Abstract:
The present invention relates generally to ferrule holders and associated fiber optic connectors used in optical communications networks, optical devices, and the like to optically couple optical fibers. More specifically, the present invention relates to a ferrule holder and an associated fiber optic connector having improved anti-withdrawal and anti-rotation features, such as a twin-threaded configuration, a single-threaded configuration, a splined configuration, a broached configuration, a counter-bored configuration, a dented configuration, a finned configuration, etc. These anti-withdrawal and anti-rotation features assist in holding an optical fiber in secure optical and/or physical contact with a ferrule within the ferrule holder and associated fiber optic connector.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to ferrule holders and associated fiber optic connectors used in optical communications networks, optical devices, and the like to optically couple optical fibers. More specifically, the present invention relates to a ferrule holder and an associated fiber optic connector having improved anti-withdrawal and anti-rotation features, such as a twin-threaded configuration, a single-threaded configuration, a splined configuration, a broached configuration, a counter-bored configuration, a dented configuration, a finned configuration, etc. These anti-withdrawal and anti-rotation features assist in holding an optical fiber in secure optical and/or physical contact with a ferrule within the ferrule holder and associated fiber optic connector. 
   2. Technical Background of the Invention 
   A conventional fiber optic connector includes, among other parts, an outer housing, an alignment sleeve, an inner structure that is configured to retain an optical fiber cable, a heat shrink and/or boot that is/are configured to retain and protect the optical fiber cable, and a ferrule holder that is configured to hold a ferrule. This ferrule is in optical and/or physical contact with an optical fiber that typically enters the ferrule holder opposite the ferrule. In operation, the fiber optic connector is mated with another fiber optic connector, such as a plug with a receptacle, for example, bringing the corresponding ferrules into optical and/or physical contact. This, of course, brings the corresponding optical fibers into optical contact, thereby creating an optical connection. The ferrules may be single or multi-fiber ferrules. The ferrule holders holding these ferrules may assume a variety of shapes, but are typically substantially cylindrical, and are manufactured from a metallic material or plastic material, due to the fact that such materials are relatively easy to machine or cast. 
   The optical fiber that enters the ferrule holder opposite the ferrule is typically secured in the ferrule holder and to the ferrule using an adhesive, preventing withdrawal and rotation of the optical fiber in relation to the ferrule holder and the ferrule. One major problem that the fiber optic industry currently struggles with, however, is that of delamination of the adhesive, caused by the poor bonding that exists between an optical fiber and a metallic material ferrule holder, for example. In addition, the adhesive used is prone to shrinking and detaching from the underlying substrate. 
   A variety of techniques have been developed to deal with the problems described above, including the use of various mechanical anchoring mechanisms and adhesive compositions. None of these techniques, however, provide adequate anti-withdrawal and anti-rotation characteristics. The techniques fail existing pull and twist tests in the face of the delamination and shrinkage problems described above. Thus, what is still needed in the art is a ferrule holder and associated fiber optic connector having improved anti-withdrawal and anti-rotation features. 
   BRIEF SUMMARY OF THE INVENTION 
   In various embodiments, the present invention provides a ferrule holder and associated fiber optic connector having improved anti-withdrawal and anti-rotation features, such as a twin-threaded configuration, a single-threaded configuration, a splined configuration, a broached configuration, a counter-bored configuration, a dented configuration, a finned configuration, etc. These anti-withdrawal and anti-rotation features assist in holding an optical fiber in secure optical and/or physical contact with a ferrule within the ferrule holder and associated fiber optic connector. 
   In one embodiment, the present invention provides a ferrule holder for use in a fiber optic connector or the like, including: a first end portion defining a bore that is configured and sized to receive an optical fiber; a second end portion defining a bore that is configured and sized to receive a ferrule; and a center portion defining a bore that is configured and sized to receive the optical fiber disposed between the first end portion and the second end portion, wherein an inside surface of the center portion includes an anti-withdrawal and anti-rotation geometry for holding the optical fiber in secure optical and/or physical contact with the ferrule. The anti-withdrawal and anti-rotation geometry includes a structure selected from the group consisting of a twin thread, a single thread, a spline, a broach, a counter-bore, a dent, one or more fins, and a combination thereof. The ferrule holder also includes an adhesive disposed on the inside surface of the center portion for holding the optical fiber in secure optical and/or physical contact with the ferrule. 
