Optoelectronic packaging

Abstract

Packaging of micromechanical and microelectromechanical devices is carried out by mechanical couplers for connecting pairs or arrays of optical fibers in end-to-end alignment. In another embodiment, a coupler interconnects one or more optical components on a substrate. The electrical components may be active elements such as light sources or light sensors, while the optical components may be waveguides. The fibers are secured in a coupler block, and a substrate carrying the light detector or light source is mounted on or in the block and is secured in alignment with the fibers. The fibers are removably secured within the block by spring fingers. The coupler block may include electrical circuitry connectable to the sensors or light sources on the substrate mounted on the block through wire bonding techniques.

What is claimed is:  
     
         1 . An optical coupler, comprising: 
 a coupler block;    at least one fiber guide in said block for receiving an optical fiber; and means on said block for transferring light between an optical fiber in said guide and an optical element.    
     
     
         2 . The optical coupler of  claim 1 , wherein said optical element is a second fiber guide for receiving a second optical fiber axially aligned with said first fiber guide.  
     
     
         3 . The optical coupler of  claim 1 , wherein said optical element is located on a substrate edge-mounted in said optical block.  
     
     
         4 . The optical coupler of  claim 1 , wherein said optical element is a waveguide.  
     
     
         5 . The optical coupler of  claim 1 , wherein said optical element is an active element.  
     
     
         6 . The optical coupler of  claim 1 , wherein said optical element is a substrate surface mounted on said block.  
     
     
         7 . The optical coupler of  claim 1 , wherein said means comprises an elongated trench in said block between said fiber guide and said optical element.  
     
     
         8 . The optical coupler of  claim 1 , wherein said means comprises a reflector integral with said block.  
     
     
         9 . The optical coupler of  claim 1 , wherein said means comprises a waveguide having a first end aligned with said fiber guide and a second end aligned with said optical element.  
     
     
         10 . The optical coupler of  claim 9 , wherein said waveguide is embedded in said block.  
     
     
         11 . The optical coupler of  claim 9 , wherein said waveguide is located on the surface of said block.  
     
     
         12 . The optical coupler of  claim 1 , wherein said optical element is a second fiber guide coaxial with said at least one fiber guide for receiving a corresponding optical fiber, and wherein said means for transferring light includes an intermediate guide portion between said fiber guides, and further including a fiber stop in said intermediate guide portion.  
     
     
         13 . The optical coupler of  claim 12 , further including a flared end portion for each fiber guide for facilitating the insertion of optical fibers.  
     
     
         14 . The optical coupler of  claim 13 , wherein said block is single crystal silicon and wherein said fiber guides and said intermediate guide portions are etched in said block.  
     
     
         15 . The optical coupler of  claim 14 , wherein said at least one fiber guide and said second fiber guide comprise a fiber guide pair, and wherein said coupler block includes a multiplicity of fiber guide pairs for coupling optical fiber arrays.  
     
     
         16 . The optical coupler of  claim 1 , wherein said optical element is an active element mounted on a substrate edge-mounted in said optical block with said active element aligned with said fiber guide.  
     
     
         17 . The optical coupler of  claim 16 , wherein said active element is a light emitter.  
     
     
         18 . The optical coupler of  claim 16 , wherein said active element is a light detector.  
     
     
         19 . The optical coupler of  claim 16 , further including circuit means on said block and electrically connected to said active element.  
     
     
         20 . The optical coupler of  claim 1 , wherein said coupler block has a top surface, said at least one fiber guide having a longitudinal axis located in said block below said surface; 
 further including an elongated, narrow, deep trench in said block and perpendicular to said fiber guide axis;    a substrate edge-mounted in said trench and having a wall perpendicular to said fiber guide axis, said optical element comprising an active optical element mounted on said substrate wall; and    alignment means in said trench for aligning said optical element and said longitudinal axis of said fiber guide.    
     
     
         21 . The optical coupler of  claim 20 , further including multiple optical guides in said coupler and multiple active optical elements on said substrate wall, said optical elements corresponding to said fiber guides, wherein said alignment means in said trench aligns said optical elements and the longitudinal axes of corresponding fiber guides.  
     
     
         22 . The optical coupler of  claim 20 , wherein said alignment means comprises a precision-etched trench wall perpendicular to said fiber guide axis.  
     
     
         23 . The optical coupler of  claim 20 , wherein said alignment means includes at least one microspring in said trench for engaging said substrate.  
     
     
         24 . The optical coupler of  claim 23 , wherein said microspring is fabricated from and is integral with said block.  
     
     
         25 . The optical coupler of  claim 24 , wherein said microspring is a micromechanical cantilever beam structure extending into said trench to engage said substrate.  
     
     
         26 . The optical coupler of  claim 25 , wherein said microspring includes a retractor for releasing said substrate.  
     
     
         27 . The optical coupler of  claim 23 , wherein said microspring is located in said trench to engage an edge of said substrate.  
     
     
         28 . The optical coupler of  claim 23 , wherein said microspring is located in said trench to engage a back surface of said substrate.  
     
     
         29 . The optical coupler of  claim 23 , wherein said microspring is located in said trench to engage a corner of said substrate.  
     
