Abstract:
An optical switch and method for assembling are described. Optical arrays are mounted on a flex plate with an interface between them. The direction of certain forces on the flex plate allows coupling/decoupling of the optical arrays. The flex plate includes an area which exhibits a different flex profile than the remainder of the flex plate and that is located beneath the optical arrays interface. Flexing of the flex plate optically couples the optical arrays. A tool with grooves is used to align the optical arrays relative to each other. The tool uses grooves and spheres to mate with the optical arrays in such a way as to provide an appropriate interface between the optical arrays.

Description:
This is a divisional application of U.S. application Ser. No. 10/022,726 filed Dec. 20, 2001 now U.S. Pat. No. 6,810,162 which claims priority from provisional application Ser. No. 60/257,020 filed Dec. 20, 2000, such applications being incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention related to a frustrated total internal reflection/total internal reflection (FTIR/TIR) optical fiber switch. 
     BACKGROUND 
     Conventional frustrated total internal reflection/total internal reflection optical fiber switches operate by displacing at least one of the fibers to contact, or come within less than a micron from contact with, the other fiber (closed position) or to release contact with the other fiber (opened position). Generally, the optical fibers connect one another at ends which are formed transverse to the longitudinal axis of the fibers and coplanar to one another. In the closed position, input light is transmitted from one optical fiber to the other with little or no transmission loss. In the opened position, in which a gap exists of greater than one micron between the optical fibers, input light is reflected from one of the fibers, leading to complete or partial transmission loss. Complete transmission loss occurs during total internal reflection, when light approaches a dielectric interface at or above a critical angle and is thereby suppressed from being transmitted to the other optical fiber. When the angle is below the critical angle, or the distance between the optical fibers is sufficiently small, some input light may cross the gap between the optical fibers and thereby frustrate the total internal reflection. An example of such a conventional optical switch is described in U.S. Pat. Nos. 5,390,266 and 4,176,908. 
     SUMMARY 
     The invention provides an optical switch that includes first and second optical arrays separated by an interface, and a support structure upon which the optical arrays are mounted. The support structure includes an area which has a flexing profile that differs from the remainder of the support structure such that upon the operation of force on the support structure the optical arrays are optically coupled or decoupled. 
     The invention also provides an optical switch that includes first, second, third, fourth and fifth optical arrays and a support structure upon which the first, second and third optical arrays are mounted. The third optical array is interposed between the first and second optical arrays, the first and third optical arrays are separated by a first interface, and the second and third optical arrays are separated by a second interface. The support structure includes a pair of areas which each have a flexing profile that differs from the remainder of the support structure. The fourth optical array is positioned transverse to the first and third optical arrays in the vicinity of the first interface and the fifth optical array is positioned transverse to the second and third optical arrays in the vicinity of the second interface. 
     The invention further provides a method for assembling an optical switch. The method includes aligning at least a first optical array and a second optical array relative to one another with an alignment tool, positioning the at least first and second optical arrays on a support structure, immobilizing the at least first and second optical arrays relative to the support structure, and removing the tool from the at least first and second optical arrays. 
     The foregoing and other advantages and features of the invention will be more readily understood from the following detailed description of the invention, which is provided in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1–3  is a side view of an optical switch assembly constructed in accordance with an embodiment of the invention. 
         FIG. 4  is a perspective view of the flex plate of the optical switch assembly of  FIG. 1 . 
         FIG. 5  is a side view of an optical switch assembly constructed in accordance with another embodiment of the invention. 
         FIG. 6  is a side view of an optical switch assembly constructed in accordance with another embodiment of the invention. 
         FIGS. 7–9  is a side view of an optical switch assembly constructed in accordance with another embodiment of the invention. 
         FIG. 10  is a schematic drawing of a conventional optical system. 
         FIG. 11  is a schematic drawing of an optical system utilizing the optical switch assembly of  FIG. 7  in accordance with another embodiment of the invention. 
         FIGS. 12–13  are side views showing the assembly of an optical switch assembly in accordance with another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1–4 , in which like numerals designate like elements, an optical FTIR/TIR switch assembly  10  is shown including a first angled optical array  11 , a second angled optical array  21 , and a flexible support structure, such as a flex plate  40 . The first optical array  11  includes a support structure, such as a chip  12 , that has a face  20  and first and second surfaces  14 ,  18 . The first surface  14  includes at least one first surface groove  16 . The second optical array  21  includes a support structure, such as a chip  22 , that has a face  30  and first and second surfaces  24 ,  28 . The first surface  24  has at least one first surface groove  26 . The chips  12 ,  22  are preferably formed of silicon. 
     The flex plate  40  includes a trench  42  which is preferably formed through isotropic etching. Each of the optical arrays  11 ,  21  is mounted on the flex plate  40 , which is preferably formed of single crystal silicon, such that there is an interface  25  (e.g., a gap) between the faces  20 ,  30  and such that the interface  25  is positioned above the trench  42 . The first and second arrays  11 ,  21  are positioned and adhered to the flex plate  40 . Preferably an adhering material is utilized to immobilize the first and second arrays  11 ,  21 . 
