Optoelectronic integrated circuits and method of fabricating and reducing losses using same

• US 5,526,449 A
• Filed: 07/14/1994
• Issued: 06/11/1996
• Est. Priority Date: 01/08/1993
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Meade, Robert, Alerhand, Oscar L., Joannopoulos, John
• Primary Examiner(s): Healy, Brian
• Application Number:
  US08/280,105
• Time in Patent Office: 698 Days
• Field of Search: 385/14, 385/129, 385/130, 385/131, 385/132, 385/1, 385/2, 385/24, 385/32, 385/43, 437/15, 437/16, 437/20, 437/21, 437/51
• US Class Current: 385/14
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 6/00 Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
• 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 6/125 Bends, branchings or intersections
• CPC Class Codes: H01P 1/2005 Electromagnetic photonic bandgaps [EPB], or photonic bandgaps [PBG]
• CPC Class Codes: H01S 5/11 Comprising a photonic bandgap structure

Abstract

An optical circuit and a method for substantially eliminating radiation losses associated with optical integrated circuits and, in particular, bends in optical waveguides, is disclosed. The circuit and waveguide are fabricated on a substrate having a periodic dielectric structure. The periodic dielectric structure exhibits a range of frequencies of electromagnetic radiation which cannot propagate into the structure. The range of frequencies is known as a photonic band gap or frequency band gap. Radiation at a frequency within the frequency band gap of the structure is confined within the circuit and waveguide by the periodic dielectric structure surrounding the circuit and waveguide. Radiation losses are substantially eliminated.

Claims

1. A method of reducing radiation losses in optical integrated circuits, comprising:

providing a substrate;

forming the optical integrated circuit on or in the substrate; and

forming a region of said substrate with a periodic dielectric lattice structure having a spatially periodic variation in dielectric constant in at least two dimensions in which the lattice dimensions are proportioned to produce a frequency band gap defining a band of frequencies of electromagnetic radiation at which the optical integrated circuit is operable such that radiation at such frequencies is substantially prevented from propagating in at least one dimension within the region.

2. The method of claim 1 wherein the periodic dielectric lattice structure is formed at least partially within the optical integrated circuit.

3. The method of claim 1 wherein the step of forming the optical integrated circuit comprises forming a laser.

4. The method of claim 1 wherein the step of forming the optical integrated circuit comprises forming a detector.

5. The method of claim 1 wherein the step of forming the optical integrated circuit comprises forming a filter.

6. The method of claim 1 wherein the step of forming the optical integrated circuit comprises forming a modulator.

7. The method of claim 1 wherein the step of forming the optical integrated circuit comprises forming a power divider.

8. The method of claim 1 wherein the step of forming the optical integrated circuit comprises forming a power combiner.

9. The method of claim 1 wherein the step of forming the optical integrated circuit comprises forming a switch.

10. The method of claim 1 wherein the periodic dielectric lattice structure is formed periodic in two dimensions.

11. The method of claim 1 wherein the periodic dielectric lattice structure is formed periodic in three dimensions.

12. The method of claim 1 wherein the step of providing a substrate comprises providing a semiconductor material.

13. The method of claim 1 wherein the step of forming a region comprises forming a periodic pattern of void regions in the substrate.

49. The method of claim 1 wherein the region with the periodic dielectric lattice structure is formed proximate to the optical integrated circuit.

50. The method of claim 1 wherein the region with the periodic dielectric lattice structure is formed within the optical integrated circuit.

53. The method of claim 1 wherein the step of forming a region comprises forming a periodic pattern of holes in the substrate to form a periodic pattern of elements of a dielectric constant different from the dielectric constant of the substrate.

54. The method of claim 53 wherein the periodic pattern of elements formed is periodic in two dimensions.

55. The method of claim 53 wherein the periodic pattern of elements formed is periodic in three dimensions.

56. The method of claim 53 wherein the step of forming a periodic pattern of holes comprises drilling.

57. The method of claim 53 wherein the step of forming a periodic pattern of holes comprises reactive ion etching.

14. A method of reducing radiation losses associated with optical waveguides, comprising:

providing a substrate;

forming an optical waveguide on or in the substrate; and

forming a region of said substrate with a periodic dielectric lattice structure having a spatially periodic variation in dielectric constant in at least two dimensions in which the lattice dimensions are proportioned to produce a frequency band gap defining a band of frequencies of electromagnetic radiation at which the optical waveguide is operable such that radiation at such frequencies is substantially prevented from propagating in at least one dimension within the region, said region being proximate to said waveguide.

15. The method of claim 14 wherein the waveguide is formed with a bend.

16. The method of claim 14 wherein the waveguide is formed with a taper.

17. The method of claim 14 wherein the periodic dielectric lattice structure is formed periodic in two dimensions.

18. The method of claim 14 wherein the periodic dielectric lattice structure is formed periodic in three dimensions.

19. The method of claim 14 wherein the step of providing a substrate comprises providing a semiconductor material.

20. The method of claim 14 wherein the step of forming a region comprises forming a periodic pattern of void regions in the substrate.

