there is an expanded beam at a connection point. The expanded beam is typically obtained by diverging a light beam from a source or optical fiber. In many cases, the diverging beam is processed by optical elements such as a lens or mirror into an expanded beam that is approximately collimated. The expanded beam is then received by another waveguide after focusing of the beam via another lens or mirror. 
     BRIEF SUMMARY 
     Embodiments described herein are directed to optical ferrules, connector assemblies using the optical ferrules, and method of making the optical ferrules. In one embodiment, an optical ferrule includes an optical coupling member that includes one or more light redirecting elements configured to redirect input light from a waveguide attached to the optical coupling member toward an output window of the optical coupling member. The optical coupling member has a mating surface that includes the output window. The mating surface is configured to slidably mate with a mating surface of a mating optical coupling member along a longitudinal axis of the optical ferrule. The optical ferrule also includes at least one stacking member along a longitudinal edge of the optical coupling member. The at least one stacking member has a distal end extending beyond one of the mating surface and a top surface opposed to the mating surface. The stacking member also has a contact surface opposed to the distal end. The contact surface is configured to rotatably interface with a corresponding distal end of a corresponding stacking support member of an adjacently stacked optical ferrule. 
     In some configurations, the contact surface is further configured to slidably interface with the corresponding distal end of the corresponding stacking support member. The at least one stacking member may include first and second stacking members respectively located along opposing longitudinal edges of the optical coupling member. In such an embodiment the first and second stacking members may be mirror images of one another, and the first and second stacking members may optionally align the optical ferrule in a side-to-side direction with a corresponding optical coupling member of the adjacently stacked optical ferrule. 
     In other configurations, the contact surface may include a flat surface or a curved surface. The stacking member may include a triangular shape, a vertex of the triangular shape corresponding to the distal end. The contact surface and the corresponding distal end may include a groove and a ridge. In such a case, the ridge fits into the groove in an unmated configuration of the optical ferrule and the adjacently stacked optical ferrule. The ridge and the groove align the optical ferrule and the adjacently stacked optical ferrule in a side-to-side direction. 
     In some configurations, the distal end extends beyond the mating surface and the contact surface may be recessed below the top surface of the optical coupling member. Alternatively, the distal end may extend beyond the mating surface and the contact surface may extend beyond the top surface of the optical coupling member. Or, the distal end may extend beyond the top surface and the contact surface may be recessed below the mating surface of the optical coupling member. 
     In one configuration, the optical ferrule and the adjacently stacked optical ferrule are part of a first connector and configured to optically interface with respective first and second stacked mating optical ferrules of a second connector in a mated configuration,. In such a case, the contact surface is separated from the corresponding distal end of the corresponding stacking support member in the mated configuration. The stacking members of the optical ferrule and the adjacently stacked optical ferrule of the first connector may include stop surfaces that contact with corresponding stop surfaces of first and second stacking support members of the first and second stacked optical ferrules of the first connector in the mated configuration. 
     In another embodiment, an optical ferrule includes an optical coupling member having one or more light redirecting elements configured to redirect input light toward an output window of the optical coupling member. The optical coupling member has a mating surface that includes the output window. The mating surface configured to slidably mate with a mating surface of a mating optical coupling member along a longitudinal axis of the optical ferrule. First and second extensions are on opposed longitudinal edges of the optical coupling member, the first and second extensions extending beyond at least one of the mating surface and a top surface opposed to the mating surface. A first contact surface is on the first extension. The first contact surface is configured to slidably interface with an extension of a corresponding stacking support member of an adjacently stacked optical ferrule. 
     In some configurations, the optical ferrule may further include a second contact surface on the second extension. The second contact surface is configured to slidably interface with another extension of the corresponding stacking support member. In some configurations, the first and second extensions may be mirror images of one another, and/or the first contact surface may include a flat surface or a curved surface. 
     In some configurations, the extension may include a triangular shape. A vertex of the triangular shape slidably interfaces with a contact surface of a second adjacently stacked optical ferrule. In other configurations, the first contact surface may be recessed below a top surface of the optical coupling member, the top surface being opposed to the mating surface. 
     In some embodiments, the optical ferrule and the adjacently stacked optical ferrule may be part of a first connector and are configured to optically interface with respective first and second stacked mating optical ferrules of a second connector in a mated configuration. The first contact surface is separated from the corresponding distal end of the corresponding stacking support member in the mated configuration. The stacking support members of the optical ferrule and the adjacently stacked optical ferrule of the first connector may include stop surfaces that contact with corresponding stop surfaces of first and second stacking support members of the first and second stacked optical ferrules of the first connector in the mated configuration. 
     In another embodiment, a connector includes a housing and at least one column of one or more adjacent optical cable assemblies disposed in the housing. Each set of optical cable subassemblies includes at least two optical cable subassemblies. Each optical cable subassembly includes an optical ferrule with an optical coupling member. The optical coupling member includes one or more light redirecting elements configured to redirect input light toward an output window of the optical coupling member. The optical coupling member also has a mating surface that includes the output window. The mating surface is configured to slidably mate with a mating surface of a mating optical coupling member along a longitudinal axis of the optical ferrule. The optical ferrule further includes at least one extension along a longitudinal edge of the optical coupling member. The extension includes a distal end extending beyond the mating surface and a contact surface opposed to the distal end. The contact surface is configured to rotatably interface with a corresponding distal end of a corresponding extension of an adjacently stacked optical ferrule. Each optical cable subassembly further includes one or more optical waveguides attached to the optical ferrule. In an unmated configuration of the connector, the distal end of a first optical cable subassembly of the at least one column rotatably interfaces with the contact surface of a second optical cable subassembly of the at least one column. 
     In one configuration, the distal end of the first optical cable subassembly may slidably interface with the contact surface of the second optical cable subassembly. The distal end of the extension of only a selected one of the optical ferrules of the at least one column may interface with a ferrule support attached to or integral with the connector housing. The optical ferrules of the column may be unsupported by the housing except for the selected optical ferrule. The one or more optical waveguides in the cable assemblies may apply spring forces to the respective optical ferrules. The spring forces hold the distal end of the first optical cable subassembly against the contact surface of the second optical cable subassembly and further hold the extension of selected optical ferrule against the ferrule support. In a mated configuration, the spring forces may be applied between the mating surfaces of the at least one column with corresponding mating surfaces of a column of mating optical cable assemblies such that the extension of the first optical cable subassembly is separated from the contact surface of the second optical cable subassembly and the extension of the selected optical ferrule is separated from the ferrule support. 
