Patent Publication Number: US-9417406-B2

Title: Cable assemblies and optical connector assemblies employing a unitary alignment pin and translating element

Description:
BACKGROUND 
     1. Field of the Disclosure 
     The technology of the disclosure relates to optical connectors having a translating element, wherein the translating element may be utilized for facilitating optical connections. 
     2. Technical Background 
     Benefits of optical fiber include extremely wide bandwidth and low noise operation. Because of these advantages, optical fiber is increasingly being used for a variety of applications, including, but not limited to, broadband voice, video, and data transmission. Fiber optic networks employing optical fiber are being developed and used to deliver voice, video, and data transmissions to subscribers over both private and public networks. These fiber optic networks often include separated connection points linking optical fibers to provide “live fiber” from one connection point to another connection point. In this regard, fiber optic equipment is located in data distribution centers or central offices to support optical fiber interconnections. Additionally, optical cable assemblies may be utilized in consumer applications to communicate between personal computing devices and auxiliary electronic device, such as smart phones, media players, external storage components, and the like. 
     SUMMARY OF THE DETAILED DESCRIPTION 
     Fiber optic connectors are provided to facilitate optical connections with optical fibers for the transfer of light. For example, optical fibers can be optically connected to another optical device, such as a light-emitting diode (LED), laser diode, or opto-electronic device, for light transfer. As another example, optical fibers can be optically connected to other optical fibers through mated fiber optic connectors. In any of these cases, it is important that the end face of an optically connected optical fiber be precisely aligned with the optical device or other optical fiber to avoid or reduce coupling loss. For example, the optical fiber is disposed through a ferrule that precisely locates the optical fiber with relation to the fiber optic connector housing. 
     Flat end-faced multi-fiber ferrules may be provided to more easily facilitate multiple optical fiber connections between the fiber optic connector supporting the ferrule and other fiber optic connectors or other optical devices. In this regard, it may be important that fiber optic connectors be designed to allow the end faces of the optical fibers disposed in the ferrule to be placed into contact or closely spaced with an optical device or other optical fiber for light transfer. In conventional multi-fiber, fiber optic connectors, the excess fiber is removed by laser cleaving and the remaining protruding fiber precision polished to form a highly planar fiber array. When these connectors are mated, the end faces touch providing for low loss. This high precision polishing is costly and difficult. 
     Gradient index (GRIN) lenses offer an alternative to high precision polishing. GRIN lenses focus light through a precisely controlled radial variation of the lens material&#39;s index of refraction from the optical axis to the edge of the lens. The internal structure of this index gradient can dramatically reduce the need for high precision polishing and results in a simple, compact lens. This allows a GRIN lens with flat surfaces to collimate light emitted from an optical fiber or to focus an incident beam into an optical fiber. The GRIN lens can be provided in the form of a glass rod that is disposed in a lens holder as part of a fiber optic connector. The flat surfaces of a GRIN lens allow easy bonding or fusing of one end to an optical fiber disposed inside the fiber optic connector with the other end of the GRIN lens disposed on the ferrule end face. The flat surface on the end face of a GRIN lens can reduce aberrations, because the end faces can be polished to be planar to slightly inset with respect to the end face of the ferrule. The flat surface of the GRIN lens allows for easy cleaning of end faces of the GRIN lens. It is important that the lens holder assembly be designed with internal holders that place and secure the GRIN lenses in alignment with the desired angular accuracy to avoid or reduce coupling loss. Optical connectors having the unitary alignment pins and translating elements disclosed herein may be optically connected to one or more optical fibers in another fiber optic connector or to an optical device, such as a laser-emitting diode (LED), laser diode, vertical-cavity surface-emitting laser (VCSEL), or opto-electronic device for light transfer. 
     Embodiments disclosed herein are directed to optical cable assemblies, optical connector assemblies, and optical connector subassemblies having a unitary alignment pin on which a translating element maintaining an optical interface may translate within a housing. Non-limiting examples of such optical connectors include plugs and receptacles. In one embodiment, the translating element maintains one or more GRIN lenses. The unitary alignment pin has a first pin portion and a second pin portion, and is fabricated from a single component rather than two or more components. Use of a single component may reduce complexity and cost. The translating element may include first and second bores that accept first and second pin portions, respectively. The translating element, which may be biased toward an opening of the connector housing by one or more bias members, may translate on the first and second pin portions within the connector housing. When the translating element is in an unconnected state and positioned toward the connector housing opening, the optical interface is easily accessible to a user for cleaning purposes. Upon connection to a mated optical connector, such as a receptacle, the translating element translates back within the connector housing by contact with a face of the mated optical connector. 
