Abstract:
An improved optical switch includes a movable optical switching element configured to selectively direct optical signals traveling in an optical input path to one of at least two optical output paths. The movable optical switching element may include waveguide portions and/or mirrors to direct the optical signals. In an alternative embodiment, the moveable optical switching element may include waveguide grating couplers to allow the selective reflection of a particular wavelength of light from an optical waveguide carrying a number of such of optical wavelengths.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates generally to optical switches, and, more particularly, to an apparatus and method for directing optical signals using a movable optical switching element.  
         BACKGROUND OF THE INVENTION  
         [0002]    Communication technology has progressed significantly in the past few years. Today, much information is carried over optical communications fiber. This fiber optic technology allows the transport of information at data rates currently exceeding millions of bits of information per second. Part of the technology that enables this optical communication is the ability to direct light onto an optical fiber and switch that light appropriately. Typically, a number of optical fibers are combined into a fiber optic cable. When a fiber optic cable is carrying many individual signals over large distances, it is necessary to have the ability to switch those signals onto other fiber optic cables. A mesh of fiber optic cable infrastructure spans the world. At certain places in the mesh it is desirable to have the ability to switch the light signals from one fiber optic cable to another. A typical fiber optic cable may be comprised of a plurality of individual optical fibers bound together, for example, in a ribbon arrangement. A typical fiber optic ribbon cable may contain  32  individual optical fibers. Each optical fiber is capable of carrying one signal, or in the case of dense wave division multiplexing (DWDM), in which many signals may be multiplexed onto a single optical fiber through the use of multiple colors of light, each optical fiber may carry a plurality of light colors (wavelengths), with each color representing a single signal.  
           [0003]    Optical switches capable of routing light from one direction to another have been known for some time. One type of optical switch element is disclosed in commonly assigned U.S. Pat. No. 5,699,462 to Fouquet et al., in which an optical switch element is located at an intersection of two optical waveguides. Depending on the state of a material within the optical switch element, light is either transmitted through the switch element continuing axially on the original waveguide, or reflected by the switch element onto a waveguide that intersects the original waveguide. The switch element is filled with a material that, while in a transmissive state, has an index of refraction substantially equal to that of the waveguide, thus allowing light in the waveguide to pass through the switch element. The state of the material within the switch element may be changed, through the operation of heaters within the switch element, so as to vaporize the liquid in the switch element to form a bubble. While present in the switch element the bubble causes a refractive index mismatch between the waveguide and the switch element, thus causing the light in the waveguide to be reflected onto the intersecting waveguide. This state is known as the reflective state. The operation of a preferred and many alternative embodiments of this switch element is set forth in detail in the above-identified commonly assigned U.S. patent to Fouquet et al.  
           [0004]    When placed at an intersection of two waveguide segments, one of the abovementioned optical switch elements forms an optical switch point, which may be used to switch signals on a plurality of optical fibers. The optical switch points may be further arranged so as to form a switching matrix. For example, when arranged in a 32×32 matrix, formed by 32 rows and 32 columns of optical switch points, a 32 fiber optic ribbon cable can be connected to 32 input lines and another 32 fiber optic ribbon cable can be connected to 32 output lines, the output lines intersecting the 32 input lines. Because a switch element is located at each optical switch point it is possible to switch any of the 32 input lines to any of the 32 output lines. In this manner, optical signals may be directed from one fiber optic cable onto another, resulting in a compact optical switch.  
           [0005]    Although the above-described switch element is useful in many applications, there may be situations in which the use of an optical switch that does not use fluid, and that does not require a heater to form a bubble in the fluid, may be desirable.  
           [0006]    Therefore, an alternative manner for switching light in an optical fiber switch matrix would be desirable.  
         SUMMARY OF THE INVENTION  
         [0007]    The invention provides an apparatus and method for directing optical signals using a movable optical switching element.  
           [0008]    In architecture, the present invention may be conceptualized as an apparatus for directing optical signals. The apparatus comprises an optical input path; and a movable optical switching element aligned with the optical input path. The movable optical switching element is configured to selectively direct the optical signal from the optical input path to one of at least two optical output paths.  
           [0009]    The present invention may also be conceptualized as a method for selectively directing optical signals. The method comprises the following steps: providing an optical input path; providing a moveable optical switching element; directing the optical signal from the optical input path to the movable optical switching element disposed in the optical input path; and using the movable optical switching element to selectively direct the optical signal to one of at least two optical output paths.  
