Abstract:
A molded mount of non-crystalline polymer material is configured to have a channel for retaining a silicon chip having a plurality of juxtaposed V-groove formed in a top surface between right and left side portions, thereof, a recessed area being provided in the channel behind the chip for accommodating fiber buffer coating, and a notch being formed in a top portion of the mount between the channel and one side portion thereof, for retaining strengthening fibers of an optical fiber cable, with the V-groove being configured to receive individual optical fibers therein respectively. Two such molded mounts with silicon chips are securely sandwiched together with V-groove of the chips opposing one another to retain optical fibers therebetween.

Description:
RELATED APPLICATIONS  
       [0001]    This Application is related to, and takes priority from, Provisional Application No. 60/243,446, filed Oct. 26, 2000, for “A Fiber Array With V-Groove Chip and Mount.” The present Application is co-pending with the aforesaid Provisional Application, and is owned by a common Assignee. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The field of the present invention relates generally to optical fiber connectors, for connecting together optical fibers of optical fiber cables to one another, and to various devices, and more particularly relates to fiber arrays for holding or retaining optical fibers in V-groove formed in a semiconductor substrate.  
         BACKGROUND OF THE INVENTION  
         [0003]    It is known in the prior art to provide a fiber array for holding optical fibers within a semiconductor substrate that has V-groove formed in a portion thereof for retaining optical fibers in very precise alignment relative to the longitudinal axis of the substrate.  
           [0004]    [0004]FIG. 1 shows a typical semiconductor substrate  1 , having a plurality of V-groove  3  formed in one portion thereof for retaining uncoated optical fibers (not shown). The fibers are sometimes mechanically secured within the grooves by means not shown, or secured in the grooves  3  through use of an appropriate adhesive. The substrate  1  shown in FIG. 1 also includes a recessed portion  5 , in this example, that may be used for receiving a buffer coating for the associated optical fibers. The substrate  1  typically consists of silicon. A problem in the prior art is that a fiber array chip  7 , configured as shown in FIG. 1, and consisting of silicon is very expensive. Accordingly, in order to reduce the cost of such a fiber array chip  7 , it is desirable to reduce to the greatest extent possible the amount of silicon material that must be used.  
         SUMMARY OF THE INVENTION  
         [0005]    In one embodiment of the invention, a relatively small substrate of silicon material has a plurality of V-groove formed across its top face for providing the necessary retention of optical fibers therein for a typical fiber array. The V-groove silicon chip is then secured within an open channel or slotway of a plastic or ceramic mount, that is molded or otherwise formed to provide other necessary mechanical aspects of the fiber array, such as a recessed area adjacent the silicon chip for receiving a buffer coating for the optical fibers, as previously described. Any other required mechanical features can be readily formed in the mount. The V-groove silicon chip can either be secured within the channel of a previously molded mount, or the chip can be placed into mold, for permitting the mount to be molded about the silicon chip during formation of the mount. When the silicon chip is inserted into the channel of the mount after the mount is formed, an appropriate adhesive can be used for rigidly securing the two together. The silicon V-groove chip provides precisely dimensioned and aligned V-groove that cannot otherwise be provided by molding of plastic or ceramic materials, for example. The molded mount provides mechanical features that do not require accurate mechanical sizing, location, and alignment, thereby eliminating the need for using silicon material to provide such other features.  
           [0006]    In another embodiment of the invention, the silicon V-groove chip, and molded mount, are formed to provide for joining or interlocking the two together through means of dovetails.  
           [0007]    In a third embodiment of the invention, two molded mounts each with a silicon V-groove chip retained therein are sandwiched together with respective V-groove opposing one another for retaining optical fibers therebetween.  
           [0008]    In a fourth embodiment of the invention, the molded mounts are provided with means for interlocking the pair of molded mounts with silicon V-groove chips, respectively, in a sandwiched configuration that is securely locked together.  
           [0009]    In other embodiments of the invention, the dovetailed interlocking between the V-groove silicon chip and an associated molded mount can include interior corners having non-acute angles. Also, the pair of molded mounts sandwiched together with their respective silicon V-groove chips may include relief pockets in one of the mounts opposing ultrasonic energy directors in the other molded mount to which it is to be mounted, for permitting ultrasonic welding to be used for holding the two together in the sandwiched configuration.  
           [0010]    In another embodiment, the silicon V-groove chip may include a transverse trench or slotway in a bottom face, with the top face containing the V-groove, whereby the slotway is filled with the same material used to provide the molded mount, for substantially reducing sliding of the silicon chip within the molded mount.  
           [0011]    In yet another embodiment of the invention, a front face of the molded mount is provided with vertically oriented grooves for controlling the wicking of glue, and to also provide a surface area for enhancing the bonding of the glue.  