     In another embodiment, a connector includes a housing having at least one support extending respectively from at least one of first and second interior walls of the housing. Two or more optical cables assemblies are stacked between the first and second interior walls. Each of the two or more optical cable subassemblies include one or more optical waveguides and an optical ferrule having one or more light redirecting elements configured to redirect input light toward an output window of the optical coupling member. The optical ferrule has a mating surface that includes the output window. The mating surface is configured to slidably mate with a mating surface of a mating optical coupling member along a longitudinal axis of the optical ferrule. An extension is located along a longitudinal edge of the optical ferrule and extends beyond the mating surface. A contact surface is located along the longitudinal edge. The extension of a first of the two or more optical cable assemblies slidably interfaces with the contact surface of a second of the two or more optical cable assemblies. The extension of the second optical cable subassembly slidably interfaces with the at least one support of the housing. 
     In some configurations, the distal end of the first optical cable subassembly may rotatably interface with the contact surface of the second optical cable subassembly. The two or more optical cable assemblies are unsupported by the at least one support except for the first optical cable subassembly. The one or more optical waveguides may apply spring forces to the respective optical ferrules. The spring forces may hold the extension of the first optical cable subassembly against the contact surface of the second optical cable subassembly and further hold the extension of second optical cable subassembly against the at least one support. In a mated configuration, the spring forces may be applied between the mating surfaces of the two or more optical cable assemblies with corresponding mating surfaces of mating optical cable assemblies such that the extension of the first optical cable subassembly is separated from the contact surface of the second optical cable subassembly and the extension of the selected optical ferrule is separated from at least one support. 
     In another embodiment, a connector includes a housing and two or more columns of optical cable assemblies located side-by-side within the housing. Each optical cable subassembly includes an optical ferrule with an optical coupling member that has one or more light redirecting elements configured to redirect input light toward an output window of the optical coupling member. The optical coupling member has a mating surface that includes the output window. The mating surface is configured to slidably mate with a mating surface of a mating optical coupling member along a longitudinal axis of the optical ferrule. The optical ferrule includes at least one extension along a longitudinal edge of the optical coupling member. The at least one extension extends beyond the mating surface. The optical ferrule includes a contact surface opposed to the at least one extension. The contact surface is configured to rotatably interface with a corresponding extension of an adjacently stacked optical ferrule. One or more optical waveguides are attached to the optical ferrule. The extension of a first optical cable subassembly of each column slidably interfaces with the contact surface of a second optical cable subassembly of each column. 
     In some configurations, the extension of only a selected one optical ferrule of each column may interface with a ferrule support attached to or integral with the connector housing. The optical ferrules of the two or more columns may be unsupported by the housing except for the selected optical ferrules of each column. For each column, the one or more optical waveguides in the cable assemblies may apply spring forces to the respective optical ferrules. The spring forces hold the distal end of the first optical cable subassembly against the contact surface of the second optical cable subassembly and further hold the extension of selected optical ferrule against the ferrule support. In a mated configuration, the spring forces may be applied between the mating surfaces of each column with corresponding mating surfaces of corresponding columns of mating optical cable assemblies such that, for each column, the extension of the first optical cable subassembly is separated from the contact surface of the second optical cable subassembly and the extension of the selected optical ferrule is separated from the ferrule support. 
     In some configurations, the housing may further include one or more inner sidewalls separating the two or more columns of optical cable assemblies, the one or more inner sidewalls limiting side-to-side movement of the two or more columns within the housing. The connector may include one or more side supports separating the two or more columns of optical cable assemblies. The one or more side supports limit side-to-side movement within the housing of at least one optical ferrule within each of the two or more columns. 
     In another embodiment, a molded, unitary, optical ferrule includes at least one stacking member along a longitudinal edge of the optical ferrule and one or more parting line artifacts. The one or more parting line artifacts include a parting line artifact extending substantially around an external perimeter of the optical ferrule. The parting line artifacts divide a surface of the optical ferrule into a first section along a first direction of a thickness axis and an opposing second section along a second direction of the thickness axis. The first section includes a contact surface of the stacking member, one or more elements configured to receive and secure an optical waveguide, and one or more elements configured to redirect input light within the unitary optical ferrule. The second section includes at least one output window configured to transmit the redirected light out of a mating surface and a distal end of the stacking member extending beyond the mating surface. The distal end is configured to interface with a corresponding contact surface of a corresponding optical ferrule. 
     In some configurations, at least part of the parting artifact may extend along an intersection between the mating surface and the longitudinal edge. The stacking member may include first and second stacking members respectively located along opposing longitudinal edges of the optical coupling member. The first and second stacking members may be mirror images of one another. The contact surface may include a flat surface or a curved surface. The stacking member may have a triangular shape, a vertex of the triangular shape configured to interface with the corresponding contact surface. The contact surface may be recessed below a top surface of the optical coupling member, the top surface opposed to the mating surface. 
     In another embodiment, a mold is operable to injection mold a unitary, optical ferrule. The mold has a first part configured to form: a contact surface of a stacking member of the unitary, optical ferrule; one or more elements of the unitary, optical ferrule configured to receive and secure an optical waveguide; and one or more elements of the unitary, optical ferrule configured to redirect input light within the unitary optical ferrule. The mold includes a second part configured to form: at least one output window of the unitary, optical ferrule configured to transmit the redirected light out of a mating surface of the unitary, optical ferrule; and a distal end of the stacking member extending beyond the mating surface. The distal end is configured to interface with a corresponding contact surface of a corresponding optical ferrule. Respective first and second surfaces of the first and second parts form one or more parting line artifacts. The one or more parting line artifacts including a parting line artifact extending substantially around an external perimeter of the unitary optical ferrule. At least part of the parting artifact may extend along an intersection between the mating surface and the longitudinal edge. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS.  1  and  2    are perspective views of an optical cable subassembly in accordance with some embodiments; 
         FIG.  3    is a front view of a connector according to an example embodiment; 
         FIG.  4    is a side view of mating columns of optical cable subassemblies in an unmated configuration according to an example embodiment; 
         FIGS.  5  and  6    are side views of a connector according to an example embodiment; 
         FIG.  7    is a side view of mating columns of optical cable subassemblies in a mated configuration according to an example embodiment; 
         FIG.  8    is a side view of mating optical ferrules in an unmated configuration according to another example embodiment; 
         FIG.  9    is a side view of the ferrules of  FIG.  8    in a mated configuration; 
         FIG.  10    is a side view of mating optical ferrules in an unmated configuration according to another example embodiment; 
         FIG.  11    is a side view of the ferrules of  FIG.  10    in a mated configuration; 
         FIGS.  12  and  13    are front views of optical ferrules showing alignment features according to other example embodiments; 
         FIG.  14    is a front view of a multiple-column optical connector according to an example embodiment; 
         FIG.  15    is a front view of a multiple-column optical connector according to another example embodiment; 
         FIGS.  16  and  17    are cross-sectional views of mold parts and molding artifacts according to an example embodiment; 
         FIG.  18    is a side view of a unitary, molded, optical ferrule according to an example embodiment; 
         FIGS.  19  and  20    are cross-sectional views of molds used to form ferrules according to example embodiments; 
         FIGS.  21  and  22    are perspective views of ferrules according to another example embodiment in unmated and mated configurations; and 
         FIGS.  23  and  24    are perspective views of ferrules according to another example embodiment in unmated and mated configurations. 
     
