Abstract:
An optical module includes a housing, an actuator and a fiber clamp having at least one spring member. The actuator and housing are moveable in a sliding manner relative to one another such that the actuator can assume a first actuator position or a second actuator position relative to the housing. The spring member has a first portion in sliding contact with a ramped surface of the actuator and a second portion movable between a first clamp position and a second clamp position in response to sliding movement of the actuator between the first actuator position and second actuator position, respectively. Movement of the second portion of the spring member to the second clamp position reduces a dimension of a fiber passage in the module to frictionally engage an optical fiber in the fiber passage.

Description:
BACKGROUND 
     In data communication systems, it is often useful to modularize interface electronics and other interface elements in a data communication module. For example, in an optical data communication system, an opto-electronic transceiver module may include a light source such as a laser, and a light receiver such as a photodiode. To use such an opto-electronic transceiver module, an optical fiber cable is coupled to a port in the module. Such a module also includes electrical contacts that can be coupled to an external electronic system. 
     In an instance in which the end of an optical fiber is terminated with a plug, the optical fiber can be coupled to an optical data communication module by plugging the plug into a receptacle on the module. In some instances, however, it is desirable to couple a bare fiber (i.e., a fiber not terminated with a plug) to an optical data communication module. Such modules commonly include a housing and an actuator. To couple a bare fiber, the actuator is moved to a first position relative to the housing. Then, the end of the fiber is inserted into a port in the module. The actuator is then moved to a second position relative to the housing. With the actuator in the second position, a portion of the actuator grips or otherwise engages the surface of the fiber end. Various actuator mechanisms for engaging the surface of the fiber end are known in such modules. 
     Problems with prior modules that engage the end of a bare optical fiber include poor electromagnetic interference (EMI) shielding of electronic elements within the housing and insufficient retention or clamping force to securely retain the fiber. It would be desirable to provide an improved bare fiber clamping optical module. 
     SUMMARY 
     Embodiments of the present invention relate to an optical module that includes a housing, an actuator, and a fiber clamp having at least one spring member. In an exemplary embodiment, the actuator has a portion slideably engageable with the housing. The actuator and housing are moveable in a sliding manner relative to one another such that the actuator can assume a first actuator position or a second actuator position relative to the housing. The actuator has a portion that includes a ramped surface. In the exemplary embodiment, the spring member of the fiber clamp has a first portion in sliding contact with the ramped surface of the actuator and a second portion movable between a first clamp position and a second clamp position in response to movement of the actuator between the first actuator position and second actuator position, respectively. Movement of the second portion of the spring member to the second clamp position reduces a dimension of a fiber passage in the optical module, thereby frictionally engaging an optical fiber in the fiber passage. 
     Other systems, methods, features, and advantages will be or become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the specification, and be protected by the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. 
         FIG. 1  is a perspective view of a bare fiber clamping optical module, in accordance with an exemplary embodiment of the invention. 
         FIG. 2  is a perspective view similar to  FIG. 1 , with the EMI shield removed and with two optical fibers retained in the module. 
         FIG. 3A  is a top plan view of the module of  FIGS. 1-2 , prior to inserting the fibers. 
         FIG. 3B  is similar to  FIG. 3A , showing the module in a clamped state after the fibers have been inserted and clamped. 
         FIG. 3C  is similar to  FIGS. 3A-B , showing the module in an unclamped state. 
         FIG. 4A  is similar to  FIG. 3A , but showing the actuator and spring members only. 
         FIG. 4B  is similar to  FIG. 3C , but showing the actuator and spring members only. 
         FIG. 5  is an exploded view of the module of  FIGS. 1-4 . 
         FIG. 6  is similar to  FIG. 5 , showing the assembly of the EMI shield to the remainder of the module. 
         FIG. 7  is a rear perspective view of the module of  FIGS. 1-6 . 
         FIG. 8  is a front perspective view of the module of  FIGS. 1-6 , with the EMI shield and actuator removed. 
     
    
    
     DETAILED DESCRIPTION 
     As illustrated in  FIG. 1 , in an illustrative or exemplary embodiment of the invention, an optical data communication module  10  includes a housing  12  and an actuator  14 . Housing  12  is enclosed in an electromagnetic interference (EMI) shield  16  (FIGS.  1  and  5 - 7 ). When optical data communication module  10  is mounted on a circuit board (not shown), terminals  18  extending from EMI shield  16  can be coupled to a ground potential on the circuit board to ground EMI shield  16 . Housing  12  has protrusions  20  that can be inserted into holes in such a circuit board to mount optical data communication module  10  on the surface of the circuit board. 
