Patent Publication Number: US-10782494-B2

Title: Advanced fiber-optic contact and method

Description:
RELATED APPLICATIONS 
     This application is a continuation application of copending U.S. patent application Ser. No. 15/920,138 filed on Mar. 13, 2018, which is a continuation application of U.S. patent application Ser. No. 15/050,444 filed on Feb. 22, 2016 and issued as U.S. Pat. No. 9,946,041 on Apr. 17, 2018, which is a divisional application of U.S. patent application Ser. No. 13/562,267 filed on Jul. 30, 2012 and issued as U.S. Pat. No. 9,297,972 on Mar. 29, 2016, the disclosures of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     The present invention is generally related to the field of fiber optic connectors and, more particularly, to an advanced fiber optic contact that includes active components. 
     An electronic rack assembly can define one or more positions each of which is configured for receiving a module. The rack assembly can include a connection back plane such that each module can include a complementary connection arrangement that blind-mates to the connection back plane when each module is installed. In this way, a large number of interface connections can simultaneously be made or broken such that each module can be conveniently installed and/or replaced. Such rack assemblies, by way of example, have become popular in the avionics field. 
     Data rates have increased between modules, at least in the avionics field, due to a desire to provide for high-definition digital video for in-flight entertainment systems, cockpit displays, AFDX (Avionics Full Duplex Switched Ethernet) interconnect protocol and the like. Accordingly, avionics systems and aircraft manufacturers hope to take advantage of the extremely high bandwidth and light weight, ease of routing, and immunity to electromagnetic interference (EMI) offered by the optical fiber transport medium. There is a need, therefore, for avionics rack assemblies and associated modules to accommodate fiber optic connections therebetween. Some standards such as the ARINC 801-804 standards, by way of non-limiting example, detail specifications for fiber-optic connector interfaces that can be inserted into an ARINC module connector, as well as into rack connectors. These standards pertain to passive optical connectors for blind-mate interfaces that are inserted into industry-standard “Size 8” cavities, so-named due to the approximate 8 mm diameter of the cavity. 
     One approach that has been taken on the module side in such systems employs an optical converter component inside of the module. The optical converter is mounted on a printed circuit board and can support an optical fiber that serves as a pigtail leading to an ARNIC 801 passive fiber-optic connector for connection to the module external interface. During assembly of a module such as an avionics module, fibers associated with such optical converter modules must be routed very carefully through the module between the optical converters and the module interface. This is fundamentally an operation not suited to automated assembly techniques, and requires a relatively skilled technician. In this regard, optical fibers are easily susceptible to damage due to excessively small bend radius, high heat, handling errors, and the like. Therefore, as packaging densities of avionics modules have increased, the routing of optical fibers inside of a module has become problematic. Since manufacturing of modules incorporating both optical fibers and electrical cabling between circuit boards requires operators with specialized training and skill to handle, terminate, dress, and restrain the optical fibers so that they survive the rigors of the aerospace environment, assembly costs for avionics manufacturers are driven upward and the number of available contract manufacturers is limited to those with fiber-optics manufacturing expertise. While the example of “avionics modules” is used here as a primary example, it is noted that the problems described herein with realizing fiber-optic interfaces in electronics modules pertain to application in many other fields, and the usefulness of the invention described herein is therefore not limited to the avionics industry. 
     Another prior art approach attempts to provide for the use of optical fiber, for example, in an overall avionics environment external to modules while eliminating the need to route optical fiber within the avionics module itself. Generally, this approach moves the optical converter into the module interface. One example of a prior art attempt that adopts this approach is seen in U.S. Pat. No. 7,690,849 (hereinafter, the &#39;849 Patent). The patent teaches an “active optical contact” for use in size-8 cavities in ARINC connectors and incorporates its conversion hardware entirely into the size-8 contact body. 
     In the &#39;849 Patent, the optical converter is soldered to a longitudinally-mounted printed circuit board (PCB). The same PCB supports electrical interface pins on an opposing end thereof having internal ends which are also soldered to the PCB. The entire PCB is then sealed into a contact body using an epoxy potting material such that projecting or external ends of the interface pins project outwardly for purposes of externally electrically interfacing the contact. Applicants recognize that this design is problematic for a number of reasons. For example, the optical connection of the optical converter is positionally fixed and cannot float or move with resilient axial biasing to effectively accommodate blind-mating, for example, in accordance with ARINC requirements that are set forth for passive fiber-optic connectors. At the same time, the configuration of the electrical interface pins, for external electrical connection, is constrained based on connecting to one or both surfaces of the PCB. The limitations on pin location can become serious when it is remembered that the diameter of the contact body can be very small in the first instance. Another concern arises, based on this design, when it is desired to form solder connections to the projecting ends of the electrical interface ends since the soldering process used to attach the unit to an external PCB is constrained to the use a solder having a significantly lower melting temperature than the solder used to attach the internal ends of the pins to the PCB. This is especially problematic when non-leaded solders are mandated to satisfy the requirements of RoHS (Reduction of Hazardous Substances) act of the European Union. These concerns as well as related concerns may be addressed at one or more appropriate points hereinafter. 
     The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings. 
