Patent Abstract:
An optical fiber splitter has a higher density fiber optic array that allows for smaller packaging. The optical fibers that extend from the optical fiber splitter have one end connectorized and their spacing at the other end reduced, thereby eliminating components that were heretofore required. A method of making the fiber optic array includes interleaving the optical fibers to reduce the overall dimensions of the fiber optic array and the fiber optic splitter. A tool is used to reduce the spacing of the optical fibers in the fiber optic array.

Full Description:
RELATED APPLICATIONS 
     This application is a Divisional of U.S. Ser. No. 11/333,039, filed on Jan. 17, 2006 now U.S. Pat. No. 7,756,382, which is a Continuation-In-Part of U.S. Ser. No. 11/171,915, filed on Jun. 30, 2005 now abandoned, the disclosures of which are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention relates generally to an optical fiber splitter module with a higher density fiber optic array that allows for smaller packaging of the fiber optic array and splitter. The optical fibers that extend from the optical fiber splitter module have one end connectorized and the spacing at the second end reduced, thereby eliminating components that were heretofore required and made the splitter modules large and cumbersome. 
     2. Technical Background 
     Communications networks, and particularly high bandwidth optical networks, are being installed closer to the subscribers&#39; homes. However, installing the optical fibers closer to the subscribers&#39; homes can be cost prohibitive. Therefore, the network owners are conscious of the expenses related to installing the optical fibers and the associated equipment further away from the central office and closer to the subscribers. Currently, one expensive component of the network that is limiting the installation of the optical fibers closer to the home is the optical splitter. An optical splitter divides the optical signals into individual signals for the subscribers. Typically, as more subscribers are added to a network, new optical splitters are required in a space that is already relatively crowded. Therefore, a new optical splitter module that allows for higher densities of optical fibers in a similar space requirement is needed. A new method for arranging the optical fibers and a tool are also needed to assemble the fiber array of the high density splitter module. 
     SUMMARY 
     To achieve these and other advantages and in accordance with the purpose of the invention as embodied and broadly described herein, the invention is directed in one aspect to a splitter module that includes a housing having a first end, a second end, and an opening extending therebetween, a splitter chip disposed within the housing, a plurality of optical fibers having a first end and a second end, the first end of the plurality of optical fibers being attached to a first edge of the splitter chip, the second end of each of the plurality of optical fibers having a coating thereupon with an outer diameter between about five and about twenty times larger than a diameter of each of the plurality of optical fibers at the first end, and at least one optical fiber attached to a second edge of the splitter chip and being in optical communication with each of the plurality of optical fibers extending from the first edge of the splitter chip. 
     In another aspect, the invention is directed to a fiber array that includes a base member having a first edge, a second edge, and a central portion, and a plurality of optical fibers extending from the first edge to the second edge, the plurality of optical fibers being parallel to one another in a first portion adjacent the first edge and in a second portion adjacent the second edge, and the plurality of optical fibers being nonparallel to one another in the central portion of the base member. 
     In yet another aspect, the invention is directed to fiber array that includes a base member having a first edge, a second edge, and a central portion, and a plurality of optical fibers extending from the first edge across the central portion and beyond the second edge, each of the plurality of optical fibers having a first end adjacent the first edge and being connectorized at a second end, the second end of the optical fibers extending beyond the second edge of the base member. 
     In another aspect, the invention is directed to a method of assembling an interleaved fiber array, the fiber array having at least two pluralities of optical fibers, the optical fibers having a diameter and including the steps of providing a first plurality of optical fibers, each of the first plurality of optical fibers having a first end and a second end and each of the optical fibers having a coating at the first end such that the diameter of the optical fibers at the first end is at least 3.5 times the diameter of the optical fibers at the second end, and the optical fibers generally being aligned in a first plane at the first end; providing a second plurality of optical fibers, each of the second plurality of optical fibers having a first end and a second end and each of the optical fibers having a coating at the first end such that the diameter of the optical fibers at the first end is at least 3.5 times the diameter of the optical fibers at the second end, and the optical fibers generally being aligned in a second plane at the first end; aligning the first and second plurality of optical fibers relative to one another at the first ends such that each of the optical fibers in the first and second plurality of optical fibers is aligned in a plane orthogonal to the first and second planes, and each of the orthogonal planes for each of the optical fibers in the first and second pluralities of optical fibers are different from one another; and interleaving the second ends of the optical fibers of the first and second pluralities of optical fibers into a third plane wherein an optical fiber from one plurality of optical fibers is not adjacent to another optical fiber from the same plurality of optical fibers. 