    
    
     The figures are not necessarily to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number. 
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Embodiments described herein involve optical cable subassemblies, optical connectors and related methods. Optical cables and connectors used in many applications may make use of one waveguide or arrays of multiple parallel waveguides (e.g., 4, 8 or 12 or more parallel waveguides). The individual waveguides are typically optical fibers made of glass with a protective buffer coating, and the parallel buffered fibers are enclosed by a jacket. Optical connectors are useful for connecting optical waveguides to optical waveguides, or waveguides to optoelectronic components, for in-line interconnects and/or printed circuit board (PCB) connections, e.g., backplane, frontplane, or midplane connections. 
     One type of connector is an expanded beam connector, in which light is coupled between waveguides in a beam that is larger in diameter than the core of an associated optical waveguide and, in the case of waveguide arrays, typically somewhat less than the waveguide-to-waveguide pitch. The waveguides may comprise optical fibers, e.g., single-mode fibers or multi-mode fibers for fiber optic communication systems. These expanded beam optical connectors can have non-contact optical coupling and can provide effective optical coupling with relaxed connector-to-connector mechanical alignment precision when compared with other types of optical connectors, such as physical contact connectors. 
       FIG.  1    shows an optical cable subassembly  100  in accordance with some embodiments. The optical cable subassembly  100  includes one or more optical waveguides  110  (shown here as optical fibers) and an optical ferrule  102  (also sometimes referred to as an optical coupling unit). The illustrated optical waveguide  110  includes at least one core with a cladding, wherein the core and cladding are configured propagate light within the core, e.g., by total internal reflection. The optical waveguide  110  may be, for example, a single or multi-mode waveguide, a single core fiber, a multi-core optical fiber, or a polymeric waveguide. The waveguide may have any suitable cross-sectional shape, e.g., circular, square, rectangular etc. 
     The optical ferrule  102  is configured to mate, e.g., hermaphroditically, with another optical ferrule. The optical ferrule  102  illustrated in  FIG.  1    includes an optical coupling member  106  generally configured to redirect light input from the optical waveguide  110 . The optical coupling member  106  includes a light-redirecting element  108  which may be configured as one or more optical components (e.g., mirrors, prisms, lenses, etc.) formed within the optical coupling member  106 . The light-redirecting element  108  redirects the light from the optical waveguide  110  to a mating surface  106   a  of the optical coupling member  106  that includes an output window (see  FIG.  2   ). The mating surface  106   a  is opposed to a top surface  106   c  of the optical coupling member  106 . 
     A mechanical mating tongue  104  extends from (and may be integral to) the optical coupling member  106 . The mating tongue  104  aligns the optical ferrule  102  with a corresponding mechanical mating tongue of a mating optical ferrule (not shown in  FIG.  1   ). As will be described in greater detail below, the mating optical ferrule includes a corresponding mating surface that facilitates mechanical and optical coupling with the mating surface  106   a  in a mated configuration of the optical ferrules. The mating surface  106   a  is configured to slidably contact the corresponding mating surface along a longitudinal direction  114  of the optical ferrule  102 . Generally, the mating optical ferrule is longitudinally aligned with and inverted in orientation relative to the illustrated optical ferrule  102  such that the corresponding mating surface of the mating optical ferrule faces towards the mating surface  106   a . In some embodiments, the mating tongue  104  can have a tapering width along at least a portion of a length of the tongue portion as shown in the illustrations. The mating tongue  104  can extend towards or outwardly from a front of a connector housing (not shown in  FIG.  1   ). 
     The optical coupling member  106  includes an attachment area  112  with plurality of grooves. In the illustrated embodiment, the grooves  112   a  within the attachment area  112  are aligned in the longitudinal direction  114 . Each groove  112   a  is configured to accommodate a different one of the optical waveguides  110 . The grooves  112   a  are oriented in the longitudinal direction  114  and configured to receive and permanently attach respective ones of the optical waveguides  110  to a respective groove at the attachment area  112 , e.g., using an adhesive. 
     At least one stacking support member  116  is located along a longitudinal edge  106   b  of the optical coupling member  106 . The stacking support member  116  has a distal end  116   a  extending beyond the mating surface  106   a  and a contact surface  116   b  opposed to the distal end  116   a . The contact surface  116   b  is configured to rotatably and/or slidably interface with a corresponding distal end of a corresponding stacking support member of an adjacently stacked optical ferrule (not shown in  FIG.  1   ). The illustrated contact surface  116   b  is a flat surface, although in some configurations the contact surface  116   b  could be either a convex or concave curve, and may include a combination of curves and flats. Generally, the adjacently stacked optical ferrule is located vertically above the illustrated optical ferrule  102 , and other adjacently stacked optical ferrules may be vertically below the illustrated optical ferrule  102 . The vertical direction is indicated by arrow  118 , is normal to the mating direction of a housing that contains the optical ferrule  102 . In the latter case, the distal end  116   a  of the stacking support member  116  rotatably and/or slidably interfaces with a corresponding contact surface of the adjacently stacked optical ferrule. 
     The stacking support member  116  is also shown with a stop surface  120  that contacts a corresponding stop surface of a mating optical ferrule in the mated configuration. The stop surfaces fix the longitudinal orientation of the mated optical ferrules relative to one another. As will be described in further detail below, other features of the optical ferrule  102  such as the shape of the mating tongue  104  provide alignment in other directions between the mated optical ferrules, and may be used instead of or in addition to the stop surface  120 . 
     In  FIG.  2   , a perspective view shows additional features of the optical cable subassembly  100  according to an example embodiment. As seen in this view, the mating surface  106   a  of the optical coupling member  106  includes a window  200  which is part of an optical path within the optical coupling member  106 . Light received from the optical waveguide  110  is redirected through the optical coupling member  106  where it exits the window  200  and enters a corresponding window of a mating optical ferrule. 
     Also seen in this view is a ridge  202  that is configured to interface with a mating tongue of a mating optical ferrule. A second ridge (not shown in this figure) mirrors the ridge  202  about a longitudinal centerline of the optical coupling member  106 . The dimensions of the ridges correspond to those of the mating tongue  104  such that the mating tongue of another, mating optical ferrule is aligned together with the illustrated ferrule  102 . As will be shown in detail below, the ridges  202 , mating tongue  104 , stop surfaces  120  and mating surface  106   a  allow mating optical ferrule to align respective windows  200  without requiring, for example, significant longitudinal forces to be applied on the mating optical ferrules. 
     As seen in the view of  FIG.  2   , the optical ferrule  102  includes two stacking support members  116  located along opposing longitudinal edges of the optical coupling member  106 . Note that only one of the longitudinal edges, edge  106   b , is seen in this view. The two stacking members  116  (also referred to as “first and second stacking members”) are mirror images of one another, e.g., mirrored across a plane formed by axes along the longitudinal and vertical directions  114 ,  118 , the plane bisecting the optical coupling member  106 . 
     In  FIG.  3   , a front view shows a connector  300  according to an example embodiment. The connector  300  includes four optical cable subassemblies  301 - 304  configured similarly to the optical cable subassembly  100  shown in  FIGS.  1  and  2   . Note that any number of optical subassemblies may be used. This figure uses the same convention for vertical orientation as was used in  FIGS.  1  and  2   , as indicated by arrow  118 . As seen in this view, the stackable ferrules of the optical cable subassemblies  301 - 304  result in a vertical pitch of the ferrules being equal to the vertical pitch of the optical waveguide ribbons and cable retainers (see retainer  504  in  FIG.  5   ) in the connector  300 . 
