Abstract:
A method and structure for an optical switch. A channel is housed within a solid material. Contacts coupled to the channel are further coupled to the solid material, while a plurality of piezoelectric elements are coupled to chamber and further coupled to a slug. Optical waveguides are coupled to the channel. The contacts are coupled to a plurality of liquid metal globules, wherein one or more of the plurality of liquid metal globules are coupled to a slug. One or more piezoelectric elements are actuated, causing the slug to be moved within the channel. The motion of the slug is operable to block or unblock one or more of the plurality of optical waveguides.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is related to the following co-pending U.S. Patent Applications, being identified by the below enumerated identifiers and arranged in alphanumerical order, which have the same ownership as the present application and to that extent are related to the present application and which are hereby incorporated by reference:
     Application 10010448-1, titled “Piezoelectrically Actuated Liquid Metal Switch”, filed May 2, 2002 and identified by Ser. No. 10/137,691;   Application 10010529-1, “Bending Mode Latching Relay”, and having the same filing date as the present application;   Application 10010531-1, “High Frequency Bending Mode Latching Relay”, and having the same filing date as the present application;   Application 10010570-1, titled “Piezoelectrically Actuated Liquid Metal Switch”, filed May 2, 2002 and identified by Ser. No. 10/142,076;   Application 10010571-1, “High-frequency, Liquid Metal, Latching Relay with Face Contact”, and having the same filing date as the present application;   Application 10010572-1, “Liquid Metal, Latching Relay with Face Contact”, and having the same filing date as the present application;   Application 10010573-1, “Insertion Type Liquid Metal Latching Relay”, and having the same filing date as the present application;   Application 10010617-1, “High-frequency, Liquid Metal, Latching Relay Array”, and having the same filing date as the present application;   Application 10010618-1, “Insertion Type Liquid Metal Latching Relay Array”, and having the same filing date as the present application;   Application 10010634-1, “Liquid Metal Optical Relay”, and having the same filing date as the present application;   Application 10010640-1, titled “A Longitudinal Piezoelectric Optical Latching Relay”, filed Oct. 31, 2001 and identified by Ser. No. 09/999,590;   Application 10010643-1, “Shear Mode Liquid Metal Switch”, and having the same filing date as the present application;   Application 10010644-1, “Bending Mode Liquid Metal Switch”, and having the same filing date as the present application;   Application 10010656-1, titled “A Longitudinal Mode Optical Latching Relay”, and having the same filing date as the present application;   Application 10010663-1, “Method and Structure for a Pusher-Mode Piezoelectrically Actuated Liquid Metal Switch”, and having the same filing date as the present application;   Application 10010664-1, “Method and Structure for a Pusher-Mode Piezoelectrically Actuated Liquid Metal Optical Switch”, and having the same filing date as the present application;   Application 10010790-1, titled “Switch and Production Thereof”, filed Dec. 12, 2002 and identified by Ser. No. 10/317,597;   Application 10011055-1, “High Frequency Latching Relay with Bending Switch Bar”, and having the same filing date as the present application;   Application 10011056-1, “Latching Relay with Switch Bar”, and having the same filing date as the present application;   Application 10011064-1, “High Frequency Push-mode Latching Relay”, and having the same filing date as the present application;   Application 10011065-1, “Push-mode Latching Relay”, and having the same filing date as the present application;   Application 10011121-1, “Closed Loop Piezoelectric Pump”, and having the same filing date as the present application;   Application 10011329-1, titled “Solid Slug Longitudinal Piezoelectric Latching Relay”, filed May 2, 2002 and identified by Ser. No. 10/137,692;   Application 10011344-1, “Method and Structure for a Slug Pusher-Mode Piezoelectrically Actuated Liquid Metal Switch”, and having the same filing date as the present application;   Application 10011397-1, “Method and Structure for a Slug Assisted Pusher-Mode Piezoelectrically Actuated Liquid Metal Optical Switch”, and having the same filing date as the present application;   Application 10011398-1, “Polymeric Liquid Metal Switch”, and having the same filing date as the present application;   