   In another embodiment, the present invention provides a device for use in a fiber optic connector or the like, including: a first end portion defining a bore that is configured and sized to receive a first optical fiber; a second end portion defining a bore that is configured and sized to receive a second optical fiber; and a center portion defining a bore that is configured and sized to receive the first optical fiber disposed between the first end portion and the second end portion, wherein an inside surface of the center portion includes an anti-withdrawal and anti-rotation geometry for holding the first optical fiber in secure optical and/or physical contact with the second optical fiber. Again, the anti-withdrawal and anti-rotation geometry includes a structure selected from the group consisting of a twin thread, a single thread, a spline, a broach, a counter-bore, a dent, one or more fins, and a combination thereof. The device also includes an adhesive disposed on the inside surface of the center portion for holding the first optical fiber in secure optical and/or physical contact with the second optical fiber. 
   In a further embodiment, the present invention provides a fiber optic connector including a ferrule holder, including: a first end portion defining a bore that is configured and sized to receive an optical fiber; a second end portion defining a bore that is configured and sized to receive a ferrule; and a center portion defining a bore that is configured and sized to receive the optical fiber disposed between the first end portion and the second end portion, wherein an inside surface of the center portion includes an anti-withdrawal and anti-rotation geometry for holding the optical fiber in secure optical and/or physical contact with the ferrule. The anti-withdrawal and anti-rotation geometry includes a structure selected from the group consisting of a twin thread, a single thread, a spline, a broach, a counter-bore, a dent, one or more fins, and a combination thereof. The fiber optic connector also includes an adhesive disposed on the inside surface of the center portion for holding the optical fiber in secure optical and/or physical contact with the ferrule. 
   It is to be understood that both the foregoing general description and the following detailed description provide exemplary embodiments of the present invention, and an overview or framework for understanding the nature and character of the present invention as it is claimed. The accompanying drawings are included in order to provide a further understanding of the present invention, and are incorporated into and constitute a part of this specification. The accompanying drawings illustrate the various exemplary embodiments of the present invention, and together with the detailed description, serve to explain the principles of operation thereof. The accompanying drawings are meant to be illustrative, and not limiting. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is illustrated and described herein with reference to the various drawings, in which like reference numbers are used to denote like method steps and/or device components, as appropriate, and in which: 
       FIG. 1  is a planar side view illustrating one embodiment of the ferrule holder of the present invention, specifically the ferrule holder having a twin-threaded configuration. 
       FIG. 2  is a planar side view illustrating another embodiment of the ferrule holder of the present invention, specifically the ferrule holder having a single-threaded configuration. 
       FIG. 3  is a planar side view illustrating a further embodiment of the ferrule holder of the present invention, specifically the ferrule holder having a splined configuration. 
       FIG. 4  is a planar side view illustrating a still further embodiment of the ferrule holder of the present invention, specifically the ferrule holder having a broached configuration. 
       FIG. 5  is a planar side view illustrating a still further embodiment of the ferrule holder of the present invention, specifically the ferrule holder having a counter-bored configuration. 
       FIG. 6  is a planar side view illustrating a still further embodiment of the ferrule holder of the present invention, specifically the ferrule holder having a dented configuration. 
       FIG. 7  is a planar side view illustrating a still further embodiment of the ferrule holder of the present invention, specifically the ferrule holder having a finned configuration. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In various embodiments, the present invention provides a ferrule holder and associated fiber optic connector having improved anti-withdrawal and anti-rotation features, such as a twin-threaded configuration, a single-threaded configuration, a splined configuration, a broached configuration, a counter-bored configuration, a dented configuration, a finned configuration, etc. These anti-withdrawal and anti-rotation features assist in holding an optical fiber in secure optical and/or physical contact with a ferrule within the ferrule holder and associated fiber optic connector. 
