Abstract:
A multi-fiber ferrule has openings for optical fibers, an integral fiber optic guide pin and an opening to receive a fiber optic guide pin. A plate is provided to align the optical fibers with the front face of the multi-fiber ferrule. A method for aligning the optical fibers with the front face of the multi-fiber ferrule is also provided.

Description:
REFERENCE TO RELATED CASE 
       [0001]    This application claims priority under 35 U.S.C. §119 (e) to provisional application No. 61/109,145, filed on Oct. 28, 2008, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    Typically, MT ferrules are molded with 2 guide holes in each ferrule. During the manufacturing process, metal guide pins attached to a guide pin clamp are added to  1  connector (male MT) and the mating ferrule is left with holes (female MT). Occasionally, the male/female configuration of connectors causes confusion and requires connectors to be reworked and changed from male to female or vice versa. The metal pins and pin clamp also add additional cost to the assembly. 
         [0003]    In the past, it has not been possible to mold the pin into the ferrule because the ferrule must be polished after installing the fibers into the ferrule. The polishing process creates a near planar surface on the end face of the completed ferrule with no protruding features. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention is for a multi-fiber ferrule that consists of one molded guide pin and one molded guide hole. It is possible to allow for a molded guide pin protruding from the end face surface because the typical polishing process is replaced with a process that accurately locates the array of fibers at the end face of the ferrule and then epoxies them in place. The accuracy of the fibers is better than 20 microns coplanarity. This accuracy is sufficient for a reasonable insertion loss (&lt;1 dB), even though is does not achieve physical contact of the fiber tips consistently. 
         [0005]    According to one aspect of the present invention, a multi-fiber ferrule is provided that includes a main body having a front face and a middle portion, a plurality of openings extending between the front face and the middle portion of the main body to receive optical fibers therein, a fiber optic guide pin integrally formed with the main body and extending outwardly from the front face, and a fiber optic guide pin opening extending through the front face and rearwardly to receive a corresponding fiber optic guide pin. 
         [0006]    In yet another aspect, a method of inserting optical fibers into a multi-fiber ferrule, the multi-fiber ferrule including a main body having a front face and a middle portion, a plurality of openings extending between the front face and the middle portion of the main body to receive optical fibers therein, a fiber optic guide pin integrally formed with the main body and extending outwardly from the front face, and a fiber optic guide pin opening extending through the front face and rearwardly to receive a corresponding fiber optic guide pin, the method includes providing a plate having a front face, a fiber optic guide pin extending outwardly from the front face away from the plate, a fiber optic guide pin opening extending from the front face towards the plate and a recessed portion between the fiber optic guide pin and the fiber optic guide pin opening, aligning the multi-fiber ferrule with plate such that the fiber optic guide pin from the multi-fiber ferrule engages the fiber optic guide pin opening in the plate, inserting an optical fiber in each of the plurality of openings in the multi-fiber ferrule, pushing the optical fibers toward the plate until ends of the optical fibers touch the plate, and securing the optical fibers in the multi-fiber ferrule. 
         [0007]    Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings. 
         [0008]    It is to be understood that both the foregoing general description and the following detailed description of the present embodiments of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the description serve to explain the principles and operations of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view of one embodiment of a multi-fiber ferrule according to the present invention; 
           [0010]      FIG. 2  is a perspective view of one embodiment of a plate used with the multi-fiber ferrule of  FIG. 1  according to the present invention; 
           [0011]      FIG. 3  is a top view of the multi-fiber ferrule of  FIG. 1  and fiber optic ribbon inserted therein engaging the plate of  FIG. 3  to appropriately place the optical fibers in the fiber optic ribbon with regard to the molded guide pin and end face of the multi-fiber ferrule; and 
           [0012]      FIG. 4  is a cross-sectional view of the multi-fiber ferrule and plate of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0013]    Reference will now be made in detail to the present preferred embodiment(s) of the invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. 
