Compact optical engine and method of manufacturing same

Abstract

Systems, devices, and methods of manufacturing optical engines and laser projectors that are well-suited for use in wearable heads-up displays (WHUDs) are described. Generally, the optical engines of the present disclosure integrate a plurality of laser diodes (e.g., 3 laser diodes, 4 laser diodes) within a single, hermetically or partially hermetically sealed, encapsulated package. Such optical engines may have various advantages over existing designs including, for example, smaller volumes, better manufacturability, faster modulation speed, etc. WHUDs that employ such optical engines and laser projectors are also described.

1 . A method of manufacturing an optical engine, the method comprising:
 bonding a plurality of laser diodes directly or indirectly to a base substrate; and   bonding a cap comprising at least one wall and at least one optical window to the base substrate, the at least one wall, the at least one optical window, and at least a portion of the base substrate together delimit an interior volume sized and dimensioned to receive at least the plurality of laser diodes bonded to the base substrate, the bonding of the cap to the base substrate providing a hermetic or partially hermetic seal between the interior volume of the cap and a volume exterior to the cap, and the optical window positioned and oriented to allow light emitted from the laser diodes to exit the interior volume.   
     
     
         2 . The method of  claim 1 , further comprising:
 bonding at least one of the laser diodes indirectly to the base substrate by bonding the at least one laser diode to a respective chip submount; and   bonding the chip submount to the base substrate.   
     
     
         3 . The method of  claim 1 , further comprising:
 bonding each of the laser diodes indirectly to the base substrate by bonding each laser diode to a respective chip submount; and   bonding each chip submount to the base substrate.   
     
     
         4 . The method of  claim 3  wherein bonding each laser diode to a respective chip submount comprises bonding each laser diode to a respective chip submount using a eutectic gold tin (AuSn) solder process. 
     
     
         5 . The method of  claim 3  wherein bonding each chip submount to the base substrate comprises step-soldering each chip submount to the base substrate. 
     
     
         6 . The method of  claim 3  wherein bonding each chip submount to the base substrate comprises bonding each chip submount to the base substrate using at least one of a reflow oven process, thermosonic bonding, thermocompression bonding, transient liquid phase (TLP) bonding, or laser soldering. 
     
     
         7 . The method of  claim 3  wherein bonding each chip submount to the base substrate comprises bonding a chip submount that has a red laser diode bonded thereto, bonding a chip submount that has a green laser diode bonded thereto, bonding a chip submount that has a blue laser diode bonded thereto, and bonding a chip submount that has an infrared laser diode bonded thereto. 
     
     
         8 . The method of  claim 3  wherein bonding each chip submount to the base substrate comprises soldering each chip submount to the base substrate using a reactive multi-layer foil material preform. 
     
     
         9 . The method of  claim 1 , further comprising:
 positioning a plurality of collimation lenses to be adjacent the at least one optical window, each of the plurality of collimation lenses positioned and oriented to receive light from a corresponding one of the laser diodes through the at least one optical window; and   actively aligning each of the plurality of collimation lenses.   
     
     
         10 . The method of  claim 9 , further comprising:
 subsequent to actively aligning each of the plurality of collimation lenses, bonding each of the collimation lenses to the at least one optical window.   
     
     
         11 . The method of  claim 9  wherein actively aligning each of the plurality of collimation lenses comprises positioning each of the collimation lenses to optimize spot and pointing for each of the respective laser diodes. 
     
     
         12 . The method of  claim 9 , further comprising:
 positioning a beam combiner to combine light beams received from each of the collimation lenses into a single aggregate beam.   
     
     
         13 . The method of  claim 1 , further comprising:
 prior to bonding the cap to the base substrate, bonding an optical director element to the base substrate proximate the laser diodes, the optical director element positioned and oriented to direct laser light from the laser diodes toward the optical window of the cap.   
     
     
         14 . The method of  claim 13  wherein bonding an optical director element comprises bonding one of a mirror or prism to the base substrate proximate the laser diodes. 
     
     
         15 . The method of  claim 13  wherein bonding an optical director element comprises bonding an optical director element to a base substrate using at least one of a reflow oven process, thermosonic bonding, thermocompression bonding, transient liquid phase (TLP) bonding, or laser soldering. 
     
     
         16 . The method of  claim 1 , further comprising:
 providing a coupling between at least one laser diode driver circuit and the laser diodes, in operation the at least one laser diode driver circuit selectively drives current to the laser diodes.   
     
     
         17 . The method of  claim 1 , further comprising:
 bonding at least one laser diode driver circuit to the base substrate; and   providing a coupling between the at least one laser diode driver circuit and the laser diodes, in operation the at least one laser diode driver circuit selectively drives current to the laser diodes.   
     
     
         18 . The method of  claim 1 , further comprising:
 providing the base substrate, wherein the base substrate is formed from one of low temperature co-fired ceramic, aluminum nitride (AlN), Kovar®, or alumina.   
     
     
         19 . The method of  claim 1  wherein bonding a cap to the base substrate comprises bonding a cap to the base substrate using at least one of a seam welding process, a laser assisted soldering process, or a diffusion bonding process. 
     
     
         20 . The method of  claim 1 , further comprising:
 prior to bonding the cap to the base substrate, flooding the interior volume with an oxygen rich atmosphere.