   Referring to  FIG. 1 , in one embodiment, the ferrule holder  10  of the present invention includes a first end  12  including a bore that is configured and sized to receive an optical fiber (not illustrated) and a second end  14  including a bore that is configured and sized to receive a ferrule (not illustrated). The first end  12  including the bore that is configured and sized to receive the optical fiber is substantially cylindrical, in the event that a single optical fiber is used, or substantially rectangular, in the event that multiple optical fibers are used. Similarly, the second end  14  including the bore that is configured and sized to receive the ferrule is substantially cylindrical, in the event that a single-fiber ferrule is used, or substantially rectangular, in the event that a multi-fiber ferrule is used. It should be noted that any suitable shapes may be used. In this embodiment, the outside and inside diameters of the first end  12  including the bore that is configured and sized to receive the optical fiber are substantially smaller than the outside and inside diameters of the second end  14  including the bore that is configured and sized to receive the ferrule. As described above, the ferrule holder  10  is manufactured from a metallic material, plastic material, or the like. A retention bore  16  is disposed between the bores of the first end  12  and the second end  14  of the ferrule holder  10 . This retention bore  16  is configured to receive and retain the optical fiber, holding it in optical and/or physical contact with the ferrule. In this embodiment, the retention bore  16  includes twin threads  18  manufactured into its inside surface. These twin threads  18  physically enhance the anti-withdrawal and anti-rotation characteristics of the retention bore  16 , acting as an anchor, as well as provide additional surface area for an adhesive (not illustrated) disposed between the optical fiber and the retention bore  16  to adhere to, if used, effectively eliminating delamination and shrinkage problems. Alternatively, a plurality of retention bores  16  each include twin threads  18  manufactured into their inside surfaces. Again, these twin threads  18  physically enhance the anti-withdrawal and anti-rotation characteristics of the retention bores  16 , acting as anchors, as well as provide additional surface area for an adhesive disposed between the optical fiber and the retention bores  16  to adhere to, if used. This twin-threaded configuration allows the ferrule holder  10  to pass existing pull and twist tests, as the adhesive-fiber-matrix is effectively strengthened. Thus, robust optical contact between the optical fiber and the ferrule is ensured, even in the face of destructives forces applied to the optical fiber. 
   Referring to  FIG. 2 , in another embodiment, the ferrule holder  10  of the present invention includes a first end  12  including a bore that is configured and sized to receive an optical fiber (not illustrated) and a second end  14  including a bore that is configured and sized to receive a ferrule (not illustrated). The first end  12  including the bore that is configured and sized to receive the optical fiber is substantially cylindrical, in the event that a single optical fiber is used, or substantially rectangular, in the event that multiple optical fibers are used. Similarly, the second end  14  including the bore that is configured and sized to receive the ferrule is substantially cylindrical, in the event that a single-fiber ferrule is used, or substantially rectangular, in the event that a multi-fiber ferrule is used. It should be noted that any suitable shapes may be used. In this embodiment, the outside and inside diameters of the first end  12  including the bore that is configured and sized to receive the optical fiber are substantially smaller than the outside and inside diameters of the second end  14  including the bore that is configured and sized to receive the ferrule. As described above, the ferrule holder  10  is manufactured from a metallic material, plastic material, or the like. A retention bore  16  is disposed between the bores of the first end  12  and the second end  14  of the ferrule holder  10 . This retention bore  16  is configured to receive and retain the optical fiber, holding it in optical and/or physical contact with the ferrule. In this embodiment, the retention bore  16  includes a single thread  20  manufactured into its inside surface. This single thread  20  physically enhances the anti-withdrawal and anti-rotation characteristics of the retention bore  16 , acting as an anchor, as well as provides additional surface area for an adhesive (not illustrated) disposed between the optical fiber and the retention bore  16  to adhere to, if used, effectively eliminating delamination and shrinkage problems. Alternatively, a plurality of retention bores  16  each include a single thread  20  manufactured into their inside surfaces. Again, this single thread  20  physically enhances the anti-withdrawal and anti-rotation characteristics of the retention bores  16 , acting as anchors, as well as provides additional surface area for an adhesive disposed between the optical fiber and the retention bores  16  to adhere to, if used. This single-threaded configuration allows the ferrule holder  10  to pass existing pull and twist tests, as the adhesive-fiber-matrix is effectively strengthened. Thus, robust optical contact between the optical fiber and the ferrule is ensured, even in the face of destructives forces applied to the optical fiber. 