     In this regard, in one embodiment, an optical connector assembly includes a connector housing defining a connector enclosure and a connector housing opening, a unitary alignment pin including a first pin portion and a second pin portion, and a translating element including a first bore, a second bore, and an optical interface. The unitary alignment pin is secured within the connector enclosure. The first pin portion is disposed within the first bore and the second pin portion is disposed within the second bore such that the translating element translates along the first pin portion and the second pin portion within the connector enclosure. 
     In another embodiment, an optical connector subassembly includes a guide frame, a unitary alignment pin coupled to the guide frame, a translating element, and first and second bias members. The guide frame includes a base portion, a first arm portion, and a second arm portion. The first arm portion and the second arm portion extend from the base portion such that there is a gap between the first arm portion and the second arm portion. The guide frame is configured to be disposed in a connector housing. The unitary alignment pin includes a first pin portion and a second pin portion and is secured to the guide frame at the base portion. The first pin portion and the second pin portion are positioned within the gap between the first arm portion and the second arm portion. The translating element includes a first bore, a second bore, and an optical interface. The first pin portion is disposed within the first bore and the second pin portion is disposed within the second bore. The first bias member is disposed about the first pin portion between the translating element and the base portion of the guide frame, and the second bias member is disposed about the second pin portion between the translating element and the base portion of the guide frame such that the translating element translates along the first pin portion and the second pin portion. 
     In yet another embodiment, a cable assembly includes an optical connector body, an optical cable extending from a rear portion of the optical connector body, a plug housing extending from a front surface of the optical connector body, a unitary alignment pin having a first pin portion and a second pin portion, and translating element. The optical cable has at least one optical fiber. The plug housing defines an optical connector opening. The unitary alignment pin is disposed within the optical connector body and the plug housing. The translating element includes a first bore, a second bore, and at least one GRIN lens. The first pin portion is disposed within the first bore and the second pin portion is disposed within the second bore such that the translating element translates along the first pin portion and the second pin portion. The at least one optical fiber is optically coupled to the at least one GRIN lens. 
     Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description that follows, the claims, as well as the appended drawings. 
     It is to be understood that both the foregoing general description and the following detailed description present embodiments, and are intended to provide an overview or framework for understanding the nature and character of the disclosure. The accompanying drawings are included to provide a further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments, and together with the description serve to explain the principles and operation of the concepts disclosed. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a front perspective view of an exemplary optical connector assembly of an exemplary cable assembly; 
         FIG. 2  is a front perspective view of an exemplary receptacle configured to mate with the exemplary optical connector depicted in  FIG. 1 ; 
         FIG. 3A  is a top perspective view of an exemplary optical connector subassembly wherein the translating element is biased in a forward position; 
         FIG. 3B  is a bottom perspective view of the exemplary optical connector subassembly depicted in  FIG. 3A ; 
         FIG. 3C  is a top perspective view of the exemplary optical connector subassembly depicted in  FIG. 3A  wherein the translating element is in a retracted position; 
         FIG. 4A  is a top perspective view of an exemplary unitary alignment pin of the exemplary optical connector subassembly depicted in  FIGS. 3A-3C ; 
         FIG. 4B  is a bottom perspective view of the exemplary unitary alignment pin depicted in  FIG. 4A ; 
         FIG. 5  is a top perspective view of an exemplary unitary alignment pin wherein the rear portion is in the same plane as first and second pin portions; 
         FIG. 6  is a top perspective view of an exemplary unitary alignment pin having a single bent portion; 
         FIG. 7  is a top perspective view of an exemplary unitary alignment pin having an off centerline rear portion; 
         FIG. 8  is a front, top perspective view of an exemplary single-piece translating element; 
         FIG. 9A  is a front, top exploded view of an exemplary two-piece translating element; 
         FIG. 9B  is a front, bottom exploded view of the exemplary two-piece translating element depicted in  FIG. 9A ; 
         FIG. 9C  is a front, top perspective view of an assembled exemplary two-piece translating element depicted in  FIG. 9A ; and 
         FIG. 10  is a front, top perspective view of an exemplary single-piece translating element having a wide bore and a circular bore. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all embodiments are shown. Indeed, the concepts may be embodied in many different forms and should not be construed as limiting herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts. 
     Embodiments disclosed herein include optical cable assemblies, optical connector assemblies, and optical connector subassemblies employing a translating element having an optical interface for passing optical signals, and a unitary alignment pin on which the translating element is free to translate. Non-limiting examples of connectors include plugs and receptacles. The translating elements described herein are configured to translate within a connector housing on a unitary alignment pin. The unitary alignment pin is a single, unitary component having a first pin portion and a second pin portion that are disposed within first and second bores through the translating element. The unitary alignment pin may reduce complexity and cost over the use of multiple alignment pin components. The translating element is biased toward an opening of the connector housing such that when the optical connector is in a disengaged state, a coupling surface and optical interface of the translating element is accessible to a user for the wiping away of debris and liquid. When the optical connector is coupled to a mated optical connector, such as a receptacle of an electronic device, for example, the translating element is translated back into the connector housing along the first and second pin portions of the unitary alignment pin. 