Application 10011410-1, “Polymeric Liquid Metal Optical Switch”, and having the same filing date as the present application;   Application 10011436-1, “Longitudinal Electromagnetic Latching Optical Relay”, and having the same filing date as the present application;   Application 10011437-1, “Longitudinal Electromagnetic Latching Relay”, and having the same filing date as the present application;   Application 10011458-1, “Damped Longitudinal Mode Optical Latching Relay”, and having the same filing date as the present application;   Application 10011459-1, “Damped Longitudinal Mode Latching Relay”, and having the same filing date as the present application;   Application 10020013-1, titled “Switch and Method for Producing the Same”, filed Dec. 12, 2002 and identified by Ser. No. 10/317,963;   Application 10020027-1, titled “Piezoelectric Optical Relay”, filed Mar. 28, 2002 and identified by Ser. No. 10/109,309;   Application 10020071-1, titled “Electrically Isolated Liquid Metal Micro-Switches for Integrally Shielded Microcircuits”, filed Oct. 8, 2002 and identified by Ser. No. 10/266,872;   Application 10020073-1, titled “Piezoelectric Optical Demultiplexing Switch”, filed Apr. 10, 2002 and identified by Ser. No. 10/119,503;   Application 10020162-1, titled “Volume Adjustment Apparatus and Method for Use”, filed Dec. 12, 2002 and identified by Ser. No. 10/317,293;   Application 10020241-1, “Method and Apparatus for Maintaining a Liquid Metal Switch in a Ready-to-Switch Condition”, and having the same filing date as the present application;   Application 10020242-1, titled “A Longitudinal Mode Solid Slug Optical Latching Relay”, and having the same filing date as the present application;   Application 10020473-1, titled “Reflecting Wedge Optical Wavelength Multiplexer/Demultiplexer”, and having the same filing date as the present application;   Application 10020540-1, “Method and Structure for a Solid Slug Caterpillar Piezoelectric Relay”, and having the same filing date as the present application;   Application 10020541-1, titled “Method and Structure for a Solid Slug Caterpillar Piezoelectric Optical Relay”, and having the same filing date as the present application;   Application 10030438-1, “Inserting-finger Liquid Metal Relay”, and having the same filing date as the present application;   Application 10030440-1, “Wetting Finger Liquid Metal Latching Relay”, and having the same filing date as the present application;   Application 10030521-1, “Pressure Actuated Optical Latching Relay”, and having the same filing date as the present application;   Application 10030522-1, “Pressure Actuated Solid Slug Optical Latching Relay”, and having the same filing date as the present application; and   Application 10030546-1, “Method and Structure for a Slug Caterpillar Piezoelectric Reflective Optical Relay”, and having the same filing date as the present application.   

   TECHNICAL FIELD 
   This invention relates generally to the field of electronic devices and systems, and more specifically to optical switching technology. 
   BACKGROUND 
   A relay or switch may be used to change an optical signal from a first state to a second state. In general there may be more than two states. In applications that require a small switch geometry or a large number of switches within a small region, microelectronic fabrication techniques may be used to create switches with a small footprint. A semiconductor switch may be used in a variety of applications, such as industrial equipment, telecommunications equipment and control of electro-mechanical devices such as ink jet printers. 
   In switching applications, the use of piezoelectric technology may be used to actuate a switch. Piezoelectric materials have several unique characteristics. A piezoelectric material can be made to expand or contract in response to an applied voltage. This is known as the indirect piezoelectric effect. The amount of expansion or contraction, the force generated by the expansion or contraction, and the amount of time between successive contractions are important material properties that influence the selection of a piezoelectric material in a particular application. Piezoelectric material also exhibits a direct piezoelectric effect, in which an electric field is generated in response to an applied force. This electric field may be converted to a voltage if contacts are properly coupled to the piezoelectric material. The indirect piezoelectric effect is useful in making or breaking a contact within a switching element, while the direct piezoelectric effect is useful in generating a switching signal in response to an applied force. 
