Optical Converter and Method of Manufacturing the Same

• US 20120328243A1
• Filed: 12/23/2009
• Published: 12/27/2012
• Est. Priority Date: 12/23/2009
• Status: Active Grant

• Current Assignee: Advanced Micro Foundry Pte., Ltd.
• Original Assignee: Agency For Science Technology and Research (Government of Singapore)
• Inventors: Fang, Qing, Yu, Mingbin, Lo, Guo Qiang Patrick, Liow, Tsung-Yang
• Granted Patent: US 9,002,163 B2
• Time in Patent Office: Days
• US Class Current: 385/50
• CPC Class Codes: G02B 6/1228 Tapered waveguides, e.g. integrated spot-size transformers for coupling with fibres G02B6/305
• CPC Class Codes: G02B 6/136 by etching
• CPC Class Codes: G02B 6/305 and having an integrated mode-size expanding section, e.g. tapered waveguide

Abstract

An optical converter and a method of manufacturing the optical converter are provided. The optical converter may include a signal receiving portion configured to receive an optical signal from an optical fiber which can be coupled to the optical converter, a signal output portion configured to output the optical signal received by the signal receiving portion, and a signal coupling portion being disposed between the signal receiving portion and the signal output portion and being configured to couple the optical signal received by the signal receiving portion into the signal output portion. The signal output portion may include a waveguide element having at least one tapered end section, and being partially or wholly surrounded by the signal coupling portion. The at least one tapered end section may be configured to couple the optical signal from the signal coupling portion into the waveguide element and the waveguide element may be configured to output the optical signal.

Claims

1. An optical converter, comprising:

a signal receiving portion configured to receive an optical signal from an optical fiber which can be coupled to the optical converter,

a signal output portion configured to output the optical signal received by the signal receiving portion, and

a signal coupling portion being disposed between the signal receiving portion and the signal output portion and being configured to couple the optical signal received by the signal receiving portion into the signal output portion,

wherein the signal output portion comprises a waveguide element having at least one tapered end section, and being partially or wholly surrounded by the signal coupling portion;

wherein the at least one tapered end section is configured to couple the optical signal from the signal coupling portion into the waveguide element and the waveguide element is configured to output the optical signal.

2. The optical converter of claim 1,

further comprising a joining portion disposed between the signal receiving portion and the signal coupling portion, wherein the joining portion is configured to couple the optical signal from the signal receiving portion into the signal coupling portion.

3. The optical converter of any one of claim 1 or 2,

wherein the signal receiving portion and the signal coupling portion have the same cross-sectional size.

4. The optical converter of any one of claim 1 or 2,

wherein the signal receiving portion has a larger cross-sectional size than that of the signal coupling portion.

5. The optical converter of claim 4,

wherein the joining portion tapers from the signal receiving portion towards the signal coupling portion.

6. The optical converter of any one of claims 2 to 5,

wherein the signal receiving portion, the signal coupling portion and the joining portion respectively form a part of a waveguide structure.

7. The optical converter of claim 6,

wherein the waveguide structure comprises silicon dioxide.

8. The optical converter of any one of claims 2 to 7,

wherein the at least one tapered end section is facing the joining portion.

9. The optical converter of any one of claims 1 to 8,

wherein the waveguide element has a first tapered end section and a second tapered end section.

10. The optical converter of claim 9,

wherein the first tapered end section is arranged on the second tapered end section such that a distance between the first tapered end section and the joining portion is larger than the distance between the second tapered end section and the joining portion.

11. The optical converter of claim 9 or 10,

wherein the second tapered end section is in contact with an end of the joining portion which is coupled to the signal coupling portion.

12. The optical converter of claim 9,

wherein the second tapered end section extends into the joining portion.

13. The optical converter of claim 12,

wherein the joining portion is configured to couple the optical signal from the signal receiving portion into the second tapered end section.

14. The optical converter of claim 9,

wherein the first tapered end section is adjacent to and spaced apart from the second tapered end section.

15. The optical converter of claim 14,

wherein a distance between the first tapered end section and the joining portion and a distance between the second tapered end section and the joining portion are the same.