     The optical cable subassemblies  301 - 304  are located between opposing walls  312 ,  314  of a housing  310 . The optical ferrules of the subassemblies  301 - 304  are stacked one upon the other such that, in an unmated state of the connector  300 , there is no intervening support (e.g., from housing  310 ) between adjacently stacked optical ferrules. A clearance  323  may be provided between interior surfaces of the opposing side walls  312 ,  314  and the ferrules of the optical cable subassemblies  301 - 304 . This clearance  323  allows the side walls  312 ,  314  to restrain excessive movement of the optical ferrules in a side-to-side direction, as indicated by arrow  322 , while still allowing for some freedom of movement by the ferrules. Also note that the extensions of the stacking support members also provide side-to-side alignment between stacked optical ferrules. For example, distal ends  306  of optical cable subassembly  301  straddle the optical coupling member  307  of optical cable subassembly  302 . In order to support the stack of optical cable subassemblies  301 - 304  within the housing  310  in the vertical direction  118 , ferrule supports  318 ,  320  extend from interior surfaces of the walls  312 ,  314 . 
     While the housing  310  may include other members besides the side walls  312 ,  314  (e.g., top and/or bottom walls), the ferrule supports  318 ,  320  are attached or integral with the housing  310  may be the only members that provide vertical support for the stack of ferrules. In this example, the ferrule supports  318 ,  320  interface with the bottom ferrule&#39;s extensions. For example, extension  305  of optical cable subassembly  304  is shown contacting ferrule support  320 . In other embodiments described herein, ferrule supports may be located and configured to contact other parts of the ferrules. For example, upper ferrule supports, as indicated by dashed outlines  330 ,  332 , may serve to limit the upward motion of the ferrule stack by contacting surfaces  307  and  309 . 
     Generally, the optical waveguides of the optical cable subassemblies  301 - 304  on both mating connectors are configured to flex within the housing  310 , causing the ferrules to be at an angle to the housing  310  but parallel to each other. This angling involves rotating and sliding all of the adjacently stacked ferrules relative to one another, e.g., during manufacture of a connector that houses the subassemblies  301 - 304 . Because the distal end of the stacking support member (e.g., distal end  306  of optical cable subassembly  301  shown in  FIG.  3   ) is shaped to rotate and/or slide against the contact surface (e.g., contact surface  308  of subassembly  302 ) of an adjacent ferrule, the illustrated subassemblies  301 - 304  can achieve this rotation without any support members between adjacent ferrules. This allows the connector  300  to achieve a high density and simplifies subassembly of the connector  300 . 
     In  FIG.  4   , a side view illustrates two columns  400 ,  420  that respectively include ferrules  401 - 404  and  421 - 424  of mating optical cable subassemblies. These columns  400 ,  401  are part of mating connectors that each include a housing as shown in  FIG.  3   , although the housings are not shown in  FIG.  4   . The ferrules  401 - 404 ,  421 - 424  have substantially the same shape. Ferrules  401 - 404  of column  400  are inverted relative to ferrules  411 - 414  of column  420 , such that the respective mating surfaces of a pair of mating ferrules are facing each other. The ferrules  401 - 404 ,  411 - 414  are hermaphroditic, meaning they can be made from the same mold and do not require differing features, e.g., as with male/female connectors. 
     Ferrule support members  410 ,  430  are integral with or attached to the respective housings that enclose columns  400 ,  401 . In this figure, the ferrules  401 - 404  and  421 - 424  are in an unmated configuration, shown just before or after being mated with one another. Mating the ferrules  401 - 404  and  421 - 424  involves moving one or both of the columns in respective directions indicated by arrows  411 ,  431 . The arrows  411 ,  431  are generally aligned with a longitudinal direction of the housing. Lines  412 ,  432  represent the longitudinal directions of the ferrules  401 - 404 ,  421 - 424 , which are generally parallel. The longitudinal directions  412 ,  432  are at approximately equal acute angles  413 ,  433  with respect to the longitudinal direction of the housing. The orientation of the ferrules  401 - 404 ,  421 - 424  at the acute angles  413 ,  433  as opposed to aligned with the longitudinal directions  411 ,  431  of the housings results in opposing forces being applied that are normal to the mating surfaces of the ferrules  401 - 404 ,  421 - 424 . These normal forces help ensure positive mechanical engagement between the mating surfaces of the ferrules  401 - 404 ,  421 - 424 , as well as other alignment features included with the ferrules  401 - 404 ,  421 - 424  (e.g., mating tongue  104  and ridge  202  as seen in  FIG.  2   ). Note that the acute angles  413 ,  433  change during mating as the ferrules rotate, resulting in bending of the fibers, and thereby increasing the normal force. 
     In  FIG.  5   , the column  400  of  FIG.  4    is shown in housing  502  of optical connector  500 . The housing  502  is shown cut away along a center-plane in this view. Note that two ferrule support members  410   a - b  are shown, one support member  410   a  being attached to/integrated with the illustrated half of the housing  502  and the other support member  410   b  shown “floating” to facilitate understanding of the interaction between the ferrules  401 - 404  and the support members  410   a -B. This illustration in  FIG.  5    shows optical connector subassemblies of the column before being finally assembled into the housing  502 . A cable retainer  504  is shown attached to the optical waveguides  505 - 508  of the subassemblies. 
     As shown in  FIG.  6   , the cable retainer  504  is slidably inserted into the housing, causing a bend in the optical waveguides  505 - 508  and causing the ferrules  401 - 404  to be oriented at the acute angle  413  with respect to the housing  502 . The extensions of ferrules  401 - 403  are pressed against, slide and/or rotate relative to the contact surfaces of respective lower adjacent stacked ferrules  402 - 404 . The extensions of ferrule  404  are pressed against, slide, and/or rotate relative to the ferrule support members  410   a - b . Note that the sliding and/or rotation of adjacently stacked ferrules  401 - 404  against each other or against the ferrule support members  410   a - b  allows the ends of the ferrules to  401 - 404  to be vertically aligned as they are angled, as indicated by vertical line  600 . 
     The bending of the waveguides  505 - 508  due to sliding of the cable retainer  504  results in a force being applied to the ferrules  401 - 404  in an unmated configuration, causing the column of ferrules  401 - 404  to be pressed against the ferrule support members  410   a - b . Note that in this configuration/state only the bottom ferrule  404  is directly supported by the ferrule support members  410   a - b  that are attached to or integral with the housing  502 . The other ferrules  401 - 403  are supported by the immediately adjacent ferrule and not directly supported by the housing  502 . When the ferrules  401 - 404  are mated with ferrules of another connector, this spring force applied by the bending of the waveguides  505 - 508  is transferred to mating surfaces of the mating ferrules, causing the ferrules  401 - 404  to be lifted off of the support members  410   a - b  and also causing separation between extensions and contact surfaces of adjacent ferrules  401 - 404 . 
     In  FIG.  7   , a side view shows ferrules  401 - 404 ,  421 - 424  in a mated configuration. In this configuration, the windows on the mating surfaces of the ferrules  401 - 404 ,  421 - 424  are facing each other and aligned such that light is coupled therebetween. Note that in the mated configuration, gaps  700  exist between respective extensions and contact surfaces of adjacent ferrules. These gaps  700  are due to the spring forces formerly being applied between ferrule extensions and ferrule contact surfaces to be shifted such that the forces are instead applied between the mating surfaces of the ferrules  401 - 404 ,  421 - 424 , resulting in separation between extensions and contact surfaces of adjacent ferrules Similarly, gaps  702 ,  704  exist between support members  410 ,  430  and respective extensions of ferrules  404 ,  421 . The gaps  700 ,  702 ,  704  in the mated configuration help ensure that the spring force applied by the optical waveguide fibers is fully applied between the mating surfaces of the ferrules  401 - 404 ,  421 - 424  and not lessened due to full or partial contact with the support members  410 ,  430  or with other ferrules. 
     In  FIGS.  8  and  9   , side views show ferrules  801 - 804  according to another example embodiment. Ferrules  801 ,  802  are part of a first optical connector and ferrules  803 ,  804  are part of a second optical connector that mates with the first optical connector. Ferrules  801 ,  802  include optical coupling member  811 ,  812 . The optical coupling members  811 ,  812  include light redirecting elements  811   a ,  812   a  configured to redirect input light from waveguide arrays  805 ,  806  attached to the optical coupling members  811 ,  812 . The optical coupling members  811 ,  812  include mating surfaces  811   b ,  812   b  with output windows (not shown). The mating surfaces  811   b ,  812   b  are configured to slidably mate with mating surfaces  813   b ,  814   b  of mating optical coupling members  813 ,  814  along a longitudinal axis  807  of the optical ferrules. 
     Each of the optical ferrules  801 ,  802  includes at least one stacking member  821 ,  822  along a longitudinal edge of the optical coupling members  811 ,  812 . The stacking members  821 ,  822  include distal ends  821   a ,  822   a  extending beyond the mating surfaces  811   b ,  812   b  and contact surfaces  821   b ,  822   b  opposed to the distal ends  821   a ,  822   a . The contact surface  822   b  is configured to slidably and/or rotatably interface with corresponding distal end  821   a  of a corresponding stacking support member  821  of adjacently stacked optical ferrule  801 . The optical ferrules  803 ,  804  of the second optical connector also include similarly configured stacking members  823 ,  824 . The stacking members of ferrules  801  are sufficiently large to provide a gap  900  between ferrules  801  and  802  to allow ferrule  803  to mate with ferrule  801  without colliding with ferrule  802 . 