     The unitary alignment pin may be configured as a precision wire that is bent into the desired form having a first and second pin portions on which the translating element slides. In some embodiments, the unitary alignment pin comprises bent portion that act as engagement and alignment features for precise placement within the optical connector assembly. As described in detail below, the configuration of the unitary alignment pin may take on a variety of forms. 
     In one embodiment, the translating element comprises one or more internal groove alignment features configured to secure one or more gradient index (GRIN) lenses in the translating element. The groove alignment features are also configured to accurately align the end faces of the GRIN lenses. In another embodiment, the translating element comprises one or more refractive lens at the optical interface for optically coupling the translating element to a mated connector. 
     A fiber optic connector assembly containing the unitary alignment pins disclosed herein may be optically connected to one or more optical fibers in another fiber optic connector or to an optical device, such as a laser-emitting diode (LED), laser diode, vertical-cavity surface-emitting laser (VCSEL), or opto-electronic device for light transfer. As a non-limiting example, the optical connectors disclosed herein can be provided as part of a plug or receptacle containing one or more optical fibers for establishing optical connections. 
     In this regard,  FIG. 1  is a perspective view of an assembled exemplary cable assembly  100  comprising an optical connector assembly  101  employing a translating element  110  configured to support and align optical components  122  of an optical interface  120  to pass optical signals through the lens holder assembly. The optical connector assembly  101  in the illustrated embodiment is configured as a male plug connector. For example, the optical connector assembly  101  may be a fiber optic connection plug that supports optical components for establishing optical connections and communication over the cable assembly  100 . 
     More specifically, the optical connector assembly  101  generally comprises a connector housing  105  having a plug housing  111  extending from a front surface  106 . The plug housing  111  defines a plug portion that may be inserted into a receptacle  270  ( FIG. 3 ). In other embodiments, the optical connector assembly  101  may not include a plug housing  111 . In such embodiments, the optical connector assembly  101  may be configured as a female optical connector, wherein the connector housing  105  defines an opening to expose a coupling surface  126  of the translating element  110 . 
     The optical connector assembly  101  further comprises optical fibers  104  disposed in a cable  102  extending from a rear surface  107  of the connector housing  105 . The plug housing  111  comprises engagement tabs  113   a ,  113   b  that are configured to engage mated engagement tabs  275   a ,  275   b  of a receptacle housing  272 , as described below with reference to  FIG. 3 . 
     In the illustrated embodiment, the plug housing  111  defines an optical connector opening  123  that exposes the translating element  110  that is maintained in a connector enclosure defined in part by the plug housing  111 . As depicted in  FIGS. 1, 3A-3C , the translating element  110  of the particular embodiment is configured to translate along an x-axis (i.e., an optical axis of the optical connector assembly  101 ) within the connector housing  105 . Still referring to  FIG. 1 , the illustrated translating element  110  comprises a coupling surface  126 . Optical components, such as GRIN lenses  122 , refractive lenses, and the like, are exposed at the coupling surface  126  to align the optical components, such as the optical fibers  104 , within the translating element to a mated optical connector. Although embodiments described herein recite GRIN lenses, other optical components may be disposed within the translating element  110 , such as optical fiber stubs and waveguides, for example. 
     The GRIN lenses  122  focus light through a precisely controlled radial variation of the lens material&#39;s index of refraction from the optical axis to the edge of the lens. The internal structure of this index gradient can dramatically reduce the need for tightly controlled surface curvatures and results in a simple, compact lens. This allows the GRIN lenses  122  with flat surfaces to collimate light emitted from the optical fibers  104  or to focus an incident beam into the optical fibers  104 . In this embodiment, the GRIN lenses  122  are provided in the form of glass rods that are disposed in the translating element  110 . The flat end face surfaces of the GRIN lenses  122  allow simple optical coupling of ends of the GRIN lenses  122  to end portions of the optical fibers  104  inside the optical connector assembly  101 , with the other end of the GRIN lenses  122  disposed on the coupling surface  126  of the translating element  110 . The flat end face surfaces of the GRIN lenses  122  can also reduce aberrations. 
