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 first base substrate;   bonding a plurality of electrical connections to the first base substrate, each electrical connection coupled to a respective laser diode in the plurality of laser diodes;   bonding an electrically insulating cover to the first base substrate over the plurality of electrical connections; and   bonding a cap comprising at least one wall and at least one optical window to the first base substrate and the electrically insulating cover, wherein the at least one wall, the at least one optical window, the electrically insulating cover, and at least a portion of the first base substrate together delimit an interior volume sized and dimensioned to receive at least the plurality of laser diodes, the bonding of the cap to the first base substrate and the electrically insulating cover 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 first base substrate by bonding the at least one laser diode to a respective chip submount; and   bonding the chip submount to the first base substrate.   
     
     
         3 . The method of  claim 1 , further comprising:
 bonding each of the laser diodes indirectly to the first base substrate by bonding each laser diode to a respective chip submount; and   bonding each chip submount to the first 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 first base substrate comprises step-soldering each chip submount to the first base substrate. 
     
     
         6 . The method of  claim 3  wherein bonding each chip submount to the first base substrate comprises bonding each chip submount to the first 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 first 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 first base substrate comprises soldering each chip submount to the first 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 first base substrate and electrically insulating cover, bonding an optical director element to the first 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 first 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 first 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 plurality of electrical connections, in operation the at least one laser diode driver circuit selectively drives current to the laser diodes via the plurality of electrical connections.   
     
     
         17 . The method of  claim 1 , further comprising:
 bonding at least one laser diode driver circuit to the first base substrate; and   providing a coupling between the at least one laser diode driver circuit and the plurality of electrical connections, in operation the at least one laser diode driver circuit selectively drives current to the laser diodes via the plurality of electrical connections.   
     
     
         18 . The method of  claim 17  wherein:
 bonding the at least one laser diode driver circuit to the first base substrate comprises bonding the at least one laser diode driver circuit to a first surface of the first base substrate; 
 bonding the plurality of electrical connections to the first base substrate comprises bonding the plurality of electrical connections to the first surface of the first base substrate; 
 bonding the electrically insulating cover to the first base substrate comprises bonding the electrically insulating cover to the first surface of the first base substrate over the plurality of electrical connections; and 
 bonding the cap to the first base substrate and the electrically insulating cover comprises bonding the cap to the first surface of the base substrate and the electrically insulating cover. 
 
     
     
         19 . The method of  claim 1 , further comprising bonding a plurality of electrical contacts to the first base substrate, each electrical contact coupled to a respective one of the plurality of electrical connections. 
     
     
         20 . The method of  claim 19 , further comprising:
 bonding at least one laser diode driver circuit to a second base substrate; and   providing a coupling between the at least one laser diode driver circuit and the plurality of electrical contacts, in operation the at least one laser diode driver circuit selectively drives current to the laser diodes via the plurality of electrical contacts and the plurality of electrical connections.   
     
     
         21 . The method of  claim 1 , further comprising:
 providing the first base substrate, wherein the first base substrate is formed from one of low temperature co-fired ceramic, aluminum nitride (AlN), Kovar®, or alumina.   
     
     
         22 . The method of  claim 1  wherein bonding a cap to the first base substrate and the electrically insulating cover comprises bonding a cap to the first base substrate using at least one of a seam welding process, a laser assisted soldering process, or a diffusion bonding process. 
     
     
         23 . The method of  claim 1 , further comprising:
 prior to bonding the cap to the first base substrate and the electrically insulating cover, flooding the interior volume with an oxygen rich atmosphere.