   Referring to  FIG. 3 , in a further embodiment, the ferrule holder  10  of the present invention includes a first end  12  including a bore that is configured and sized to receive an optical fiber (not illustrated) and a second end  14  including a bore that is configured and sized to receive a ferrule (not illustrated). The first end  12  including the bore that is configured and sized to receive the optical fiber is substantially cylindrical, in the event that a single optical fiber is used, or substantially rectangular, in the event that multiple optical fibers are used. Similarly, the second end  14  including the bore that is configured and sized to receive the ferrule is substantially cylindrical, in the event that a single-fiber ferrule is used, or substantially rectangular, in the event that a multi-fiber ferrule is used. It should be noted that any suitable shapes may be used. In this embodiment, the outside and inside diameters of the first end  12  including the bore that is configured and sized to receive the optical fiber are substantially smaller than the outside and inside diameters of the second end  14  including the bore that is configured and sized to receive the ferrule. As described above, the ferrule holder  10  is manufactured from a metallic material, plastic material, or the like. A retention bore  16  is disposed between the bores of the first end  12  and the second end  14  of the ferrule holder  10 . This retention bore  16  is configured to receive and retain the optical fiber, holding it in optical and/or physical contact with the ferrule. In this embodiment, the retention bore  16  includes a spline  22  manufactured into its inside surface. This spline  22  physically enhance the anti-withdrawal and anti-rotation characteristics of the retention bore  16 , acting as an anchor, as well as provides additional surface area for an adhesive (not illustrated) disposed between the optical fiber and the retention bore  16  to adhere to, if used, effectively eliminating delamination and shrinkage problems. Alternatively, a plurality of retention bores  16  each include a spline  22  manufactured into their inside surfaces. Again, this spline  22  physically enhances the anti-withdrawal and anti-rotation characteristics of the retention bores  16 , acting as anchors, as well as provides additional surface area for an adhesive disposed between the optical fiber and the retention bores  16  to adhere to, if used. This splined configuration allows the ferrule holder  10  to pass existing pull and twist tests, as the adhesive-fiber-matrix is effectively strengthened. Thus, robust optical contact between the optical fiber and the ferrule is ensured, even in the face of destructives forces applied to the optical fiber. 
   Referring to  FIG. 4 , in a still further embodiment, the ferrule holder  10  of the present invention includes a first end  12  including a bore that is configured and sized to receive an optical fiber (not illustrated) and a second end  14  including a bore that is configured and sized to receive a ferrule (not illustrated). The first end  12  including the bore that is configured and sized to receive the optical fiber is substantially cylindrical, in the event that a single optical fiber is used, or substantially rectangular, in the event that multiple optical fibers are used. Similarly, the second end  14  including the bore that is configured and sized to receive the ferrule is substantially cylindrical, in the event that a single-fiber ferrule is used, or substantially rectangular, in the event that a multi-fiber ferrule is used. It should be noted that any suitable shapes may be used. In this embodiment, the outside and inside diameters of the first end  12  including the bore that is configured and sized to receive the optical fiber are substantially smaller than the outside and inside diameters of the second end  14  including the bore that is configured and sized to receive the ferrule. As described above, the ferrule holder  10  is manufactured from a metallic material, plastic material, or the like. A retention bore  16  is disposed between the bores of the first end  12  and the second end  14  of the ferrule holder  10 . This retention bore  16  is configured to receive and retain the optical fiber, holding it in optical and/or physical contact with the ferrule. In this embodiment, the retention bore  16  includes a broach  24  manufactured into its inside surface. This broach  24  physically enhances the anti-withdrawal and anti-rotation characteristics of the retention bore  16 , acting as an anchor, as well as provides additional surface area for an adhesive (not illustrated) disposed between the optical fiber and the retention bore  16  to adhere to, if used, effectively eliminating delamination and shrinkage problems. The broach  24  may vary in length and depth, as appropriate. For example, the broach  24  may run the entire length of the retention bore  16 , or only a small portion of the length of the retention bore  16 . Alternatively, a plurality of retention bores  16  each include a broach  24  manufactured into their inside surfaces. Again, this broach  24  physically enhances the anti-withdrawal and anti-rotation characteristics of the retention bores  16 , acting as anchors, as well as provides additional surface area for an adhesive disposed between the optical fiber and the retention bores  16  to adhere to, if used. This broached configuration allows the ferrule holder  10  to pass existing pull and twist tests, as the adhesive-fiber-matrix is effectively strengthened. Thus, robust optical contact between the optical fiber and the ferrule is ensured, even in the face of destructives forces applied to the optical fiber. 