           [0010]    The invention has numerous advantages, a few of which are delineated, hereafter, as merely examples.  
           [0011]    An advantage of the invention is that it allows a plurality of optical signals to be switched simultaneously.  
           [0012]    Another advantage of the invention is that it allows a single optical signal to be extracted from an optical fiber carrying a plurality of optical signals.  
           [0013]    Another advantage of the invention is that it can be structured not to require constant power to maintain a switched state.  
           [0014]    Other features and advantages of the invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. These additional features and advantages are intended to be included herein within the scope of the present invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The present invention, as defined in the claims, can be better understood with reference to the following drawings. The components within the drawings are not necessarily to scale relative to each other, emphasis instead being placed upon clearly illustrating the principles of the present invention.  
         [0016]    FIGS.  1 A- 1 C are plan views illustrating a first embodiment of the invention;  
         [0017]    FIGS.  2 A- 2 C are plan views illustrating a second embodiment of the optical switch point including a second embodiment of the moveable optical switching element of the invention;  
         [0018]    [0018]FIG. 3 is a cross-sectional schematic view illustrating the optical switch point of FIG. 1A;  
         [0019]    FIGS.  4 A- 4 C are plan views illustrating a third embodiment of the optical switch point including a third embodiment of a moveable optical switching element in accordance with the invention;  
         [0020]    [0020]FIG. 5 is a cross-sectional schematic view illustrating the optical switch point of FIGS.  4 A- 4 C;  
         [0021]    [0021]FIGS. 6A and 6B are plan views illustrating a fourth embodiment of the optical switch point including a fourth embodiment of a moveable optical switching element of the invention;  
         [0022]    [0022]FIGS. 7A and 7B are plan views illustrating an alternative embodiment of the optical switch point of FIGS. 6A and 6B including a fifth embodiment of a moveable optical switching element of the invention, FIGS. 8A and 8B are plan views illustrating yet another embodiment of an optical switch point including a sixth embodiment of a moveable optical switching element of the invention;  
         [0023]    [0023]FIG. 9 is a plan view illustrating an alternative embodiment of the optical switch point of FIGS. 8A and 8 b  including a seventh embodiment of a moveable optical switching element in accordance with the invention; and  
         [0024]    [0024]FIG. 10 is a perspective view illustrating the optical switch point of FIG. 9. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    Turning now to the drawings, FIGS.  1 A- 1 C are plan views illustrating a first embodiment of the invention. As shown in FIG. 1A, optical switch point  10  includes waveguide portion  11  and waveguide portion  12 . Situated at the optical switch point  10  is moveable optical switching element  15 . Moveable optical switching element  15  includes waveguide portion  17  and waveguide portion  18 . As illustrated in FIG. 1A, waveguide portion  17  is aligned with waveguide portion  11  and waveguide portion  12 , resulting in the transmission of an optical signal, designated by arrow  13 , directly through optical switch point  10 . Optical switch point  10  also includes waveguide portion  14  and waveguide portion  16 , which are situated substantially perpendicular to waveguide portion  11  and waveguide portion  12 .  
         [0026]    [0026]FIG. 1B illustrates the optical switch point  10  in which the moveable optical switching element  15  has been rotated through approximately 45 degrees, resulting in one end of waveguide portion  18  being disposed to receive the optical signal represented by arrow  13  from waveguide portion  11 . The optical signal traveling in waveguide portion  11  enters waveguide portion  18  and is directed therethrough into waveguide portion  16 . As shown in FIG. 1B, the optical signal  13  traveling in waveguide portion  11  is efficiently and effectively switched through a direction change of approximately 90 degrees into waveguide portion  16 . In this manner, the moveable optical switching element  15  allows the selective switching of optical signals.  
         [0027]    [0027]FIG. 1C illustrates optical switch point  10  in which the moveable optical switching element  15  has been rotated through an additional 45 degrees, or a total of approximately 90 degrees with respect to its position shown in FIG. 1A. In the position illustrated in FIG. 1C, optical switch point  10  allows the transmission of light from waveguide portion  14  through the waveguide portion  17  of moveable waveguide  15  and out through waveguide portion  16 . With respect to an optical signal traveling in waveguide portion  11 , the light of the optical signal meets a non-waveguide portion  21  of moveable optical switching element  15 , resulting in the termination of the optical signal  13  traveling in waveguide portion  11 . An optical signal traveling in waveguide portion  14  may be selectively directed to waveguide portions  16  or  11 , depending upon the position of moveable optical switching element  15 . Indeed, the moveable optical switching element  15  may be rotated into any position resulting in the capability of routing an optical signal in any waveguide either through the waveguide portion aligned therewith, or toward the waveguide portion offset 90 degrees therefrom. Furthermore, while illustrated at right angles, waveguide portions  11 ,  12 ,  14  and  16  may be fabricated at other than right angles to each other, as will be described below with respect to FIGS. 6A, 6B,  7 A and  7 B.  
