Patent Publication Number: US-7708474-B2

Title: Optical transceiver module and duplex fiber optic connector

Description:
This application is a divisional application of, and claims the benefit of the priority of, copending U.S. patent application Ser. No. 12/040,986, entitled “Optical Transceiver Module and Duplex Fiber Optic Connector,” filed on Mar. 3, 2008, which is hereby incorporated by reference in its entirety. 

   BACKGROUND 
   In the area of wire communications, there are electrical and optical communication links between equipment. An electrical link commonly comprises an electrical transmitter and an electrical receiver that are connected by metal wire. The electrical transmitter converts information to an electrical signal and then transmits it over the metal wire which acts as a transmission medium. The electrical receiver converts the received electrical signal back to useful information. An optical link generally comprises an optical transmitter and an optical receiver component that are connected by a fiber optic cable. The optical transmitter typically comprises a light source, such as, for example, a light-emitting diode (LED), which converts an electrical data signal into a modulated light signal. This light signal is transmitted through fiber optic cable and is received by the optical receiver, which generally comprises a light detector, such as, for example, a photosensor, photodiode, etc. The optical receiver converts the light signal back into an electrical data signal. 
   The housing of an optical transmitter or receiver includes appropriate electrical pins which provide an electrical input/output (I/O) data interface with the communications equipment. The front face of the housing (which comprises a plastic or similar material) includes an alignment port for receiving a fiber optic connector to which a fiber optic cable is terminated. The optical transmitter and receiver are connected by an optical fiber. 
   To secure the fiber optic connector within the alignment port, the housing may also include features for retaining the connector in the alignment port. A typical industrial connector such as Versatile Link includes a horizontal C-shaped feature defined by opposing elements that protrude from the front face at the alignment port. 
   The use of fiber optics provides a number of advantages over metal wires. Fiber optic cable allows the transport of data signals over longer distances. Fiber cables are lighter than metal wires because they are made of clear glass, polymer, or similar materials. The fiber optic cable is non-conductive and, therefore, protects against electrical shorts and lightning strikes. Optical signals are not degraded by electromagnetic interference (EMI) and, therefore, may provide better signal integrity than metal wires. Optical fiber also provides better data security protection because it is much more difficult to tap signals along a fiber. 
   In fiber optic applications, the polymer optical fiber (POF) cable is more cost effective than glass optical fiber cable. It also provides easy field termination and is less sensitive to dust contamination due to large fiber core diameter. 
   SUMMARY 
   Various embodiments of optical transceiver modules and duplex fiber optic connectors are provided. One embodiment comprises an optical transceiver module. One such module comprises: an integrally-formed housing having a duplex front port with a pair of alignment holes for receiving a pair of ferrules from a duplex fiber optic connector, the duplex front port having an upper flexible retaining element and a lower flexible retaining element for retaining the pair of ferrules from the duplex fiber optic connector; an opto-electronic assembly contained within the housing; and an electrical interface extending from the integrally-formed housing. 
   Another embodiment comprises a duplex fiber optic connector. One such connector comprises: an integrally-formed housing having a top portion and a bottom portion connected via a flexible hinge and defining a pair of channels for receiving a transmitter fiber optic cable and a receiver fiber optic cable at a first end of the integrally-formed housing; a pair of ferrules disposed on a second end of the integrally-formed housing opposite the first end, one ferrule for receiving a first fiber core associated with the transmitter fiber optic cable and the other ferrule for receiving a second fiber core associated with the receiver fiber optic cable; a connector latching element disposed on one of the top portion and the bottom portion; and a connector orientation key or keyway disposed on the other of the top portion and the bottom portion. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective diagram of one embodiment of an optical transceiver module adapted to receive the duplex fiber optic connector of  FIGS. 3-5 . 
       FIG. 2  is a partially exploded view of the optical transceiver module of  FIG. 1 . 