     Note that in these embodiments, the stacking members  821 ,  822  have circular shape, such that the distal ends  821   a ,  822   a  and contact surfaces  821   b ,  822   b  are respective first and second segments of the respective circles. The ferrules  801 - 804  are shown in an unmated configuration in  FIG.  8   , and shown in a mated configuration in  FIG.  9   . Note that in the mated configuration, there is no gap in the longitudinal direction  807  between the respective stacking members  821 - 824 . In one embodiment, contact between stacking members of mating ferrules (e.g., between members  821  and  823 , between  822  and  824 ) can serve as stops that position the optical coupling members  811 - 814  relative to one another in the ferrule&#39;s longitudinal direction  807 . In other embodiments, the stacking members  821 - 824  can be positioned such that there is no longitudinal contact, and other features (e.g., ridges  202  in  FIG.  2   ) can be used to provide this alignment. 
     In  FIGS.  10  and  11   , side views show ferrules  1001 - 1004  according to another example embodiment. The unmated configuration of ferrules  1001 - 1004  is shown in  FIG.  10    and the mated configuration is shown in  FIG.  11   . The ferrules  1001 - 1004  are configured similarly to the embodiment shown in  FIGS.  8  and  9   , except that the ferrules  1001 - 1004  include elliptical stacking members  1021 - 1024 . Thus, the contact surfaces and extensions of the stacking members  1021 - 1024  are elliptical sections. As with the previous embodiment, the major and minor axes of the stacking members  1021 - 1024  can be sized to reduce/increase stacking gap  1100  and to cause contact between the stacking members  1021 - 1024  of mating ferrules  1001 - 1004  in the longitudinal direction  1007 . In this embodiment, the stacking members of each mated ferrule are no longer in contact with the adjacent ferrules in its stack. The separation  1025  is caused by the rotation of the ferrules during the mating process. 
     In  FIG.  12   , a front view shows stacking members  1204 ,  1206  extending from sides of optical ferrules  1200   1202  according to one embodiment. Distal end of stacking member  1204  includes a ridge  1208  that aligns with and fits into groove  1212  on contact surface  1215  of ferrule  1202 . Distal end of stacking member  1206  includes a ridge  1210  that aligns with and fits into groove  1214  of ferrule support  1216 . The ridges  1208 ,  1210  and grooves  1212 ,  1214  facilitate maintaining side-to-side alignment of the ferrules  1200 , 1202  in an unmated configuration such that a column formed by the stacked ferrules  1200 ,  1202  will more easily mate with a corresponding ferrule column that uses similar alignment features. While the illustrated ridges  1208 ,  1210  and grooves  1212 ,  1214  have a triangular, or V-shape, any suitable shape may be used, including circular, elliptical, square, etc. It is also possible that grooves and ridges have different shapes, e.g., a V-shaped ridge that fits into a rectangular groove. Note that the grooves and ridges may be sized such that the separation of stacking members from contact surfaces in the mated configuration will lift the ridges  1208 ,  1210  out of the grooves  1212 ,  1214 . As a result, small misalignments between the ridges  1208 ,  1210  and the grooves  1212 ,  1214  should not affect optical alignment between mating ferrules in the mated configuration. 
     In  FIG.  13   , a front view shows stacking members  1304 ,  1306  extending from optical ferrules  1300   1302 . Distal end of stacking member  1304  includes a groove  1308  that aligns with and fits around ridge  1312  on contact surface  1315  of ferrule  1302 . Distal end of stacking member  1306  includes a groove  1310  that aligns with and fits around ridge  1314  of ferrule support  1316 . The ridges  1312 ,  1314  and grooves  1308 ,  1310  operates similarly to like named components in  FIG.  12   , and may include different shapes as described in that embodiment. 
     In the embodiments shown above, an optical connector includes a housing and at least one column of one or more sets of adjacent optical cable assemblies disposed in the housing. The optical cable assemblies include a ferrule according to various embodiments described above, as well as optical waveguides (e.g., optical fiber ribbons) coupled to the ferrules. This concept can be extended to multiple adjacent columns in some embodiments, as seen in the front view of  FIG.  14   . A housing  1400  includes outer sidewalls  1400   a - b  and inner sidewalls  140   c - e . Two or more columns  1402 - 1404  of optical cable assemblies are located between respective sidewalls  1400   a - e . The optical cable assemblies within the columns  1402 - 1404  may be configured with ferrules and waveguides according to any of the embodiments described herein. 
     Each of the columns  1402 - 1404  may be supported by a one or more ferrule supports, as indicated by ferrule supports  1400   aa  and  1400   ca  that extend respectively from sidewalls  1400   a  and  1400   c . Distal ends of one set of ferrule extensions (e.g., extensions  1402   a - b  of column  1402 ) ride against the ferrule supports. As in previous embodiments, alternate ferrule supports can be provided on the enclosure  1400  instead of or in addition to the illustrated supports (e.g., supports  330 ,  332  shown in  FIG.  3   ). Similarly, in this and other embodiments, a single ferrule support can span the width of one more columns such that it supports two or more extensions from bottom ferrules. Also seen in this view are top and bottom walls  1400 F-G of the enclosure  1400 , which are at a non-zero angle to (e.g., 90-degree angle) and join at least the outer sidewalls  1400   a - b . As shown, the top and bottom walls  1400   f - g  also join the inner sidewalls  1400   c - e.    
     In  FIG.  15   , a front view shows an arrangement of an optical connector with multiple adjacent columns according to another example embodiment. A housing  1500  includes outer sidewalls  1500   a - b  and top and bottom walls  1500   c - d  that are at a non-zero angle to (e.g., 90-degree angle) and that join the sidewalls  1500   a - b . Two or more columns  1502 - 1504  of optical cable assemblies are located between the sidewalls  1500   a - b . The optical cable assemblies within the columns  1502 - 1504  may be configured with ferrules and waveguides according to any of the embodiments described herein. Each of the columns  1502 - 1504  may be supported by a pair of ferrule supports, as indicated by ferrule support  1500   aa  that is proximate to (and may extend from) from sidewall  1500   a . Ferrule support  1500   da  extends from the bottom wall  1500   d , and may optionally include a protrusion  1500   daa  that separates adjacent columns  1502 ,  1503 . Distal ends of one set of ferrule extensions (e.g., extensions  1502   a - b  of column  1502 ) ride against the ferrule supports  1500   aa ,  1500   da . The housing  1500  may include side supports  1500   ab ,  1500   ca  that extend from the top wall  1500   c  (side support  1500   ab  may in addition or instead extend from the sidewall  1500   a ). These alternate side supports  1500   ab ,  1500   ca  may ride against the optical coupling members of the ferrules (e.g., against vertical surfaces that intersect contact surfaces  1502   c - d  of column  1502 ) to prevent excessive side-to-side movement of the columns  1502 - 1504 . 
     Optical ferrules as described above can be formed as unitary, molded structures. Some embodiments described herein involve molded optical ferrules and molds for making optical ferrules. Molding ferrules involves the use of two primary mold parts which are referred to herein as the “first mold side” and the “second mold side”. The first mold side includes first mold features configured to mold a first set of the features of the optical ferrule. The second mold side includes second mold features configured to mold a second set of the features of the optical ferrule. When the mold is operated, the two halves are brought together along what is referred to herein as the “parting axis”, the first side and the second side define a cavity for molding a unitary optical ferrule. A moldable material is injected or otherwise placed into the cavity and hardens, e.g., due to cooling of the mold material, to form the unitary ferrule. The mold halves are then separated along the parting axis to allow the ferrule to be removed. Some materials useful for molded ferrules include thermoplastic and thermosetting polymers, ceramics, metals, glasses, etc. 
     The error in alignment of the mold sides can be significant, e.g., on the order of about 10 μm or more. In reference again to  FIGS.  1  and  2   , if the attachment area  112 , the light-redirecting element  108 , and mechanical alignment features (e.g., mating tongue  104 ) are not molded by a single side of the mold, the attachment area  112  and the light-redirecting element  108  may be misaligned with the alignment features. When such a defective ferrule is mated with a mating ferrule, the alignment features cause the optical transmission elements to be improperly aligned with the mating ferrule, thereby increasing the optical insertion loss of the connector. As such, the ferrule-to-ferrule alignment features (e.g., tongue  104 , ridges  202 , and stops  120  shown  FIG.  2   ) can be formed on the same side of the mold with the optical features such as the light redirecting element  108  and attachment area  112  to ensure accurate alignment even if the mold sides are misaligned. Because the stacking members  116  will not affect to the optical alignment of mated ferrules, it is possible to mold them on the other side of the mold than the optical features even if the other side of the mold is misaligned. 