     SUMMARY 
     The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other improvements. 
     In general, embodiments, systems and methods are described in relation to an opto-electronic contact. In one aspect of the present disclosure, the contact includes an opto-electronic converter including a converter length extending between opposing first and second ends. The first end being configured for removable optical engagement with a fiber optic connector, or other suitable component, and the second end including a converter electrical connection arrangement. A barrel housing defines an interior cavity characterized by an elongated length defining an elongation axis extending between opposing first and second barrel openings for receiving the opto-electronic converter in the interior cavity to provide for limited relative movement between the barrel housing and the opto-electronic converter with the first end of the opto-electronic converter supported in the interior cavity proximate to the first barrel opening for external optical engagement to the opposing fiber optic connector via the first barrel opening. A flexible circuit board assembly includes an internal electrical connection end, an external electrical connection end and an elongated length extending therebetween. The internal connection end electrically engages the converter electrical connection arrangement of the opto-electronic connector and the external connection end is fixedly positioned proximate to the second barrel opening for external electrical connection to the contact such that the external connection end is positioned on the elongation axis at a distance from the second end of the opto-electronic connector that is less than the elongated length of the flexible circuit board and the elongated length is captured within the interior cavity of the barrel housing. 
     In another aspect of the present disclosure, an opto-electronic contact includes an active opto-electronic converter including a converter length extending between opposing first and second ends to define a converter axis with the first end being configured for removable optical engagement with a fiber optic connector. A barrel housing defines an interior cavity having an elongated length extending between opposing first and second barrel openings to define an elongation axis and having the opto-electronic converter captured in the interior cavity for external optical engagement to the fiber optic connector via the first barrel opening for relative movement of the converter axis along the elongation axis, transverse thereto, and oblique thereto to accommodate mating tolerances responsive to engaging the fiber optic connector. 
     In still another aspect of the present disclosure, a method is disclosed to compensate for mating tolerances when mating an opto-electronic contact to an opposing fiber optic connector. The method includes configuring a barrel housing defining an interior cavity having an elongated length extending between opposing first and second barrel openings to define an elongation axis. An opto-electronic converter is supported in the interior cavity in a way that isolates the converter from mating misalignment responsive at least to engaging the opposing fiber optic connector by capturing the converter in the interior cavity for external optical engagement to the fiber optic connector via the first barrel opening for relative movement of the converter axis along the elongation axis, transverse thereto, and oblique thereto to accommodate mating tolerances responsive to engaging the opposing fiber optic connector. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
       Exemplary embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be illustrative rather than limiting. 
         FIG. 1  is a diagrammatic view, in perspective of an embodiment of an opto-electronic contact that is produced according to the present disclosure. 
         FIG. 2  is a diagrammatic, partially cutaway view, in elevation, of an embodiment of a standard connector system supporting the opto-electronic contact of  FIG. 1  for blind mating with an opposing connector. 
         FIG. 3  is a diagrammatic exploded view, in perspective, of an embodiment of contact  10  of  FIG. 1 . 
         FIG. 4  is a further enlarged diagrammatic cutaway view, in perspective, of an embodiment of a barrel housing that can form part of the contact of  FIGS. 1-3 . 
         FIG. 5  is a diagrammatic view, in perspective, of an assembly including an opto-electronic converter and flexible circuit board assembly that can be used in embodiments of the contact of the present disclosure such as, for example, those of  FIGS. 1-3 . 
         FIG. 6  is another diagrammatic view, in perspective, of the assembly of  FIG. 5  shown as partially cutaway to reveal details of its internal structure. 
         FIGS. 7 and 8  are diagrammatic views, in perspective, showing details of a flexible circuit board assembly that can be used in embodiments of the contact of the present disclosure. 
         FIG. 9  is a diagrammatic exploded view, in perspective, of an embodiment of the flexible circuit board assembly of the present disclosure, shown here to illustrate details with respect to the use of a flexible circuit board substrate in a sandwiched/layered overall structure. 
         FIG. 10  is a diagrammatic view, in perspective, of another embodiment of an opto-electronic converter according to the present disclosure. 
         FIG. 11  is another diagrammatic view, in perspective, of still another embodiment of an opto-electronic converter according to the present disclosure. 
         FIG. 12  is a diagrammatic partially cutaway view, in perspective, showing the internal structure of the opto-electronic converter of  FIG. 11  in relation to selected external optical elements. 
         FIG. 13  is a diagrammatic partially cutaway view, in perspective, illustrating an assembled embodiment of an opto-electronic contact according to the present disclosure using, by way of non-limiting example, the opto-electronic converter of  FIGS. 11 and 12 . 
         FIG. 14  is a diagrammatic view, in perspective, illustrating an assembled embodiment of an opto-electronic contact according to the present disclosure including a flexible circuit board extension which extends outside of a barrel housing of the contact for external electrical connection purposes. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the described embodiments will be readily apparent to those skilled in the art and the generic principles taught herein may be applied to other embodiments. Thus, the present invention is not intended to be limited to the embodiment shown, but is to be accorded the widest scope consistent with the principles and features described herein including modifications and equivalents, as defined within the scope of the appended claims. It is noted that the drawings are not to scale and are diagrammatic in nature in a way that is thought to best illustrate features of interest. Descriptive terminology may be used with respect to these descriptions, however, this terminology has been adopted with the intent of facilitating the reader&#39;s understanding and is not intended as being limiting. Further, the figures are not to scale for purposes of illustrative clarity. 