   Referring to  FIG. 5 , in a still further embodiment, the ferrule holder  10  of the present invention includes a first end  12  including a bore that is configured and sized to receive an optical fiber (not illustrated) and a second end  14  including a bore that is configured and sized to receive a ferrule (not illustrated). The first end  12  including the bore that is configured and sized to receive the optical fiber is substantially cylindrical, in the event that a single optical fiber is used, or substantially rectangular, in the event that multiple optical fibers are used. Similarly, the second end  14  including the bore that is configured and sized to receive the ferrule is substantially cylindrical, in the event that a single-fiber ferrule is used, or substantially rectangular, in the event that a multi-fiber ferrule is used. It should be noted that any suitable shapes may be used. In this embodiment, the outside and inside diameters of the first end  12  including the bore that is configured and sized to receive the optical fiber are substantially smaller than the outside and inside diameters of the second end  14  including the bore that is configured and sized to receive the ferrule. As described above, the ferrule holder  10  is manufactured from a metallic material, plastic material, or the like. A retention bore  16  is disposed between the bores of the first end  12  and the second end  14  of the ferrule holder  10 . This retention bore  16  is configured to receive and retain the optical fiber, holding it in optical and/or physical contact with the ferrule. In this embodiment, the retention bore  16  includes a counter-bore  26  manufactured into its inside surface. This counter-bore  26  physically enhances the anti-withdrawal and anti-rotation characteristics of the retention bore  16 , acting as an anchor, as well as provides additional surface area for an adhesive (not illustrated) disposed between the optical fiber and the retention bore  16  to adhere to, if used, effectively eliminating delamination and shrinkage problems. Alternatively, a plurality of retention bores  16  each include a counter-bore  26  manufactured into their inside surfaces. Again, this counter-bore  26  physically enhances the anti-withdrawal and anti-rotation characteristics of the retention bores  16 , acting as anchors, as well as provides additional surface area for an adhesive disposed between the optical fiber and the retention bores  16  to adhere to, if used. This counter-bored configuration allows the ferrule holder  10  to pass existing pull and twist tests, as the adhesive-fiber-matrix is effectively strengthened. Thus, robust optical contact between the optical fiber and the ferrule is ensured, even in the face of destructives forces applied to the optical fiber. 