         [0028]    FIGS.  2 A- 2 C are plan views illustrating a second embodiment  30  of the optical switch point including a second embodiment  25  of the moveable optical switching element of the invention.  
         [0029]    Optical switch point  30  includes waveguide portions  11 ,  12 ,  14  and  16 , which are identical to those described with respect to FIG. 1. Indeed, the like-numbered elements shown in FIGS.  2 A- 2 C that correspond to those described in FIGS.  1 A- 1 C are identical thereto and will not be described again. Optical switch point  30  also includes moveable optical switching element  25 , which includes waveguide portion  17 , and waveguide portions  38   a  and  38   b.  Waveguide portions  38   a  and  38   b  of FIG. 2A are similar to waveguide portion  18  of FIG. 1A. However, in a departure from that shown with respect to FIG. 1A, two waveguide portions  38   a  and  38   b  are illustrated in FIG. 2A.  
         [0030]    As illustrated in FIG. 2A, an optical signal represented by arrow  13  traveling in waveguide portion  11  is directed into and through waveguide portion  17  of moveable optical switching element  25  and then directed into waveguide portion  12 . The optical signal  33  traveling in waveguide  14  meets non-waveguide portion  41  of moveable optical switching element  25  and is terminated.  
         [0031]    [0031]FIG. 2B illustrates optical switch point  30  in which the moveable optical switching element  25  has been rotated through approximately 45 degrees. As shown, an optical signal, represented by arrow  13 , traveling in waveguide portion  11  enters waveguide portion  38   b  of moveable optical switching element  25  and is directed into waveguide portion  16 . Concurrently therewith, an optical signal, represented by arrow  33 , traveling in waveguide  14  is directed into waveguide portion  38   a  of moveable optical switching element  25  and is directed into waveguide portion  12 . In this manner, the direction of two optical signals can be simultaneously switched using the optical switch point  30 .  
         [0032]    [0032]FIG. 2C illustrates optical switch point  30  in which the moveable optical switching element  25  has been rotated through an additional 45 degrees to a position that is approximately 90 degrees offset from that shown in FIG. 2A. An optical signal represented by arrow  33  traveling in waveguide portion  14  enters waveguide portion  17  of moveable optical switching element  25  and is directed to waveguide portion  16 . An optical signal  13  traveling in waveguide portion  11  meets non-waveguide portion  41  of moveable optical switching element  25  and is terminated.  
         [0033]    [0033]FIG. 3 is a cross-sectional schematic view illustrating the optical switch point  10  of FIG. 1A. FIG. 3 illustrates in detail waveguide portion  11 , waveguide portion  12  and movable optical switching element  15 . Moveable optical switching element  15  is part of turntable  19 . Turntable  19  is illustrated as a platform that rotates about an axis  23  that is perpendicular to waveguide portions  11  and  12 . However, turntable  19  may be any means for rotating moveable optical switching element  15 . For example, turntable  19  may be part of a micro-machined motor assembly, which provides the rotational force for moveable optical switching element  15 . Also shown in FIG. 3 as dotted lines is waveguide portion  18  of moveable optical switching element  15 . The above-described micro-machined motor over which turntable  19  may reside may be constructed using optical micro electro-mechanical systems (MEMS) technology. Further details of MEMS and optical MEMS technology can be found at the Sandia National Foundry for MEMS technology and which has an Internet website located at: http://www.mdl.sandia.gov/scripts/index.asp.  
         [0034]    The description of a rotary motor can be found at this web site and is a common device used in optical MEMS technology.  
         [0035]    Furthermore, co-pending, commonly assigned U.S. patent application Ser. No. 08/818,209, entitled ELECTROSTATIC ACTUATOR WITH SPATIALLY ALTERNATING VOLTAGE PATTERNS, and filed on Mar. 14, 1997, describes an electrostatic motor that may be used to provide the above-described rotational motion, and the translational motion to be described below, for turntable  19 , and is hereby incorporated into this document by reference.  