     Turning now to the figures wherein like components may be designated by like reference numbers throughout the various figures, attention is immediately directed to  FIG. 1  which is a diagrammatic view, in perspective, illustrating an embodiment of an opto-electronic contact that is produced in accordance with the present disclosure and generally indicated by the reference number  10 . Contact  10  can be either a transmitter optical subassembly (TOSA) or a receiver optical subassembly (ROSA). In the instance of the former, the contact can include, for example, a laser diode and associated drive electronics while, in the instance of the latter, the contact can include, for example, a photodiode and associated electronics. Generally, contact  10  can include a barrel housing  20  having an elongated length that can define an elongation axis  22  that is illustrated by a dashed line. The housing can be formed having indexing features such as, for example, one or more flats  24  for use in embodiments that benefit from indexing of the rotational orientation, as will be further discussed. While the housing and overall contact  10  may be described below in terms of satisfying the standards to meet a particular type of specification, it should be understood that the assembly can be configured to satisfy any suitable connector specification, either currently in existence or yet to be developed. Housing  20  can be configured to receive an alignment sleeve retainer cap  26 , for example, using threaded engagement and having an O-ring groove that receives an O-ring  28 . An opposing end of housing  20  can support an external electrical connection interface  30  which, in the present example, includes an arrangement of electrically conductive pins  32 . As will be seen, pins  32  can be arranged in any suitable geometric pattern. In other embodiments, electrical interfacing can be accomplished using suitable expedients other than electrically conductive pins. In the embodiment of  FIG. 1 , straight electrical pins are shown for clarity, but it is noted that some or all of the pins may be replaced with other high-speed electrical interconnection means, such as coax, twinax, or quadrax interconnections, or a flexible circuit board, as appropriate for the signal type being transmitted. The barrel housing and alignment sleeve retainer cap can be formed from suitable materials including, but not limited to stainless steel or aluminum. 
     Referring to  FIG. 2 , in conjunction with  FIG. 1 , the former is a diagrammatic, partially cutaway view that illustrates a standard connector system, generally indicated by the reference number  60 , which is suitable, by way of non-limiting example, for use in the avionics and aerospace industries. In particular, system  60  can conform to the well-known ARINC 600 standard and includes a receptacle connector  64  that defines three bays (not shown) for purposes of receiving inserts that can support electrical and/or optical interconnections, even though the original intent of the standard was to support electrical interconnections. According to the standard, a plug connector  66  can be received in each bay of receptacle connector  64 , by way of blind mating, having the receptacle connector mounted on a module and plug connector  66  mounted in a bay of a rack assembly. In the present example, receptacle connector  64  can support a plurality of opto-electronic contacts  10 , only one of which is shown. In an embodiment, one insert in the receptacle connector can support eleven instances of opto-electronic contact  10 . Electrical connection interface  30  of each contact can be electrically connected, for example, to a printed circuit board  70  that can be located in a module such as an avionics module. Contact  10  is received in a cavity  74  which can be referred to, in the present example, as a size-8 cavity that can comply with the ARINC 801 standard. As noted above, this standard pertains to passive optical connectors for blind-mate interfaces having a diameter of approximately 8 mm. Opto-electronic contact  10  includes an annular shoulder  80  that is seatable against an annular floor within the receptacle cavity. The contact can be inserted from a front or exterior side  82  of receptacle connector  64  (i.e., “front-release” type) such that an annular retention clip  86  removably snaps into position over shoulder  80  to retain the contact within the receptacle cavity. Other connector types can also make use of this type of contact, in either front-release or rear-release configurations. 
     Referring to  FIG. 2 , plug connector  66  defines a cavity that can receive, by way of non-limiting example, an opposing contact  90 . The opposing contact can be optical or opto-electronic. An opposing optical contact can be “passive”, as in an optical fiber ferrule. An opposing opto-electronic contact can be “active”, incorporating electronics and/or opto-electronic devices, for example, as taught herein. In the present example, the opposing contact supports a fiber optic cable  92  that is terminated by a ferrule  94  to support an optical fiber such that the ferrule tip can be directly biased in physical contact against an opposing ferrule tip to provide for optical communication between two optical fibers as detailed, for example, in ARINC 801. It should be appreciated that, while contact  90  can be characterized as a fiber optic contact, a wide variety of physical outlines and/or standards can be employed for contact  90  while remaining within the scope of the present disclosure so long as the contact is configured for optical engagement. In some embodiments, contact  90  can be an active contact which can even be produced according to the teachings that have been brought to light hereinafter. In the present example, contact  90  is configured to engage an opposing ferrule in receptacle connector  64  that is identified by the reference number  100  and is provided as part of contact  10 , as will be further described. For the moment, it is sufficient to note that ARINC 801 sets forth details relating to the positional relationship between the opposing ferrules as the opposing contacts are partially engaged and then reach full engagement. Other specifications, such as MIL-T-29504, MIL-C-28876 and others also describe similar detailed relationships between the opposing ferrules in optical contacts. In the present example, ferrule  100  does not form part of a passive fiber optic connection but rather forms part of opto-electronic contact  10 , as will be further described, with respect to subsequent figures. 
