Active optical alignment and attachment thereto of an optical component with an optical element formed on a planar lightwave circuit

Abstract

A method and apparatus is provided for attaching a external optical component processing an optical beam to a PLC and optically aligning the external optical component with an optical element formed on the PLC. The method begins by securing the external optical component to a first side of a submount. A first side of a flexure element is secured to the first side of the submount. A second side of the flexure element is secured to a first side of the PLC on which the optical element is formed such that the external optical component and the optical element are in optical alignment to within a first level of tolerance. Subsequent to the step of securing the second side of the flexure element, a force is exerted on at least a second side of the submount to thereby flex the flexure element. The force causes sufficient flexure of the flexure element to optically align the external optical component and optical element to within a second level of tolerance that is more stringent than the first level of tolerance.

1 . A method of attaching an external optical component processing an optical beam to a PLC and optically aligning the external optical component with an optical element formed on the PLC, said method comprising the steps of: 
 a. securing the external optical component to a first side of a submount;    b. securing a first side of a flexure assembly to the first side of the submount;    c. securing a second side of the flexure assembly to a first side of the PLC on which the optical element is located, such that the external optical component and the optical element are in optical alignment to within a first level of tolerance and;    d. subsequent to step (c), exerting a force on at least a second side of the submount to thereby flex the flexure assembly, said force causing sufficient flexure of the flexure assembly to optically align the external optical component and optical element to within a second level of tolerance that is more stringent than the first level of tolerance.    
   
   
       2 . The method of  claim 1  wherein the flexure assembly has a prescribed shape and is formed as a single unitary element.  
   
   
       3 . The method of  claim 1  wherein the flexure assembly has a prescribed shape and is formed from a plurality of different elements.  
   
   
       4 . The method of  claim 3  further comprising the step of forming the flexure assembly by connecting each of the plurality of different elements by a process selected from the group consisting of soldering, brazing, thermo-compression bonding and welding.  
   
   
       5 . The method of  claim 1  wherein the flexure assembly comprises a first flexure element affixed to a second flexure element such that that the first and second flexure elements are situated one above the other and laterally offset from one another.  
   
   
       6 . The method of  claim 5  wherein the first and second flexure elements are substantially planar flexure elements.  
   
   
       7 . The method of  claim 1  further comprising the step of monitoring an optical coupling efficiency of an optical beam propagating between the external optical component and optical element on PLC.  
   
   
       8 . The method of  claim 7  wherein the step of exerting a force is performed on the submount, such that the coupling efficiency is maximized.  
   
   
       9 . The method of  claim 1  wherein the optical element is a facet of a planar waveguide formed on the PLC.  
   
   
       10 . The method of  claim 1  wherein the optical element is a grating formed on the PLC for facilitating optical coupling from the external optical component into another structure located on the PLC.  
   
   
       11 . The method of  claim 1  wherein the external optical component is selected from the group consisting of a semiconductor laser, a semiconductor optical amplifier, a LED, a beam splitter, a thin film filter, an optical filter, a lens, a passive optical component, a mirror, a birefringent material, a polarizer, and a diffractive element.  
   
   
       12 . The method of  claim 1  wherein the external optical component is a semiconductor laser.  
   
   
       13 . The method of  claim 1  wherein the external optical component is a LED.  
   
   
       14 . The method of  claim 1  wherein the external optical component has an active, light emitting surface that faces the PLC.  
   
   
       15 . The method of  claim 1  wherein the submount is formed from aluminum nitride.  
   
   
       16 . The method of  claim 1  wherein the flexure assembly is fabricated from a low yield material that is given to deformation without a restoring reaction.  
   
   
       17 . The method of  claim 1  wherein the flexure assembly is formed from gold or a gold alloy.  
   
   
       18 . The method of  claim 1  wherein the flexure assembly is formed from lead.  
   
   
       19 . The method of  claim 1  wherein the flexure assembly is formed from nickel or a nickel alloy.  
   
   
       20 . The method of  claim 1  wherein the flexure assembly element is formed from TM Kovar™.  
   
   
       21 . The method of  claim 1  wherein the flexure assembly is formed from a thermally conductive material sufficient to serve as a heat sink for the external optical component.  
   
   
       22 . The method of  claim 1  wherein the second side of the submount on which the force is exerted is a back surface of the submount opposing the first side of the submount.  
   
   
       23 . The method of  claim 1  wherein the second side of the submount on which the force is exerted is an edge of the submount.  
   
   
       24 . The method of  claim 1  further comprising the step of etching a pocket in the PLC at a location under the external optical component so that sufficient clearance is available for attaching the external optical component below a surface of the PLC inside the pocket.  
   
   
       25 . The method of  claim 1  further comprising the step of enclosing the external optical component and the submount with a cover that mates with the first side of the PLC.  
   
   
       26 . The method of  claim 25  wherein said cover has an etched pocket allowing clearance for the external optical component and the submount.  
   
   
       27 . The method of  claim 26  wherein the cover forms a hermetic seal with the first side of the PLC.  
   
   
       28 . The method of  claim 27  wherein the cover is formed from a material having a thermal expansion comparable to silicon so that the cover it will not break during attachment or device operation.  
   