           [0012]    In another embodiment of the invention, the V-groove chip is mounted to extend from the molded mount a sufficient amount to permit reliable and optimal contact between the endfaces of optical fibers to be butt-coupled with the endfaces of optical fibers of an opposing array, for example, with the optical fibers each being retained in an associated V-groove.  
           [0013]    In another embodiment of the invention, a strain relief is formed to extend from the rear portion adjacent the recessed area of the molded mount. The strain relief provides for reducing strain upon the optical fibers retained in the associated V-groove of the silicon chip.  
           [0014]    In another embodiment of the invention, a notch is formed on a top portion of the molded mount extending from the recessed area thereof, for receiving strengthening fibers typically used in optical fiber cables, to enhance the bonding between an associated optical fiber cable and the molded mount. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    Various embodiments of the present invention are described below with reference to the drawings, in which like items are identified by the same reference designation, wherein:  
         [0016]    [0016]FIG. 1 is a pictorial view of a silicon V-groove chip of the prior art useful for optical fiber arrays;  
         [0017]    [0017]FIG. 2 is a pictorial view of a first embodiment of the invention showing a relatively small silicon chip limited to only providing V-groove, and retained within a molded mount of plastic or ceramic material;  
         [0018]    [0018]FIG. 3 shows a front elevational view of a relatively small silicon chip having only V-groove, and formed to have angled side edge portions for dovetailed interlocking in a molded mount, for another embodiment of the invention;  
         [0019]    [0019]FIG. 4 is a front elevational view of two molded mounts each with a dovetailed silicon chip, with respective V-groove opposing one another for retaining optical fibers therebetween for another embodiment of the invention;  
         [0020]    [0020]FIG. 5 is a front elevational view showing first interlocking means for securing or locking together two molded mounts each with dovetailed silicon chips, in yet another embodiment of the invention;  
         [0021]    [0021]FIG. 6 is a front elevational view of another embodiment of the invention using alternative locking means relative to the locking means of FIG. 5;  
         [0022]    [0022]FIG. 7 shows a front elevational view of another embodiment of the invention providing non-acute angles for the dovetailed interlocking configuration between a molded mount and a silicon V-groove chip;  
         [0023]    [0023]FIG. 8 shows a front elevational view of another embodiment of the invention for rigidly securing two molded mounts each with silicon chips, with associated V-grooves opposing one another, whereby relief pockets are provided in one of the molded mounts for ultrasonic welding to ultrasonic energy directors of the other molded mount;  
         [0024]    [0024]FIG. 9A shows a pictorial view of another embodiment of the invention that includes a transverse slotway or trench in a bottom face of a silicon chip having V-grooves formed on its top face;  
         [0025]    [0025]FIG. 9B shows a pictorial exploded assembly diagram of the chip of FIG. 9A oriented for insertion into the channel of a molded mount;  
         [0026]    [0026]FIG. 10 shows a pictorial view of another embodiment of the invention for providing vertically oriented front face grooves in a molded mount carrying a Silicon V-groove Chip, whereby the grooves provide both control over the wicking of glue, and enhanced bonding thereof;  
         [0027]    [0027]FIG. 11 shows a pictorial view of another embodiment of the invention in which a Silicon V-groove Chip extends away from its associated molded mount a sufficient distance to facilitate butt-coupling between the endfaces of optical fibers retained in the associated V-groove, and the endfaces of optical fibers external to the associated silicon chip and its molded mount;  
         [0028]    [0028]FIG. 12 is a pictorial view of another embodiment of the invention for including a strain relief extending from a back surface of a molded mount carrying a Silicon V-groove Chip;  
         [0029]    [0029]FIG. 13 is a pictorial view of another embodiment of the invention showing a molded mount carrying a Silicon V-groove Chip, with the molded mount including a notch formed into a top surface thereof for receiving strengthening fibers from an optical fiber cable; and  
         [0030]    [0030]FIG. 14 shows a pictorial view of the embodiment of FIG. 13, in association with an optical fiber cable having strengthening fibers, and an optical fiber therefrom installed in a V-groove of the associated silicon chip, and the notch of the molded mount, respectively. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]    [0031]FIG. 1 shows a typical optical fiber array of the prior art for retaining optical fibers (not shown) in V-groove  3  formed in a silicon substrate  1 . As previously explained, the fiber array chip  7  typically includes a recessed portion  5  for accommodating fiber buffer coating material. A major problem with this configuration is that it is expensive to produce because of the large amounts of silicon required. Note that truncated V-grooves, known in the art as “U-grooves” may also be used to fabricate fiber arrays. V-grooves and U-grooves can be made by potassium hydroxide etching of (100) silicon, as is well known in the art.  
