Waveguide coupling into photonic crystal waveguides

• US 20040109644A1
• Filed: 06/18/2003
• Published: 06/10/2004
• Est. Priority Date: 06/18/2002
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Assefa, Solomon, Joannopoulos, John D., Johnson, Steven G., Erchak, Alexei A., Kolodziejski, Leslie A., Petrich, Gale S., Bienstman, Peter
• Granted Patent: US 7,072,547 B2
• Time in Patent Office: Days
• US Class Current: 385/39
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 6/12004 Combinations of two or more optical elements
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: G02B 6/1228 Tapered waveguides, e.g. integrated spot-size transformers for coupling with fibres G02B6/305

Abstract

A coupling element includes a first stage having a dielectric waveguide that is transitioned to a waveguide having a sequence of resonators with a fixed period. A second stage transitions the waveguide to a photonic crystal waveguide by gradually bringing closer at an angle the cladding bulk of the photonic crystal to the waveguide.

Claims

1. A coupling element comprising:

a first stage having a dielectric waveguide that is transitioned to a waveguide having a sequence of resonators with a fixed period; and

a second stage that transitions said waveguide to a photonic crystal waveguide by gradually bringing closer at an angle the cladding bulk of said photonic crystal to said waveguide.

2. The coupling element of claim 1, wherein said first stage comprises a smooth transition from a traditional index guiding dielectric waveguide to said waveguide.

3. The coupling element of claim 1, wherein said resonators convert said forward propagating components to a mode that has both forward and backward propagating components.

4. The coupling element of claim 1, wherein said first stage comprises high index material relative to its surrounding.

5. The coupling element of claim 1, wherein said second stage comprises periodic rods that gradually approach the defect of said photonic crystal waveguide.

6. The coupling element of claim 1, wherein said photonic crystal waveguide comprises both a forward and backward propagating component.

7. The coupling element of claim 1, wherein said resonators comprise a coupled cavity waveguide.

14. The method of claim 7, wherein said resonators comprise a coupled cavity waveguide.

30. The coupling element of claim 1, wherein said waveguide is formed using holes.

31. The coupling element of claim 30, wherein said waveguide is formed using holes.

32. The coupling element of claim 1, wherein said photonic crystal waveguide is formed using holes.

8. A method of forming a coupling element comprising:

providing a first stage having a dielectric waveguide that is transitioned to a waveguide having a sequence of resonators with a fixed period; and

providing a second stage that transitions said waveguide to a photonic crystal waveguide by gradually bringing closer at an angle the cladding bulk of said photonic crystal to said waveguide.

9. The method of claim 8, wherein said first stage comprises a smooth transition from a traditional index guiding dielectric waveguide to said waveguide.

10. The method of claim 8, wherein said resonators convert said forward propagating components to a mode that has both forward and backward propagating components.

11. The method of claim 8, wherein said first stage comprises high index material relative to its surrounding.

12. The method of claim 8, wherein said second stage comprises periodic rods that gradually approach the defect of said photonic crystal waveguide.

13. The method of claim 8, wherein said photonic crystal waveguide comprises both a forward and backward propagating component.

34. The method of claim 8, wherein said waveguide is formed using holes.

35. The method of claim 8, wherein said photonic crystal waveguide is formed using holes.

15. A coupling element comprising:

a first stage that transitions a photonic crystal waveguide into a waveguide having a sequence of resonators with a fixed period by gradually diverging away at an angle the cladding bulk of said photonic crystal waveguide from said waveguide; and

a second stage that transitions said waveguide to a dielectric element.

16. The coupling element of claim 15, wherein said second stage comprises a smooth transition from said waveguide to said dielectric waveguide.

17. The coupling element of claim 15, wherein said resonators convert the forward and backward propagating components to a mode that has a forward propagating components.

18. The coupling element of claim 15, wherein said second stage comprises high index material relative to its surrounding.

19. The coupling element of claim 15, wherein said first stage comprises periodic rods that gradually approach the defect of said photonic crystal waveguide.

20. The coupling element of claim 15, wherein said photonic crystal waveguide comprises both a forward and backward propagating component.

36. The coupling element of claim 15, wherein said photonic crystal waveguide is formed using holes.

37. The coupling element of claim 15, wherein said waveguide is formed using holes.

21. The coupling element of claim 21, wherein said resonators comprise a coupled cavity waveguide.

22. A method of forming a coupling element comprising:

providing a first stage that transitions a photonic crystal waveguide into a waveguide by gradually diverging away at an angle the cladding bulk of said photonic crystal waveguide from said waveguide; and

providing a second stage that transitions said waveguide to a dielectric element.

23. The method of claim 22, wherein said second stage comprises a smooth transition from said waveguide to said dielectric waveguide.

24. The method of claim 22, wherein said resonators convert said forward and backward propagating components to a mode that has forward propagating components.

25. The method of claim 22, wherein said second stage comprises high index material relative to its surrounding.

26. The method of claim 22, wherein said first stage comprises periodic rods that gradually approach the defect of said photonic crystal waveguide.

27. The method of claim 22, wherein said resonators comprise a coupled cavity waveguide.

28. The method of claim 22, wherein said photonic crystal waveguide comprises both a forward and backward propagating component.

38. The method of claim 22, wherein said waveguide is formed using holes.

39. The method of claim 22, wherein said photonic crystal waveguide is formed using holes.

29. A coupling element comprising:

an input coupling element comprising a first stage having a first dielectric waveguide that is transitioned to a waveguide having a sequence of resonators with a fixed period and a second stage that transitions said waveguide to a photonic crystal waveguide by gradually bringing closer at an angle the cladding bulk of said photonic crystal waveguide to said waveguide; and

an output coupling element comprising a third stage that transitions said photonic crystal waveguide into said waveguide by gradually diverging away at an angle the cladding bulk of said photonic crystal waveguide from said waveguide and a fourth stage that transitions said waveguide to a second dielectric element.

33. The coupling element of claim 29, wherein said photonic crystal waveguide is formed using holes.