         [0036]    Additional layers, which constitute the optical waveguides of the invention can be fabricated over all or a portion of the motor assembly. Similarly, a mirror (to be described below) may be fabricated over all or a portion of the motor assembly. The optical waveguides typically consists of a guiding layer, also known as a “core”, surrounded by cladding. The core typically has an optical refractive index higher than the optical refractive index of the surrounding cladding. The optical waveguides can be fabricated with polymer based material, or spin-on glass that is compatible with post processing of the optical MEMS devices.  
         [0037]    For example, a technique known as “self-assembly” can be used to fabricate the optical waveguides or the mirror on a turntable formed on a surface of the above-described rotary motor. Using this technique, the optical waveguides or mirror can be fabricated with “mating slots”, which correspond to mating slots formed on the surface of the rotary motor. These mating slots simplify assembly of the optical waveguide or mirror to the surface of the rotary motor. An example of this technology can be found on the Internet at http://www.alientechnology.com/, where a technique that is used to assemble liquid crystal displays is described.  
         [0038]    FIGS.  4 A- 4 C are plan views illustrating a third embodiment  50  of the optical switch point including a third embodiment  35  of a moveable optical switching element in accordance with the invention.  
         [0039]    The optical switch point  50  of FIG. 4A is similar to that shown with respect to FIG. 1A and FIG. 2A with the difference being that moveable optical switching element  35  includes mirror  58  instead of any waveguide portions. Mirror  58  resides in free space region  59 . This means that an optical signal  13  traveling through waveguide portion  11  travels through free space region  59  into waveguide portion  12 . Note that mirror  58  is offset from the center of moveable optical switching element  35  to facilitate the transmission of an optical signal when the moveable optical switching element  35  is positioned as shown in FIG. 4A.  
         [0040]    [0040]FIG. 4B illustrates the optical switch point  50  in which the moveable optical switching element  35  has been rotated through approximately 45 degrees so that a surface  57  of mirror  58  is in the path of an optical signal traveling in waveguide portion  11 . As illustrated, an optical signal traveling in waveguide portion  11  is directed onto surface  57  of mirror  58 , which reflects the optical signal into waveguide portion  16 . In this manner, an optical signal traveling in waveguide portion  11  is selectively deflected, or switched, into waveguide portion  16 .  
         [0041]    [0041]FIG. 4C illustrates the optical switch point  50  in which the moveable optical switching element  35  has been rotated through an additional 45 degrees to a position that is approximately 90 degrees offset from that shown in FIG. 4A. An optical signal  53  traveling in waveguide portion  14  passes through free space region  59  and into waveguide portion  16 . As illustrated, because mirror  58  is offset from the center of moveable optical switching element  35 , the free space transmission of an optical signal traveling in waveguide  14  is permitted.  
         [0042]    In the embodiment illustrated in FIG. 4C, the signal  13  in waveguide  11  would meet mirror  58  and be reflected back into the waveguide  11 , possibly causing instability in the optical signals traversing the optical switch point  50 . Instead of being perpendicular to waveguide portion  11 , mirror  58  can be positioned at a small angle with respect to waveguide portion  11 . In this manner, signal  13  could be prevented from being reflected back into waveguide portion  11 . Alternatively, a light absorber (not shown) may be added adjacent to waveguide portion  11  to capture the portion of signal  13  reflected back into waveguide portion  11 .  
         [0043]    In an alternative embodiment, the surface of the mirror  58  can be curved such that it collects the light exiting waveguide  11  into free space region  59  and focuses it onto waveguide  16  as in FIG. 4B. One example would be for the mirror to be a part of an ellipsoidal surface such that the exit of one waveguide and the entrance of the second waveguide (or optical fibers) are located at the foci of the ellipsoidal mirror.  
         [0044]    [0044]FIG. 5 is a cross-sectional schematic view illustrating the optical switch point  50  of FIGS.  4 A- 4 C. In the optical switch point  50  of FIG. 5, mirror  58  resides on turntable  19 . Irrespective of the manner in which turntable  19  is actuated, mirror  58  rotates with turntable  19  to provide the optical switching capability referred to above with respect to FIGS.  4 A- 4 C.  
         [0045]    [0045]FIGS. 6A and 6B are plan views illustrating a fourth embodiment  70  of the optical switch point including a fourth embodiment  45  of a moveable optical switching element of the invention.  