     In yet another aspect, the invention is directed to a tool for adjusting horizontal and vertical spacing between optical fibers that includes an upper surface defining a length and a depth, and at least two side surfaces extending into the upper surface to create a cavity therein, the side surfaces generally extending toward one another along at least a portion of the length of the upper surface thereby defining a generally V-shaped configuration, the cavity having a depth of at least 130 microns. 
     In yet another aspect, the invention is directed to a tool for adjusting spacing between optical fibers that includes a base member having a front face and a rear face, and an opening in the base member extending between the front face and the rear face, the opening defining a depth and a width, the width of the opening decreasing between the front face and the rear face as the depth decreases. 
     Additional features and advantages of the invention are set out in the detailed description which follows, and in part and are 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. 
     It is to be understood that both the foregoing general description and the following detailed description present exemplary and explanatory 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 exemplary 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 top view of an optical fiber array according to one embodiment of the present invention; 
         FIG. 2  is a side view of the optical fiber array in  FIG. 1 ; 
         FIG. 3  is a top view of one embodiment of a fiber optic splitter module according to the present invention; 
         FIG. 4  is a lengthwise cross sectional view of the fiber optic splitter module in  FIG. 3 ; 
         FIG. 5  is a top view of another embodiment of a fiber optic splitter module according to the present invention shown with the top portion removed for purposes of clarity; 
         FIG. 6  is a top view of another embodiment of a fiber optic splitter module according to the present invention; 
         FIG. 7  is an end view of two pluralities of optical fibers partially interleaved according to one embodiment of the present invention; 
         FIG. 8  is an end view of four pluralities of optical fibers interleaved according to another embodiment of the present invention; 
         FIG. 9  is a perspective view of one embodiment of a tool according to the present invention; 
         FIG. 10  is a top view of the tool in  FIG. 9  shown in a planar representation for purposes of explanation; 
         FIG. 11  is a front view of another embodiment of a tool according to the present invention; 
         FIG. 12  is a perspective view as seen from the bottom of the tool in  FIG. 11 ; and 
         FIG. 13  is a perspective view of another embodiment of a tool according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Reference will now be made in detail to exemplary embodiments of the invention, examples of which are described herein and shown in the accompanying drawings. Whenever practical, the same reference numerals are used throughout the drawings to refer to the same or similar parts or features. One embodiment of an optical fiber array according to the present invention is illustrated in  FIGS. 1 and 2  and is designated generally throughout the following detailed description by the reference numeral  100 . 
     The optical fiber array  100  has a base member  102  to which the optical fibers  104  are attached. The base member  102  is preferably made of glass, but any material suitable for the purpose may be used. The optical fibers  104  have a first end  106  and a second end  108 . The second end  108  of the optical fibers  104  have the largest diameter, and in  FIGS. 1 and 2 , are buffered optical fibers having an outer diameter of 2 mm. As defined herein, the terms “optical fiber” and “optical fibers” include optical waveguides that may or may not have a coating (matrix or otherwise) or a jacket or other coverings or elements that increase the overall diameter thereof. For example, optical fibers would include those optical fibers that are only 125 micron in diameter (i.e., bare optical fibers), as well as those that have been up-jacketed to 900 microns, 2 mm, or greater. 
     At first end  106 , the optical fibers  104  are attached directly to the plate  102  and are preferably bare optical fibers having a diameter of about 125-127 microns. However, in the depicted embodiment, the optical fibers  104  are originally presented as 2 mm buffered fibers  110  at the second end, which are preferably then stripped to 900 micron fibers at portion  112 , and then to 250 micron fibers at portion  114 , before being stripped to bare optical fibers  116  at first end  106 . As illustrated, the 900 micron fibers at portion  112  are preferably attached to the base plate  102  of the fiber array  100  with an epoxy adhesive  118 , but any adhesive suitable for the purpose may be used. The 250 micron fibers at portion  114  are also attached to the base plate as well with an epoxy adhesive  120 , thereby preventing as much stress on the bare optical fibers  116  as possible, particularly at the leading edge  126 . 