         [0032]    In a first embodiment of the invention as shown in FIG. 2, a small silicon chip  9  (relative to the fiber array chip  7 ) (see FIG. 1) is provided with a plurality of V-groove  11 . The V-groove chip  9  requires substantially less silicon than the fiber array chip  7 , by eliminating the latters recessed portion  5 , and substantial side portions. The eliminated silicon portions relative to the fiber array chip  7 , have been replaced by a mount  13  that consists of plastic or ceramic material. An open channel or slotway  15  is formed in the mount  13  on a top surface thereof. The channel  15  is dimensioned to permit the silicon chip  9  to be snugly mounted therein, and secured by an appropriate adhesive, in one embodiment of the invention. Alternatively, the silicon chip  9  can be placed into an insert mold prior to forming the molded mount  13 , and the material of the molded mount  13  can be formed around the silicon chip  9  as the entire molded mount  13  itself is formed. The portion of the channel  15  not occupied by the silicon chip  9  provides a recessed area  17 , that functions identically as the recessed area  5  of the silicon substrate  1  of FIG. 1. The molded mount  13  is relatively inexpensive to produce, compared to the fiber array chip  7  of FIG. 1, and does not require the precise dimensioning and alignment of the V-groove  11  of silicon chip  9 , or V-groove  3  of the fiber array chip  7 . Through use of the molded mount  13 , the silicon chip  9  is substantially smaller than the silicon chip  7 , thereby providing substantial cost savings from the reduced amount of silicon. Also, reduced manufacturing costs are provided relative to the prior art, by the ease of molding mount  13 , and the lack of any requirement for providing the precise dimensioning and alignment of the various features thereof, as with the V-groove  11  of the associated silicon chip  9 .  
         [0033]    Insert molding techniques known in the art can be used to first insert the silicon chip  9  into a die configured for making the molded mount  13 . Thereafter, the desired material for the mount  13  is injected into the associated mold, and permitted to flow around the silicon chip  9 , whereafter the material is permitted to solidify. Alternatively, the silicon chip  9  can be pressed or glued into the channel  15  of the molded mount  13 . Examples of material applicable for use in providing the molded mount  13  is ABS plastic, ULTEM, or any other moldable polymer. In one aspect of the invention, the moldable polymer is noncrystalline. In another aspect of the invention, the moldable polymer is a thermoset that forms a polymer upon cure, such as epoxies and the like.  
         [0034]    In a preferred embodiment of the invention, dovetailing is used to interlock the silicon chip  9   a  into a compatibly modified molded mount  13   a , as shown in FIG. 3. As shown, to provide the dovetail interlocking feature, the side or edge portions  19  of the silicon chip  9   a  have an acute angle with the bottom thereof. The sidewall portions  21  of the channel or slotway  15  are correspondingly angled inward, as shown.  
         [0035]    In FIG. 4, two loaded mounts  13   a , with the respective silicon chips  9   a , are assembled together with their respective top faces  14  opposing one another, for securing optical fibers  23  within the opposing V-groove  11 , as shown. In a preferred embodiment of the invention shown in FIG. 5, rather than or in addition to using adhesives for securing the mounts  13   a  together, interlocking pawls  25  are provided on one side portion of the top faces  27  thereof, as shown. However, adhesives will likely be necessary even if pawls  25  are used. On the opposite ends of the top faces  27  of the molded mounts  13   a , keyways  29  are provided as shown, for respectively receiving a pawl  25 .  
         [0036]    In another embodiment of the invention, an alternative locking mechanism is employed in FIG. 6. In this embodiment, a molded mount  13   b  is configured to have locking pawls  25   a  protruding from the ends of its top face  27   a , as shown. Another molded mount  13   c  is configured to have angulated L-shaped notches  31  cut into a lower portion of each side thereof near a top face  27   b , as shown. In the embodiments of FIGS. 5 and 6, a user first places optical fibers  23  in the V-groove  11  of one of the molded mounts of  13   a , or  13   b , respectively. Next, a mating molded mount  13   a  or  13   c , respectively, is then positioned as shown in FIG. 5 or  6 , respectively, and pushed toward its mating molded mount to cause the pawls  25  to snap into and engage the keyways  29 , or pawls  25   a  and engage the notches  31 , respectively, as shown.  
         [0037]    In a preferred embodiment of the invention, as shown in FIG. 7, the silicon chip  9   b  has a dovetailed configuration having corners  33  with non-acute angles, as shown, to provide a re-entrant shape. Note that the bottom of the chip  9   b  is wider than its top. The structural integrity of the molded mount  13 d might otherwise be impaired if sharp corners are used. The side walls  21   a  of the corresponding slotway or channel of the molded mount  13   d  are configured to have the same configuration as the silicon chip  9   b  sidewalls, for mating therewith, as shown.  