16. The optical converter of any one of claims 1 to 15,

wherein the signal output portion comprises silicon.

17. The optical converter of any one of claims 4 to 16,

further comprising a further joining portion arranged on the joining portion.

18. The optical converter of any one of claims 6 to 17,

wherein the waveguide structure is arranged such that the waveguide structure is suspended above a substrate or a wafer.

19. The optical converter of any one of claims 6 to 18,

wherein the waveguide structure is disposed between two layers, wherein the material of the waveguide structure and the material of the two layers are the same.

20. The optical converter of claim 19,

wherein the material of the two layers comprises silicon dioxide.

21. The optical converter of claim 19 or 20,

further comprising a plurality of support beams disposed between the waveguide structure and the two respective layers, wherein the plurality of support beams are configured to couple the waveguide structure to the two layers, and wherein the material of the support beams is the same as that of the waveguide structure and the two layers.

22. The optical converter of claim 21,

wherein the waveguide structure, the two layers and the plurality of support beams are parts of a planar layer having a constant thickness.

23. A method of forming an optical converter according to any one of the claims 1 to 22, the method comprising:

forming a signal output portion; and

forming a waveguide structure which at least partially surrounds the signal output portion.

24. The method of claim 23,

wherein forming the signal output portion comprises:

forming a first layer of silicon dioxide above a silicon wafer layer;

forming a layer of silicon above the first layer of silicon dioxide;

forming a second layer of silicon dioxide above the layer of silicon.

25. The method of claim 24,

wherein the first layer of silicon dioxide forms a layer of buried oxide.

26. The method of claim 24 or 25,

wherein the second layer of silicon dioxide is formed by plasma-enhanced chemical vapour deposition.

27. The method of any one of claims 24 to 26,

wherein forming the signal output portion further comprises:

forming a first etching mask above the second layer of silicon dioxide;

etching the second layer of silicon dioxide; and

partially etching the layer of silicon to form a first tapered end section.

28. The method of claim 27,

wherein the second layer of silicon dioxide is etched by carbon tetraflouride.

29. The method of claim 27 or 28,

wherein the layer of silicon is partially etched by chlorine.

30. The method of any one of claims 27 to 29,

wherein forming the signal output portion further comprises:

covering the first etching mask, the etched second layer of silicon dioxide, the partially etched layer of silicon with a second etching mask; and

etching the remaining layer of silicon to form a second tapered end section and a waveguide element of the signal output portion.

31. The method of claim 30,

wherein the second etching mask comprises photoresist.

32. The method of claim 30 or 31,

wherein the remaining layer of silicon is etched by chlorine.

33. The method of any one of claims 30 to 32,

wherein forming the waveguide structure comprises:

removing the second etching mask;

removing the first etching mask;

forming a third layer of silicon dioxide layer above the first layer of silicon dioxide layer to cover the waveguide element having the first tapered end section and the second tapered end section.

34. The method of claim 33,

wherein the third layer of silicon dioxide is formed by plasma-enhanced chemical vapour deposition.

35. The method of claim 33 or 34,

wherein forming the waveguide structure further comprises:

forming a third etching mask above the third layer of silicon dioxide;

etching a trench structure into the silicon wafer layer, the first layer of silicon dioxide and the third layer of silicon dioxide such that the trench structure at least partially surrounds the waveguide structure, and that the waveguide structure at least partially surrounds the waveguide element.

36. The method of claim 35,

wherein the third etching mask used for etching the silicon wafer layer, the first layer of silicon dioxide and the third layer of silicon dioxide is structured such that a plurality of support beams of silicon dioxide remains between the waveguide structure and the remaining parts of the first layer of silicon dioxide and the third layer of silicon dioxide.

37. The method of claim 35 or 36,

wherein the first layer of silicon dioxide and the third layer of silicon dioxide are etched by octofluorocyclobutane.

38. The method of any one of claims 35 to 37,

wherein the trench structure is etched such that the waveguide structure is suspended above the silicon wafer layer.

39. The method of any one of claims 35 to 38,

wherein the silicon wafer layer is etched by any one of a group consisting of sulphur hexafluoride, potassium hydroxide and tetramethylammonium hydroxide.