     
         30 . The optical coupler of  claim 23 , wherein said microspring is located in said trench to engage a front surface of said substrate.  
     
     
         31 . The optical coupler of  claim 23 , wherein said substrate includes at least one positioning notch for receiving said microspring.  
     
     
         32 . The optical coupler of  claim 31  wherein said notch is tapered to accurately position said substrate with respect to said microspring.  
     
     
         33 . The optical coupler of  claim 31 , wherein said notch includes a V-groove for positioning said substrate.  
     
     
         34 . The optical coupler of  claim 31 , wherein said notch is precision etched on a front surface of said substrate, and wherein said microspring includes a tip for engaging said notch.  
     
     
         35 . The optical coupler of  claim 20 , wherein said alignment means includes at least one stop precision etched in said trench for engaging said substrate.  
     
     
         36 . The optical coupler of  claim 20 , further including electrical contact pads on said substrate and on said coupler block for electrically connecting said active optical element on said substrate to circuitry on said block.  
     
     
         37 . The optical coupler of  claim 36 , further including a wirebond connection between said contact pads.  
     
     
         38 . The optical coupler of  claim 36 , further including reflowed solder balls interconnecting said contact pads.  
     
     
         39 . The optical coupler of  claim 38 , wherein said contact pad on said coupler block is mounted on a released cantilevered microstructure beam.  
     
     
         40 . The optical coupler of  claim 36 , wherein said contact pad on said coupler block is mounted on an end tip of a released, cantilevered microstructure beam, said contact pad on said tip engaging said contact pad on said substrate.  
     
     
         41 . The optical coupler of  claim 1 , wherein said fiber guide is an etched trench in said coupler block, said coupler further including multiple fiber alignment fingers along said trench to receive and secure an optical fiber in said guide.  
     
     
         42 . The optical coupler of  claim 1 , wherein said optical element is an active element located on a surface-mounted substrate, and wherein said means for transferring light comprises a reflector integral with said block.  
     
     
         43 . The optical coupler of  claim 42 , wherein said reflector is a precision etched reflective surface in said block, said surface being aligned with said fiber guide and with said active element.  
     
     
         44 . The optical coupler of  claim 1 , wherein said optical element is an active element mounted on the edge of a substrate, said substrate being surface-mounted in a cavity on said block, said cavity being sufficiently deep to align said active element with said fiber guide.  
     
     
         45 . The optical coupler of  claim 1 , wherein said optical element is a first waveguide mounted on said block, and wherein said means for transferring light is a deep-etched second waveguide fabricated in said block and having a first end aligned with said fiber guide and a second end aligned with said first waveguide.  
     
     
         46 . The optical coupler of  claim 45 , further including a lens between said fiber guide and said second waveguide.  
     
     
         47 . A micromechanical optical coupler for interconnecting a small-diameter optical fiber with an optical element, comprising: 
 a single crystal silicon block;    a fiber guide trench etched through a top surface of said block, said guide trench adapted to receive an optical fiber; and    a receptacle etched through the top surface of said block for receiving a substrate carrying active optical elements to be optically coupled to an optical fiber in said fiber guide, said receptacle comprising a precision etched trench intersecting said guide trench    
     
     
         48 . The optical coupler of  claim 47 , said receptacle containing at least one released beam microspring integral with said block and cantilevered on a wall of said trench, said microspring having a movable free end adapted to engage and secure a substrate in said receptacle.  
     
     
         49 . The optical coupler of  claim 48 , said block carrying electrical circuit means, and contacts on said block on said substrate which are connectable to electrically connect said optical element to said circuit.  
     
     
         50 . The optical coupler of  claim 49 , said microspring including release means for releasing said substrate.  
     
     
         51 . A method of fabricating a micromechanical optical coupler in a single crystal silicon block comprising: 
 patterning a top surface of the silicon block;    anisotropically etching a first trench in said top surface to define the location of a fiber guide channel extending the length of said block;    isotropically etching through said first trench a continuous subsurface fiber guide channel extending the length of said first trench, said guide channel having first and second ends terminating at first and second end walls of said block; and    controlling the diameter of said guide channel to receive and hold first and second optical fibers inserted into said first and second ends of said guide channel, respectively, said optical fibers being axially aligned with each other by said guide channel.    
     
     
         52 . A method for fabricating a micromechanical optical coupler in a single crystal silicon block, comprising: 
 patterning a surface of said block to define the location of a fiber guide channel and an intersecting trench; and    etching through said pattern to produce a subsurface fiber guide channel and an intersecting trench open to the surface of said block, said fiber guide channel being adapted to receive an optical fiber and said intersecting trench permitting coupling of light between a fiber in said guide channel and an optical element.    
     
     
         53 . The method of  claim 52 , further including mounting on said block a substrate carrying said optical element.  
     
     
         54 . The method of  claim 53 , further including fabricating a reflective surface in said intersecting trench.  
     
     
         55 . The method of  claim 53 , further including fabricating a waveguide in said intersecting trench.  
     
     
         56 . The method of  claim 55  further including fabricating microsprings in said intersecting trench; 
 inserting a substrate carrying an optical element in said trench; and  
 engaging said substrate with said microspring to secure said substrate and align said optical element with said guide channel.