Method for fabricating optical devices by assembling multiple wafers containing planar optical waveguides

Abstract

A method for fabricating an optical device wherein the device comprises a first substrate wafer with at least one buried optical waveguide on an approximately flat planar surface of the substrate and a second substrate wafer with at least a second buried optical waveguide. The waveguides so formed may be straight or curved along the surface of the wafer or curved by burying the waveguide at varying depth along its length. The second wafer is turned (flipped) and bonded to the first wafer in such a manner that the waveguides, for example, may form an optical coupler or may cross over one another and be in proximate relationship along a region of each. As a result, three-dimensional optical devices are formed avoiding the convention techniques of layering on a single substrate wafer.

1 . A method of fabricating an optical device comprising the steps of: forming at least one buried optical waveguide in a planar surface of a first wafer substrate; forming at least one buried optical waveguide in a planar surface of a second wafer substrate; placing the second wafer substrate onto the planar surface of the first wafer substrate and bonding the first and second wafer substrates together.  
   
   
       2 . A method of fabricating an optical device as recited in  claim 1  further comprising the step of forming a recessed area on the planar surface of one wafer substrate before bonding the first and second wafer substrates together.  
   
   
       3 . A method of fabricating an optical device as recited in  claim 1  wherein said at least one planar waveguide of one or the other wafer substrate is curved.  
   
   
       4 . A method of fabricating an optical device as recited in  claim 1  wherein said at least one planar optical waveguide of said first wafer substrate crosses said at least one planar optical waveguide of said second wafer substrate at an angle of less than fifty degrees after bonding.  
   
   
       5 . A method of fabricating an optical device as recited in  claim 2  further comprising the step of filling said recessed area with a material other than one of a vacuum, air and an inert gas.  
   
   
       6 . A method of fabricating an optical device as recited in  claim 1  wherein one waveguide is buried at varying depth along its length in relation to the planar surface of its corresponding wafer substrate.