     In  FIGS.  16  and  17   , cross-sectional views show molds used to form a unitary ferrule according to an example embodiment. Mold  1600  in  FIG.  16    has first  1602  and second  1604  sides, with molded material  1606  between the first and second mold sides  1602 ,  1604 . A parting line flash artifact  1608  occurs where the molded material  170  penetrates a small gap between the mold sides  1602 ,  1604 . Mold  1700  in  FIG.  17    has first  1702  and second  1704  sides, with molded material  1706  between the first and second mold sides  1702 ,  1704 . A flash parting line artifact  1708  occurs where the mold material  190  penetrates a small gap between the mold sides  1702 ,  1704 . A step parting line artifact  1710  occurs where the second side  1704  of the mold includes a vertical wall  1704   a  that is slightly misaligned with the vertical wall  1702   a  of the first side and the molded material penetrates a small gap between mold sides  1702 ,  1704 . 
     In  FIG.  18   , a side view shows a molded unitary optical ferrule  1800  according to an example embodiment. The ferrule  1800  includes one or more parting line artifacts  1802 . At least one of the parting line artifacts  1802  extending substantially around an external perimeter of the optical ferrule  1800 . The parting line artifacts  1802  divide a surface of the optical ferrule  1800  into a first section  1804  along a first direction  1806  of a thickness axis and an opposing second section  1808  along a second direction  1810  of the thickness axis. 
     The first section  1804  includes one or more elements  1812  configured to receive and secure an optical waveguide, such as grooves, supports, etc. (see  FIG.  1   , for example). The first section  1804  also includes one or more elements  1814  configured to redirect input light within the unitary optical ferrule  1800 . The elements  1814  may include mirrors, lenses, internal waveguides, etc. A stacking contact surface  1816  and angled front  1817  is also included with the first section  1804 , as well as a mating tongue  1825 . 
     The second section  1808  includes at least one output window  1818  configured to transmit the redirected light out of a mating surface  1820 . The mating surface  1820  may also be considered part of the second section  1808 . The second section  1808  further includes at least one stacking support member  1822  along a longitudinal edge  1824  of the optical ferrule  1800 . The at least one stacking member  1822  includes an extension  1822   a  having a distal end  1822   aa  extending beyond the mating surface  1820 . The distal end  1822   aa  is configured to rotatably interface with a contact surface of a corresponding stacking support member. 
     Note that in this example, the parting line artifact  1802  is located at an intersection between longitudinal sides  1824  and the mating surface  1820 . Also, the parting line artifact  1802  extends along an outward facing surface of the stacking support member  1822 . In other embodiments, parting line artifacts may extend along an edge of the extensions  1822 , e.g., where two surfaces of extensions  1822  meet. This is shown in the following figures with illustrates example molding parts used to form the ferrule  1800 . 
     In  FIGS.  19  and  20   , cross-sectional views show first and second parts  1900 ,  1902  of a mold used to form the optical ferrule  1800  shown in  FIG.  18   . The view of  FIG.  19    corresponds to Section  19 - 19  through the ferrule  1800  shown in  FIG.  18   , and illustrates details of the elements  1812  configured to receive and secure optical waveguides that are formed by mold feature  1900   b . Also seen in  FIG.  19    are extensions  1822   a  and stacking contact surfaces  1816  on opposing longitudinal edges of the ferrule, and corresponding features  1902   b ,  1900   c  of mold parts  1902 ,  1900  used to form these features. Note that the intersection between surfaces  1900   a ,  1902   a  of the mold parts  1900 ,  1902  results in the parting line artifact  1802  shown in  FIG.  18   . The view of  FIG.  20    corresponds to Section  20 - 20  through the ferrule  1800  shown in  FIG.  18   , and illustrates details of the mating tongue  1825  and features  1900   d  and  1902   c  used to form the tongue  1825 . 
     In  FIGS.  21  and  22   , perspective views show ferrules  2101 - 2104  according to another example embodiment. The unmated configuration of ferrules  2101 - 2104  is shown in  FIG.  21    and the mated configuration is shown in  FIG.  22   . The ferrules  2101 - 2104  include elliptical stacking members  2121 - 2124  having distal ends  2121   a - 2124   a  extending beyond top surfaces  2111   a - 2114   a  of optical coupling members  2111 - 2114 . The top surfaces  2111   a - 2114   a  are opposed to mating surfaces  2111   b - 2114   b  of the optical coupling members  2111 - 2114 . Contact surfaces  2121   b - 2124   b  of the stacking members  2121 - 2124  may be recessed below, be aligned with, or extend beyond the mating surfaces  2111   b - 2114   b.    
     Two of the contact members  2122   b ,  2123   b  are shown riding against ferrule support members  2130 ,  2132  in the unmated configuration shown in  FIG.  21   . As with other embodiments, the ferrule support members  2130 ,  2132  are attached to a connector housing or other connector support. In the mated configuration shown in  FIG.  22   , the contact members  2122   b ,  2123   b  are lifted away from the ferrule support members  2130 ,  2132 . Additionally in the unmated configuration, the distal ends  2122   a  and  2123   a  are lifted off of respective adjacent contact members  2121   b ,  2124   b . Also note in the unmated configuration that the optical coupling members  2111 - 2114  have ridges extending from the top surfaces that (see ridges  2113   c  and  2114   c  in  FIG.  21    extending from top surfaces  2113   a ,  2114   a ) act as stop/alignment features in the longitudinal direction  2107 . 
     In  FIGS.  23  and  24   , perspective views show ferrules  2301 - 2304  according to another example embodiment. The unmated configuration of ferrules  2301 - 2304  is shown in  FIG.  23    and the mated configuration is shown in  FIG.  24   . The ferrules  2301 - 2304  include rectangular stacking members  2321 - 2324  having distal ends  2321   a - 2324   a  extending beyond top surfaces  2311   a - 2314   a  of optical coupling members  2311 - 2314 . The top surfaces  2311   a - 2314   a  are opposed to mating surfaces  2311   b - 2314   b  of the optical coupling members  2311 - 2314 . Contact surfaces  2321   b - 2324   b  of the stacking members  2321 - 2324  in this example extend beyond the mating surfaces  2311   b - 2314   b.    
     Two of the contact members  2322   b ,  2323   b  are shown riding against ferrule support members  2330 ,  2332  in the unmated configuration shown in  FIG.  23   . As with other embodiments, the ferrule support members  2330 ,  2332  are attached to a connector housing or other connector support. In the mated configuration shown in  FIG.  24   , the contact members  2322   b ,  2323   b  are lifted away from the ferrule support members  2330 ,  2332 . Also note in this configuration that the optical coupling members  2311 - 2314  have top surface ridges (see ridges  2323   c  and  2324   c  extending from top surfaces  2313   a ,  2314   a  in  FIG.  23   ) that act as stops/alignment features in the longitudinal direction  2307 . In this example, the forces applied by the waveguides/fibers prevent the ferrules  2301 - 2304  from sliding forward while stacked in the mated configuration. 
     It will be understood that the stacking members shown in  FIGS.  21 - 24    may include other shapes, including triangular shapes previously shown. The stacking members may also be referred to as extensions. Reference is made to other figures for analogous features shown in  FIGS.  21 - 24    but not specifically described, such as optical waveguides, elements configured to redirect output light, etc. 
     Additional information regarding ferrules and connectors that may be used in conjunction with the approaches described herein is provided in the following commonly owned and concurrently filed U.S. Patent Applications which are incorporated herein by reference: U.S. patent application Ser. No. 62/239,998, having the title “Connector with Latching Mechanism” and identified by Attorney Docket Number 76663US002; U.S. patent application Ser. No. 62/240,069, having the title “Optical Ferrules” and identified by Attorney Docket Number 76982US002; U.S. patent application Ser. No. 62/240,066, having the title “Ferrules, Alignment Frames and Connectors,” and identified by Attorney Docket Number 75767US002; U.S. patent application Ser. No. 62/240,008, having the title “Optical Cable Assembly with Retainer,” identified by Attorney Docket Number 76662US002; U.S. patent application Ser. No. 62/240,010, having the title “Optical Coupling Device with Waveguide Assisted Registration,” identified by Attorney Docket Number 76660US002; U.S. Patent Application 62/239,996, having the title “Optical Ferrules and Optical Ferrule Molds,” identified by Attorney Docket Number 75985US002; U.S. Patent Application 62/104,196, having the title “Configurable Modular Connectors,” identified by Attorney Docket No. 75907US002; and U.S. Patent Application 62/240,005, having the title “Hybrid Connectors,” identified by Attorney Docket Number 76908US002. 
     Embodiments described in this disclosure include:
 