     The optical fibers  104  could also be attached at portion  110  (with a corresponding larger base  102 ) or only at portion  114 . As will be explained later, the optical fibers  104  at portion  114  (which are 250 microns in diameter) are spaced at a distance of about 900 microns and are generally parallel to one another as they step down in size from the 900 micron diameter size to the 250 micron diameter size. In the portion  114 , the spacing between the optical fibers  104  is reduced, causing the optical fibers to no longer be parallel to one another through a central portion  122  of the base member  102 . The bare optical fibers  116 , having been stripped of coatings or matrix at first end  106 , are placed in close proximity to one another before being aligned and secured under a v-groove plate  124 , which is also preferably made of glass, but may also be made of silicone. It is also possible that the v-grooves are part of the base member  102 , in which case the plate  124  can either be a flat glass plate or a v-groove plate. The optical fibers  116  must be parallel to one another at the first end  106  since the first edge  126  of the base member  102  mates with a splitter chip (not shown in  FIGS. 1 and 2 ). 
     The first edge  126  of the fiber array  100  is then polished, preferably at an 8° angle to allow for an angled physical contact (APC) optical connection with an optical chip, whose edges are also polished at a complementary angle. The optical fibers  116  are preferably bonded to the base plate near the leading edge  126  with an adhesive. The optical fibers  104  may be in any format, including an optical fiber ribbon, single loose optical fibers, or, as illustrated in  FIGS. 1 and 2 , buffered optical fibers. 
     The optical fibers  104  extend beyond the second edge  127  of the base member  102  where the second end  108  of the optical fibers  104  are preferably connectorized with an appropriate fiber optic connector  128 . While an SC connector is illustrated, any other type or configuration of fiber optic connector is within the scope of the present invention and should be matched to the type and configuration of the optical fibers  104  at the second end  108 . 
     The fiber optic array  100  is preferably used with a splitter module  200  of the type illustrated in  FIGS. 3 and 4 . As best illustrated in  FIG. 4 , the fiber optic array  100  is located within an opening  201  of the housing  202  of the splitter module  200  between a first end  204  and a second end  206  of the housing. The fiber optic array  100  is attached along first edge  126  to a first edge  207  of an optical splitter chip  208 . The optical splitter chip  208  is also attached at a second edge  209  to an optical ferrule  210 , which allows for optical communication with an input optical fiber  212  entering the splitter module  200  at the second end  206 . The optical fiber  212  may be of any configuration suitable for the purpose and may include a strain relief boot  214 . 
     The splitter module  200  is preferably filled with a potting compound  216 , for example silicone, to hold the internal components in place and to protect them from contacting the sides  218  of the housing  202  and from shock and vibration. The splitter module  200  is illustrated to be in a generally rectangular configuration, but any suitable configuration may be used, i.e., cube, cylinder, etc. 
     The optical fibers  110  entering the first end  204  may also be strain relieved by a strain relief member  220 . As is usual in the art, the strain relief  220  is wider at the first end  204  of housing  202  and becomes narrower as it extends down the optical fibers  110  and away from housing  202 . However, as is illustrated with reference to the splitter module  200 ′ in  FIG. 5 , the strain relief member  220 ′ is reversed with the widest point  222 ′ positioned away from the housing  202 . This configuration likewise provides strain relief to the optical fibers  110 , but also allows for more variation in the angle that the optical fibers  110  enter the housing  202 . 
     Another embodiment of a splitter module  250  is illustrated in  FIG. 6 . In this embodiment, the internal components of the splitter module may be the same as the two previous embodiments, but the optical fiber  252  entering the splitter module  250  and connecting to the optical splitter chip  208  through the optical ferrule  258  is longer in length than optical fiber  212  of the previous embodiment. In this embodiment, the optical fibers enter and leave the splitter module  250  from the same end  254  of the housing  256 . The optical fiber  252  enters the housing, and once past the optical splitter chip  208 , curves back around to the optical ferrule  258  at a radius larger than the minimum bend radius of the optical fiber  252 . This configuration allows for the splitter module  250  to be used in even tighter spaces and/or where no access is allowed or possible to both ends of the splitter module. 