         [0046]    Optical switch point  70  includes waveguide portions  11 ,  12 , and  16 . However, in a departure from that described above, waveguide portion  16  is not substantially perpendicular to waveguide portions  11  and  12 . This illustrates a feature of the invention in which the moveable optical switching element  45  includes waveguide portion  78 , which is configured to redirect an optical signal between waveguides that are not perpendicular to each other. Moveable optical switching element  45  also includes waveguide portion  17 , which, as shown in FIG. 6A, is configured to direct an optical signal traveling in waveguide portion  11  to waveguide portion  12 .  
         [0047]    [0047]FIG. 6B illustrates the optical switch point  70  in which the moveable optical switching element  45  has been rotated through an angle such that waveguide portion  78  is in the path of an optical signal  13  traveling in waveguide portion  11 . Waveguide portion  78  then directs the optical signal  13  received from waveguide portion  11  to waveguide portion  16 . As mentioned above, waveguide portion  16  is disposed at an angle other than 90 degrees with respect to waveguide portion  11 . Although shown as greater than 90 degrees, waveguide portion  16  may also be disposed at an angle of less than 90 degrees with respect to waveguide portion  11 . In this manner, light may be selectively directed from waveguide portion  11  into waveguide portion  16 .  
         [0048]    [0048]FIGS. 7A and 7B are plan views illustrating an alternative embodiment  90  of the optical switch point of FIGS. 6A and 6B and includes a fifth embodiment  55  of a moveable optical switching element of the invention. Moveable optical switching element  55  includes waveguide portions  17 , and  98   a  and  98   b.  Waveguide portion  17  is configured to direct an optical signal  13  traveling in waveguide portion  11  to waveguide portion  12 . Waveguide portion  98   b  corresponds to waveguide portion  78  of FIG. 6A. Moveable optical switching element  55  also includes waveguide portion  98   a.    
         [0049]    [0049]FIG. 7B illustrates optical switch point  90  in which the moveable optical switching element  55  is rotated in a direction opposite that described above with respect to FIG. 6B, so that waveguide portion  98   a  receives an optical signal  13  traveling in waveguide portion  11 . Waveguide portion  98   a  then directs this optical signal  13  into waveguide portion  14 . As is evident with respect to FIG. 7B, moveable optical switching element  55 , and indeed all of the above described embodiments of the moveable optical switching element, are able to rotate in either direction, thus allowing a number of different optical signal switching options.  
         [0050]    [0050]FIGS. 8A and 8B are plan views illustrating yet another embodiment  100  of an optical switch point including a sixth embodiment  65  of a moveable optical switching element of the invention. Optical switch point  100  includes waveguide portions  101 ,  102  and  106 . In this embodiment, moveable optical switching element  65  slides, or otherwise translates, within channel  109 . Moveable optical switching element  65  includes waveguide portion  107  and waveguide portion  108 . As illustrated in FIG. 8A, an optical signal, represented by arrow  113  is directed through waveguide portion  101  into waveguide portion  107  of moveable optical switching element  65 . The optical signal  113  is then directed through waveguide portion  107  into waveguide portion  102 .  
         [0051]    [0051]FIG. 8B illustrates the optical switch point  100  in which the moveable optical switching element  65  has translated in a direction indicated by arrow  111  such that waveguide portion  108  of moveable optical switching element  65  is in position to receive an optical signal represented by arrow  113  traveling in waveguide portion  101 . The optical signal  113  is then directed through waveguide portion  108  and into waveguide portion  106 . In this manner, an optical signal may be selectively redirected from waveguide portion  101  into waveguide portion  106 . Although illustrated as having only two waveguide portions, moveable optical switching element  65  may have more than two waveguide portions. Also, moveable optical switching element  65  may slide in the direction opposite that indicated by arrow  111  depending upon the desired application.  
         [0052]    [0052]FIG. 9 is a plan view illustrating an alternative embodiment  120  of the optical switch point  100  of FIGS. 8A and 8b including a seventh embodiment  75  of a moveable optical switching element in accordance with the invention. Optical switch point  120  includes waveguide portion  121 , waveguide portion  122  and moveable optical switching element  75 . In this embodiment, moveable optical switching element  75  translates within channel  129 . Moveable optical switching element  75  also includes a plurality of waveguide grating couplers  128 - 1  through  128 - n.  Waveguide grating couplers  128  are each configured to reflect light of a particular optical frequency. To illustrate, assume that an optical signal represented by arrow  123  traveling in waveguide portion  121  includes four optical frequencies, represented by the symbols λ 1 , λ 2 , λ 3 , and λ 4 .  