     Further, with continuing reference to  FIG. 1 , the end faces of the GRIN lenses  122  can be planar to slightly inset to the coupling surface  126  (e.g., within 0-25 μm). In some embodiments, the end faces of the GRIN lenses  122  may be slightly recessed with respect to the coupling surface  126  to avoid physical contact with the GRIN lenses of a mated optical connector to prevent damage to the GRIN lenses  122 . If the offset distance between the end faces of the GRIN lenses  122  is too large, it may create a dirt collection recess. In alternative embodiments the end faces of the GRIN lenses  122  may be flush with the coupling surface  126 . The flat surface of the GRIN lenses  122  allows for easy cleaning of end faces of the GRIN lenses  122 . As will be discussed in more detail below, the translating element  110  may be designed with internal alignment features that support and align the GRIN lenses  122  in alignment with translating element  110  and the optical connector assembly  101  to avoid or reduce coupling loss between the GRIN lenses  122  and optical components optically connected to the GRIN lens  122  through a mating to the optical connector assembly  101 . 
     The exemplary translating element  110  of the optical connector assembly  101  depicted in  FIG. 1  comprises a first bore  121   a  and a second bore  121   b . The first and second bores  121   a ,  121   b  fully extend through the body of the translating element  110 . As described in detail below, the optical connector assembly  101  comprises a unitary alignment pin  132  having a first pin portion  135   a  and a second pin portion  135   b . The first pin portion  135   a  is disposed within the first bore  121   a  of the translating element and the second pin portion  135   b  is disposed within the second bore  121   b  of the translating element. The translating element  110  may translate back and forth along the x-axis (i.e., the optical axis of the optical connector assembly) on the first and second pin portions  135   a ,  135   b  within the connector enclosure defined by the plug housing  111  and the connector housing  105 . 
     The illustrated optical connector assembly  101  further comprises a guide frame  130  comprising a first arm portion  131   a  and a second arm portion  131   b  that is disposed within a connector enclosure defined by the plug housing  111 . The guide frame  130  is described in detail below with reference to  FIGS. 3A-3C . Generally, the first and second arm portion  131   a ,  131   b  act as a guide for the translation of the translating element  110  within the plug housing  111  and the connector housing  105 . The first arm portion  131   a  and the second arm portion  131   b  of the guide frame  130  of the illustrated embodiment are configured to define a first opening  140   a  and a second opening  140   b  within the plug housing  111  that are adjacent to the translating element  110 . A first electrical contact  141   a  may be positioned on the first arm portion  131   a  and exposed within the first opening  140   a  and a second electrical contact  141   b  may be positioned on the second arm portion  131   b  and exposed within the second opening  140   b . The first and second openings may be configured to accept engagement prongs  282   a ,  282   b  (see  FIG. 3 ) of a mated optical connector assembly to robustly couple the optical connector assembly  101  to the mated optical connector assembly by resisting external angular forces upon the optical connector assembly  101  that may disturb the optical connection between the coupled components. The first and second electrical contacts  141   a ,  141   b  may be configured to pass electrical power and/or data across the cable assembly  100 . In such an embodiment, electrical conductors may span the length of the cable  102 . 
     In other embodiments, the first and second arm portions  131   a ,  131   b  may not define opening within the plug housing  111  for receipt of engagement prongs. In this embodiment, the first and second arm portions  131   a ,  131   b  have a face that is approximately flush with respect to the plug housing  111  at the opening  123 . In still further embodiments, the first and second arm portions  131   a ,  131   b  may define first and second openings  140   a ,  140   b  wherein the first and second electrical contacts are not provided. 
       FIG. 2  depicts a mated optical connector assembly configured as a receptacle  270  configured to be mated to the optical connector assembly  101  depicted in  FIG. 1 . It should be understood that receptacle  270  is provided as an example, and other configurations are also possible. The receptacle  270  may provide a communications port for an electronic device, such as, but not limited to, a personal computer, an electronic data storage device, a tablet computer, a mobile communications device, and an application specific computing device. The receptacle  270  illustrated in  FIG. 2  generally comprises a receptacle housing  272  that is coupled to a printed circuit board (PCB)  271 , which may be a PCB maintained within a housing of an electronic device. The exemplary receptacle housing  272  comprises mounting tabs  275 M which may be used to couple the receptacle housing  272  to the PCB  271 , such as by the use of solder or an adhesive. The receptacle housing  272  further comprises engagement tabs  275   a ,  275   b  that are configured to be removably engaged with the engagement tabs  113   a ,  113   b  of the plug housing  111  when the two components are coupled together. 