     A method of interleaving the optical fibers  104  that may be used in conjunction with the optical fiber array  100  or with any other suitable fiber array or splitter module will now be described in reference to  FIGS. 7-8 . As noted above with reference to  FIGS. 1 and 2 , the optical fibers  104  are preferably stacked in a generally rectangular configuration with the optical fibers  110  forming four rows of eight fibers for a total of 32 optical fibers. It should be noted that other multi-row configurations are possible and within the scope of the present invention. While the optical fibers  104  may be in a perfect rectangular configuration, it is preferable that the optical fibers are arranged as illustrated in an end view in  FIG. 7 . The optical fibers  110  are illustrated to be 2 mm buffered optical fibers  300 , with a 900 micron jacket  302 , a 250 micron diameter outer jacket  304  and the 125 micron bare optical fiber  306 . The optical fibers  104  may be loose or attached to one another in rows (e.g., ribbonized) to make the handling of the optical fibers easier and with less damage to the optical fibers. As illustrated in  FIG. 7 , the optical fibers  110  are arranged in two sets of eight optical fibers (only two sets are shown for purposes of clarity), with each set of eight optical fibers arranged in a different plane  308 , 310 , which are generally parallel to one another. The sets of optical fibers  110  are preferably offset from one another for reasons that will be described in reference to  FIG. 8 , which illustrates all four sets of optical fibers. 
     As described above, the bare optical fibers  116  are to be to secured to the base member  102  of the optical fiber array  100  in a single plane. However, in order to keep the fiber array  100  to its smallest overall width (including the optical fibers  110  at the second end  108 ), the larger diameter ends of the optical fibers  110  are preferably stacked in multiple horizontal planes to keep the overall width to a minimum. When the optical fibers  110  are stacked, they must then be interleaved to orient the bare optical fibers  116  into the single plane. While only two of the sets of optical fibers are illustrated in  FIG. 7  for purposes of clarity, the same principles also apply to a larger number of sets of optical fibers  110 . However, the optical fibers  110  preferably begin at the second end  108  as 2 mm buffered optical fibers. As shown herein, the optical fibers  104  are arranged in a generally rectangular configuration, with the 2 mm optical fiber portions  110  arranged into sets of eight fibers. The 900 micron optical fiber portion  112  are interleaved and then the 250 micron optical fiber portions  114  are interleaved to produce the 125 micron optical fiber portions  116  in a single horizontal plane, as will be described. 
     The outer covering  300  of the optical fiber is removed, thereby reducing the outer diameter of the optical fibers to 900 mm (see also portions  110  and  112  in  FIGS. 1 and 2 ). With the optical fibers  110  offset in the horizontal direction from one another, they can be combined into a different plane ( FIG. 8  illustrates the optical fibers  110  of plane  308  being moved to plane  310  by arrows A,B). Rather than one set or plurality of optical fibers  110  being moved from one plane (e.g.,  308 ) into the plane (e.g.,  310 ) of another set or plurality of optical fibers  110 , the optical fibers from both pluralities of optical fibers could be combined in a third plane that is not common with either of the planes  308 , 310 . This process continues until all of the optical fibers  110  from all of the sets of optical fibers are in a common plane and have the desired outer diameter. 
     Four pluralities  402 , 404 , 406 , 408  of optical fibers  110  are illustrated in  FIG. 8  from an end view. The optical fibers  110  in each of the four pluralities  402 , 404 , 406 , 408  lie in a different horizontal plane P H . Each of the optical fibers  110  in each of the four pluralities  402 , 404 , 406 , 408  also lie in a different vertical plane P V  so that when the optical fibers are moved into a single horizontal plane, as will be described in more detail below, the optical fibers will not have to be moved horizontally (along plane P H ) as they are moved vertically (along plane P V ). 
     The optical fibers  110  are, as in the previous figures, illustrated as starting at one end as 2 mm buffered optical fibers, although the present method can be used with any configuration and number of optical fibers. The optical fibers  110  can then be stripped down to 900 micron fibers  410  and even down to the 250 micron outer jacket  412  before the bare 125 micron optical fiber  414  is reached. 
     The optical fibers from the first plurality  402  are illustrated as being moved vertically (in the plane of the figure) downward to the horizontal plane of the second plurality  404  in the 900 micron format (see arrow C). The optical fibers from the first and second pluralities  402 , 404  of optical fibers are then moved vertically downward into a central plane P C  (see arrow D). Similarly, the optical fibers from the fourth plurality  408  are moved vertically upward into the plane of the third plurality  406  of optical fibers (see arrow E) before the optical fibers from the third and the fourth pluralities  406 , 408  are moved vertically upward into the central plane P C  (see arrow F). The optical fibers  104  are illustrated as being in their 125 micron diameter size when they are being moved into the central plane P C . It should be understood that the optical fibers illustrated as being a different diameter corresponds to the diameters of the optical fibers at different positions along the optical fibers as one moves toward the viewer, for example, the different diameters are illustrated as they would be seen if looking from the first end  106  toward the second end  108  in  FIG. 1 . 