       FIG. 3  is perspective diagram of one embodiment of a duplex fiber optic connector adapted to be received by the optical transceiver module of  FIGS. 1 &amp; 2 . 
       FIG. 4  illustrates the duplex fiber optic connector of  FIG. 3  with the housing closed. 
       FIG. 5  is a bottom view of the duplex fiber optic connector of  FIGS. 3 &amp; 4 . 
       FIG. 6  illustrates the installation of the duplex fiber optic connector into the optical transceiver module. 
       FIG. 7  illustrates the engagement of the duplex fiber optic connector and the optical transceiver module. 
       FIG. 8  is a side view that illustrates the engagement of the duplex fiber optic connector and the optical transceiver module. 
       FIG. 9   a  is a side view of an alternative embodiment of an optical transceiver module adapted to receive the duplex fiber optic connector of  FIGS. 3-5 . 
       FIG. 9   b  is a front view of the optical transceiver module of  FIG. 9   a.    
       FIG. 9   c  is a perspective bottom view of the optical transceiver module of  FIG. 9   c , illustrating optical transceiver mounted within communication equipment with electrical I/O interface layout and mounting holes. 
   

   DETAILED DESCRIPTION 
   Various embodiments of a duplex fiber optic connector  100  and an associated optical transceiver module  200  are described. The optical communication module  200  and the corresponding duplex fiber optic connector  100  accommodate a transmitter and receiver component to form an optical transceiver module. As described below in more detail, in one embodiment, the optical transceiver module  200  comprises two generally C-shaped vertical protrusions that are adapted to hold the duplex fiber optic connector  100 . This configuration reduces the physical footprint of existing modules to untwisted pair (UTP) module size and also shares the same layout for the electrical I/O pins. Therefore, the optical transceiver module  200  may be conveniently substituted for an electrical transceiver in, for example, high density electrical network hubs, routers, and switches. This general configuration for the optical transceiver module may also enable backwards compatibility with existing Simplex Versatile Link (VL) connectors that are commonly used in, for example, industrial fiber optic links. Furthermore, the duplex fiber optic connector  100  and the optical transceiver module  200  support an improved connector latching feature that improves the retention force robustness, is less prone to breakage as compared to existing modules and connectors, such as the current range of VL connectors, and also offers a connector orientation feature for ease of insertion. 
     FIGS. 1 &amp; 2  illustrate an embodiment of the optical transceiver module  200  which is configured to receive the duplex fiber optic connector  100 . The optical transceiver module  200  is further configured to support a connector latching feature and a connector orientation feature, as described below in more detail. Referring to  FIGS. 1 and 2 , the optical transceiver module  200  comprises a housing  202  having a duplex front port  208  and an electro-optical assembly  210 . The electro-optical assembly  210  includes an optical transmitter and an optical receiver. As known in the art, the optical transmitter generally comprises the components for generating an optical signal (e.g., a light source, such as a light-emitting diode (LED), and focus elements), and the optical receiver generally comprises the components for receiving an optical signal (e.g., a photodetector or photosensor). The optical transceiver module  200  has electrical pins  214  to provide the electrical interface to a communication management system, such as, for example, a network hub, a router, a switch, or any other data communication device or equipment. To provide support when installed into the communication equipment, the optical transceiver module  200  may include support pedestals  216 . 
   The housing  202  may comprise any suitable material. In one embodiment, the housing  202  may be integrally formed from a plastic or similar material using, for example, injection molding or other manufacturing techniques. In other embodiments, the housing  202  may comprise separate components made of other materials, which are joined together to form the optical transceiver module  200 , as illustrated in  FIG. 2 . The housing  202  may be protected by a metal shell  212  that fits over the housing  202 , while providing functional access to the duplex front port  208  and pins  214 . 
