Abstract:
Disclosed herein is an optical fiber coupler enclosure. The optical fiber coupler enclosure includes a lid member, a base member, and a first end cap. The lid member includes two lid side walls and a first open end. The base member is opposite the lid member. The base member includes two base side walls and a first open end. The base member includes at least one mounting channel proximate to each of the base side walls. The mounting channels are configured to fixedly dispose at least two fiber optic couplers adjacent to one another. The first end cap is disposed between the lid member first open end and the base member first open end.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119(e) to U.S. provisional patent application No. 60/751,007 filed Dec. 16, 2005 which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an enclosure for passive fiber optic components and, more particularly, to a dual-optical fiber coupler enclosure. 
     2. Brief Description of Prior Developments 
     Passive fiber optic products, such as couplers for example, are generally designed for use in optical networking systems and test equipment. Couplers enable users to split optical signals into multiple paths or combine multiple signals on one path. Additionally, couplers may also provide for the transmission of data through the optical fiber via multiple modes simultaneously. Couplers are used across a wide range of applications ranging from data communications for military and commercial aircraft to ignition control on power generators. There is a continuing desire among many of these applications for ever smaller data communications devices. This desire has caused manufacturers to seek new ways in which to further miniaturize the data communications devices being produced. Additionally there is an industry wide need for more rugged, robust and reliable data communications devices. 
     Accordingly, there is a need to provide a compact structure for enclosing fiber optic couplers with high reliability fiber coating, wherein the couplers are mounted opposed and parallel, and wherein the fibers are routed and bended while maintaining small bending radii. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, an optical fiber coupler enclosure is disclosed. The optical fiber coupler enclosure includes a lid member, a base member, and a first end cap. The lid member includes two lid side walls and a first open end. The base member is opposite the lid member. The base member includes two base side walls and a first open end. The base member includes at least one mounting channel proximate to each of the base side walls. The mounting channels are configured to fixedly dispose at least two fiber optic couplers adjacent to one another. The first end cap is disposed between the lid member first open end and the base member first open end. 
     In accordance with another aspect of the present invention, an optical fiber coupler enclosure is disclosed. The optical fiber coupler enclosure includes a base member and a lid member. The base member includes a first side and two base side walls. The base member includes at least one first peg proximate each of the base side walls. The first pegs extend from the first side. The lid member is connected to the base member. The lid member includes a second side and two lid side walls. The lid member includes at least one second peg proximate each of the lid side walls. The second pegs extend from the second side. The second pegs are aligned with the first pegs. The second pegs and the first pegs are configured to maintain an optical fiber bend radius. 
     In accordance with yet another aspect of the present invention, an optical fiber coupler enclosure is disclosed. The optical fiber coupler enclosure includes a base member, a lid member, and at least one end cap. The base member includes two base side walls and a first open end. The base member first open end includes a first groove portion. The lid member is opposite the base member. The lid member includes two lid side walls and a first open end. The lid member first open end comprises a first groove portion. The base member and the lid member are configured to hold a first optical fiber coupler therebetween. The end cap is disposed between the base member and the lid member. The end cap includes a first rim portion. The first rim portion is disposed within the base member first groove portion and the lid member first groove portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and other features of the present invention are explained in the following description, taken in connection with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of an optical fiber coupler enclosure; 
         FIG. 2  is an exploded perspective view of the optical fiber coupler enclosure shown in  FIG. 1  with optical fiber couplers installed therein; 
         FIG. 3  is a bottom perspective view of a base of the optical fiber coupler enclosure shown in  FIG. 1 ; 
         FIG. 4  is a top perspective view of the base of the optical fiber coupler enclosure shown in  FIG. 1 ; 
         FIG. 5  is a perspective view of one of the end caps of the optical fiber coupler enclosure shown in  FIG. 1 ; 
         FIG. 6  is a perspective view from an opposite direction of one of the end caps of the optical fiber coupler enclosure shown in  FIG. 1 ; 
         FIG. 7  is a partially exploded perspective view of the optical fiber coupler enclosure shown in  FIG. 1 ; 
         FIG. 8  is a top perspective view of a lid of the optical fiber coupler enclosure shown in  FIG. 1 ; and 
         FIG. 9  is a bottom perspective view of the lid of the optical fiber coupler enclosure shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , there is shown a perspective view of a dual-optical fiber coupler enclosure  10  incorporating features of the present invention. Although the present invention will be described with reference to the exemplary embodiment shown in the drawings, it should be understood that the present invention can be embodied in many alternate forms of embodiments. In addition, any suitable size, shape or type of elements or materials could be used. 