     Upon each of the optical arrays  11 ,  21  are mounted one or more optical fibers, which are preferably formed of silica. As shown, an optical fiber  32  is mounted within the groove  16  of the chip  12 , and a corresponding optical fiber  36  is mounted within the groove  26  of the chip  22 . The optical fibers  32 ,  36  have endfaces  34 ,  38 , respectively, that are angled at an angle greater than a total internal reflection angle of the optical fiber material. The optical fibers  32 ,  36  may be adhered to the grooves  16 ,  26  through the use of an adhering material or mechanism (not shown). Any suitable adhering material or mechanism may be used, such as, for example, ultraviolet curable epoxy, solder, aluminum-oxide direct thermal compression bonding, or sol-gel or spin-on glass. 
     The optical switch assembly  10  is shown in  FIGS. 2–3  in, respectively, an opened and a closed state. In  FIG. 2 , forces are directed upon the flex plate  40  at certain locations. Specifically, a force in a direction B is directed toward the flex plate  40  generally near the trench  42 . Further, forces in a direction A are directed away from the flex plate  40  at ends of the flex plate  40 . The forces tend to allow the flex plate  40  to flex such that its ends move generally in direction A. Since the chips  12 ,  22  are mounted on the flex plate  40 , such movement results in the endfaces  34  and  38  of the optical fibers  32 ,  36  moving apart from one another, thus opening the optical switch assembly  10 . 
       FIG. 3  illustrates the optical switch assembly  10  in the closed position. As shown, force is directed away from the flex plate  40  in the direction A in the general vicinity of the trench  42 , while forces are directed toward the flex plate  40  at its ends in the direction B. Through this arrangement of forces, the flex plate  40  tends to push the endfaces  34 ,  38  together, thereby closing the optical switch assembly  10 . 
     As noted above, the trench  42  of the flex plate  40  is preferably isotropically etched. The trench  42  should preferably extend across the flex plate as shown in  FIG. 4 . It is preferred that the trench  42  has a smooth sidewall  43  to prevent any localized mechanical stress during the previously described flexing operations. It is to be understood that a suitable flex plate  40  includes an area, such as the trench  42  or any other similar structure, that has a different flexing capability or profile relative to the remaining portion of the flex plate  40 . 
       FIG. 5  illustrates another aspect of the invention with reference to an optical switch assembly  100  which includes a first optical array  111  and a second optical array  121  positioned on a flex plate  140 . The optical arrays  111 ,  121  are each mounted on spheres  139 . Specifically, the first optical array  111  has a second surface  118  including one or more grooves  119  and the second optical array  121  has a second surface  128  having at least one groove  129 . The flex plate  140  also has a plurality of grooves  141  on an upper surface thereof which mate with the grooves  119 ,  129 . Spheres  139  seat within the grooves  141 . As shown, the groove  129  is elongated relative to the grooves  141 . Elongation of the groove  129  relative to its mating groove  141  allows the second optical array  121  to move in a direction C relative to the first optical array  111  during assembly, thus allowing adjustment of the gap between the endfaces  34 ,  38 . Once the gap has been properly adjusted, the optical arrays  111 ,  121  are then immobilized relative to the flex plate  140 . Preferably, the grooves  119 ,  129 ,  141  are anisotropically wet etched with potassium hydroxide or other suitable etchant material. 
       FIG. 6  illustrates another optical switch assembly  200 , which includes the first optical array  12 , the second optical array  22 , and a flex plate  240 . The flex plate  240  is a silicon-on-insulator (SOI) wafer which includes a pair of silicon layers  244 ,  248  sandwiching an insulator layer  246 . The trench  42  is isotropically etched in the silicon layer  244  by etchant materials. The insulator layer  246  is preferably formed of a material which is resistant to the etchant materials used to etch the silicon layer  244 . The proper depth of the trench  42  is obtained by the position of the insulator layer  246 , which suppresses etching of the trench  42 . 
     With reference to  FIGS. 7–9 , another aspect of the invention is shown with reference to an optical switch  300  which includes a first optical array  211 , a second optical array  221 , a third optical array  231 , a fourth optical array  261 , a fifth optical array  271 , and a flex plate  280 . The first optical array  211  includes a chip  212 , which has a first surface  214 , a second surface  218 , and a face  220 . The second optical array  221  includes a chip  222 , which has a first surface  224 , a second surface  228 , and a face  230 . The third optical array  231  is positioned between the first and second optical arrays  211 ,  221 , and includes a chip  232 , which has a first surface  234 , a second surface  238 , and a pair of faces  237 ,  239 . The face  237  mates with the face  220  of the first optical array  211 , while the face  239  mates with the face  230  of the second optical array  221 . 