   SUMMARY 
   A method and structure for an optical switch is disclosed. According to the structure of the present invention, a channel coupled to a plurality of optical waveguides is housed within a solid material. Contacts within the channel are coupled to the solid material, while piezoelectric elements coupled to the channel are coupled to a slug. Liquid metal within the channel is coupled to the slug and coupled to the contacts. According to the method of the present invention, piezoelectric elements are actuated, causing the slug to be moved within the channel. The movement of the slug blocks or unblocks one or more optical waveguides. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself however, both as to organization and method of operation, together with objects and advantages thereof, may be best understood by reference to the following detailed description of the invention, which describes certain exemplary embodiments of the invention, taken in conjunction with the accompanying drawings in which: 
       FIG. 1  is a side view of a slug assisted longitudinal liquid metal optical switch, according to certain embodiments of the present invention. 
       FIG. 2  is a sectional drawing end view of a slug assisted longitudinal liquid metal optical switch, according to certain embodiments of the present invention. 
       FIG. 3  is a sectional drawing side view of a slug assisted longitudinal liquid metal optical switch, according to certain embodiments of the present invention. 
       FIG. 4  is a top view of a piezoelectric substrate layer of a slug assisted longitudinal liquid metal optical switch with cap layer and via layer removed, according to certain embodiments of the present invention. 
       FIG. 5  is a top view of a substrate layer of a slug assisted longitudinal liquid metal optical switch, according to certain embodiments of the present invention. 
       FIG. 6  is a top view of a piezoelectric layer of a slug assisted longitudinal liquid metal optical switch, according to certain embodiments of the present invention. 
       FIG. 7  is a top view of a via layer of a slug assisted longitudinal liquid metal optical switch, according to certain embodiments of the present invention. 
       FIG. 8  is a top view of a cap layer of a slug assisted longitudinal liquid metal optical switch, according to certain embodiments of the present invention. 
   

   DETAILED DESCRIPTION 
   While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail specific embodiments, with the understanding that the present disclosure is to be considered as an example of the principles of the invention and not intended to limit the invention to the specific embodiments shown and described. In the description below, like reference numerals are used to describe the same, similar or corresponding parts in the several views of the drawings. 
   A liquid metal switch may be represented using a plurality of layers, wherein the plurality of layers represent layers created during a fabrication of the liquid metal switch. 
   Referring now to  FIG. 1  a side view  100  of a slug assisted longitudinal liquid metal optical switch  105  is shown, according to certain embodiments of the present invention. Slug assisted longitudinal liquid metal optical switch  105  comprises a top cap layer  110 , via layer  120 , piezoelectric layer  130 , wetting pad substrate layer  140 , and optical waveguide  150 . In certain embodiments of the present invention, cap layer  110  is coupled to via layer  120 , via layer  120  is coupled to piezoelectric layer  130 , piezoelectric layer  130  is coupled to wetting pad substrate layer  140 , and plurality of optical waveguides  150  is coupled to one or more of via layer  120  and piezoelectric layer  130 . It is noted that wetting pad substrate layer  150  may further comprise a plurality of circuit traces, wherein the plurality of circuit traces are not shown in FIG.  1 . It is noted that one or more of the layers shown in  FIG. 1  may be combined without departing from the spirit and scope of the present invention. In certain embodiments of the present invention, the cap layer  110 , via layer  120 , piezoelectric layer  130 , and wetting pad substrate layer  140  may be composed of one or more of glass, ceramic, composite material and ceramic-coated material. 
   Referring now to  FIG. 2  a sectional drawing end view  200  of slug assisted longitudinal liquid metal optical switch  105  is shown, according to certain embodiments of the present invention. The sectional drawing end view  200  illustrates how a slug  220  moves within a channel  230  under an applied force of piezoelectric elements  210 . Piezoelectric elements  210  are coupled to piezoelectric layer  130 , and slug  220  is coupled to the piezoelectric elements  210 , coupled to liquid metal  225  and coupled to one or more of a plurality of contacts  215 . The liquid metal  225 , such as mercury or a Gallium alloy, acts as a friction-reducing lubricant. Plurality of contacts are coupled to wetting pad substrate layer  140 . In certain embodiments of the present invention, slug  220  is coupled to two of the plurality of contacts  215 . Slug  220  may be solid or hollow, and may be composed of a wettable material, such as metallic compounds, ceramic or plastic. Liquid metal  225  is coupled to slug  220  and the plurality of contacts  215 . In certain embodiments of the present invention, slug  220  and plurality of contacts  215  are wettable. The channel  230  further comprises an inert gas that is operable to fill the portions of the channel  230  not occupied by plurality of contacts  215 , slug  220 , and piezoelectric elements  210 . 