     The dual-optical fiber coupler enclosure  10  is provided comprising a base  12 , a lid  14 , and two identical end caps  16 . In one example of a preferred embodiment, the overall dimension of the assembled components of the enclosure  10  is about 22.0 millimeters wide, 14.0 millimeters high, and 105.0 millimeters long. The enclosure base  12  embodies two pairs of mounting channels  18  which function to mount two optical fiber couplers  20  (shown in  FIG. 2 ); locating the two optical fiber couplers  20  transversally near vertical walls (or base side walls)  22  and parallel to each other. One type of optical fiber  24  which can be used to fabricate the optical fiber coupler  20  requires exceptional coating performance under harsh environment in low bending radius, such as a polyimide coating. The two end caps  16  function as mounts for the fiber cables or polymer tubings, as well as a strain relief. The end cap mounting mechanism can comprise interlocking the end caps  16  to both ends of the base  12  and the lid  14 . The base  12 , lid  14 , and end caps  16  may be fabricated from any suitable material such as composite polymer resin for example. 
     The design provides a compact structure for enclosing two fiber optic couplers  20  with high reliability fiber coating, in which two couplers  20  are mounted opposed and parallel, whereas the optical fibers  24  can be routed and bent in small bending radius. Each optical fiber coupler  20  functions independently to serve different purpose of data transmission. Certain optical fiber channels on each input and output of each coupler  20  are required to be looped back internally to serve the purpose and requirement of the application. The looping optical fiber is eventually routed through and exits to its reversal direction. 
     The present design can replace a conventional data communication device which comprises of two optical fiber couplers  20  installed in physical series relative to each other. The overall dimension of the conventional series configuration is about 20.0 millimeters wide, 17.0 millimeters high and 245.0 millimeters long. The present design decreases the physical size in height and length compared to the conventional enclosure noted above. The invention can comprise a greater ruggedness, robustness, and mechanical strength. The fabrication process is also made easier. 
     Referring now to  FIGS. 3 and 4 , the enclosure base (or base member)  12  has fiber optic coupler mounting channels  18  which each have a semi-circular shape to receive the cylindrical shape of one of the two optical fiber couplers  20 . In one type of preferred example, the enclosure  10  has flexibility to accept physical dimensions of optical fiber coupler  20  that are ranging from about 2.00-3.30 millimeters in diameter and about 35.00-52.00 millimeters in length. The physical dimension of the optical fiber coupler  20  is directly proportional to the optical configuration. The enclosure  10  of the invention can be designed to be able to accommodate couplers having anywhere from a 1×1 configuration up to a 6×6 configuration, which translates to a maximum of six fiber optic channels on each side of the input and output. It should be noted that although the figures illustrate the mounting channels  18  as having a semi-circular shape to receive cylindrical couplers, any complementary shape to receive an alternatively shaped coupler may be provided. 
     Each mounting channel  18  has a generally rectangular cavity  26  at the center of its block. This cavity is for receiving RTV silicone which is used for mounting the coupler  20  to the base  12 . Besides being used for a coupler mounting purpose, the RTV silicone can act as a shock and vibration absorbing barrier between the coupler  20  and the base  12 . 
     In the embodiment shown, there is a one-millimeter curved and elevated wall  28  near each open end  30  and  32  of the platform (or side)  34  of the base  12 . It should be noted that alternative embodiments may comprise elevated walls having a height greater than or less than 1.00 millimeters. The purpose of this wall  28  is to provide smooth fiber routing and limit the minimum fiber-bending radius. The fiber  24  coating type can be crucial to this type of enclosure  10 . The high reliability coating for an optical fiber  24 , such as polyimide material or Pyrocoat™ (a trademark of Furukawa Electric North America, Inc.), has exceptional performance in mechanical and environmental properties. To meet the minimum fiber  24  bending radius requirement of this enclosure  10  design, the fiber bending radius specification is preferably at least about 10.0 millimeters. 
     In addition, there are four pegs  36 ; two at, or proximate to, each end  30 ,  32 . The pegs  36  may have any suitable diameter, such as 3.00 millimeters, for example. The pegs  36  extend from the side  34  of the base  12 . The pegs  36  function as strength support in the vertical direction. These pegs  36  are not only provided for mechanical strength. The pegs  36  also provide a smooth transition of fiber bending while the fiber  24  is entering the curvature wall  28 ; in order to maximizing the bending radius of the fiber  24 . In fiber optic characteristic, fiber bending causes the optics or light able to escape from the fiber  24 . This phenomenon is called optical loss. Additionally, the disclosed enclosure  10  preferably supports fiber cladding up to 140 micrometers in diameter. Fiber cladding diameters greater than 140 micrometers may experience excessive loss or attenuation. It should be noted that the fibers  24  extending from the couplers  20  may loop around the pegs  36  any number of times depending on the specific application. The base  12  further comprises an extending groove portion  38  extending along the base side walls  22 . The groove portion  38  serves as a lateral engagement feature for the lid  14  and provides for increased stability and durability. 