   Referring to  FIG. 6 , in a still further embodiment, the ferrule holder  10  of the present invention includes a first end  12  including a bore that is configured and sized to receive an optical fiber (not illustrated) and a second end  14  including a bore that is configured and sized to receive a ferrule (not illustrated). The first end  12  including the bore that is configured and sized to receive the optical fiber is substantially cylindrical, in the event that a single optical fiber is used, or substantially rectangular, in the event that multiple optical fibers are used. Similarly, the second end  14  including the bore that is configured and sized to receive the ferrule is substantially cylindrical, in the event that a single-fiber ferrule is used, or substantially rectangular, in the event that a multi-fiber ferrule is used. It should be noted that any suitable shapes may be used. In this embodiment, the outside and inside diameters of the first end  12  including the bore that is configured and sized to receive the optical fiber are substantially smaller than the outside and inside diameters of the second end  14  including the bore that is configured and sized to receive the ferrule. As described above, the ferrule holder  10  is manufactured from a metallic material, plastic material, or the like. A retention bore  16  is disposed between the bores of the first end  12  and the second end  14  of the ferrule holder  10 . This retention bore  16  is configured to receive and retain the optical fiber, holding it in optical and/or physical contact with the ferrule. In this embodiment, the retention bore  16  includes a dent  28  manufactured into its inside surface. This dent  28  physically enhances the anti-withdrawal and anti-rotation characteristics of the retention bore  16 , acting as an anchor, as well as provides additional surface area for an adhesive (not illustrated) disposed between the optical fiber and the retention bore  16  to adhere to, if used, effectively eliminating delamination and shrinkage problems. Alternatively, a plurality of retention bores  16  each include a dent  28  manufactured into their inside surfaces. Again, this dent  28  physically enhances the anti-withdrawal and anti-rotation characteristics of the retention bores  16 , acting as anchors, as well as provides additional surface area for an adhesive disposed between the optical fiber and the retention bores  16  to adhere to, if used. This dented configuration allows the ferrule holder  10  to pass existing pull and twist tests, as the adhesive-fiber-matrix is effectively strengthened. Thus, robust optical contact between the optical fiber and the ferrule is ensured, even in the face of destructives forces applied to the optical fiber. 
   Referring to  FIG. 7 , in a still further embodiment, the ferrule holder  10  of the present invention includes a first end  12  including a bore that is configured and sized to receive an optical fiber (not illustrated) and a second end  14  including a bore that is configured and sized to receive a ferrule (not illustrated). The first end  12  including the bore that is configured and sized to receive the optical fiber is substantially cylindrical, in the event that a single optical fiber is used, or substantially rectangular, in the event that multiple optical fibers are used. Similarly, the second end  14  including the bore that is configured and sized to receive the ferrule is substantially cylindrical, in the event that a single-fiber ferrule is used, or substantially rectangular, in the event that a multi-fiber ferrule is used. It should be noted that any suitable shapes may be used. In this embodiment, the outside and inside diameters of the first end  12  including the bore that is configured and sized to receive the optical fiber are substantially smaller than the outside and inside diameters of the second end  14  including the bore that is configured and sized to receive the ferrule. As described above, the ferrule holder  10  is manufactured from a metallic material, plastic material, or the like. A retention bore  16  is disposed between the bores of the first end  12  and the second end  14  of the ferrule holder  10 . This retention bore  16  is configured to receive and retain the optical fiber, holding it in optical and/or physical contact with the ferrule. In this embodiment, the retention bore  16  includes one or more non-intersecting and non-conjoined fins  30  manufactured into its inside surface. These one or more fins  30  physically enhance the anti-withdrawal and anti-rotation characteristics of the retention bore  16 , acting as an anchor, as well as provide additional surface area for an adhesive (not illustrated) disposed between the optical fiber and the retention bore  16  to adhere to, if used, effectively eliminating delamination and shrinkage problems. Alternatively, a plurality of retention bores  16  each include one or more fins  30  manufactured into their inside surfaces. Again, these one or more fins  30  physically enhance the anti-withdrawal and anti-rotation characteristics of the retention bores  16 , acting as anchors, as well as provide additional surface area for an adhesive disposed between the optical fiber and the retention bores  16  to adhere to, if used. This finned configuration allows the ferrule holder  10  to pass existing pull and twist tests, as the adhesive-fiber-matrix is effectively strengthened. Thus, robust optical contact between the optical fiber and the ferrule is ensured, even in the face of destructives forces applied to the optical fiber. 
   It should be noted that any suitable anti-withdrawal and anti-rotation geometry is with respect to the retention bore(s)  16  ( FIGS. 1-7 ) is contemplated by the present invention. Likewise, the present invention is not limited in its application to a ferrule holder  10  ( FIGS. 1-7 ). It may be applied variously to any housing that is used to hold an optical fiber during fiber optic connector assembly, for example. Both ceramic and non-ceramic ferrules are contemplated by the present invention. 
   Although the present invention has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present invention and are intended to be covered by the following claims.