   In certain embodiments of the present invention, channel  230  lies within piezoelectric layer  130  and channel layer  230  is further coupled to via layer  120  and wetting pad substrate layer  140 . Plurality of optical waveguides  150  are coupled to channel  230  along an axis perpendicular to a long axis of channel  230 . The piezoelectric elements  210  are oriented so that a direction of extension of piezoelectric elements is aligned with a long axis of slug  220 . A plurality of vias  205  are further coupled to channel  230 , wherein said plurality of vias  205  are located in the via layer  120 . In certain embodiments of the present invention, plurality of vias are oriented in the via layer  120  directly above the corresponding plurality of piezoelectric elements  210 . Plurality of vias  205  are further coupled to an upper channel  235 . Upper channel  235  is operable to equalize a pressure of the inert gas of the channel  230 . In certain embodiments of the present invention, upper channel  235  is located within cap layer  110 . 
   Referring now to  FIG. 3  a sectional drawing side view  300  of slug assisted longitudinal liquid metal optical switch  105  is shown, according to certain embodiments of the present invention. The sectional drawing side view  300  of  FIG. 3  has an orientation that is 90 degrees rotated with respect to the sectional drawing end view  200 . The plurality of optical waveguides  150  are further coupled to an encapsulant  310 , wherein said encapsulant is further coupled to piezoelectric layer  130 . In certain embodiments of the present invention, encapsulant  310  is composed of an inert, mechanically stable, quick-setting adhesive such as a UV curable epoxy or acrylic. 
   Referring now to  FIG. 4  a top view  400  of piezoelectric substrate layer  130  of slug assisted longitudinal liquid metal optical switch  105  with cap layer  110  and via layer  120  removed is shown, according to certain embodiments of the present invention. The top view  400  illustrates that plurality of optical waveguides  150  are placed with respect to plurality of contacts  215  so that an optical waveguide of plurality of optical waveguides  150  passes between two contacts of plurality of contacts  215 . Although only two optical waveguides and three contacts are illustrated in  FIG. 4 , it is noted that a greater or fewer number of optical waveguides and a greater or fewer number of contacts could be present in slug assisted longitudinal liquid metal optical switch  105  without departing from the spirit and scope of the present invention. Although it is not shown in  FIG. 4 , it will be evident to one of skill in the art that plurality of piezoelectric elements  210  are coupled to a corresponding plurality of actuating contacts, wherein the plurality of actuating contacts are operable to control actuation of the plurality of piezoelectric elements  210 . 
     FIG. 4  further illustrates a side view  410  of the top view  400 . The side view  410  illustrates how the encapsulant  310  and plurality of optical waveguides  150  are coupled to piezoelectric layer  130 . In certain embodiments of the present invention, encapsulant  310  and plurality of optical waveguides  150  are placed in a V-shaped groove of piezoelectric layer  130   
   Referring now to  FIG. 5  a top view  500  of wetting pad substrate layer  140  of slug assisted longitudinal liquid metal optical switch  105  is shown, according to certain embodiments of the present invention.  FIG. 5  illustrates a potential placement of the coupling of plurality of contacts  215  to wetting pad substrate layer  140 . It is noted that although the plurality of contacts  215  are shown as square, other geometries could be used without departing from the spirit and scope of the present invention. In certain embodiments of the present invention, plurality of contacts  215  are equally spaced relative to wetting pad substrate layer  140 . 
   Referring now to  FIG. 6  a top view  600  of piezoelectric layer  130  of a slug assisted longitudinal liquid metal optical switch  105  is shown, according to certain embodiments of the present invention. The top view  600  illustrates an orientation of channel  230  and plurality of piezoelectric elements  210  relative to piezoelectric layer  130 . In certain embodiments of the present invention, channel  230  is centered within piezoelectric layer  130  when piezoelectric layer  130  is viewed using the top view  600 . A cross-section  610  of top view  600  is also shown in FIG.  6 . The cross-section  610  further illustrates a placement of channel  230  relative to piezoelectric layer  130 . 