     FIGS. 9A-9C  illustrate another embodiment of the optical transceiver module  200 . In this embodiment, the metal shell  212  with more than one protrusion serves as grounding connectors  230  for the housing  202 , which is connected to equipment, such as, a printed circuit board (PCB) ground plane  232  to reduce EMI emission. Flexible metal fingers  234  may be located, for example, on the front side of the metal shell  212 . The flexible metal fingers  234  make contact with communication equipment metal housing  236  to further improve electromagnetic interface shielding. 
   The duplex front port  208  comprises a pair of ferrule alignment holes  204  and  206 . Alignment hole  204  is associated with the optical transmitter and the alignment hole  206  is associated with the optical receiver. The duplex front port  208  is adapted to receive and retain the duplex fiber optic connector  100 . The duplex front port  208  includes a pair of flexible retaining elements for retaining the duplex fiber optic connector  100 . In the embodiment illustrated in  FIGS. 1 and 2 , an upper flexible retaining element  218  and a lower flexible retaining element  220  extend outward from the duplex front port  208 . The flexible retaining elements  218  and  220  may be slightly angled toward the ferrule alignment holes  204  and  206 . In this manner, the flexible retaining elements may clamp down on the duplex fiber optic connector  100  when the ferrules  114  and  116  are inserted into the alignment holes  204  and  206 , as described below. The slot  222  and cut-out  224  allow the left and right side of the flexible retaining elements  218  and  220  to deflect independently. It should be appreciated that, in certain embodiments, this feature may enable flexible retaining elements  218  and  220  to clamp down, for example, two simplex Versatile Link connectors with varying ferrule diameters. 
   As illustrated in  FIG. 9   c , in certain embodiments, the optical transceiver module  200  may be configured with the same electrical I/O interface layout as a conventional unshielded twisted pair (UTP) electrical transceiver module, with two flexible snap-fit pedestals  216 . The snap-fit pedestals  216  may serve two general functions: (1) to support the module and (2) to prevent module dislodges from the equipment PCB before soldering. It should be further appreciated that the the duplex fiber optic connector  100  may be configured with the same connector physical size as a conventional UTP connector. The reduced external footprint may offer a space savings advantage for fiber communication solutions in, for example, consumer and industrial applications where the spacing between transceiver modules becomes critical (e.g., in network hubs, routers and switches). Furthermore, this may allow the optical transceiver module  200  to be easily incorporated into existing UTP designs. 
   The duplex fiber optic connector  100  comprises a connector housing  102  having a top portion  104  and a bottom portion  106 . The top portion  104  and the bottom portion  106  may be joined at adjacent edges by a flexible hinge  108 , which enables the connector housing  102  to be opened ( FIG. 3 ) and closed ( FIGS. 4 &amp; 5 ) and, thereby, provide access to the interior of the connector housing  102  for installing a pair of fiber optic cables (i.e., a transmitter fiber optic cable  110  and a receiver fiber optic cable  112 ). In one embodiment, to provide a low cost connector, the connector housing  102  may be integrally formed from a plastic or similar material using, for example, injection molding or other manufacturing techniques. In other embodiments, the connector housing  102  may comprise separate components made of other materials, which are joined together to form the connector housing  102 . 
   One end of the connector housing  102  supports ferrules  114  and  116 , and the opposing end receives the transmitter fiber optic cable  110  and the receiver fiber optic cable  112 . Ferrule  114  receives a fiber core  118  associated with the transmitter fiber optic cable  110 , and the ferrule  116  receives a fiber core  118  associated with the receiver fiber optic cable  112 . Ferrules  114  and  116  provide the structure for precisely aligning the corresponding fiber cores  118  with a transmitter port and a receiver port disposed on a front face of the optical transceiver module  200 . In this manner, optical signals may be carried along transmitter fiber optic cable  110  and ferrule  114 , and optical signals may be carried along receiver fiber optic cable  112  and ferrule  116 . The installation of the duplex fiber optic connector  100  into the optical transceiver module  200  is described in more detail below. 