Item 1. An optical ferrule, comprising:
 
     an optical coupling member comprising:
         one or more light redirecting elements configured to redirect input light from a waveguide attached to the optical coupling member toward an output window of the optical coupling member; and   a mating surface that includes the output window, the mating surface configured to slidably mate with a mating surface of a mating optical coupling member along a longitudinal axis of the optical ferrule; and       

     at least one stacking member along a longitudinal edge of the optical coupling member, the at least one stacking member comprising:
         a distal end extending beyond one of the mating surface and a top surface opposed to the mating surface; and   a contact surface opposed to the distal end, the contact surface configured to rotatably interface with a corresponding distal end of a corresponding stacking support member of an adjacently stacked optical ferrule.
 
Item 2. The optical ferrule of item 1, wherein the contact surface is further configured to slidably interface with the corresponding distal end of the corresponding stacking support member.
 
Item 3. The optical ferrule of any of items 1 and 2, where the at least one stacking member comprises first and second stacking members respectively located along opposing longitudinal edges of the optical coupling member.
 
Item 4. The optical ferrule of item 3, wherein the first and second stacking members are mirror images of one another.
 
Item 5. The optical ferrule of item 3, wherein the first and second stacking members align the optical ferrule in a side-to-side direction with a corresponding optical coupling member of the adjacently stacked optical ferrule.
 
Item 6. The optical ferrule of any of items 1-5, wherein the contact surface comprises a flat surface.
 
Item 7. The optical ferrule of any of item 1-5, wherein the contact surface comprises a curved surface.
 
Item 8. The optical ferrule of any of items 1-7, wherein the stacking member comprises a triangular shape, a vertex of the triangular shape corresponding to the distal end.
 
Item 9. The optical ferrule of any of items 1-8, wherein the contact surface and the corresponding distal end comprise a groove and a ridge, the ridge fitting into the groove in an unmated configuration of the optical ferrule and the adjacently stacked optical ferrule, the ridge and the groove aligning the optical ferrule and the adjacently stacked optical ferrule in a side-to-side direction.
 
Item 10. The optical ferrule of any of items 1-9, wherein the distal end extends beyond the mating surface and the contact surface is recessed below the top surface of the optical coupling member.
 
Item 11. The optical ferrule of any of items 1-9, wherein the distal end extends beyond the mating surface and the contact surface extends beyond the top surface of the optical coupling member.
 
Item 12. The optical ferrule of any of items 1-9, wherein the distal end extends beyond the top surface and the contact surface is recessed below the mating surface of the optical coupling member.
 
Item 13. The optical ferrule of any of items 1-12, wherein the optical ferrule and the adjacently stacked optical ferrule are part of a first connector and configured to optically interface with respective first and second stacked mating optical ferrules of a second connector in a mated configuration, wherein the contact surface is separated from the corresponding distal end of the corresponding stacking support member in the mated configuration.
 
Item 14. The optical ferrule of any of items 1-13, wherein the stacking members of the optical ferrule and the adjacently stacked optical ferrule of the first connector comprise stop surfaces that contact with corresponding stop surfaces of first and second stacking support members of the first and second stacked optical ferrules of the first connector in the mated configuration.
 
Item 15. An optical ferrule, comprising:
       

     an optical coupling member comprising:
         one or more light redirecting elements configured to redirect input light toward an output window of the optical coupling member; and   a mating surface that includes the output window, the mating surface configured to slidably mate with a mating surface of a mating optical coupling member along a longitudinal axis of the optical ferrule;       

     first and second extensions on opposed longitudinal edges of the optical coupling member, the first and second extensions extending beyond at least one of the mating surface and a top surface opposed to the mating surface; and 
     a first contact surface on the first extension, the first contact surface configured to slidably interface with an extension of a corresponding stacking support member of an adjacently stacked optical ferrule. 
     Item 16. The optical ferrule of item 15, further comprising a second contact surface on the second extension, the second contact surface configured to slidably interface with another extension of the corresponding stacking support member.
 
Item 17. The optical ferrule of any of items 15 and 16, wherein the first and second extensions are mirror images of one another.
 
Item 18. The optical ferrule of any of items 15-17, wherein the first contact surface comprises a flat surface.
 
Item 19. The optical ferrule of any of items 15-17, wherein the first contact surface comprises a curved surface.
 
Item 20. The optical ferrule of any of items 15-19, wherein the extension comprises a triangular shape, a vertex of the triangular shape slidably interfacing with a contact surface of a second adjacently stacked optical ferrule.
 
Item 21. The optical ferrule of any of items 15-20, wherein the first contact surface is recessed below a top surface of the optical coupling member, the top surface being opposed to the mating surface.
 
Item 22. The optical ferrule of any of items 15-21, wherein the optical ferrule and the adjacently stacked optical ferrule are part of a first connector and configured to optically interface with respective first and second stacked mating optical ferrules of a second connector in a mated configuration, wherein the first contact surface is separated from the corresponding distal end of the corresponding stacking support member in the mated configuration.
 
Item 23. The optical ferrule of item 22, wherein the stacking support members of the optical ferrule and the adjacently stacked optical ferrule of the first connector comprise stop surfaces that contact with corresponding stop surfaces of first and second stacking support members of the first and second stacked optical ferrules of the first connector in the mated configuration.
 
Item 24. A connector comprising:
 
     a housing; and 
     at least one column of one or more adjacent optical cable assemblies disposed in the housing, each set of optical cable subassemblies comprising at least two optical cable subassemblies, each optical cable subassembly comprising:
         an optical ferrule comprising:
           an optical coupling member comprising:
               one or more light redirecting elements configured to redirect input light toward an output window of the optical coupling member; and   a mating surface that includes the output window, the mating surface configured to slidably mate with a mating surface of a mating optical coupling member along a longitudinal axis of the optical ferrule; and   
               at least one extension along a longitudinal edge of the optical coupling member, the extension comprising:
               a distal end extending beyond the mating surface; and   a contact surface opposed to the distal end, the contact surface configured to rotatably interface with a corresponding distal end of a corresponding extension of an adjacently stacked optical ferrule; and   
               one or more optical waveguides attached to the optical ferrule,   
           wherein, in an unmated configuration of the connector, the distal end of a first optical cable subassembly of the at least one column rotatably interfaces with the contact surface of a second optical cable subassembly of the at least one column.
 
Item 25. The connector of item 24, wherein the distal end of the first optical cable subassembly slidably interfaces with the contact surface of the second optical cable subassembly.
 
Item 26. The connector of any of items 24 and 25, wherein the distal end of the extension of only a selected one of the optical ferrules of the at least one column interfaces with a ferrule support attached to or integral with the connector housing.
 
Item 27. The connector of item 26, wherein the optical ferrules of the column are unsupported by the housing except for the selected optical ferrule.
 
Item 28. The connector of item 27, wherein the one or more optical waveguides in the cable assemblies apply spring forces to the respective optical ferrules, the spring forces holding the distal end of the first optical cable subassembly against the contact surface of the second optical cable subassembly and further hold the extension of selected optical ferrule against the ferrule support.
 