     In  FIGS. 3C and 4B , optical data communication module  10  is shown in an “unclamped” state or state in which optical fibers  22  and  24  ( FIGS. 2 ,  3 A-B and  4 A) can be freely inserted into or removed from optical data communication module  10 , i.e., without optical fibers  22  and  24  being engaged or experiencing the frictional retention forces described below. Actuator  14  has two openings  26  and  28  ( FIG. 1 ) for receiving the ends of such optical fibers  22  and  24 , respectively, when optical data communication module  10  is in the unclamped state. Note that openings  26  and  28  are disposed symmetrically on either side of a central axis  30  ( FIGS. 1-2 ) of optical data communication module  10 . 
     After the ends of optical fibers  22  and  24  have been inserted into openings  26  and  28 , a user can grip the front portion  32  of actuator  14  and push front portion  32  toward housing  12 . Pushing actuator  14  and housing  12  together in this manner causes a portion of actuator  14  to retract into housing  12  in a sliding manner, as illustrated in  FIGS. 3A ,  3 B and  4 A. In  FIGS. 1 ,  2 ,  3 A,  3 B,  4 A,  6  and  7  optical data communication module  10  is shown in a “clamped” state or state in which optical fibers  22  and  24  cannot freely be inserted into or removed from optical data communication module  10  because optical data communication module  10  exerts a frictional clamping force that retains the ends of optical fibers  22  and  24  in optical data communication module  10 . Optical data communication module  10  provides this clamping force in the following manner. 
     As illustrated in  FIGS. 2 ,  3 A-C,  4 A-B,  5  and  6 , optical data communication module  10  further includes a fiber clamp comprising two spring members  34  and  36 . Spring members  34  and  36  are retained within a recess  40  ( FIGS. 2 ,  5  and  8 ) in a body  38  of housing  12 . Actuator  14  includes two arms  42  and  44  ( FIGS. 3-5 ) that extend perpendicularly from front portion  32 , thus forming a U-shape. Arms  42  and  44  engage and slide within grooves  46  and  48  ( FIG. 8 ), respectively, in body  38 , thus enabling actuator  14  to extend and retract relative to housing  12  in the manner described above. Body  38  has ports  50  and  52  ( FIGS. 5 and 8 ) extending through it to accommodate fibers  22  and  24 , respectively. Ports  50  and  52  of housing  12  are axially aligned (i.e., along an axis parallel to central axis  30 ) with openings  26  and  28  in actuator  14 . The combination of respective ports  50  and  52  and openings  26  and  28  and any other similarly axially aligned regions in optical data communication module  10  define two fiber passages for accommodating portions of fibers  22  and  24 , respectively, or the optical signals coupled thereto. 
     As illustrated in  FIGS. 4A-B  and  5 , arms  42  and  44  have ramped surfaces  54  and  56  ( FIGS. 4B and 5 ), respectively. “Ramped” in this context means oriented at a non-zero angle with respect to central axis  30  and thus similarly angled with respect to the ends of fibers  22  and  24  inside housing  12 . A first portion  58  of spring member  34  slides against ramped surface  54 . Likewise, a first portion  60  of spring member  36  slides against ramped surface  56 . 
     When optical data communication module  10  is placed in the unclamped state or position by extending actuator  14  in the manner described above, first portions  58  and  60  rest against flat surfaces (i.e., parallel to central axis  30 )  62  and  64  ( FIGS. 4A and 5 ) adjacent to ramped surfaces  56  and  58 , respectively. In this state, since flat surfaces  62  and  64  are closer to their respective fibers than ramped surfaces  54  and  56 , flat surfaces  62  and  64  displace first portions  58  and  60 . First portions  58  and  60  flex resiliently because they are made of sheet metal or similar resilient or spring-like material. In this flexed or displaced state, first portions  58  and  60  exert a resilient bias force against flat surfaces  62  and  64 . 
     As illustrated in  FIGS. 4A-B  and  5 , spring members  34  and  36  have second portions  66  and  68 , respectively. First portions  58  and  60  and second portions  66  and  68 , respectively, are unitarily formed with each other in the exemplary embodiment. For example, first portion  58  and second portion  66  may define legs of a single strip of sheet metal formed by bending the strip at an angle where first and second portions  58  and  66  adjoin. Likewise, first portion  60  and second portion  68  may define legs of a single strip of sheet metal formed by bending the strip at an angle where first and second portions  60  and  68  adjoin. 
     As illustrated in  FIG. 5 , second portion  66  of spring member  34  has an opening  70 , and second portion  68  of spring member  36  has an opening  72 . When optical data communication module  10  is in the unclamped state, the above-described displacement or movement of first portions  58  and  60  moves second portions  66  and  68  to the state shown in  FIG. 4B . In this first “clamp state” or unclamped state, each opening  70  and  72  is aligned with the remainder of the respective fiber passage within optical data communication module  10 . That is, no portion of the peripheral walls of openings  70  and  72  are interposed within the fiber passages in a manner that would decrease the diameters of the fiber passages and thus impede withdrawal or insertion of fibers  22  and  24 . Note that the diameters of the fiber passages and their constituent elements (e.g., openings  26  and  28  in actuator  14  and ports  50  and  52  in body  38 ) are substantially equal to (or just slightly larger than) the diameter of an average or common optical fiber, so as to guide the ends of fibers  22  and  24  within optical data communication module  10 . 