     FIG. 3  shows a partially exploded view of the duplex fiber optic connector  100  with the connector housing  102  open to expose the interior of the duplex fiber optic connector  100 . In the embodiment illustrated in  FIG. 3 , a pair of channels  120  is formed on both the top portion  104  and the bottom portion  106  of the connector housing  102  for receiving fiber cores  118 . The pairs of channels  120  are aligned such that the transmitter fiber optic cable  110  and the receiver fiber optic cable  112  are securely positioned within the channels  120  and the fiber cores are precisely aligned with the ferrules  114  and  116 . Cable alignment/restraining elements  122  may be positioned along the channels  120  to guide and hold the fiber optic cables  110  and  112  during installation, or further support or align the fiber core  118  or the fiber optic cables  110  and  112 . 
   As further illustrated in  FIG. 3 , the fiber optic cables  110  and  112  enter the connector housing  102  at the end opposite ferrules  114  and  116 . Cables  110  and  112  comprise a predefined length of fiber core  118 . The length of core exposed may be based on the physical dimensions of the interior of the duplex fiber optic connector  100 . For example, the length of fiber core  118  may be based on the length of core to be received in ferrules  114  and  116 . During installation, the fiber core  118  may be exposed by stripping off the fiber cable jacket with, for example, a fiber stripping tool. In one embodiment, the fiber optic cables  110  and  112  may comprise a plastic or acrylic optical fiber with, for example, a general-purpose resin as the core material and a polymer material for the cladding material. It should be appreciated, however, that alternative materials may be used for the core, cladding, or other components. Slight protrusions which are sloping forward and backward away from the protrusion can be found behind ferrule  114 ,  116  and which act as connector retention features  140  ( FIG. 8 ). The flexible retaining elements  218 ,  220  will hold the retention features  140  in place with resultant force  240  once the connector is fully inserted into the transceiver module. The resultant force  240  is translated into vertical force component  242  and horizontal force component  244  which are acting on the connector. The horizontal force component  244  pushes the connector which in turn preloads ferrule  114 ,  116  end faces to mate with transceiver optical reference  226  as demonstrated on  FIG. 7 . 
   The fiber optic cables  110  and  112  may include a strain relief boot  124 . The strain relief boots  124  may cover the fiber optic cable at or near the point at which the cable enters the connector housing  102 . The strain relief boots  124  may be formed on the fiber optic cable or, alternatively, may be inserted over the fiber cables  110  and  112  during installation. To assist in the installation process and support the retention of the fiber optic cables  110  and  112  within the connector housing  102 , the strain relief boots  124  may incorporate a ring  126  which engages with a corresponding recess in the top portion  104  or the bottom portion  106  of the housing ( FIG. 3 ). During installation, the strain relief boots  124  may be placed onto the bottom portion  106  of the connector housing  102  with the ring  126  resting in the recess and the fiber cores  118  inserted into the corresponding ferrules. The fiber core  118  extends along the length of the corresponding ferrule and ends at or near a ferrule front face  119 . The cable alignment/restraining elements  122  restrain the fiber optic cables in place when the top portion  104  and the bottom portion  106  are closed onto each other. 
   With the fiber optic cables  110  and  112  in place within the connector housing  102 , the top portion  104  and the bottom portion  106  may be clamped together via a latching mechanism. As illustrated in  FIG. 3 , one or more flexible latching elements  128  may be placed on the underside of the top portion  104 . One or more corresponding latch holding features  130  may be placed on the bottom portion  106 . The flexible latching elements  128  and the latch holding features  130  may be formed integrally with the connector housing  102  or otherwise attached to the connector housing  102 . The flexible latching elements  128  are positioned to latch onto the latch holding features  130  when the top portion  104  is closed onto the bottom portion  106 . The flexible latching elements  128  may be depressed to release the latching mechanism and enable the connector housing  102  to be opened. 