Item 29. The connector of item 28, wherein, in a mated configuration, the spring forces are applied between the mating surfaces of the at least one column with corresponding mating surfaces of a column of mating optical cable assemblies such that the extension of the first optical cable subassembly is separated from the contact surface of the second optical cable subassembly and the extension of the selected optical ferrule is separated from the ferrule support.
 
Item 30. A connector comprising:
       

     a housing comprising at least one support extending respectively from at least one of first and second interior walls of the housing; 
     two or more optical cables assemblies stacked between the first and second interior walls, each comprising:
         one or more optical waveguides;   an optical ferrule comprising one or more light redirecting elements configured to redirect input light toward an output window of the optical coupling member and a mating surface that includes the output window, the mating surface configured to slidably mate with a mating surface of a mating optical coupling member along a longitudinal axis of the optical ferrule;   an extension along a longitudinal edge of the optical ferrule, the extension extending beyond the mating surface; and   a contact surface along the longitudinal edge; and   wherein the extension of a first of the two or more optical cable assemblies slidably interfaces with the contact surface of a second of the two or more optical cable assemblies, and       

     wherein the extension of the second optical cable subassembly slidably interfaces with the at least one support of the housing. 
     Item 31. The connector of item 30, wherein the distal end of the first optical cable subassembly rotatably interfaces with the contact surface of the second optical cable subassembly.
 
Item 32. The connector of any of items 30-31, wherein the two or more optical cable assemblies are unsupported by the at least one support except for the first optical cable subassembly.
 
Item 33. The connector of item 32, wherein the one or more optical waveguides apply spring forces to the respective optical ferrules, the spring forces holding the extension of the first optical cable subassembly against the contact surface of the second optical cable subassembly and further hold the extension of second optical cable subassembly against the at least one support.
 
Item 34. The connector of item 33, wherein, in a mated configuration, the spring forces are applied between the mating surfaces of the two or more optical cable assemblies with corresponding mating surfaces of mating optical cable assemblies such that the extension of the first optical cable subassembly is separated from the contact surface of the second optical cable subassembly and the extension of the selected optical ferrule is separated from at least one support.
 
Item 35. A connector comprising:
 
     a housing; 
     two or more columns of optical cable assemblies located side-by-side within the housing, each optical cable subassembly comprising:
         an optical ferrule comprising:
           an optical coupling member comprising:
               one or more light redirecting elements configured to redirect input light toward an output window of the optical coupling member; and   a mating surface that includes the output window, the mating surface configured to slidably mate with a mating surface of a mating optical coupling member along a longitudinal axis of the optical ferrule; and   
               at least one extension along a longitudinal edge of the optical coupling member, the at least one extension extending beyond the mating surface; and   a contact surface opposed to the at least one extension, the contact surface configured to rotatably interface with a corresponding extension of a an adjacently stacked optical ferrule; and   
           one or more optical waveguides attached to the optical ferrule,       

     wherein the extension of a first optical cable subassembly of each column slidably interfaces with the contact surface of a second optical cable subassembly of each column. 
     Item 36. The connector of item 35, wherein the extension of only a selected one optical ferrule of each column interfaces with a ferrule support attached to or integral with the connector housing.
 
Item 37. The connector of item 36, wherein the optical ferrules of the two or more columns are unsupported by the housing except for the selected optical ferrules of each column.
 
Item 38. The connector of item 37, wherein, for each column, the one or more optical waveguides in the cable assemblies apply spring forces to the respective optical ferrules, the spring forces holding the extension of the first optical cable subassembly against the contact surface of the second optical cable subassembly and further hold the extension of selected optical ferrule against the ferrule support.
 
Item 39. The connector of item 38, wherein, in a mated configuration, the spring forces are applied between the mating surfaces of each column with corresponding mating surfaces of corresponding columns of mating optical cable assemblies such that, for each column, the extension of the first optical cable subassembly is separated from the contact surface of the second optical cable subassembly and the extension of the selected optical ferrule is separated from the ferrule support.
 
Item 40. The connector of any of items 35-39, wherein the housing further comprises one or more inner sidewalls separating the two or more columns of optical cable assemblies, the one or more inner sidewalls limiting side-to-side movement of the two or more columns within the housing.
 
Item 41. The connector of item any of items 35-40, further comprising one or more side supports separating the two or more columns of optical cable assemblies, the one or more side supports limiting side-to-side movement within the housing of at least one optical ferrule within each of the two or more columns
 
Item 42. A molded, unitary, optical ferrule comprising:
 
     at least one stacking member along a longitudinal edge of the optical ferrule; 
     one or more parting line artifacts, the one or more parting line artifacts including a parting line artifact extending substantially around an external perimeter of the optical ferrule, the parting line artifacts dividing a surface of the optical ferrule into a first section along a first direction of a thickness axis and an opposing second section along a second direction of the thickness axis, wherein the first section comprises:
         a contact surface of the stacking member;   one or more elements configured to receive and secure an optical waveguide; and   one or more elements configured to redirect input light within the unitary optical ferrule; and       

     wherein the second section comprises
         at least one output window configured to transmit the redirected light out of a mating surface; and       

     a distal end of the stacking member extending beyond the mating surface, the distal end configured to interface with a corresponding contact surface of a corresponding optical ferrule. 
     Item 43. The molded, unitary, optical ferrule of item 42, wherein at least part of the parting artifact extends along an intersection between the mating surface and the longitudinal edge.
 
Item 44. The molded, unitary, optical ferrule of any of items 42-43, wherein the stacking member comprises two stacking members respectively located along opposing longitudinal edges of the optical coupling member.
 
Item 45. The molded, unitary, optical ferrule of item 44, wherein the first and second stacking members are mirror images of one another.
 
Item 46. The molded, unitary, optical ferrule of any of items 42-45, wherein the contact surface comprises a flat surface.
 
Item 47. The molded, unitary, optical ferrule of any of items 42-45, wherein the contact surface comprises a curved surface.
 
Item 48. The molded, unitary, optical ferrule of any of items 42-47, wherein the stacking member comprises a triangular shape, a vertex of the triangular shape configured to interface with the corresponding contact surface.
 
Item 49. The molded, unitary, optical ferrule of any of items 42-48, wherein the contact surface is recessed below a top surface of the optical coupling member, the top surface opposed to the mating surface.
 
Item 50. A mold operable to injection mold a unitary, optical ferrule, the mold comprising:
 
     a first part configured to form:
         a contact surface of a stacking member of the unitary, optical ferrule;   one or more elements of the unitary, optical ferrule configured to receive and secure an optical waveguide; and   one or more elements of the unitary, optical ferrule configured to redirect input light within the unitary optical ferrule; and       

     a second part configured to form:
         at least one output window of the unitary, optical ferrule configured to transmit the redirected light out of a mating surface of the unitary, optical ferrule; and   an extension of the stacking member comprising a distal end extending beyond the mating surface, the distal end configured to interface with a corresponding contact surface of a corresponding optical ferrule;   wherein respective first and second surfaces of the first and second parts form one or more parting line artifacts, the one or more parting line artifacts including a parting line artifact extending substantially around an external perimeter of the unitary optical ferrule.
 
Item 51. The mold of claim 50, wherein at least part of the parting artifact extends along an intersection between the mating surface and the longitudinal edge.
       

     Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein. The use of numerical ranges by endpoints includes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range. 
     Various modifications and alterations of the embodiments discussed above will be apparent to those skilled in the art, and it should be understood that this disclosure is not limited to the illustrative embodiments set forth herein. The reader should assume that features of one disclosed embodiment can also be applied to all other disclosed embodiments unless otherwise indicated. It should also be understood that all U.S. patents, patent applications, patent application publications, and other patent and non-patent documents referred to herein are incorporated by reference, to the extent they do not contradict the foregoing disclosure.