Patent Publication Number: US-2023161110-A1

Title: Optical fiber support structure

Description:
REFERENCE TO RELATED CASE 
     This application claims priority under 35 U.S.C. § 119 (e) to U.S. provisional application No. 63/019,528 filed on May 4, 2020, the contents of which are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Optical fibers are used as an optical transport medium in various communications scenarios. In some cases, they are mated to other optical fibers, while in some cases, they are aligned to a transceiver that transmits and receives the optical output to and from the optical fibers. When mated with other optical fibers, the optical fibers need to be precisely positioned and aligned due to the micrometer level dimensions of the output beam profile and of the optical fibers. 
     Optical fibers may be supported by a silicon or a glass substrate having a groove-like structure upon which the optical fibers are placed and an adhesive applied to secure the optical fibers within the substrate. Such groove-like structures may include V-grooves or U-grooves, such as the one shown in U.S. Pat. No. 7,058,275 assigned to Oz Optics of CA. Alternatively, optical fibers are commonly used in fiber optic ferrules that have cylindrical openings into which the optical fibers are inserted from the rear of the fiber optic ferrules. These fiber optic ferrules may be single fiber or multi-fiber, and typically mated to other ferrules. In certain cases, these fiber optic ferrules may be aligned to on-board optics that bi-directionally transfer the optical beam between the fiber optic ferrule and the transceiver. Certain fiber optic ferrules may utilize groove-like structures too, and the optical fibers are typically placed in these grooves and an adhesive is applied to secure the optical fibers. However, such fiber optic ferrules with grooves do not have any optical fiber openings associated with conventional MT or lensed ferrules. Additionally, mechanical forces applied through a cap may be used to push the optical fibers toward the base of the grooves. 
     Each of the optical fiber openings in a ferrule material, and grooves in glass or silicon, have their own set of challenges in manufacturing from a precision and tolerance perspective. In the case of multi-fiber groove support structures, such as V-grooves, a uniform pair of angled opposing surfaces has to be created throughout the length of the V-groove support structure. Similar issues exist for U-grooves. Typically, making V-grooves involves processes such as etching (when the V-groove is in Silicon) or the use of a diamond disc (when the structure is on a glass substrate). Further, due to the inherent crystal structure of silicon, the optimal angle between the opposing surfaces of the V-groove is 54.6°. However, with glass, this angle is typically 60°. This may lead to misalignment when the optical transport utilizes both, one side being a glass ferrule, and the other side being a silicon substrate. 
     When V-grooves are used in ferrules, the contact of the optical fibers with the ferrule material creates a depression on the walls of the V-grooves in the ferrule material that is dependent on the force that is applied to the optical fibers when placed in the grooves. This occurs due to the difference in the optical fiber and ferrule material, and creates potential misalignment of the optical fibers during mating with other optical fibers. 
     In the case of fiber openings inside the fiber optic ferrule, they need to have uniform diameters throughout the length to ensure proper insertion and subsequent positioning of the optical fibers therein. Measuring such uniformity of the fiber openings is challenging and cumbersome and may be error prone. 
     SUMMARY OF THE INVENTION 
     According to one aspect, the present invention is directed to an optical fiber support structure for an optical fiber that includes a substrate having a groove configured to receive the optical fiber and running lengthwise generally parallel to the optical fiber, and at least two projections from the substrate and into the groove, each of said at least two projections including a surface to receive the optical fiber. 
     In some embodiments, the at least two projections comprise six projections, the projections being spaced from one another in a lengthwise direction, a lateral direction, or both. 
     In some embodiments, the at least two projections have a curved surface directed toward the groove. 
     In some embodiments, the curved surface on each of the at least two projections have a curvature that is the same as that of the optical fiber. 
     In yet another aspect, there is a fiber optic ferrule for receiving a plurality of optical fibers in a plurality of optical fiber support structures that includes a main body extending between a front end and a rear end, the main body having a top surface and a bottom surface, a longitudinal axis extending between the front end and the rear end and parallel to the plurality of optical fiber support structures, the plurality of support structures being disposed in the main body, each of the plurality of support structures have a groove and being generally parallel to the longitudinal axis of the ferrule and each being configured to receive an optical fiber, and a plurality of fiber openings, a respective one of the plurality of fiber openings is aligned with a respective one of the plurality of optical fiber support structures and rearward thereof, each of the plurality of fiber openings having an tubular configuration to accept the optical fibers insertable from the rear end of the ferrule and onto a respective one of the plurality of optical fiber support structures. 