     The first surfaces  214 ,  224 ,  234  each include at least one groove  216 ,  226 ,  236 , respectively. An optical fiber  250  is positioned within the groove  216 , an optical fiber  252  is positioned within the groove  226 , and an optical fiber  254  is positioned within the groove  236 . There is an interface  256  that extends between the face  237  of the chip  232  and the endface of its respective optical fiber  254  and the face  220  of the chip  212  and the endface of its respective optical fiber  250 . Further, there is an interface  258  that extends between the face  239  of the chip  232  and the endface of optical fiber  254  and the face  230  of the chip  222  and the endface of its respective optical fiber  252 . 
     The fourth and fifth optical arrays  261  and  271  are on-edge optical arrays which collect light which has been reflected from the interfaces  256 ,  258 . The fourth optical array  261  includes a chip  262 , having a groove  264 , and an optical fiber  266 . The fifth optical array  271  includes a chip  272 , having a groove  274 , and an optical fiber  276 . The fourth optical array  261  is positioned transverse to the alignment of the first, second and third optical arrays  211 ,  221 ,  231  and generally in the vicinity of the interface  256 . The fifth optical array  271  is positioned transverse to the alignment of the first, second and third optical arrays  211 ,  221 ,  231  and generally in the vicinity of the interface  258 . 
     The flex plate  280  includes a pair of etched trenches  282 ,  284 . Each of the trenches  282 ,  284  is positioned beneath one of the interfaces  256 ,  258 . With specific reference to  FIG. 8 , by directing a force in the direction A away from the flex plate  280  in the general vicinity of the third optical array  232 , and by concurrently directing forces in the direction B toward the flex plate  280  at its edges, light which is input from a light source  286  is transmitted along the optical fibers  250 ,  254 , and  252  to an output destination  288 . If instead, as shown in  FIG. 9 , a force is directed in the direction B toward the flex plate  280  in the general vicinity of the third optical array  232 , and forces are directed away from the flex plate  280  in the direction A at the plate&#39;s  280  edges, the interfaces  256 ,  258  are misaligned to such an extent as to suppress light from being transmitted through the optical fibers  250 ,  254 , and  252 . Instead, light from the light source  286  may be sent through the optical fiber  250 , reflected at the gap between the optical fiber  250  and the optical fiber  254 , collected by the optical fiber  266 , and transmitted to the output destination  288 . In addition, light from a second light source  290  concurrently may be sent through the optical fiber  252 , reflected at the gap between the optical fiber  252  and the optical fiber  254 , collected by the optical fiber  276 , and transmitted to a second output destination  292 . 
     The optical switch assembly  300  is particularly useful for ring networks in which a switch must be continuously connected and disconnected from a data ring. A conventional ring network  350 , shown in  FIG. 10 , includes a plurality of nodes  302  in communication with each other.  FIG. 11  illustrates the inclusion of the optical switch assembly  300  in a data ring  400 . Light from a light source  286  which is within the data ring  400  is transmitted to the optical switch  300  and reflected into the optical array  262  and sent to the output destination  288 , which in this instance is one of the nodes  302 . Further, light from a light source  290  which is within the data ring  400  also is transmitted to the optical switch  300 , reflected into the optical array  272  and sent to the output destination  292 , which in this instance is the same node  302 . 
     With reference to  FIGS. 12–13 , next will be described a method of assembling an optical switch assembly in accordance with an embodiment of the invention. The optical switch assembly shown in  FIGS. 12–13  includes a first optical array  312  and a second optical array  322 . The first optical array  312  includes a first surface  314  and a second surface  318 . At least one groove  316  is located in the first surface  314 , and at least one pit  317  is also located in the first surface  314 . The second optical array  322  includes a first surface  324  and a second surface  328 . At least one groove  326  is located in the first surface  324 , and at least one pit  327  is further located in the first surface  324 . The second surfaces  318 ,  328  are to be mounted on the flex plate  40 . 
     A tool  330 , having at least a pair of pits  334  in a first surface  332  is used to align the first optical array  312  relative to the second optical array  322 . Spheres  336  are positioned within the pits  334  and the optical arrays  312 ,  322  are moved so that the spheres  336  concurrently fit within the pits  317 ,  327 , thereby adjusting the position of the first optical array  312  with respect to the second optical array  322 . The spheres  336  may be adhered to the pits  334  with an adhesive material  338 . Once proper position has been obtained, the optical arrays  312 ,  322  are immobilized relative to the flex plate  40  and the tool  330  is removed. 
     While the invention has been described in detail in connection with the preferred embodiments known at the time, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. For example, although the flex plate  40  has been shown to have a semicircularly-shaped trench  42 , it should be understood that the trench may be any suitable shape capable of localizing the flexing potential of the flex plate  40 . Also, instead of a trench  42 , the area with a different flex profile from the remainder of the flex plate  40  may be formed with a hinge or biasing member or other suitable mechanism. Further, while the tool  330  has been illustrated to show alignment of one optical array with another, it is to be understood that the tool  330  may be modified to align three optical arrays, such as optical arrays  211 ,  221 ,  231  shown in  FIG. 7 , and the remaining optical arrays  261  and  271  may be separately aligned. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.