   The duplex fiber optic connector  100  may include a latching feature for releasable latching the connector to the optical transceiver module  200 , and an orientation feature for properly orienting the connector relative to the optical transceiver module  200 . The orientation feature ensures that the duplex fiber optic connector  100  is inserted into the optical transceiver module  200  with the transmitter and receiver cables  110  and  112  linked to the appropriate transmitter and receiver ports. The latching feature provides a convenient mechanism for releasable securing the duplex fiber optic connector  100  to the optical transceiver module. 
   Having described the general components of the duplex fiber optic connector  100  and the optical transceiver module  200 , the orientation and latching features mentioned above will now be described in more details. To enable the latching feature, in one embodiment as illustrated in  FIG. 4 , a latch element  132  is positioned on the top portion  104  of the duplex fiber optic connector  100 . The latch element is designed to be lower than top potion  104  of connector housing and strategically placed in between ferrules  114 ,  116  which provides three-way protections against damage from external element. The latch element comprises a flexible base element having a latch  132 . The flexible base element may be configured to vertically flex relative to the connector housing  102  such that the latch  132  is depressed as the duplex fiber optic connector  100  is inserted into the optical transceiver module  200 . The latch  132  may include an angled front surface which engages the upper flexible retaining element  218  as the duplex fiber optic connector is inserted. 
   As illustrated in  FIGS. 1 &amp; 2 , the upper flexible retaining element  218  on the optical transceiver module  200  may include a suitably-shaped cut-out  222  to receive the latch  132 .  FIG. 7  shows the proper engagement of the latch  132  and the cut-out  222  to retain the duplex fiber optic connector  100  in the optical transceiver module  200 . It should be appreciated that the latch  132  and the cut-out  222  may be shaped in various ways to implement the latching function. In one embodiment, the cut-out  222  is a triangular-shaped cut-out, although key and keyway arrangements may be employed. It should be further appreciated that the location of the latching element and the cut-out  222  may be varied. Furthermore, in alternative embodiments, the latch element may further comprise a release tab  134  disposed on the flexible base element that extends above the upper surface of the connector housing  102  for releasing the latch  132  from the cut-out  222 . 
   The orientation feature is provided, in one embodiment, via an orientation key  136  which locates on the connector housing  102 . In the embodiment illustrated in  FIG. 2 , the orientation key  136  is disposed on the bottom surface of the bottom portion  106  of the connector housing  102 . As illustrated in  FIG. 2 , the bottom flexible retaining element  220  of the optical transceiver module  200  may include a slot  224  for engaging with the orientation key  136 . In this manner, the optical transceiver module  200  will only receive the duplex fiber optic connector  100  when the orientation key  136  is properly oriented with the slot  224 . This will prevent the duplex fiber optic connector from being improperly inserted with the ferrules  114  and  116  reversed relative to the alignment holes  204  and  206 . It should be appreciated that the orientation key  136  and the slot  224  may be shaped in various ways to accommodate a key-to-keyway engagement. It should be further appreciated that the number and location of these elements may be varied. Furthermore, in alternative embodiments, the orientation key  136  may be positioned on the optical transceiver module  200  and the slot  224  may be placed on the duplex fiber optic connector  100 . 
     FIG. 7  generally illustrates the manner in which the duplex fiber optic connector  100  may be inserted into the optical transceiver module  200 . The ferrules  116  and  114  may slide along the alignment holes  204  and  206 , respectively, and stop when the front face  119  comes in contact with an optical reference element (e.g., surface  226 ). As the ferrules  114  and  116  are received in the alignment holes  204  and  206 , the latch  132  engages the cut-out  222  and the orientation key  136  engages the slot  224 . 
   It should be noted that this disclosure has been presented with reference to one or more exemplary or described embodiments for the purpose of demonstrating the principles and concepts of the invention. The invention is not limited to these embodiments. As will be understood by persons skilled in the art, in view of the description provided herein, many variations may be made to the embodiments described herein and all such variations are within the scope of the invention.