     Attention is now directed to  FIG. 3  which is a diagrammatic exploded view, in perspective, of an embodiment of contact  10  that is provided for purposes of illustrating the various components that make up its overall structure. An opto-electronic converter  200  is appropriately configured to generate light in the instance of a TOSA embodiment or to receive light in the instance of a ROSA embodiment, as described above. The converter, by way of example, can include electrical interface pins  202  for external electrical connection. The converter also includes ferrule  100  supported for optical communication with an internally supported component which is shown in a subsequent figure. Ferrule  100  can be formed, for example, as a molded ceramic from any suitable material. A precision alignment sleeve  204  can be provided in a split configuration to be slidingly received on ferrule  100 , interposed between alignment sleeve retainer cap  26  and the ferrule itself. The alignment sleeve can have a length along elongation axis  22  ( FIG. 1 ) that is longer than the protruding length of ferrule  100  such that the tip of the ferrule is housed and supported within sleeve  204 . In this regard, an outward end of the precision alignment sleeve is identified by the reference number  210  in  FIG. 2 . Thus, opposing ferrule  94  extends into alignment sleeve  204  when contact  90  is mated with contact  10  with the intent of physically contacting ferrule  100 , and thus enabling optical communication between the tips of the respective ferrules.  FIG. 4  is a further enlarged and partially cut-away view of barrel housing  20  shown here to illustrate further details of its structure. In particular, the barrel housing defines an annular groove  214  that is configured for supporting opto-electronic converter  200  in a manner that is yet to be described. 
     Referring now to  FIG. 5 , attention is now directed to further details with respect to opto-electronic converter  200  and a flexible circuit board assembly  300  that is used to interface the opto-electronic converter to the outside world via external electrical connection interface  30  which, in an embodiment, supports an arrangement of electrically conductive pins  32 . In this regard, a particular pin  32 ′ can include an enlarged diameter or other suitable feature for indexing purposes. The flexible circuit board assembly includes an internal electrical connection end  304  for connection to electrical interface pins  202  of the converter and an external electrical connection end  310  for connection to electrically conductive pins  32 . A middle section  314  can be supported transversely or orthogonally to an elongation axis  316 , shown as a dashed line, of the converter using the flexible circuit board assembly. Generally, elongation axis  316  of the converter can coincide with elongation axis  22  of the barrel housing when the converter is installed in the barrel housing, although this is not a requirement. As will be further described, however, mating contact  10  with opposing contact  90  typically produces misalignment between these two axes since both the contact and the opposing contact are configured to float in a way that provides for relative movement or float that accommodates this misalignment to avoid damaging components of the contact and/or components of the opposing contact. In the present embodiment, the flexible circuit board assembly includes a first flex extension  320 , extending from internal electrical connection end  304  to middle section  314 , and a second flex extension  322  extending from external electrical connection end  310  to middle section  314 . First flex extension  320 , in the present embodiment, includes two 180° bends such that the extension passes transversely through the elongation axis of the overall assembly whereas second flex extension  322  defines one 180° bend such that a total of 540° of bending is defined. In this regard, however, it should be appreciated that the flex extensions can be configured in any suitable manner and the configuration is not limited to the described embodiment. As seen in  FIG. 1 , the opto-electronic converter and flexible circuit board assembly are configured to be received in the interior cavity of barrel housing  20  such that pins  32  extend outward from the barrel housing for purposes of forming an external electrical connection, although in other embodiments such an external electrical connection can be formed in different ways, as will be further described. When installed, the flexible circuit board assembly is fixedly attached at internal connection end  304  and external connection end  310  such that converter  200  can move relative to barrel housing  20 . In this regard, external connection end  310  can be fixedly supported at the electrical connection end of the barrel housing in a suitable manner such as, for example, using an adhesive material or potting compound which can also form an environmental seal between the barrel housing and the external electrical connection end. Suitable adhesives and/or potting compounds include, but are not limited to epoxy, and RTV sealant as well as suitable combinations thereof. At the same time, and as will be further described, flex extensions  320  and  322 , and middle section  314 , depending on the extents of any potting compound that is used, can move relative to the barrel housing responsive to relative movement of converter  200 . It should be appreciated that flex extension  320  can be configured, in an embodiment, to provide for more than adequate relative movement even when middle section  314  and an initial portion of flex extension  320  proximate to the middle section are encased in potting compound wherein potting compound  323  is indicated by a dashed line in  FIG. 5 . 