         [0014]    Referring to  FIG. 1 , a multi-fiber ferrule  10  according to the present invention is illustrated. The multi-fiber ferrule  10  preferably has an end face  12  with micro-holes  14  extending therethrough from a middle portion  15  to hold optical fibers  16  from the optical fiber ribbons  18 . While 24 micro-holes  14  are illustrated, any number may be present (i.e.,  12 ,  24 ,  48 , etc.) and fall within the scope of the present invention. The multi-fiber ferrule  10  preferably has an opening  19  on one side  20  to allow for the application of epoxy to secure the optical fibers  16  (and the optical fiber ribbon  18 ) in the multi-fiber ferrule  10 . The end face  12  also preferably includes a molded guide pin  22  and one molded opening  24 , which corresponds to the fiber optic guide pin openings in prior art ferrules. By using one molded guide pin  22  and one molded opening  24 , making it a hermaphroditic ferrule, only one hermaphroditic ferrule type needs to be manufactured and still allow for mating with the other hermaphroditic ferrules. The molded guide pin  22  preferably has a recessed area  26  at the base of the molded guide pin  22  to allow a radius to be molded at the base of the molded guide pin  22  and still allow two multi-fiber ferrules  10  to mate flush to each other. If there were no recessed area  26  and a radius was molded at the base of the molded guide pin, the radius would prevent face-to-face fating of the multi-fiber ferrules  10 . By using a hermaphroditic ferrule, fiber optic connectors using the multi-fiber ferrules  10  are mated key-up to key-up instead of the typical key-up to key-down configuration. By molding the guide pin  22 , fewer parts are needed in the assembly, since there is no need for the female pin clamp, the male pin clamp, or the metal guide pins. 
         [0015]    It should also be noted that since the multi-fiber ferrule  10  is not polished during processing, the multi-fiber ferrule  10  can be made of a lower cost resin that does not control the distribution of glass beads and does not require deflashing Additionally, the multi-fiber ferrules  10  are preferably made from a translucent material that has a base polymer of polyetherimide. Other clear or translucent polymers would also be possible such as cyclo-olefin copolymer or polyphenylsulfone. As noted below, a translucent material allows for the use of a light-curable epoxy with the multi-fiber ferrules  10 . Additionally, the material also preferably has a lower modulus than with other ferrules. In the present invention, material that has a modulus of 5 GPa rather than the typical 18 GPa is preferably used. This material allows for a better mating of the multi-fiber ferrules because it allows contact of the front faces  12 . 
         [0016]    In a preferred process, one array of optical fibers are laser cleaved at a time, and the optical fibers  16  are positioned into the multi-fiber ferrule  10  so they are positioned relative to the end face  12 . The optical fibers  16  are preferably positioned so they protrude approximately 0-20 microns from the end face  12  and epoxied into place. The epoxy used to secure the optical fibers  16  in place is a light-curable epoxy. The translucent polymer used for the multi-fiber ferrule  10  allows for the epoxy to be cure in all locations of the multi-fiber ferrule  10 . The use of a light-curable epoxy allows for the epoxy to be cured quickly, before the epoxy has time to wick to the ferrule end face  12 . 
         [0017]    Illustrated in  FIG. 2  is a plate  40  that assists in positioning the optical fibers  16  relative to the end face  12  and the molded guide pin  22  and molded opening  24 . The plate  40  has a front face  42  that is positioned against the end face  16  of the multi-fiber ferrule  10 . The plate  40  has a depression or opening  44  that corresponds to the molded guide pin  22  and a guide pin  46  that corresponds to the molded opening  24 . Positioned therebetween is a depression  48  that is between 0 and 20 microns deep, depending on the amount of protrusion of the optical fibers  16  that the user needs. 
         [0018]      FIGS. 3 and 4  illustrate the plate  40  in use with the multi-fiber ferrule  10 . As can be seen, the plate  40  is flush against the end face  16 , the fibers are pushed through the multi-fiber ferrule  10  and end face  16  to engage the plate  40 . In this position, the optical fibers  16  and optical fiber ribbon  18  are epoxied in place. Although the preferred embodiment consists of a plate with one hole and one guide pin, it is also possible to create a plate with either 2 guide pins or 2 holes that correspond to a ferrule with either 2 holes or 2 pins. 
         [0019]    It should also be noted that the end face  16  of the multi-fiber ferrule  10  may also be polished, however, the polishing of the end face  16  may only be done on that portion of the end face  16  where the molded guide pin  22  is not located. 
         [0020]    It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.