Three dimensional optical interconnects

1. A structure comprising:

a first structure comprising a grating coupler and a first optical waveguide structure; and

a second structure comprising a second optical waveguide structure in alignment with the first optical waveguide structure and which has a modal effective index that matches to the first optical waveguide structure.

2. The structure of claim 1 , wherein the first structure is silicon on insulator technology and the second structure is bulk substrate technology.

3. The structure of claim 1 , wherein the first optical waveguide structure is composed of Si material or SiN material, and the second optical waveguide structure is composed of SiN material, Si material or metal.

4. The structure of claim 1 , wherein the first optical waveguide structure and the second optical waveguide structure are separated by dielectric material of the first structure.

5. The structure of claim 4 , further comprising a third optical waveguide structure embedded within the dielectric material and aligned with the first optical waveguide structure and the second optical waveguide structure.

6. The structure of claim 5 , wherein the third optical waveguide structure has a modal effective index that matches the first optical waveguide structure and the second optical waveguide structure such that optical transmission of light passes through the first optical waveguide structure to and through the third optical waveguide structure and to and through the second optical waveguide structure without a an optical via interconnect.

7. The structure of claim 5 , wherein the second optical waveguide structure has a modal effective index that does not match the first optical waveguide structure and the third optical waveguide structure such that optical transmission of light passes from the first optical waveguide structure to the third optical waveguide structure through the second optical waveguide structure without any optical interference.

8. The structure of claim 5 , wherein the third optical waveguide structure has a modal effective index that matches the first optical waveguide structure and the second optical waveguide such that optical transmission of light passes from the first optical waveguide structure to the third optical waveguide structure through the second optical waveguide structure with low loss optical interference.

9. The structure of claim 1 , further comprising a third structure comprising a grating coupler and an upper optical waveguide structure, wherein the first structure is silicon on insulator technology, the second structure is bulk substrate technology, the third structure is the bulk substrate technology, and the grating coupler and the upper optical waveguide structure are in a same plane.

10. The structure of claim 9 , wherein the first optical waveguide structure, the second optical waveguide structure and the upper optical waveguide structure each have a matching modal effective index such that optical transmission of light passes through the first optical waveguide structure to and through the second optical waveguide structure and to and through the upper optical waveguide structure to the grating coupler of the third structure without an optical via interconnect.

11. A structure comprising:

a first structure composed of silicon on insulator technology and comprising a grating coupler, a plurality of semiconductor islands and a first optical waveguide structure;

a second structure bonded to a dielectric material of the first structure, the second structure being composed of bulk semiconductor technology and comprising a second optical waveguide structure in alignment with the first optical waveguide structure and which has a modal effective index that matches the first optical waveguide structure; and

a third structure bonded to a dielectric material of the second structure, the third structure being composed of the bulk semiconductor technology and comprising a third optical waveguide structure in a same plane as a coupler.

12. The structure of claim 11 , wherein the first optical waveguide structure is composed of Si material or SiN material, and the second optical waveguide structure and the third optical waveguide structure are composed of SiN material, Si material or metal.

13. The structure of claim 11 , wherein the first optical waveguide structure, the second optical waveguide structure and the third optical waveguide structure have a matching modal effective index.

14. The structure of claim 13 , further comprising an intermediate optical waveguide structure embedded with the dielectric material of the first structure and in alignment with the first optical waveguide structure and the second optical waveguide structure.

15. The structure of claim 14 , wherein the intermediate optical waveguide structure has a modal effective index that matches the first optical waveguide structure and the second optical waveguide structure such that optical transmission of light passes through the first optical waveguide structure to and through the intermediate optical waveguide structure and to and through the second optical waveguide structure without an optical via interconnect.

16. The structure of claim 11 , wherein the grating coupler, the plurality of semiconductor islands and the first optical waveguide structure of the first structure are in a same plane to allow an optical transmission from the grating coupler to the first optical waveguide structure.

17. The structure of claim 11 , wherein the first optical waveguide structure transmits an optical transmission through the dielectric material of the first structure to the second optical waveguide structure without an optical via interconnect.

18. The structure of claim 17 , wherein:

the second optical waveguide structure transmits the optical transmission through the bulk substrate of the second structure to the third optical waveguide structure without an optical via interconnect; and

the third optical waveguide structure transmits the optical transmission through the bulk substrate of the third structure to the grating coupler of the third structure.

19. A method comprising:

forming a first structure composed of silicon on insulator technology and comprising a grating coupler, a plurality of semiconductor islands and a first optical waveguide structure;

forming a second structure composed of bulk semiconductor technology and comprising a second optical waveguide structure having a modal effective index that matches the first optical waveguide structure;

forming a third structure composed of the bulk semiconductor technology and comprising a third optical waveguide structure in a same plane as a coupler;

placing a wafer handler on the second structure and bonding the second structure to an oxide material of the first structure such that the first optical waveguide structure and the second optical waveguide structure are in alignment;

removing the wafer handler from the second structure and placing a wafer handler on the third structure;

bonding the third structure to an oxide material of the second structure such that the third optical waveguide structure is above the second optical waveguide structure; and

forming an intermediate optical waveguide structure embedded with the dielectric material of the first structure and in alignment with the first optical waveguide structure and the second optical waveguide structure.

20. The method of claim 19 , wherein:

prior to the bonding of the second structure to the first structure, a backside etching and grinding is performed to thin a wafer of the bulk semiconductor technology of the second structure; and

prior to the bonding of the third structure to the second structure, a backside etching and grinding is performed to thin a wafer of the bulk semiconductor technology of the third structure.