     The receptacle  270  further comprises a lens holder assembly  280  disposed within an enclosure defined by the receptacle housing  272  such that a gap  281  exists between an outer surface of the lens holder assembly  280  and an inner surface of the receptacle housing  272 . The gap  281  is configured to receive the plug housing  111  when the optical connector assembly  101  is inserted into the receptacle  270 . The illustrated lens holder assembly  280  comprises a seamless, planar mating face  276  that is configured to couple with the coupling surface  126  of the translating element  110  of the optical connector assembly  101 . Although the illustrated lens holder assembly  280  is depicted as a single-piece component in  FIG. 3 , embodiments are not limited thereto. As an example and not a limitation, the lens holder assembly  280  may comprise a multi-component assembly comprising a lens holder body and a recessed cover. Further, a multi-component receptacle lens holder assembly may also have groove alignment features as described above. 
     GRIN lenses  278  may be disposed within the lens holder assembly  280  such that end faces of the GRIN lenses  278  are planar to slightly inset with respect to the mating face  276  (e.g., within 0-50 μm). Other optical components may be utilized for the optical interface, such as refractive lenses, fiber stubs, fiber ends, waveguides, and the like. The GRIN lenses  278  (or other optical components) should be arranged within the lens holder assembly  280  for alignment with the GRIN lenses  122  (or other optical components) of the optical connector assembly  101  when the optical connector assembly  101  is mated with the receptacle  270 . 
     The lens holder assembly  280  additionally comprises a first bore  279   a  and a second bore  279   b  adjacent to the GRIN lenses  278  and configured to receive the first and second pin portions  135   a ,  135   b  of the optical connector assembly  101 , respectively, when the optical connector assembly  101  is inserted into the receptacle  270 . The first and second pin portions  135   a ,  135   b  of the optical connector assembly  101  and the first and second bores  279   a ,  279   b  of the receptacle  270  provide an optical alignment of the mated GRIN lenses  122 ,  278 . The first and second bores  279   a ,  279   b  may also comprise a sleeve  277   a ,  277   b  as a bushing element to reduce friction between the first and second pins portions  135   a ,  135   b  and the inner surface of the first and second bores  279   a ,  279   b . The sleeve may be made out of a lubricious material, such as, but not limited to, sintered bronze. Sleeves may also be provided in the first and second bores  121   a ,  121   b  of the translating element  110 . 
     First and second engagement prongs  282   a ,  282   b  may be provided adjacent to the lens holder assembly  280  in embodiments where the guide frame  130  of the optical connector assembly  101  defines first and second openings  140   a ,  140   b . The first and second engagement prongs  282   a ,  282   b  are configured to be slideably disposed within the first and second openings  140   a ,  140   b  of the optical connector assembly  101 . The illustrated receptacle  270  includes a first receptacle electrical contact  283   a  located on an underside surface of the first engagement prong  282   a , and a second receptacle electrical contact  283   b  located on an underside surface of the second engagement prong  282   b . The first and second receptacle electrical contacts  283   a ,  283   b  are configured to be slideably and electrically coupled to the first and second electrical contacts  141   a ,  141   b  of the optical connector assembly  101  when the first and second engagement prongs  282   a ,  282   b  are positioned within the first and second openings  140   a ,  140   b  of the optical connector assembly  101  to provide electrical connectivity between the optical connector assembly  101  and the receptacle  270 . It should be understood that, in other embodiments, the receptacle  270  may not include the first and second engagement prongs or the first and second receptacle electrical contacts. 
     As described in more detail below, when the optical connector assembly  101  is pushes into the receptacle  270  by the user, the coupling surface  126  of the translating element  110  contacts the mating face  276  of the lens holder assembly  280  such that the mating face  276  pushes the translating element  110  back into the connector housing  105 . 
     Referring now to  FIGS. 3A-3C , an exemplary optical connector subassembly  150  configured to be disposed within a connector enclosure defined by the connector housing  105  and the plug housing  111  is illustrated.  FIG. 3A  is a top perspective view of the exemplary optical connector subassembly  150 , while  FIG. 3B  is a bottom perspective view of the exemplary optical connector subassembly  150  depicted in  FIG. 3A .  FIG. 3C  is a top perspective view of the exemplary optical connector subassembly  150  depicted in  FIG. 3A  wherein the translating element  110  is translated back along the x-axis in a negative direction. 
     The optical connector subassembly  150  generally comprises the guide frame  130 , the translating element  110 , the unitary alignment pin  132 , and first and second bias members  136   a ,  136   b . The first and second arm portions  131   a ,  131   b  define an open region  151  in which the translating element  110  is positioned and may translate along the x-axis. The first and second arm portions  131   a ,  131   b  act as a guide for the translation of the translating element  110  such that it is prevented from substantial movement along the y-axis. Movement along the z-axis may be prevented by the interior surface of the plug housing  111 . The first and second arm portions  131   a ,  131   b  may include grooves or other features (not shown) to ensure slideable engagement with the translating element  110 . 