   
       29 . The method of  claim 27  wherein the cover is formed from Kovar™.  
   
   
       30 . The method of  claim 27  wherein the cover is formed from silicon.  
   
   
       31 . The method of  claim 27  wherein the cover is formed from Pyrex™.  
   
   
       32 . The method of  claim 27  wherein the hermetic seal is established by a solder seal ring.  
   
   
       33 . An optical apparatus constructed in accordance with the method of  claim 1 .  
   
   
       34 . A method of attaching an external optical component to a planar substrate and optically aligning said device with an optical element located on the planar substrate, said method comprising the steps of: 
 a. securing the external optical component to a first side of a submount;    b. securing a first side of a flexure assembly to the first side of the submount;    c. securing a second side of a flexure assembly to a first side of the planar substrate on which the optical element is secured such that the external optical component and the optical element are in optical alignment to within a first level of tolerance and;    d. subsequent to step (c), exerting a force on at least a second side of the submount to thereby flex the flexure assembly, said force causing sufficient flexure of the flexure assembly to optically align the external optical component and the optical element to within a second level of tolerance that is more stringent than the first level of tolerance, whereby the external optical component and the planar substrate are not in direct contact with one another.    
   
   
       35 . The method of  claim 34  wherein the flexure assembly has a prescribed shape and is formed from a plurality of different elements.  
   
   
       36 . The method of  claim 34  wherein the flexure assembly has a prescribed shape and is formed as a single unitary element.  
   
   
       37 . The method of  claim 35  further comprising the step of forming the flexure assembly by connecting each of the plurality of different elements by a process selected from the group consisting of soldering, brazing, thermo-compression bonding and welding.  
   
   
       38 . The method of  claim 34  wherein the flexure assembly comprises a first flexure element affixed to a second flexure element such that that the first and second flexure elements are situated one above the other and laterally offset from one another.  
   
   
       39 . The method of  claim 38  wherein the first and second flexure elements are substantially planar flexure elements.  
   
   
       40 . The method of  claim 34  further comprising the step of monitoring an optical coupling efficiency of an optical beam propagating between the external optical component and the optical element.  
   
   
       41 . The method of  claim 40  wherein the step of exerting a force is performed such that the coupling efficiency is maximized.  
   
   
       42 . The method of  claim 34  wherein the optical element is an optical fiber.  
   
   
       43 . The method of  claim 34  wherein the optical element is a grating.  
   
   
       44 . The method of  claim 34  wherein the external optical component is selected from the group consisting of a semiconductor laser, a semiconductor optical amplifier, or a Light Emitting Diode (LED) or a combination thereof.  
   
   
       45 . The method of  claim 34  wherein the external optical component  
   
   
       46 . The method of  claim 34  wherein the external optical component is a LED.  
   
   
       47 . The method of  claim 1  wherein the external optical component has an active, light emitting surface that faces the PLC.  
   
   
       48 . The method of  claim 34  wherein the submount is formed from aluminum nitride.  
   
   
       49 . The method of  claim 34  wherein the flexure is fabricated from low yield material that is given to deformation without restoring reaction.  
   
   
       50 . The method of  claim 34  wherein the flexure assembly is formed from gold or a gold alloy.  
   
   
       51 . The method of  claim 34  wherein the flexure assembly is formed from lead.  
   
   
       52 . The method of  claim 34  wherein the flexure assembly is formed from nickel or a nickel alloy.  
   
   
       53 . The method of  claim 34  wherein the flexure assembly element is formed from Kovar™.  
   
   
       54 . The method of  claim 34  wherein the flexure assembly is formed from a thermally conductive material sufficient to serve as a heat sink for the light generating device.  
   
   
       55 . The method of  claim 34  wherein the second side of the submount on which the force is exerted is a back surface of the submount opposing the first side of the submount.  
   
   
       56 . The method of  claim 34  wherein the second side of the submount on which the force is exerted is an edge of the submount.  
   
   
       57 . The method of  claim 34  further comprises forming of etching a pocket in the planar substrate under the light generating device, so that sufficient clearance is available for attaching the light generating device.  
   
   
       58 . The method of  claim 34  comprising the step of enclosing the light generating device and the submount with a cover that mates with the first side of the planar substrate.  
   
   
       59 . The method of  claim 58  wherein said cover has an etched pocket allowing clearance for the light generating device on the submount.  
   
   
       60 . The method of  claim 58  wherein the cover forms a hermetic seal with the first side of the planar substrate.  
   
   
       61 . The method of  claim 58  wherein the cover is formed from Kovar™.  
   
   
       62 . The method of  claim 58  wherein the cover is formed from silicon.  
   
   
       63 . The method of  claim 58  wherein the cover is formed from Pyrex™.  
   
   
       64 . The method of  claim 60  wherein the hermetic seal is established by a solder seal ring.  
   
   
       65 . An optical apparatus constructed in accordance with the method of  claim 34 .  
   
   
       66 . The method of  claim 1  wherein the external optical component and the PLC are not in direct contact with one another after performing steps (a)-(d).  
   
   
       67 . The method of  claim 34  wherein the external optical component is a light generating device.