Efficient light coupler from off-chip to on-chip waveguides

Abstract

In an embodiment, light from a single mode light source may be deflected into a low index contrast (LIC) waveguide in an opto-electronic integrated circuit (OEIC) (or “opto-electronic chip”) by a 45 degree mirror. The mirror may be formed by polishing an edge of the die at a 45 degree angle and coating the polished edge with a metal layer. Light coupled into the LIC waveguide may then be transferred from the LIC waveguide to a high index contrast (HIC) waveguide by evanescent coupling.

1 . A method comprising:
 fabricating an integrated optical waveguide on a substrate;   polishing an edge of the integrated optical waveguide at an angle; and   coating the polished edge of the integrated optical waveguide with a reflective material to form a mirror positioned to couple light unto the integrated optical waveguide.   
     
     
         2 . The method of  claim 1 , wherein polishing the edge of the integrated optical waveguide comprises polishing an edge of a semiconductor die. 
     
     
         3 . The method of  claim 1 , wherein fabricating the integrated optical waveguide comprises fabricating the integrated optical waveguide substantially parallel to a surface of the substrate. 
     
     
         4 . The method of  claim 1 , further comprising coupling the substrate to a flip chip package so that light of a light source is deflected into the integrated optical waveguide. 
     
     
         5 . The method of claim  10 , wherein:
 fabricating the integrated optical waveguide comprises fabricating a low index contrast waveguide; and   the method further comprises fabricating a high index contrast waveguide adjacent to the low index contrast waveguide, wherein the high index contrast waveguide is separated from the low index contrast waveguide by a distance that allows light to evanescently couple from the low index contrast waveguide into the high index contrast waveguide.   
     
     
         6 . The method of  claim 5 , further comprising patterning the high index contrast waveguide into a distribution pattern.