     The end caps  16 , best illustrated in  FIGS. 5 and 6 , generally provide three functions: fiber cable mounting, strain relief and interlocking. In regard to fiber cable mounting, in one exemplary embodiment, the end cap  16  is designed for a small, such as about 1.00 millimeter outer diameter, Teflon or Tefzel tubing for each individual fiber  24  for the purpose of fiber ruggedization. All strands of tubing will be eventually bundled with a circular formation and installed to the end cap  16 , such as with a 2.50 millimeters outer diameter. Furthermore, a single cable, such as a 2.50 millimeter outer diameter jacket cable for example, may be used, since the inner buffer diameter is large enough to accommodate up to about twelve 170 micrometer buffer diameter fibers. The fibers  24  are looped around between the pegs  36  and the elevated walls  28  in a general racetrack configuration. The fibers  24  are then bundled and routed out through the end caps  16 . One of the end caps  16  may serve as a mount/support for a fiber cable input and the other end cap  16  may serve as a mount/support for a fiber cable output. 
     For strain relief, the fiber cable bundling in one exemplary embodiment is installed within an opening or hole  40  of the end cap  16  by using high performance epoxy resin to bond the two components together. The conical shape of the hole  40  may form the resin in a taper shape, with its thickest portion located internally at the interior facing side  42 . Due to this resin formation, plus the bonding strength between the cable bundling and the end cap  16 , it will optimize the strength of cable bundling while it is under strain. 
     For interlocking, beyond the strain relief capability, the end cap  16  has a square wedge or rim  44  around its internal perimeter. In one exemplary embodiment, the square rim  44  is about 1.50 millimeters thick and about 1.08 millimeters high. This rim feature  44  provides an interlocking mechanism to all the components  10 ,  12 ,  14 , as well as strain relief support toward fiber cable bundling. The base  12  and lid  14  have square grooves  46 ,  48  (see  FIG. 9 ), respectively, which receive the rim  44  and are preferably held together with a high performance epoxy resin. The square grooves  46  are located proximate the first open end  30  and the second open end  32  of the base  12 . The square grooves  48  are located proximate the first open end  50  and the second open end  52  of the lid  14 . It should be noted that square grooves are not required and any suitable shape may be provided. 
     The end caps  16  are installed to the base  12  as the first step by directly installing the end caps  16  from the top to the base  12  as shown in  FIG. 7 . The mechanism of installation (or engagement) is a tongue-and-groove design. There is a slight interference (or press-fit) between the two components  10 ,  14  and the lid  14  and the end caps  16  after the end cap  16  fully inserted, in order to achieve stable and rigid mounting while installing the lid  14  to the base  12  and the end caps  16  as a final stage. 
     The enclosure lid (or lid member)  14 , best illustrated in  FIGS. 8 and 9 , is the last component to be engaged with the assembly. The lid  14  also has four pegs  54  with identical mating locations to the pegs  36  of the base  12 . The four pegs  54  extend from a side  56  of the lid  14 . There are four triangular wall supports  58 , such as 2.50 millimeters tall for example. These supports  58  will increase the wall strength due to stress acting perpendicularly to the vertical walls (or lid side walls)  60 . The lid  14  is connected to the end caps  16  in a similar fashion as described above for the base  12 . When the rim  44  of the end caps  16  is engaged with the grooves  48  of the lid  14 , the pegs  36  on base  12  are aligned with the pegs  54  on the lid  14 . The aligned pegs  36 ,  54  are appropriately located to maintain the desired optical fiber bend radius. The lid  14  further comprises an extending rim portion  62  extending along the lid side walls  60 . The rim portion  62  fits within the groove portion  38  of the base  12 . The engagement between the rim portion  62  and the groove portion  38  may be provided by a high performance epoxy resin, an interference or press fit, or any other suitable fastening method. 
     It should be understood that although the figures illustrate the base  12  as having a groove portion  38  along the side walls  22  and the lid  14  as having a rim portion  62  along the side walls  60 , an alternative embodiment may provide a base  12  comprising a rim portion and a lid comprising a groove portion. Additionally, the rim portions  62  and the end cap rims  44  can have a wedge shape and/or the groove portions  38 ,  46 ,  48  can have wedge shapes. Furthermore, any other suitable shapes for providing a press fit or interference fit are envisioned. 
     The disclosed base  12 , lid  14 , and end caps  16  are preferably formed by an injection molding method. When cost and weight (as opposed to component/material strength) are the primary design application concerns, injection molding provides a preferable method of fabrication. The preferred material for the disclosed enclosure  10  is Polyphenylene Sulfide Resin with R4 series. This flame retardant polymer resin compound may include about 40% glass fiber filler material. Polyphenylene Sulfide Resin is superior in mechanical strength, as well as environmental performance when compared to other suitable materials other than metal and metal alloys. Additionally, after formation Polyphenylene Sulfide Resin provides a material surface having slight roughness which creates an excellent surface bonding for adhesive or epoxy application. 
     When mechanical strength, chemical resistance, and electrical properties (as opposed to cost and weight) are primary design application concerns, a metal alloy, such as aluminum for example, may be used to fabricate the enclosure  10 . Forming the enclosure  10  from metal or metal alloys may increase the cost and weight of the enclosure  10 . Additionally, certain features, including the sectional thickness, on the present design may not be able to be produced under conventional machining methods and may lead to enclosure design modifications. Nevertheless, the material selection for the present design is dependent on the application and requirements. 
     It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.