     In some embodiments, the each of the grooves includes at least two projections extending into the groove, each of said at least two projections including a surface to receive the optical fiber. 
     In some embodiments, there is a chamfered surface for each of the plurality of support structures disposed between respective ones of the fiber openings and each of the plurality of support structures. 
     In yet another aspect, there is a fiber optic ferrule made of an optically clear material that includes a main body of optically clear material extending between a front end and a rear end, the main body having a top surface and a bottom surface, a plurality of optical fiber support structures in the main body and having a longitudinal axis extending between the front end and the rear end and parallel to the plurality of optical fiber support structures, each of the plurality of optical fiber support structures further comprising a groove in the optically clear material, each of the grooves configured to receive optical fiber therein, each of the grooves running lengthwise between the front end and rear end and at least two projections provided in a front half of each of the grooves, each of said at least two projections including a surface to receive the optical fiber. 
     It is to be understood that both the foregoing general description and the following detailed description of the present embodiments of the invention 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 
         FIG.  1    is a perspective view of one embodiment of a fiber optic ferrule having an optical fiber support structure for an optical fiber according to the present invention; 
         FIG.  2    is a bottom side perspective view of the fiber optic ferrule in  FIG.  1   ; 
         FIG.  3    is a perspective view of the front face of the fiber optic ferrule in  FIG.  1   ; 
         FIG.  4    is a top plan view of the fiber optic ferrule in  FIG.  1   ; 
         FIG.  5    is a perspective view from the front left of a cross sectional view of the fiber optic ferrule in  FIG.  1   ; 
         FIG.  6    is a front elevation view of the fiber optic ferrule in  FIG.  1   ; 
         FIG.  7    is a rear elevation view of the fiber optic ferrule in  FIG.  1   ; 
         FIG.  8    a perspective view from the front left of a cross sectional view of the fiber optic ferrule in  FIG.  1   ; 
         FIG.  9    is a partial view of cross section of the optical fiber support structure and projections in the fiber optic ferrule in  FIG.  1   ; 
         FIG.  10    is a top elevational view of a portion of fiber optic ferrule in  FIG.  1   ; 
         FIG.  11    is a view of cross section of the optical fiber support structure and projections supporting an optical fiber in the fiber optic ferrule in  FIG.  1   ; 
         FIG.  12    is a perspective view of another embodiment of a fiber optic ferrule having an optical fiber support structure for an optical fiber according to the present invention; 
         FIG.  13    is a view of a plug attached to a window of the fiber optic ferrules of  FIG.  1  or  12   ; and 
         FIG.  14    is a cross sectional view of the fiber optical ferrule in  FIG.  13   . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     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. 
     Illustrated in  FIGS.  1 - 11    is one embodiment of a fiber optic ferrule  100  having a plurality of optical fiber support structures  102  (see, e.g.,  FIGS.  4 - 5 ,  7 - 9   ) for an optical fiber  104  (see  FIG.  11   ) according to the present invention. The fiber optic ferrule  100  has a main body  106  extending between a front end  108  and a rear end  110 . The main body  106  also has a top surface  112 , a bottom surface  114  and two side surfaces  116 , 118  extending between the top surface  112  and the bottom surface  114 . The fiber optic ferrule  100  also has a circumferential portion  120  that extends around the rear end  110  of the main body  106  and creates a shoulder  122 . The fiber optic ferrule  100  may also be shoulder-less. The term shoulder-less referring to a lack of any protrusions or other features on the side surfaces that may be used to engage the multi-fiber ferrule  100  with a receptacle or an adapter. Thus, the circumferential portion  120  would not be present in such a fiber optic ferrule The main body  106  also includes a longitudinal axis A extending between the front end  108  and the rear end  110  and parallel to the plurality of optical fiber support structures  102 . The plurality of support structures  102  are disposed in the main body  106  and have a groove  124 . As can be seen in  FIGS.  1 ,  4 ,  5 ,  8  and  10   , they are generally parallel to the longitudinal axis A of the fiber optic ferrule  100  and each is configured to receive an optical fiber  104 . 
     Applicant notes that the term “front” or “forward” means that direction where the fiber optic ferrule would meet with another fiber optic ferrule or device, while the term “rear” or “rearward” is used to mean the direction from which the optical fibers enter into the fiber-optic ferrule or fiber optic connector. In the present application, the fiber optic ferrule  100  will therefore have a front and a rear. Thus, in  FIG.  1   , the “front” of the fiber optic ferrule  100  is on the left side of the figure and pointing out of the figure. The “rear” or “back” is that part of the fiber optic ferrule  100  that is on the right side of the page and “rearward” and “backward” is toward the right and into the page. 