     Referring collectively to  FIGS. 3-5 , relative movement between barrel housing  20  and converter  200 , in addition to the use of flexible circuit board assembly  300 , is facilitated by the manner in which the barrel housing supports the converter. In the present embodiment, a retention clip  400  includes an annular configuration that is receivable around a collar  402  (best seen in  FIG. 3 ) that is defined between a main body  408  of the converter and a flange  410  which terminates the collar. An indexing feature  412 , indicated by dashed lines, can be formed, for example, as part of a peripheral outline of the converter body to cooperate with a complementary feature that can be defined on the interior of the barrel housing. Examples of suitable indexing features include but are limited to one or more slots or projections arranged around the periphery of the converter body. Such indexing is useful, for example, when an angle polished ferrule (APC) is used as ferrule  100  for purposes of establishing the rotational orientation of the converter, and thereby the ferrule, to within some tolerance of a known position. Indexing feature(s)  412  can cooperate with flats  24  (see  FIGS. 1, 3 and 4 ) to ensure that the opto-electronic contact is placed into a known rotational orientation in confronting opposing contact  90 , as seen in  FIG. 2 . The retention clip can be formed, for example, from a suitably resilient material such as, for example, spring steel, or beryllium-copper in a “C” configuration such that the retention clip can be installed on the collar by spreading the opening in the C shape. The retention clip is shown as installed in  FIG. 5  and is slidingly received on collar  402 . The inside diameter of the retention clip can be sized to provide a suitable amount of clearance relative to the collar such that the plane of the retention clip can twist and form an angle relative to elongation axis  316  of the converter for reasons which will be made evident. In the present embodiment, a coil spring  414  is also installed on collar  402  such that the coil spring is captured between collar  402  and retention clip  400 . Converter  200  can be received in the cavity of barrel housing  20  with retention clip  400  biased against a shoulder  416  ( FIG. 4 ) of the barrel housing. In this way, movement of ferrule  100  responsive to engagement/disengagement with an opposing contact allows the converter to move relative to the barrel housing in any manner that is needed to accommodate proper optical engagement with an opposing ferrule. For example, the converter can move axially along elongation axis  22  of the barrel housing such that the tip of ferrule  100  is resiliently biased against the tip of an opposing ferrule. Such axial movement can cause dynamic compression and/or expansion of spring  414 . The converter can also move in any direction radially transverse to axis  22  of the barrel housing. Further, as shown in  FIG. 5 , ferrule  100  can twist or rotate to form an angle α that is defined between elongation axis  316  of the converter and elongation axis  22  of the barrel housing. This angle can be up to 10 degrees. With regard to this feature, Applicants note that nonzero values of angle α are typically observed when opposing contacts are properly mated. Furthermore, the angle α should be able to dynamically self-adjust in response to the opposing action of the two optical ferrules  94  and  100  through the split-sleeve  204  during engagement, until full contact-to-contact optical mating is achieved. Thus, the converter is supported effectively only by retention clip  400  and centered, at least within some tolerance, within the cavity that is defined by the barrel housing. It is noted that the converter and clip along with any associated spring are installed from the enlarged diameter end of barrel housing  20 . It is further noted that in certain embodiments, spring  414  is not used, in which case the converter has minimal axial float along elongation axis  316 , but still may move in any direction radially transverse to axis  22 , or can form angle α between elongation axis  316  of the converter and elongation axis  22  of the barrel housing. This type of embodiment can be acceptable in situations where the opposing contact incorporates adequate spring travel and force to cause effective physical contact of the opposing optical ferrules in the fully-mated condition, under all conditions, including mechanical tolerances, thermal expansion, vibration, shock, and the like. 
       FIG. 6  is another diagrammatic view, in perspective, of the embodiments of opto-electronic converter  200  and flexible circuit board assembly  300  shown in  FIG. 5 . In this instance, however, converter  200  is shown as partially cut-away to reveal details of its internal structure. In particular, converter  200  includes an optical converter element  460  such as, for example, a laser diode or solid state detector that is supported in an internal housing  464  and suitably electrically interfaced to interface pins  202  of the converter. Housing  464 , in an embodiment, can be in the form of a well-known Transistor Outline (TO) package such as a TO-46 package that supports a lens  470 . While any suitable lens can be used, the present embodiment illustrates the use of a ball lens with ray traces  474  included to illustrate optical coupling and focusing between optical converter element  460  and a confronting end of an optical fiber  480  that is supported by ferrule  100 . In the present embodiment, the distal/exterior end of fiber  480  and ferrule  100  are flat polished while the interior end can be angle-polished, for example, at a suitable angle such as at least approximately 8 degrees to direct reflections outside of the overall optical path that is defined by the assembly. 