   Referring now to  FIG. 7  a top view  700  of via layer  120  of slug assisted longitudinal liquid metal optical switch  105  is shown, according to certain embodiments of the present invention. Top view  700  illustrates a location of plurality of vias  205  relative to a shape of via layer  120 . It is noted that although plurality of vias  205  are represented in  FIG. 7  as having a circular cross-section, other types of cross section geometries are possible, for example square cross-sections, without departing from the spirit and scope of the present invention. 
   Referring now to  FIG. 8  a top view  800  of cap layer  110  of slug assisted longitudinal liquid metal optical switch  105  is shown, according to certain embodiments of the present invention. The top view  800  illustrates an orientation of upper channel  235  relative to cap layer  110 . In certain embodiments of the present invention, cap layer  110  is centered within cap layer  110  along a long axis and a short axis of channel  235 . 
   Certain embodiments of the present invention use a motion of slug  220  caused by actuation of one or more of the plurality of piezoelectric elements  210  against said slug  220  to drive liquid metal  225  and slug  220  from a first two contacts of plurality of contacts  215  to a second two contacts of plurality of contacts  215 , thereby causing one or more optical waveguides of the plurality of optical waveguides  150  to be blocked or unblocked and changing a state of the slug assisted longitudinal liquid metal optical switch  105 . In certain embodiments of the present invention slug  220  is coupled to two contacts of plurality of contacts  215  while slug  220  is not in motion. The slug  220  assists in the blocking of the one or more optical waveguides  150 . The slug assisted longitudinal liquid metal optical switch  105  latches by a wetting of the one or more contacts of the plurality of contacts  215  and a surface tension of the liquid metal  225  causing the liquid metal  225  to stay in a stable position. The slug  220  is wettable and so may be maintained in a stable position due to the surface tension of the liquid metal  225  and the coupling of the slug  220  to one or more of the plurality of contacts  215 . In certain embodiments of the present invention, the plurality of optical waveguides  150  have faces that are not wettable by the liquid metal  225  in order to preserve an optical clarity of a signal path of the plurality of optical waveguides  150 . 
   Plurality of vias  205  are oriented so that an increase in a pressure of inert gas in channel  230  is equalized as slug  220  and liquid metal  225  move from the first two contacts to the second two contacts. As an example, referring again to  FIG. 2 , as a piezoelectric element is actuated slug  220  is forced into motion. The motion of slug  220  and liquid metal  225  increases the pressure in a left side of the channel  230  of FIG.  2 . The pressure is equalized with a right side of the channel  230  by plurality of vias  205  and the upper channel  235 . In certain embodiments of the present invention, slug  220  and liquid metal  225  are present in channel  230  so that there is not a gap between a bottom of channel  230 , slug  220 , liquid metal  225  and a top of channel  230 , thereby preventing a substantial amount inert gas from passing from the left side of channel  230  to the right side of channel  230  unless said inert gas passes through upper channel  235 . 
   Liquid metal  225  is contained within the channel  230  and in certain embodiments of the present invention is coupled to the plurality of contacts  215 . In certain embodiments of the present invention, slug  220  has a length operable to couple slug  220  to two contacts of plurality of contacts  215 . Slug  220  is latched to two contacts of the plurality of contacts  215  by a surface tension between the plurality of contacts  215  and the slug  220 . Latching is a stable configuration because the liquid metal  225  wets the plurality of contacts and is held in place by the surface tension. Slug  220  is wettable and in certain embodiments of the present invention liquid metal  225  and slug  220  may be moved within the channel  230  substantially more easily than only liquid metal  225 . 
   While the invention has been described in conjunction with specific embodiments, it is evident that many alternatives, modifications, permutations and variations will become apparent to those of ordinary skill in the art in light of the foregoing description. Accordingly, it is intended that the present invention embrace all such alternatives, modifications and variations as fall within the scope of the appended claims.