     The plurality of support structures  102  are each generally an open-top groove that extends parallel to the longitudinal axis A. See  FIGS.  4 ,  5 , and  8 - 11   . Each groove of the plurality of support structures  102  could be a v-shaped, u-shaped, or other configuration and still fall within the scope of the present invention. Thus, there is a space  130  that is formed by the walls  132  to receive the optical fiber  104  in the groove. A u-shaped groove is illustrated in the figures, and thus has a continuous wall. If the plurality of support structures  102  were formed by a v-shaped groove, then there would be at least two walls. Similarly, if the groove had a polygonal shape, there may be more than 2 walls. All of these configurations are covered herein. Further, while the plurality of support structures  102  are illustrated as being in a fiber optic ferrule  100 , but could be made of other materials (glass, silicon, etc.) and disposed in other structures. 
     In one aspect, the fiber support structures  102  may be provided on a substrate. Basically, the substrate would have geometry similar to the view of the fiber optic ferrule  100  shown in  FIG.  10   . The substrate may be made of glass, silicon, or other materials. Since other structures on such a substrate will be similar to the structures described herein of the fiber optic ferrule  100 , one of ordinary skill in the art after reading this disclosure will understand that the discussion of the fiber optic ferrule  100  is applicable to such a substrate, albeit with a different footprint or geometry than the fiber optic ferrule  100 . 
     A plurality of projections  134  extend into the space  130  from the walls  132 . See, e.g.,  FIG.  9   . While the plurality of projections  134  may be formed at the same time as the rest of the fiber optic ferrule  100 , they may be added later. Again, the plurality of projections may be formed on a substrate rather than inside the fiber optic ferrule  100 . Additionally, the plurality of projections  134  may be formed by the removal of material when creating the plurality of support structures  102 . Each of the plurality of projections  134  may also have a curved surface  136  directed toward the space  130  of the plurality of support structures  102 . The curved surface  136  preferably has a radius of curvature that matches the optical fibers  104 . As a result, the optical fibers  104  may be positioned more accurately inside the space  130  than standard V-grooves or u-grooves without any of the plurality of projections  134 . However, it is possible that the radius of curvature is larger, but preferably not smaller than that radius of curvature. Further, other geometries of the plurality of projections  134  (e.g., a convex bump) may be utilized as an alternative. 
     The plurality of projections  134  are preferably aligned in both a longitudinal direction as well as an orthogonal direction. That is, the longitudinal direction is parallel to the longitudinal axis A through the main body  106 . So, as illustrated in  FIG.  9   , the view is a longitudinal view down (or, up) one of the plurality of support structures  102  and shows the plurality of projections  134  are in line. Additionally, the plurality of projections  134  are preferably aligned around the walls  132  in an orthogonal direction. See also  FIG.  10   , where there are number (three as an example) of the plurality of projections  134  aligned in a row from top to bottom on the page. The plurality of projections  134  could be aligned in other directions or not have any planned alignment at all. Moreover, it should be noted that a distal end is toward the front end  108  and the proximal end is toward the rear end  110 . So the plurality of projections  134  on the left side of  FIG.  10    are at the distal end and those on the right side are at the proximal end. Further, while  FIG.  10    shows four triplets of the plurality of projections  134 , there may be only one, only two, only three, or more than four sets of the plurality of projections  134 . For example, there may be six projections, the projections being spaced from one another in a lengthwise direction, a lateral direction, or both. Similarly, only one group of the plurality of projections provided at a distal end or in the front half of the fiber support structure  102  to receive the optical fibers  104 . Furthermore, there are at least two projections  134  into the groove although triplets are shown. For example, in  FIG.  11   , the fiber may rest on only two such projections  134  (the central projection  136  being absent). 