         [0038]    In another preferred embodiment of the invention, as shown in FIG. 8, a molded mount  13   e  is provided with ultrasonic energy absorbers  35  that are small bumps of plastic near the sidewall edges of the top face  27   c  thereof, that provide material that acts as an adhesive via ultrasonic welding. A molded mount  13   f  positioned for having its V-groove  11  opposing the V-groove  11  of the molded mount  13   e , is provided with relief pockets  37  in its top face  27   d  near its side portions, as shown. When the molded mounts  13   e  and  13   f  are positioned as shown for retaining optical fibers in the respective V-groove  11 , the mounts are moved together for permitting ultrasonic welding of the energy absorbers  35  with the relief pockets  37 , whereby the energy directors  35  mold into the relief pockets  37  forming a rigid securement of the molded mounts  13   e  and  13   f  to one another.  
         [0039]    In another preferred embodiment of the invention shown in FIG. 9A, a silicon chip  9   c  is provided with a transverse trench or slotway  39  for helping to ensure that the silicon chip  9   c  is locked into an associated molded mount. More specifically, during molding of the mount about silicon chip  9 C, the trench  39  is filled with the same material that the associated molded mount is made from, whereby this will substantially prevent the silicon chip  9   c  from sliding longitudinally within its associated mount. Alternatively, the associated molded mount can be formed as shown in FIG. 9B with a transverse stepped portion  40  in its slotway  15  for mating with the trench  39  of the silicon chip  9   c , thereby also preventing longitudinal movement of the chip  9   c  therein.  
         [0040]    In another preferred embodiment of the invention, as shown in FIG. 10, a molded mount  13   g  is provided with vertical grooves  41  in its front face  43 , as shown. The grooves  41  provide control over the wicking of adhesive or glue, and also provide a greater surface area for bonding of glue, for securing the molded mount  13   g  to similar or other fiber optic devices.  
         [0041]    In another preferred embodiment of the invention, the silicon chip  9  is positioned to extend from its associated molded mount  13 , as shown in FIG. 11. In this manner, the Silicon V-groove Chip  9 , by extending by about 10 to 100 microns, for example, facilitates coupling of the endfaces of optical fibers carried in the V-groove  11  with the endfaces of optical fibers carried in another optical fiber array. In this manner, the molded mount  13  is less likely to interfere with contact between butt-coupled optical fibers, thereby ensuring optimal coupling.  
         [0042]    In yet another preferred embodiment of the invention, as shown in FIG. 12, a molded mount  13  carrying a V-groove silicon chip  9 , is provided with a strain relief  45  extending from the rear or back portion of mount  13 . The strain relief  45  reduces the strain imposed upon optical fibers located in the V-groove  11 , thereby reducing the chance of damaging the optical fibers. The strain relief  45  can be made using known molding techniques. For example, it can be made through use of a “two-shot mold”, which requires two molding steps. In this manner, the strain relief  45  can made of material different from that of the molded mount  13 . Alternatively, a single mold can be used if the strain relief  45  consists of the same material as the molded mount  13 .  
         [0043]    Note that when optical fibers are bonded to V-groove  11  of the Silicon V-groove Chips of the various embodiments of the invention described above, it is preferred that an elastomeric adhesive be used to provide the bond in the strain relief  45  portion of the package. This is sometimes necessated by recognition that the material of the various molded mounts typically have a thermal expansion co-efficient substantially greater (e.g. 10 times greater) than the optical fibers or the silicon chips. If the glue utilized is a rigid glue (e.g. epoxy), the thermal expansion of the molded mount material may cause associated optical fibers to be pulled away from their associated V-groove silicon chip. However, if an elastomeric adhesive is used, the adhesive will deform so that the optical fibers will stay fixed within the V-groove of their associated silicon chip. In practice, the optical fibers are preferably bonded to their associated V-groove silicon chip to provide a rigid bond (e.g. with a epoxy, aluminum-oxide bonding, spin-on glass, solder, and so forth).  
         [0044]    Another embodiment of the invention is shown in FIG. 13, for providing a molded mount  13   i  with a notch  47  in a top portion thereof, as shown. The notch  47  is provided for receiving strengthening fibers (e.g. nylon, kevlar, metal) typically used in optical fiber cables. Through use of the notch  47  bonded to the strengthening fibers, an improved bonding between the optical fiber cable and the molded mount  13   i  is provided. FIG. 14 shows an optical fiber cable  49  having strengthening fibers  51  secured with glue (not shown) in the notch  47 , as shown. An optical fiber  53  from the cable  49  is shown installed in a V-groove  11  of the silicon chip  9 , as shown.  
         [0045]    Although various embodiments of the invention have been shown and described, they are not meant to be limiting. Those of skill in the art may recognize certain modifications thereto, which modifications are meant to be covered by the spirit and scope of the depended claims.