     The optical cores of the bare optical fibers  116  are approximately 250 microns apart in the central plane P C  (or in any other horizontal plane into which the optical fibers  104  are interleaved), even though the optical fibers are only 125 microns in diameter. The spacing of the optical fibers  116  then needs to be reduced so that the spacing between the optical fibers is as close as possible for aligning with the v-groove plate  124  or any other appropriate structure at the end of the fiber array. One embodiment of a tool that may be used to reduce the vertical and/or horizontal spacing between the optical fibers  104  is illustrated in  FIG. 9 . 
     The tool  500  in  FIG. 9  is preferably a cylindrical tool (a handle, which is not shown, may be attached to the cylindrical tool  500  to assist in its use). The cylindrical tool  500  has a surface  502  to engage a flat surface on which the optical fibers  104  are placed. The cylindrical tool  500  has a diameter that is appropriate for the length of fibers that are to have their spacing reduced. The cylindrical tool  500  has two sides  504 , 506  that extend into the surface  502  of the cylindrical tool  500  to create a cavity  508  that is preferably about 130 microns deep. The cavity  508  is represented in  FIG. 10  as if the surface  502  of the cylindrical tool was a planar surface having a widest portion W that decreases in width to a narrowest portion N, thereby defining a generally V-shaped configuration. The widest portion W should be wide enough to accommodate the total width of the optical fibers  104  that are to be reduced in spacing, such as about 17 mm for the configuration of optical fibers shown in  FIG. 8 . As shown in  FIG. 9 , the narrowest portion N of cavity  508  is in physical communication with the widest portion W of cavity  508 , although it need not be in communication. The narrowest portion N should similarly accommodate the total width of the optical fibers that are aligned in the central plane Pc, which in  FIG. 8  is about 4 mm. 
     The sides  504 , 506  are illustrated as being generally smooth along their length. However, they may be curved, stepped, wavy, or of any configuration suitable for the purpose. The depth of the cavity  508  also preferably varies from a deeper cavity at the widest end W, where the diameter of the optical fibers is typically at least 250 microns and may be even larger, to a shallower cavity at the narrowest end N where the optical fibers are typically only 125 microns in diameter. Therefore, the cavity  508  preferably increases in depth from the narrowest end N, where it is at least 125 microns but less than 250 microns (a depth that prevents the optical fibers from crossing over one another in the cavity), to as much 900 microns at the widest end W to accommodate the larger diameter portion of the optical fibers. 
     Another embodiment of a tool  550  to reduce the spacing of the optical fibers  104  is illustrated in  FIGS. 11 and 12 . The tool  550  is similar to cylindrical tool  500 , but is designed to have the optical fibers inserted into a cavity  552  defined by two side surfaces  554 , 556  in upper surface  558 . The cavity  552  extends between a front face  560  and a rear face  562 , with the cavity  552  wider at the front face and narrowing toward the rear face  562 , defining a generally V-shaped configuration. The depth of the cavity  552  is preferably at least 125 microns and more preferably at least 130 microns. As with the prior embodiment, the depth of the cavity  552  preferably varies from between about 125 microns and about 250 microns at the narrowest end N to as deep as 900 microns at the widest end W. The side surfaces  554 , 556  may also be other than straight surfaces as depicted. They may curved, wavy, stepped, or of any other configuration as long as they generally move toward one another along the length of the sides  554 , 556  of the tool  550 . 
     The tool  550  may be used on a work surface, table top, or any other appropriate flat surface and the plurality of optical fibers  104  would be inserted into the cavity  552  through the front face  560  and the side surfaces  554 , 556  would force the optical fibers to move closer to one another without allowing them to cross over one another inside the cavity  552 . 
     Another embodiment of a tool  580  is illustrated in  FIG. 13 . The tool  580  is similar to tool  550 , but it has a bottom portion  584  that encloses the cavity  582 , and therefore, need not be used on a work surface, table top, or any surface at all. The optical fibers are simply inserted into the opening  586  in the front face  588 , and then moved along the cavity  582 , which is similar in construction to those described above with reference to tools  500 , 550 . 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the optical planar splitter of the present invention without departing from the spirit or 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.

Technology Classification (CPC): 6