     When optical data communication module  10  is placed in the clamped state by retracting actuator  14  in the manner described above, first portions  58  and  60  slide against ramped surfaces  54  and  56 , respectively, to reach the state or position shown in which they are shown in  FIGS. 3B and 4A . In this state, since ramped surfaces  54  and  56  are farther from their respective fibers than flat surfaces  62  and  64 , first portions  58  and  60  have room to resiliently relax, thus reducing the above-described displacement. In this unflexed state, first portions  58  and  60  are relaxed (in the sense of a spring), i.e., they do not exert a resilient bias force. Note that the relaxation of spring members  34  and  36  in this manner also aids retracting actuator  14 . When a user grips front portion  32  of actuator  14  and begins pushing it toward housing  12 , the spring force generated by the relaxation of spring members  34  and  36  helps snap actuator  14  into the retracted position shown in  FIGS. 1 ,  2 ,  3 A,  3 B,  4 A,  6  and  7  and retain actuator  14  in that position. With actuator  14  in this retracted position, optical data communication module  10  is in a clamped state. 
     When optical data communication module  10  is in the clamped state, the above-described displacement or movement of first portions  58  and  60  moves the adjoining second portions  66  and  68  to the positions shown in  FIG. 4A . In this second (clamped) clamp state, openings  70  and  72  are slightly offset from the remainder of the fiber passage within optical data communication module  10 . That is, portions of the peripheries or internal walls of openings  70  and  72  are interposed within the fiber passages in a manner that decreases their diameters. Since the fiber passages have diameters substantially equal to the diameters of optical fibers  22  and  24 , portions of the fiber passages frictionally engage optical fibers  22  and  24 . More specifically, the portions of the peripheries or internal walls of openings  70  and  72  in spring members  34  and  36 , respectively, contact the surfaces of optical fibers  22  and  24  and thus frictionally engage them. When engaged in this manner, optical fibers  22  and  24  cannot freely be removed from optical data communication module  10 . That is, optical data communication module  10  clamps optical fibers  22  and  24 . 
     Although in the exemplary embodiment, the peripheries or internal walls of openings  70  and  72  become interposed within the respective fiber passages and thereby reduce the diameters of the fiber passages, in other embodiments similar spring members can have any other suitable portions that can reduce a dimension of a fiber passage in a manner that frictionally engages an optical fiber with the passage. 
     It should be noted that because second portions  66  and  68  of spring members  34  and  36 , respectively, extend in a plane that is substantially perpendicular to central axis  30 , second portions  66  and  68  serve as a wall-like barrier that helps block EMI against entry into the interior of housing  12 . Note that because optical fibers  22  and  24  fit snugly within openings  70  and  72 , respectively, EMI emanating from a direction generally along central axis  30  cannot readily penetrate past the wall-like structure defined by second portions  66  and  68 . Spring members  34  and  36  include terminals  76  and  78  ( FIG. 5 ), respectively, which can be coupled to a ground potential on the circuit board. The grounded EMI shield  16  only provides EMI shielding on five sides of optical data communication module  10 , as the five-walled box-like EMI shield  16  is open on its front side (i.e., there is no wall on the front side of EMI shield  16 ). The grounded second portions  66  and  68  thus further provide EMI shielding on the front side of optical data communication module  10 , where EMI shield  16  is open. But for such EMI shielding, EMI could penetrate housing  12  and hamper the operation of an opto-electronic receiver device  74  and an opto-electronic transmitter device  75  that are mounted within housing  12  as shown in  FIGS. 5-7 . 
     Opto-electronic transmitter device  75 , which can include a laser diode or similar source of optical data signals, is optically aligned with port  50  and thus with the fiber passage in which the end of optical fiber  22  is received. Opto-electronic transmitter device  75  converts electrical signals into optical signals, which are emitted into the fiber passage and thus into the end of optical fiber  22  clamped therein. Opto-electronic transmitter device  75  receives these electrical signals from the circuit board (not shown) on which optical data communication module  10  is mounted. Similarly, opto-electronic receiver device  74 , which can include a photodiode or similar optical data signal detector, is optically aligned with port  52  and thus with the fiber passage in which the end of optical fiber  24  is received. Opto-electronic receiver device  74  converts optical signals that it receives from the end of optical fiber  24  clamped in its associated fiber passage into electrical signals. Opto-electronic receiver device  74  provides these electrical signals to the circuit board (not shown) on which optical data communication module  10  is mounted. 
     One or more illustrative embodiments of the invention have been described above. However, it is to be understood that the invention is defined by the appended claims and is not limited to the specific embodiments described.