Optical transmitter assembly for vertical coupling

Abstract

The invention relates to an optical transmitter assembly (OTA) for vertical coupling of light into a chip, and to a method for manufacturing the OTA. The OTA includes a laser diode, a microlens and a turning mirror mounted at a top face of a supporting substrate within a sealed enclosure, and an optical component, such as an optical isolator, a polarizer, or a microlens disposed in a substrate cavity that opens to the back face of the substrate. The optical component may be placed into the cavity after the enclosure is sealed.

1 . An optical transmitter assembly (OTA)comprising:
 a single substrate having a first face and a second face opposing the first face;   a laser diode (LD), disposed at the first face, configured to emit a light beam along the first face;   a turning mirror, provided at the first face, configured to re-direct the light beam to propagate through the single substrate and emerge from the second face; and   a first microlens, disposed between the LD and the turning mirror, configured to at least partially collimate or focus the light beam;
 wherein the single substrate includes a cavity that is located within the single substrate, open to the second face at a bottom portion of the single substrate, positioned in an optical path of the light beam, and configured to receive an optical component. 
   
     
     
         2 . The OTA of  claim 1 , further comprising:
 a lid, attached to the single substrate at the first face, configured to form an enclosure for enclosing the LD, the first microlens, and the turning mirror.   
     
     
         3 . The OTA of  claim 1 , further comprising,
 one or more polarization processing optical components disposed within the cavity and in the optical path of the light beam.   
     
     
         4 . The OTA of claim wherein the one or more polarization processing optical components include one or more of an optical isolator, a half-wave plate, or a polarizer. 
     
     
         5 . The OTA of  claim 1 , further comprising:
 a non-reciprocal polarization rotator disposed optically between the LD and the turning mirror.   
     
     
         6 . The OTA of  claim 5 , wherein at least one of the first microlens or the non-reciprocal polarization rotator is recessed into the first face. 
     
     
         7 . The OTA of  claim 1 , wherein the first microlens comprises an aspheric lens. 
     
     
         8 . The OTA of  claim 1 , further comprising:
 a second microlens, disposed optically after the turning mirror, configured to shape the light beam prior to egress from the OTA.   
     
     
         9 . The OTA of  claim 8 , wherein the second microlens is disposed in the cavity. 
     
     
         10 . The OTA of  claim 8 , wherein the second microlens is aspheric. 
     
     
         11 . The OTA of  claim 2 , wherein the LD and the first microlens are mounted upon the first face, and the turning mirror comprises an inclined surface formed in the lid. 
     
     
         12 . A method of making an optical transmitter assembly (OTA), the method comprising:
 providing a light source sub-assembly fixedly disposed at a first face of a single substrate, the single substrate having a cavity that is located within the single substrate and open to a second face of the single substrate opposing the first face,
 the second face being located at a bottom portion of the single substrate, and the light source sub-assembly comprising:
 a laser diode (LD), disposed at the first face, configured to emit a light beam along the first face; 
 a turning mirror configured to direct the light beam through the single substrate to be output from the second face; and 
 a first microlens, disposed between the LD and the turning mirror, configured to at least partially collimate or focus the light beam; and 
 
   placing a polarization processing or collimating optical element into the cavity and in an optical path of the light beam.   
     
     
         13 . The method of  claim 12 , further comprising:
 affixing a lid to the single substrate to form a sealed enclosure housing the light source sub-assembly at the first face.   
     
     
         14 . The method of  claim 13 , further comprising:
 testing, after affixing the lid, an ability of the light source sub-assembly to generate light.   
     
     
         15 . The method of  claim 13 , wherein
 the lid is affixed by heating the OTA to an elevated temperature, and   the polarization processing or collimating optical element is placed into the cavity when the single substrate is cooled.   
     
     
         16 . The method of  claim 12 , wherein the polarization processing or collimating optical element includes one or more of an optical isolator, a half-wave plate, or a polarizer. 
     
     
         17 . The method of  claim 12 , further comprising:
 placing a second microlens into the cavity and in the optical path of the light beam.   
     
     
         18 . The method of  claim 12  wherein providing the light source sub-assembly comprises:
 providing a non-reciprocal polarization rotator between the LD and the turning mirror wherein the first microlens and the non-reciprocal polarization rotator are recessed into the first face. 
 
     
     
         19 . The OTA of  claim 1 , wherein the first microlens comprises a ball lens. 
     
     
         20 . An optical transmitter assembly (OTA) for coupling light into an integrated circuit chip, the OTA comprising:
 a single supporting substrate;   a laser diode;   a turning mirror; and   a polarization processing element,   wherein the laser diode and the polarization processing element are disposed at opposite faces of the single supporting substrate,   wherein the turning mirror is configured to re-direct an optical path from the laser diode through the single supporting substrate and the polarization processing element, and   wherein the polarization processing element is disposed in a cavity in the single supporting substrate,   the single supporting substrate being located within the cavity and the cavity being open to a face, of the opposite faces, at a bottom portion of the single supporting substrate.