         [0053]    In the configuration shown in FIG. 9, the optical signal including the four wavelengths is directed through waveguide portion  121  onto moveable optical switching element  75 . Moveable optical switching element  75  is translated in channel  129  so that the optical signal in waveguide portion  123  is directed onto waveguide grating coupler  128 - 3 . Waveguide grating coupler  128 - 3  is configured to allow the passage of all optical frequencies, or a portion of optical frequencies, except for frequency λ 3  of the optical signal traveling in waveguide portion  121 . Waveguide grating coupler  128 - 3  filters the frequency represented by λ 3 , and transmits the optical signal including the remaining frequencies λ 1 , λ 2  and λ 4  into waveguide portion  122 . The portion of the optical signal, which includes frequency λ 3  is depicted by arrow  127  as being picked off of the optical signal and redirected to another waveguide through evanescent coupling. Alternatively, the signal can be collected by a lens system and refocused into an optical fiber or waveguide for further processing or transmission. Evanescent coupling refers to coupling between two waveguides when the optical field in a first waveguide overlaps into a second waveguide, where over a characteristic length called the coupling length, a portion of the optical power in the first waveguide transfers to the second waveguide. Evanescent coupling is known to those skilled in the art. The portion of the optical signal that contains the frequency represented by λ 3  can be reflected in a direction perpendicular to, or nearly perpendicular to, the plane of moveable optical switching element  75 , as shown in FIG. 10, which will be described below.  
         [0054]    The reflected light can terminate on a photodiode and be converted from an optical signal to an electrical signal for further processing or transmission of information. In this manner, a moveable optical switching element  75  including a plurality of waveguide grating couplers can be used to separate frequencies in an optical signal, such as in systems that use wavelength division multiplexing (WDM) and dense wavelength multiplexing (DWDM).  
         [0055]    [0055]FIG. 10 is a perspective view illustrating the optical switch point  120  of FIG. 9. As an example of a use of the optical signal containing the frequency λ 3  of FIG. 9, optical switch point  120  includes photodiode  130 . The optical signal of frequency λ 3 , after being reflected from the composite optical signal traveling in waveguide  121  as described above, is directed to photodiode  130  to allow the measurement of the power, or signal strength, of the optical signal traveling in waveguide portion  121 . As mentioned above, the light can be further transmitted or converted to an electrical signal via photodiode  130  for further electronic processing of the information contained therein. It should be noted that the waveguide grating couplers  128 - 1  through  128 - n  can also be fabricated using a Bragg filter as known in the art. If a Bragg filter is used, light is not reflected out of the waveguide but reflected back toward waveguide  121 . In such a case, an additional optical element, such as an optical circulator, can be used to extract the signal. Waveguide grating couplers (such as illustrated in FIG. 9) and Bragg filters are well known by those skilled in the art.  
         [0056]    The above-described invention makes use of optical MEMS technology. This technology is complex and rather mature. Foundries engaged in the fabrication of optical MEMS can be found at Sandia, and Cronos. As mentioned above, the web site for Sandia&#39;s foundry can be found at: http://www.mdl.sandia.gov/scripts/index.asp, and the website for Cronos is located at: http://www.memsrus.com/.  
         [0057]    Furthermore, above-mentioned, co-pending, commonly assigned U.S. patent application Ser. No. 08/818,209, describes an electrostatic motor that may be used to provide the above-described translational motion.  
         [0058]    The invention disclosed above uses optical MEMS technology, and by making some variations in the process of optical MEMS, either via post processing or changes in the actual process which are compatible with the overall MEMS process, optical waveguides made of polymer and spin on glass, for example, can be constructed. Waveguide grating couplers and Bragg filters can be similarly constructed using holographic techniques or by the interference of two laser beams, all of which are well known in the field of optics. The material used for the waveguides may be glass fiber and/or polymer fiber. It should also be noted that these elements need not be monolithically integrated, but rather, can be separately fabricated and precisely integrated onto the moving elements of the MEMS motors. Both linear and rotary motors have been developed using MEMS technology.  
         [0059]    It will be apparent to those skilled in the art that many modifications and variations may be made to the preferred embodiments of the present invention, as set forth above, without departing substantially from the principles of the present invention. For example, it is possible to practice the invention using any type of movable optical switching element located at an intersection of two optical paths. Furthermore, while the optical signals described above are described as traveling in particular directions, it is possible for the optical signals to be switched in any direction. All such modifications and variations are intended to be included herein within the scope of the present invention, as defined in the claims that follow.