21. The method of claim 14 wherein the step of forming an optical waveguide comprises preventing the region with the periodic dielectric lattice structure from being formed in a specific portion of the substrate, said specific portion of the substrate being the optical waveguide.

22. The method of claim 14 wherein the step of forming an optical waveguide comprises diffusing a material into the substrate, said material having an index of refraction higher than the index of refraction of the substrate.

23. The method of claim 14 wherein the step of forming an optical waveguide comprises depositing a material onto a surface of the substrate, said material having a higher index of refraction than the index of refraction of the substrate.

24. The method of claim 14 wherein the step of forming an optical waveguide comprises forming two substantially parallel trenches in a surface of the substrate, said trenches defining a channel of material between them, said channel of material being the optical waveguide.

58. The method of claim 14 wherein the step of forming a region comprises forming a periodic pattern of holes in the substrate to form a periodic pattern of elements of a dielectric constant different from the dielectric constant of the substrate.

59. The method of claim 58 wherein the periodic pattern of elements formed is periodic in two dimensions.

60. The method of claim 58 wherein the periodic pattern of elements formed is periodic in three dimensions.

61. The method of claim 58 wherein the step of forming a periodic pattern of holes comprises drilling.

62. The method of claim 58 wherein the step of forming a periodic pattern of holes comprises reactive ion etching.

25. An optical circuit, comprising:

a substrate having a region with a periodic dielectric lattice structure having a spatially periodic variation in dielectric constant in at least two dimensions in which the lattice dimensions are proportioned to produce a frequency band gap defining a band of frequencies of electromagnetic radiation at which the optical circuit is operable such that radiation at such frequencies is substantially prevented from propagating in at least one dimension within the region; and

at least one optical device formed on or in the substrate proximate to the region with the periodic dielectric lattice structure, such that radiation from the optical device having a frequency within the frequency band gap is substantially prevented from propagating within the substrate.

26. The optical circuit of claim 25 wherein the periodic dielectric lattice structure is formed at least partially within the optical device.

27. The optical circuit of claim 25 wherein the optical device is a laser.

28. The optical circuit of claim 25 wherein the optical device is a detector.

29. The optical circuit of claim 25 wherein the optical device is a filter.

30. The optical circuit of claim 25 wherein the optical device is a modulator.

31. The optical circuit of claim 25 wherein the optical device is a power divider.

32. The optical circuit of claim 25 wherein the optical device is a power combiner.

33. The optical circuit of claim 25 wherein the optical device is a switch.

34. The optical circuit of claim 25 wherein the periodic dielectric lattice structure is periodic in two dimensions.

35. The optical circuit of claim 25 wherein the periodic dielectric lattice structure is periodic in three dimensions.

36. The optical circuit of claim 25 wherein the substrate comprises a semiconductor material.

37. The optical circuit of claim 25 wherein the region with the frequency band gap comprises a periodic pattern of void regions in the substrate.

51. The optical circuit of claim 25 wherein the region with the periodic dielectric lattice structure is proximate to the optical device.

52. The optical circuit of claim 25 wherein the region with the periodic dielectric lattice structure is within the optical device.

38. An optical circuit, comprising:

a substrate having a region with a periodic dielectric lattice structure having a spatially periodic variation in dielectric constant in at least two dimensions in which the lattice dimensions are proportioned to produce a frequency band gap defining a band of frequencies of electromagnetic radiation at which the optical circuit is operable such that radiation at such frequencies is substantially prevented from propagating in at least one dimension within the region; and

at least one optical waveguide formed on or in the substrate proximate to the region with the periodic dielectric lattice structure, such that radiation in the waveguide at a frequency within the frequency band gap is substantially prevented from propagating into the substrate.

39. The optical circuit of claim 38 wherein the optical waveguide comprises a bend.

40. The optical circuit of claim 38 wherein the optical waveguide comprises a taper.

41. The optical circuit of claim 38 wherein the periodic dielectric lattice structure is periodic in two dimensions.

42. The optical circuit of claim 38 wherein the periodic dielectric lattice structure is periodic in three dimensions.

43. The optical circuit of claim 38 wherein the substrate comprises a semiconductor material.

44. The optical circuit of claim 38 wherein the region with the frequency band gap comprises a periodic pattern of void regions in the substrate.

45. The optical circuit of claim 38 wherein the optical waveguide is a channel in the substrate surrounded by the periodic dielectric lattice structure.

46. The optical circuit of claim 38 wherein the optical waveguide is a channel of material diffused into the substrate, said material having an index of refraction which is higher than the index of refraction of the substrate.

47. The optical circuit of claim 38 wherein the optical waveguide is a channel of material deposited on a surface of the substrate, said material having an index of refraction which is higher than the index of refraction of the substrate.

48. The optical circuit of claim 38 wherein the optical waveguide is a channel of material between two substantially parallel trenches in a surface of the substrate.