     Attention is now directed to  FIGS. 7 and 8  which are diagrammatic views, in perspective, of flexible circuit board assembly  300  showing each of the opposing major surfaces of the assembly in a planar form for purposes of illustrating details of its structure. In this regard, it should be appreciated that first flex extension  320  between internal electrical connection end  304  and middle section  314  is significantly longer than second flex extension  322  between external electrical connection end  310  and middle section  314  to support bending as shown in  FIGS. 3, 5 and 6 , although other bending arrangements may be found to be suitable. Middle circuit section  314  can support an amplifier  500 , as seen in  FIG. 7 . In the case of opto-electronic converter  200  including a light emitting element such as a laser diode, amplifier  500  can be a driver amplifier. On the other hand, in the case of opto-electronic converter  200  including a light detector or receiver element such as a photodiode, amplifier  500  can be a limiting amplifier. The middle section on the side opposite of amplifier  500 , as seen in  FIG. 8 , can support any suitable arrangement of electrical components  504  such as, for example, passive components such as, for example, passive electrical components for purposes which include but are not limited to decoupling or impedance-matching of data transmission lines, biasing of the opto-electronic device, and electrical tuning or filtering. In the instance of a driver amplifier, the electrical connection to external connection end  310  can be by way of differential drive such that at least some of passive components  504  can be used to terminate the differential drive arrangement in its characteristic impedance. For a laser diode that is intended to operate over a wide temperature range, at least some of components  504  can be passive components that are directed to providing temperature compensation. External electrical connection end  310  supports electrically conductive pins  32  which can be laid out in any suitable manner, as will be further discussed. In an embodiment, pin  32 ′ can serve as a ground pin and be of an enlarged diameter or any other suitable shape/configuration relative to the other pins to serve an indexing function. As seen in  FIG. 8 , the external electrical connection end can support electrical components  510  such as, for example, passive electrical components for purposes which can include, but are not limited to de-coupling, tuning and/or impedance-matching of the electrical data transmission lines, and filtering of electrical input power lines. Internal electrical connection end  304  is configured to engage the electrical interface arrangement of opto-electronic converter  200  such as, for example, interface pins  202  ( FIG. 3 ) using a pattern of through holes  512  each of which can be surrounded by an electrically conductive trace. In an embodiment, pins  202  can be soldered to internal electrical interface arrangement  304 . In some embodiments, the internal electrical interface arrangement can support electrical components  514  ( FIG. 7 ) such as, for example, passive electrical components for purposes which include but are not limited to decoupling or impedance-matching of data transmission lines, biasing of the opto-electronic device, and electrical tuning or filtering. 
     Attention is now directed to  FIG. 9 , which is a diagrammatic exploded view, in perspective, of an embodiment of flexible circuit board assembly  300 , shown here to illustrate still further details of its structure. In particular, a flexible circuit substrate  520  includes an elongated length  522  that can extend along the full end-to-end length of the assembly. Flexible substrate  520  can be formed from any suitable material such as, for example, polyimide or “Kapton”, and can support electrically conductive traces  524  (diagrammatically shown) that are laid out in a desired pattern for purposes of forming electrical connections. In the present embodiment, a sandwich construction is applied for purposes of forming internal electrical connection end  304 , external connection end  310 , and middle section  314 . Internal connection end  304  can include first and second circuit boards  530   a  and  530   b  arranged on opposing sides of flexible substrate  520 . Boards  530   a  and  530   b  can be formed from any suitable material such as, for example, FR4 and patterned with electrically conductive traces for electrical communication with cooperative electrically conductive traces defined on flexible substrate  520 . Through holes  534 , with surrounding electrically conductive traces, can be arranged to align with through holes  512  of the flexible substrate to receive electrically conductive pins  202  of the opto-electronic converter. Boards  530   a  and  530   b  can be fixedly attached to the flexible substrate, for example, by solder and/or suitable adhesives. In another embodiment, the internal electrical connection end of the flexible substrate can be attached to pins  202  without using rigid circuit boards or using only one of the rigid circuit boards. In this regard, flexible substrate  520  can directly support electrical components  514 . Moreover, in another embodiment, the entire circuit board may be comprised of a flexible substrate only, with no rigid sections, onto which electrical amplifier  500  and other electrical components  514  may be directly affixed by solder and/or suitable adhesives. 
     Still referring to  FIG. 9 , external connection end  310  can be configured including opposing rigid circuit boards  550   a  and  550   b  in the manner described above for the internal connection end. Openings  554  defined in the external connection end of the flexible substrate align with openings  556  of boards  550   a  and  550   b  to receive pins  32  and  32 ′ subsequent to attachment of boards  550   a  and  550   b  to the flexible substrate. In an embodiment, pins  32  and  32 ′ can be installed in the external connection end using a pressed-fit. In such an embodiment, the pins can include an annular shoulder  558  and a patterned region  560  such as, for example, a splined configuration which accommodates the pressed fit, or a “swage” type of construction. After the pins are pressed into the external connection end, solder can be applied to electrically connect the pins to electrically conductive patterns on each of boards  550   a  and  550   b  as well as to the pattern on flexible substrate  520 . It should be appreciated that the use of a pressed-fit, in the present embodiment, establishes the pin positions in a way that is resistant to shifting of the pins during soldering. In this regard, maintaining the pins in predetermined positions or at least within some desired tolerance from such predetermined positions can ensure ease of installation of the pins of interface  30  into circuit board  70  of  FIG. 2  while avoiding damage to the pins and/or circuit board  70 . Another benefit is provided with respect to flexibility in the installation pattern of the pins of interface  30 . Since the pins are installed through the major surfaces of boards  550   a  and  550   b , there are few constraints on the pin locations. In contrast, the &#39;849 patent attaches pins to circuit board edges in a highly constrained way which limits the arrangement of the pins to one row or two narrowly spaced apart rows that are spaced apart by only the thickness of the printed circuit board. In this regard, the reader is reminded that the diameter of barrel housing  20 , in the instance of ARINC 801, can be very small at approximately only approximately 0.275 inch or 6.97 mm which serves to further increase concerns that arise through limitations imposed on pin locations. Also, as described in the &#39;849 patent, the attachment of the pins to the edges of the internal circuit board using solder is much more susceptible to damage by excessive heating of the pins during soldering to external circuit board  70 , with permanent damage to the contact in the form of electrical open circuits or short circuits possible due to reflowing of the solder internal to the contact. This possibility is mitigated by the press-fit or swage construction brought to light by the Applicants. 