     The unitary alignment pin  132  is configured to be secured to the guide frame  130 . The unitary alignment pin  132  may mechanically be engaged with the guide frame  130  and/or be secured using a suitable adhesive.  FIGS. 4A and 4B  depict the exemplary unitary alignment pin  132  depicted in  FIGS. 3A-3C  in greater detail. The unitary alignment pin  132  may be configured as a precision wire that is bent, molded or otherwise worked into the desired configuration that provides the first pin portion  135   a  and the second pin portion  135   b , wherein the first and second pin portions  135   a ,  135   b  are substantially parallel with respect to one another, and separated by a distance d that corresponds to a distance between the first and second bores  121   a ,  121   b  of the translating element  110 . 
     The unitary alignment pin  132  illustrated in  FIGS. 4A and 4B  have a first bent portion  139   a  and a second bent portion  139   b  that transition a rear portion  134  of the unitary alignment pin  132  into first and second pin portions  135   a ,  135   b , respectively. The first and second bent portions  139   a ,  139   b  define two protruding portions that protrude away from the first and second pin portions  135   a ,  135   b  along the y-axis. These protruding portions (i.e., first and second bent portions  139   a ,  139   b ) are used as engagement mechanisms to couple the unitary alignment pin  132  to the guide frame  130  in the embodiment depicted in  FIGS. 3A-3C . Referring now to  FIGS. 3A-3C , the first and second arms  131   a ,  131   b  each comprise an engagement feature  137   a ,  137   b  proximate a base portion  143  of the guide frame  130 . The engagement features  137   a ,  137   b  protrude inwardly from the first and second arms  131   a ,  131   b  along the y-axis. The first and second bent portions  139   a ,  139   b  may be positioned between the engagement features  137   a ,  137   b  and the base portion  143  of the guide frame  130  (e.g., by an interference fit). In this manner, the unitary alignment pin  132  may be secured to the guide frame  130 , which is then disposed within the connector housing  105  and the plug housing  111 . The first and second bent portions  139   a ,  139   b  may also be secured to the engagement features  137   a ,  137   b  by a suitable adhesive, for example. 
     The rear portion  134  of the unitary alignment pin  132  of the illustrated embodiment is off centerline with respect to the z-axis. In other words, the rear portion  134  is in a plane that is different from the plane in which the first and second pin portions  135   a ,  135   b  are positioned. As shown in  FIGS. 3A-3C , the base portion  143  of the guide frame  130  may include a tab feature  133  that extends from the base portion  143  along the positive x-axis and is configured to support the rear portion  134  of the unitary alignment pin  132  as well as provide a stopping surface for the translating element  110  when it is retracted within the connector enclosure. Referring specifically to  FIG. 3A , the base portion  143  of the guide frame  130  further comprises a fiber groove  137  through which the optical fibers  104  may pass between the translating element  110  and the cable  102 . Because the rear portion  134  of the unitary alignment pin  132  is off centerline, the optical fibers  104  may pass under the rear portion  134  and through the fiber groove  137 . 
     The optical connector subassembly may further comprise first and second bias members  136   a ,  136   b . In the illustrated embodiment, the first and second bias members  136   a ,  136   b  are configured as compression springs, wherein the first bias member  136   a  is positioned about the first pin portion  135   a  and the second bias member  136   b  is positioned about the second pin portion  135   b . In alternative embodiments, the bias members may not be positioned about the first and second pin portions  135   a ,  135   b , a single bias member may be used, or more than two bias members may be used. The first and second bias members  136   a ,  136   b  bias the translating element  110  toward the opening  123  of the plug housing  111  such that the coupling surface  126  is accessible to a user for cleaning when the optical connector assembly  101  is in a disengaged state. 
     The exemplary translating element  110  includes first and second notch portions  128   a ,  128   b  that are adjacent to the first and second bores  121   a ,  121   b , respectively. The ends first and second arm portions  131   a ,  131   b  comprise a first stop feature  142   a  and a second stop feature  142   b , respectively. The first and second stop features  142   a ,  142   b  extend from the first and second arm portions  131   a ,  131   b  inwardly along the y-axis. The first and second notch portions  128   a ,  128   b  engage the first and second stop features  142   a ,  142   b  when the translating element  110  is biased forward along the x-axis, thereby maintaining the translating element  110  within the guide frame  130 . Other configurations to maintain the translating element  110  within the guide frame  130  may also be provided. 
