Electro-optically active device

1. A silicon based electro-optically active device comprising:

a silicon-on-insulator (SOI) waveguide;

an electro-optically active waveguide including an electro-optically active stack above a silicon substrate and separated from the silicon substrate by a crystalline cladding layer, the electro-optically active waveguide being coupled to the SOI waveguide; and

a channel between the electro-optically active waveguide and the SOI waveguide,

wherein the channel is filled with a filling material with a refractive index greater than that of a material of a portion of the SOI waveguide forming a sidewall of the channel to thereby form a bridge-waveguide in the channel between the SOI waveguide and the electro-optically active waveguide.

2. The silicon based electro-optically active device of claim 1 , wherein the electro-optically active stack includes a multiple quantum well region.

3. The silicon based electro-optically active device of claim 1 , wherein the filling material is amorphous silicon.

4. The silicon based electro-optically active device of claim 1 , wherein the filling material is silicon-germanium (SiGe).

5. The silicon based electro-optically active device of claim 1 , wherein the electro-optically active stack has a parallelogramal or trapezoidal geometry.

6. The silicon based electro-optically active device of claim 1 , wherein the electro-optically active stack comprises a buffer layer, and the crystalline cladding layer has a refractive index less than that of the buffer layer in the electro-optically active stack.

7. The silicon based electro-optically active device of claim 6 , wherein the crystalline cladding layer comprises silicon.

8. The silicon based electro-optically active device of claim 6 , wherein the crystalline cladding layer comprises silicon-germanium (SiGe).

9. A method of producing a silicon based electro-optically active device, having the steps of:

providing a silicon-on-insulator (SOI) wafer including a BOX layer above a silicon substrate, and a silicon device layer above the BOX layer;

etching a cavity in a part of the SOI wafer, the cavity extending through the silicon device layer and through the BOX layer;

growing a crystalline cladding layer on the silicon substrate within the cavity;

epitaxially growing an electro-optically active stack on the crystalline cladding layer within the cavity, wherein the electro-optically active stack has a facet in a region adjacent to a sidewall of the cavity;

etching the region to thereby remove the facet and produce a channel between the sidewall and the electro-optically active stack; and

filling the channel with a filling material which has a refractive index which is greater than that of a material forming the sidewall.

10. The method of claim 9 , wherein the electro-optically active stack includes a multiple quantum well region.

11. The method of claim 9 , wherein the filling material that the channel is filled with comprises amorphous silicon.

12. The method of claim 9 , wherein the filling material that the channel is filled with comprises silicon-germanium (SiGe).

13. The method of claim 9 , wherein the step of filling the channel is carried out by plasma-enhanced chemical vapour deposition.

14. The method of claim 9 , further including a step of planarizing the filling material through chemical-mechanical polishing.

15. The method of claim 9 , wherein:

the region is a first region and the facet is a first facet,

the electro-optically active stack has a second facet in a second region adjacent to an opposite sidewall of the cavity,

the etching of the first region also removes the second region to thereby remove the second facet and produce a second channel between the opposite sidewall and the electro-optically active stack, and

the step of filling the channel includes filling the second channel with amorphous silicon.

16. The method of claim 15 , wherein the silicon based electro-optically active device is a quantum-confined Stark effect based electro-absorption modulator.

17. The method of claim 16 , further comprising forming a waveguide in the electro-optically active stack and forming a waveguide in the SOI wafer, wherein the electro-optically active stack includes a buffer layer, and the method includes adjusting a height of the buffer layer such that an optical mode in the waveguide in the electro-optically active stack matches an optical mode in the waveguide in the SOI wafer.

18. The method of claim 9 , wherein the electro-optically active stack is grown such that it has a parallelogramal or trapezoidal geometry.

19. The method of claim 9 , wherein the step of etching a cavity in a part of the SOI wafer includes the step of etching the silicon based electro-optically active device up to or beyond a base of the BOX layer to create a cavity in the BOX layer.

20. The method of claim 19 , wherein:

the electro-optically active stack includes a buffer layer, and

the cladding layer has a refractive index which is less than the refractive index of the buffer layer of the electro-optically active stack.

21. A silicon based electro-optically active device comprising:

a silicon-on-insulator (SOI) waveguide;

an electro-optically active waveguide including an electro-optically active stack, the electro-optically active waveguide being coupled to the SOI waveguide; and

a channel between the electro-optically active waveguide and the SOI waveguide,

wherein the channel is filled with a filling material with a refractive index greater than that of a material of a portion of the SOI waveguide forming a sidewall of the channel to thereby form a bridge-waveguide in the channel between the SOI waveguide and the electro-optically active waveguide, and

a layer of the electro-optically active stack closest to a silicon substrate of the SOI waveguide includes silicon germanium.