     Middle section  314  can be configured including opposing rigid circuit boards  580   a  and  580   b  in the manner described above for the internal and external connection ends. Printed circuit board  580   a  can be patterned based on the requirements of amplifier  500  whereas printed circuit board  580   b  can be patterned to support any additional electrical components that are needed such as, for example, passive components including any suitable arrangement or combination of resistors, capacitors and/or inductors  504  (see  FIG. 8 ). 
     With continuing reference to  FIG. 9 , in other embodiments, one or both of first flex extension  320  and second flexible extension  322  can be individually formed and electrically connected, for example, by soldering, to a rigid printed circuit board that serves as any one of the internal connection end, the external connection end and/or the middle section. 
     Attention is now directed to  FIG. 10  which illustrates another embodiment of an opto-electronic converter, indicated by the reference number  200 ′ which can be used in contact  10  of  FIGS. 1-3 . Converter  200 ′ is shown in a diagrammatic, perspective view. The present discussion is limited to those features which differentiate converter  200 ′ from previously described converter  200  for purposes of brevity. The reader is directed to the discussion of converter  200 , which appears above, for details with respect to components and features that are shared by the two embodiments under immediate consideration. Converter  200 ′ includes a retention clip  400 ′ installed on collar  402  without the use of a resilient biasing element such as previously described coil spring  414 . Clip  400 ′ can include an annular rim  600  that is configured to be received in annular groove  214  ( FIG. 4 ) of barrel housing  20 , for example, by receiving clip  400 ′ into groove  214 . Clip  400 ′ can include a skirt  602 , extending from annular rim  600  and having a length along the axis of the converter that is based on the axial length of collar  402  such that predetermined tolerances are established between clip  400 ′, collar  402  and flange  410 . These tolerances provide for movement of converter  200 ′ relative to barrel housing  20  such that the converter can float relative to the barrel housing when another contact such as, for example, opposing contact  90  of  FIG. 2  is engaged. It is noted that the opposing/confronting ends of clip  400 ′, which define a gap therebetween for purposes of installing the clip onto collar  402 , can be spaced apart by any suitable angular offset. Clip  400 ′ can be formed from any suitable material such as, for example, tempered spring steel or beryllium-copper. 
     Turning to  FIG. 11 , another embodiment of an opto-electronic converter, generally indicated by the reference number  200 ″ is shown in a diagrammatic, perspective view. Like converter  200 ′, converter  200 ″ can be used in contact  10  of  FIGS. 1-3 . Accordingly, the present discussion is limited to those features which differentiate converter  200 ″ from previously described converters  200  and  200 ′ for purposes of brevity. The reader is directed to the discussion of converters  200  and  200 ′, which appear above, for details with respect to shared components and features that are illustrated. Converter  200 ″ can include previously described retention clip  400  installed on collar  402 . In the present embodiment, however, a wave spring  660  is received on collar  402  such that the wave spring is captured between retention clip  400  and flange  410 . Wave spring  660  can be installed on collar  402  in the manner described above with regard to helical coil spring  414  by spreading the opposing ends of the wave spring apart to a degree that allows installation on the collar. As described above, retention clip  400  is resiliently receivable in groove  214  ( FIG. 4 ) such that axial movement of converter  200 ″ can occur relative to barrel housing  20  much in the same manner as is provided by previously described coil spring  414 . Responsive to compression that displaces converter  200 ″ further into the barrel housing, the opposing ends of the wave spring can move toward one another and/or overlap. In the present embodiment, a gap  664  between the opposing ends of the wave spring can be aligned with a gap  668  between the opposing ends of clip  400 , although this is not a requirement. The wave spring, for a given axial length of collar  402  can provide for a relative increase in the amount of axial movement that is available for the converter relative to the housing since the wave spring can be compressed to essentially the thickness of the material from which it is formed, whereas a coil spring can compress only to the point that adjacent coils of the spring are in physical contact. In this regard, it should also be noted that the axial length of collar  402  can be customized based on the use of a given type of spring and the amount of axial movement that is to be provided. Wave spring  660  can be formed from any suitable material including, but not limited to tempered spring steel or beryllium-copper. The use of the wave spring provides for the same relative movement of the converter relative to the barrel housing in addition to resiliently biased axial movement. For example, the converter can also move in any direction radially transverse to axis  22  ( FIG. 1 ) of the barrel housing. Further, as shown in  FIG. 5 , like ferrule  100 , an optical communication end  670  can twist or rotate to form aforedescribed angle α ( FIG. 5 ) that is defined between elongation axis  316  of the converter and elongation axis  22  of the barrel housing. It should be apparent through a comparison of  FIGS. 10 and 11 , that another difference with respect to converter  200 ″ resides in the configuration of optical communication end  670  which internally supports ferrule  100  ( FIGS. 2, 3, 5, 6 and 10 ), as will be described in further detail immediately hereinafter. 