     Referring now to  FIG. 3C , the optical connector subassembly  150  is depicted in an engaged state wherein the translating element  110  has moved back into the guide frame  130  negatively along the x-axis due to insertion of the optical connector assembly  101  (not shown in  FIG. 3C ) into a mated receptacle (not shown in  FIG. 3C ). Translation of the translating element  110  as shown in  FIG. 3C  exposes the first and second pin portions  135   a ,  135   b  for insertion into corresponding bores of the mated receptacle to optically align the optical components (e.g., GRIN lenses  122 ) with optical components of the receptacle to pass optical signals therebetween. Upon disconnection of the optical connector assembly  101  from the receptacle, the first and second bias members  136   a ,  136   b  may push the translating element back toward the front of the optical connector assembly  101 , as shown in  FIG. 1 . It is noted that in some embodiments, the unitary alignment pin may be utilized in optical connectors wherein the coupling surface (e.g., on the translating element) does not translate on the first and second pin portions. Rather, in such embodiments, the both translating element  110  and the unitary alignment pin  132  are free to move within the connector enclosure. For example, the unitary alignment pin  132  may be fixed within the translating element  110 , wherein the first and second pin portions  135   a ,  135   b  extend from the coupling surface  126  of the translating element  110 . As an example and not a limitation, the unitary alignment pins described herein may be utilized in Multiple-Fiber Push-On (MPO) connectors. 
     Unitary alignment pin configurations other than the configuration depicted in  FIGS. 2A-4B  are contemplated.  FIGS. 5-7  depict alternative unitary alignment pin configurations. It should be understood that embodiments are not limited to the unitary alignment pins depicted in the figures, as many other alternative configurations are possible.  FIG. 5  depicts a unitary alignment pin  232  having a first and second pin portion  235   a ,  235   b  that extend from a rear portion  234 . Unlike the unitary alignment pin  132  depicted in  FIGS. 4A and 4B , the unitary alignment pin  232  depicted in  FIG. 5  does not include the first and second bent portions  139   a ,  139   b . Rather, the unitary alignment pin  232  of  FIG. 5  comprises a “U” shaped precision wire. The unitary alignment pin  232  may be secured a guide frame in a variety of ways, such as placement in groove features and application of adhesive, for example. 
       FIG. 6  depicts an embodiment of a unitary alignment pin  332  having a single bent portion  339  that is proximate a center point of the rear portion  334 . The single bent portion  339  defines a protrusion that may mechanically mate with a corresponding engagement feature of the guide frame (e.g., by insertion of the single bent portion  339  into a hole or groove within the base of the guide frame). First and second pin portions  335   a ,  335   b  extend from the rear portion  334 . 
       FIG. 7  depicts an embodiment of a unitary alignment pin  432  having an off centerline rear portion  434 . Similar to the rear portion  134  of the embodiment depicted in  FIGS. 4A and 4B , the off centerline rear portion  134  is offset along the z-axis with respect to the first and second pin portions  435   a ,  435   b . The unitary alignment pin  432  depicted in  FIG. 7  does not include a bent portion as the embodiments depicted in  FIGS. 4A, 4B and 6 . The guide frame may be designed to accept and secure the unitary alignment pin  432 , such as inclusion of a groove to position the off centerline rear portion  434  as well as pass the optical fibers  104 . 
     Referring now to  FIG. 8 , the illustrated translating element  110  is a single-piece component that generally comprises a coupling surface  126 , a rear surface  124 , and one or more optical components  122  (e.g., GRIN lenses) maintained within bores  127  that extend from the coupling surface  126  to the rear surface  124 . Ends of the optical components  122  are exposed at least at the coupling surface  126 . The translating element  110  may be shaped such that it may translate within the plug housing  111 . As described above, the translating element  110  may include a first notch portion  128   a  and a second notch portion  128   b  for engaging the first and second arm portions  131   a ,  131   b.    
     In alternative embodiments, the translating element is a two-piece component employing a cover and alignment grooves to maintain optical components, such as GRIN lenses.  FIGS. 9A-9C  depict a two-piece translating element  210  in partially exploded and assembled views. The two-piece translating element  210  comprises an upper component  225  and a lower component  290  configured as a cover that fits within an opening  235  defined by the upper component  225 . The assembled two-piece translating element  210  has a similar shape and configuration as the single-piece translating element  110  depicted in  FIGS. 2A-3C . Similar to the single piece translating element  110 , the two-piece translating element  210  has a coupling surface  226  that interfaces with a mated optical connector and a rear surface  229  that receives the optical fibers  104 . 
     The upper component  225  comprises the first and second through-holes  221   a ,  221   b  through which the first pin and second pin may be positioned, as described above. The upper component  225  further comprises inwardly angled walls  260  and  261  that slope from a bottom surface of the upper component to an inner surface  223 . The inwardly angled walls  260 ,  261  define an opening  235  configured to receive the lower component  290 . The upper component  225  may further include the first and second notch portions  228   a ,  228   b  for engaging the first and second arm portions  131   a ,  131   b.    
     The inner surface  223  of the upper component  225  comprises one or more grooves  227  that extend from the coupling surface  226  to the rear surface  229 . An optical component  222 , such as a GRIN lens, is positioned within each groove  227 . The two-piece translating element  210  may enable easier placement of the optical components  222  because of the access to the grooves  227  provided by the opening  235 . The grooves  227  may be of any appropriate geometry. In the illustrated embodiment, the grooves  227  have straight walls and a curved floor to accommodate the cylindrical optical components  222 , and the inner surface  223  is planer with respect to a top surface of the optical components  222 . However, other configurations are also possible, such as V-shaped grooves or rectangular grooves. The optical components  222  may be secured within the grooves  227  by a suitable adhesive, for example. 
     The lower component  290 , which acts as a cover for the optical components  222 , has an upper, optical component contacting surface  292 , a bottom surface  293 , and two angled walls  294 ,  295  that are configured to interface with inwardly angled walls  260 ,  261  of the upper component  225 , respectively. The lower component also has a coupling surface  226 ′ and a rear surface  229 ′. The lower component  290  may be positioned within the opening  235  of the upper component  225  after positioning the optical components  222  within the grooves  227  such that the optical component contacting surface  292  contacts the bottom surface  293  of the upper component  225  and the optical components  222 , and angled walls  294 ,  295  of the lower component  290  contact inwardly angled walls  260 ,  261  of the upper component  225 , respectively ( FIG. 9C ). The lower component  290  may be secured to the upper component  225  by a suitable adhesive. 
     The coupling surface  226 ′ of the lower component  290  should be substantially planar with respect to the coupling surface  226  of the upper component  225  and the end faces  428  of the optical components when the lower component  290  is mated to the upper component  225 . In one embodiment, the coupling surface  226 ′ of the lower component  290 , the coupling surface  226  of the of the upper component  225 , and the end faces of the optical components  222  are within 10 μm of each other. 
       FIG. 10  depicts a translating element  510  as described above, except that one of the bores within the coupling surface  526  is configured as a slot. In the illustrated embodiment, the second bore  521   b  is wider than the first bore  521   a . A receptacle may also include a lens holder assembly having two bores where one bore is wider than the other. 
     It should now be understood that embodiments described herein are directed to cable assemblies, optical connector assemblies, and optical connector subassemblies employing a unitary alignment pin on which a translating element comprising an optical interface is positioned. The unitary alignment pin may reduce assembly complexity as well as reduce overall cost of the connector assembly. 
     As non-limiting examples, the GRIN lenses disclosed herein may comprise a generally cylindrical glass member having a radially varying index of refraction, the glass member having a length such that the lens has a pitch of less than about 0.23. As used herein, the pitch length of the lens, Lo, is 2π/A; the fractional pitch, or, hereafter, pitch, is L/Lo=LA/2π, where L is the physical length of the lens. In various embodiments, the pitch is between about 0.08 and 0.23, such as, for example, lenses having pitches of 0.22, 0.21, 0.20, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, 0.11, 0.10, 0.09 and 0.08. Some embodiments relate to small diameter lenses, such as lenses having a diameter less than or equal to about one (1) mm, for example, 0.8 mm. In certain embodiments, lenses having a diameter less than about 1 mm are operative to produce a beam having a mode field diameter between about 350 μm and 450 μm when illuminated with a beam having a mode field diameter of about 10.4 μm. 
     Examples of optical devices that can interface with the GRIN lenses disclosed in the lens holder assemblies disclosed herein include, but are not limited to, fiber optic collimators, DWDMs, OADMs, isolators, circulators, hybrid optical devices, optical attenuators, MEMs devices, and optical switches. 
     Further, as used herein, it is intended that terms “fiber optic cables” and/or “optical fibers” include all types of single mode and multi-mode light waveguides, including one or more optical fibers that may be upcoated, colored, buffered, ribbonized and/or have other organizing or protective structure in a cable such as one or more tubes, strength members, jackets or the like. The optical fibers disclosed herein can be single mode or multi-mode optical fibers. Likewise, other types of suitable optical fibers include bend-insensitive optical fibers, or any other expedient of a medium for transmitting light signals. An example of a bend-insensitive, or bend resistant, optical fiber is ClearCurve® Multimode fiber commercially available from Corning Incorporated. Suitable fibers of this type are disclosed, for example, in U.S. Patent Application Publication Nos. 2008/0166094 and 2009/0169163, the disclosures of which are incorporated herein by reference in their entireties. 
     Many modifications and other embodiments of the embodiments set forth herein will come to mind to one skilled in the art to which the embodiments pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the description and claims are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. It is intended that the embodiments cover the modifications and variations of the embodiments provided they come within the scope of the appended claims and their equivalents. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.