     The fiber optic ferrule  100  also includes a plurality of fiber openings  140 , a respective one of the plurality of fiber openings  140  is aligned with a respective one of the plurality of optical fiber support structures  102 . The fiber openings  140  are rearward of the optical fiber support structures  102  but not at the rear end  110 . In fact, there may be a larger, rear singular opening  142  extending from the rear end  110  towards the front end  108  that provides access to the plurality of fiber openings  140 . See  FIGS.  5  and  8   . The rear singular opening  142  may have some chamfered surfaces  144  that reduce the size of the rear singular opening  142  to assist with the alignment of the optical fibers  104  and prevent the skiving of the optical fibers on the interior of the fiber optic ferrule  100 . The fiber openings  140  assist in aligning and guiding the optical fibers  104  into the optical fiber support structures  102  from the rear singular opening  142 . Each of the plurality of fiber openings  140  preferably has a tubular configuration to accept the optical fibers  104  insertable from the rear end  110  of the fiber optic ferrule  100  and onto a respective one of the plurality of optical fiber support structures  102 . (See  FIG.  10   ). The configuration of the plurality of fiber openings  140  may also take other configurations such as oval, polygonal, etc., and still be tubular. The fiber openings  140  may have one or more chamfered areas  146  to reduce the size of the fiber openings  140  and assist in centering the optical fiber  104  into the optical fiber support structures  102 . In one aspect of this disclosure, each of the fiber openings is directly behind and terminating at a proximal end of the optical fiber support structures  102 . The chamfered areas  146  may or may not be present, and when present, generally have a circular profile similar to a circular profile of the fiber openings  140 . In this respect, the combination of the fiber openings  140  and optical fiber support structures  102  forms a hybrid support structure, whether present inside the fiber optic ferrule  100  or on a substrate material—the term “hybrid” referring to the combination structure, as opposed to only the conventional fiber openings being present, or only a v-groove or a u-groove being present to receive optical fibers  104 . 
     The fiber optic ferrule  100  also has a number of windows in the top surface  112 . The first window  150  is an epoxy window and allows for the introduction of epoxy into at least a portion of the rear singular opening  142  to secure the optical fibers  104  into the fiber optic ferrule  100 . See  FIGS.  5  and  8   . The epoxy can be either light or heat cured. There is a second window  152  that is more like a well and that allows access to the optical fibers  104  that are disposed within the optical fiber support structures  102 . The second window  152  is closer to the front end  108  of the fiber optic ferrule  100 . There is a divider wall  154  that is between the first window  150  and the second window  152  that is a bit recessed from the top surface  112 . However, it could extend up to the top surface  112  if so desired. If the first window  150  is filled with epoxy first, the epoxy could spill over the divider wall  154  and into the second window  152 . The epoxy could be added to the second window  152  first or after first window  150  without it running over the divider wall  154 . The fiber openings  140  are directly underneath the divider wall  154 . See also  FIG.  4   . 
     The fiber optic ferrule  100  may have a recessed portion  160  in the bottom surface  114 . This recessed portion is not critical to the operation or the molding of the fiber optic ferrule, but does reduce the amount of material used. It should be noted that the fiber optic ferrule  100  is preferably made of an optically clear or translucent material. Alternatively, the fiber optic ferrule  100  may be made of opaque material. The front end  108  of the fiber optic ferrule  100  may have a design of the Lensed Fiber Optic Ferrule disclosed in PCT/US2020/058794, which is owned by the current applicant. 
     Another embodiment of a fiber optic ferrule  200  having a plurality of optical fiber support structures  202  for an optical fiber  104  according to the present invention is illustrated in  FIG.  12   . In this fiber optic ferrule  200 , there are a plurality of optical fiber support structures  202  as discussed above with relation to fiber optic ferrule  100 . There are also a plurality of fiber openings  240 , a respective one of the plurality of fiber openings  240  is aligned with a respective one of the plurality of optical fiber support structures  202 . While in this embodiment, the fiber openings  240  are rearward of the optical fiber support structures  202 , each of the plurality of optical fiber support structures  202  are separated from a respective one of the plurality of fiber openings  240  by an epoxy space  228 . The epoxy space  228  allows for the epoxy to get between the optical fibers  104  (while only one is illustrated, there may be as many as 4-16 optical fibers). There would also be more contact by the epoxy with the optical fibers  104  and within the epoxy space  228 . The remainder of the fiber optic ferrule  200  would be the same as discussed above for fiber optic ferrule  100 . 
       FIGS.  13  and  14    illustrate a plug  1300  that may be used to press down upon the epoxy in the fiber optic ferrule  100  or the fiber optic ferrule  200 . The plug  1300  secures the optical fibers  104  further into the fiber support structures  102 , and also prevents dust or debris from entering the second window  152 , although, the plug could be shaped to completely cover the first window  150  and the second window  152  upon termination of the fiber optic ferrule  100  or the fiber optic ferrule  200 . The perimeter of the plug  1300  is accordingly matched to the second window  152  in  FIG.  13   . Further, the plug  1300  may be removable for inspection by a user. 
     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.