       FIG. 12  is a diagrammatic cutaway view, in perspective, which illustrates further details of converter  200 ″ of  FIG. 11 . Initially, it is noted that converter  200  of  FIG. 3  is supported such that the end face or tip of ferrule  100  can physically contact the tip of an opposing ferrule to provide for optical communication therebetween. Converter  200 ″, however, is configured for use in a free space collimated configuration having a collimating lens  700  in contact, or near contact, with the tip of ferrule  100  such that light  702 , which can be collimated to a degree that is sufficient for optical coupling purposes, can travel through an empty cavity between collimating lens  700  and an opposing collimating lens  704 , shown in phantom using dashed lines, that is itself in optical communication with an opposing ferrule  706 , with the latter only partially shown and illustrated in phantom using dashed lines. It should be appreciated that light  702  can be traveling in either direction and that collimating lens  704  and opposing collimating lens  700 , in general, are selected to couple to and from the collimated light beam  702  of predetermined characteristics. Therefore, they may be identically constructed lenses, or different, depending on the type of fiber being used on each side of light beam  702 , or other design constraints. In an embodiment, these lenses can be ball lenses. In another embodiment, these lenses can be graded-index (GRIN) lenses or any suitable type of lens. 
     Referring to  FIG. 13  in conjunction with  FIGS. 11 and 12 , the former is a diagrammatic cutaway view in elevation of contact  10  supporting opto-electronic converter  200 ″ of  FIG. 12 . It should be appreciated that the contact varies little in appearance when either converter  200  or converter  200 ′ are installed, hence these additional views have not been provided for purposes of brevity. Exceptions in the appearance of these figures would entail deleting collimating lens  700  and modifying the appearance of precision alignment sleeve  204 , as well as changing the appearance of the retention clip and associated spring that are used, depending on the particular embodiment. It is noted that the assembly is shown in an unmated state such that retention clip  400  is resiliently biased against shoulder  416  (see also  FIG. 4 ) by wave spring  660 . At the same time, flange  410  is received against an inner surface  720  of alignment sleeve retainer cap  26 . Mating contact  10  with an opposing contact generally causes some combination of axial movement in the direction indicated by an arrow  704 , lateral/radial movement orthogonal to the axial movement and angular twisting indicated by an arc  710 . The combined movement provides for substantially reduced exposure of the components of contact  10 , as well as the opposing contact, to damage. Components that can be sensitive to damage include any precision alignment sleeves that are in use. By damaging such components, the optical coupling performance can be compromised, for example, by increasing coupling losses. Accordingly, contact  10  provides a sweeping improvement over prior art contacts such as are taught, for example, by the &#39;849 patent. 
       FIG. 14  illustrates an embodiment of contact  10  wherein interface  30  is accomplished using another embodiment of the second flex extension which is indicated by the reference number  322 ′. In particular, flex extension  322 ′ includes a free end  800  that extends outside the end of the barrel housing  20 . Accordingly, a wide variety of electrical connection schemes can be employed in cooperation with flex extension  322 ′, For example, pins can be soldered to traces  804  to mate with an external connector. As another example, traces  800  can be soldered directly to another circuit board or the distal/free end of extension  322 ′ can be inserted directly into another connector or socket  810 . If desired, traces  804  can be terminated with electrical pads for soldering or other electrical connection purposes. In an embodiment, connector  810  can be a zero insertion force (ZIF) connector. In still another embodiment, flex extension  322 ′ can itself support a connector that is external to barrel housing  20 . 
     Having described a number of embodiments above, it should be appreciated that a heretofore unseen opto-electronic contact, associated method and connection system have been brought to light by the present disclosure. Such a contact can include an active opto-electronic converter including a converter length extending between opposing first and second ends to define a converter axis having the first end configured for removable optical engagement with an opposing contact. A housing such as, for example, a barrel housing can define an interior cavity having an elongated length extending between opposing first and second barrel openings to define an elongation axis and having the opto-electronic converter captured in the interior cavity for external optical engagement to the opposing contact via the first barrel opening for relative movement of the converter axis along the elongation axis, transverse thereto, and oblique thereto to accommodate mating tolerances responsive to engaging the opposing contact. In an embodiment, a flexible circuit board assembly includes an internal electrical connection end, an external electrical connection end and an elongated length extending therebetween. The internal connection end electrically engages the converter and the external connection end can be fixedly positioned proximate to the second barrel opening for external electrical connection to the opto-electronic contact such that the external connection end is positioned on the elongation axis at a distance from the second end of the opto-electronic contact that is less than the elongated length of the flexible circuit board and the elongated length is captured within the interior cavity of the barrel housing. 
     The foregoing description of the invention has been presented for purposes of illustration and description. For example, in other embodiments, the contact of the present disclosure can be configured according to other connection system standards or specifications including but not limited to an ELIO contact configuration, MIL Standards 38999, 29504, 28776, 64266, and the like. Accordingly, the present application is not intended to be exhaustive or to limit the invention to the precise form or forms disclosed, and other embodiments, modifications and variations may be possible in light of the above teachings wherein those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof.