Optical coupler having evanescent coupling region

• US 6,944,369 B2
• Filed: 02/12/2002
• Issued: 09/13/2005
• Est. Priority Date: 05/17/2001
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Sioptical Inc. (Cisco Systems, Inc.)
• Inventors: Deliwala, Shrenik
• Primary Examiner(s): ULLAH, AKM E
• Application Number:
  US10/074,408
• Publication Number:
  US 20030039439A1
• Time in Patent Office: 1,309 Days
• Field of Search: 385 12- 24, 385/147, 385 30- 39, 438/458, 438/459, 110/407
• US Class Current: 385/30
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 2006/12038 Glass (SiO2 based materials)
• CPC Class Codes: G02B 2006/12061 Silicon
• CPC Class Codes: G02B 2006/12097 Ridge, rib or the like
• CPC Class Codes: G02B 2006/12104 Mirror; Reflectors or the like
• CPC Class Codes: G02B 2006/12107 Grating
• CPC Class Codes: G02B 2006/12114 Prism
• CPC Class Codes: G02B 2006/12135 Temperature control
• CPC Class Codes: G02B 2006/12161 Distributed feedback [DFB]
• CPC Class Codes: G02B 2006/12164 Multiplexing; Demultiplexing
• CPC Class Codes: G02B 2006/12176 Etching
• CPC Class Codes: G02B 27/285 comprising arrays of elements, e.g. microprisms
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 6/10 of the optical waveguide type G02B6/02, G02B6/24 take precedence; devices or arrangements for the control of light by electric, magnetic, electro-magnetic or acoustic means G02F1/00; transferring the modulation of modulated light G02F2/00; optical logic elements G02F3/00; optical analogue/digital converters G02F7/00
• CPC Class Codes: G02B 6/12004 Combinations of two or more optical elements
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02B 6/12011 characterised by the arrayed waveguides, e.g. comprising a filled groove in the array section
• CPC Class Codes: G02B 6/12026 characterised by means for reducing the temperature dependence
• CPC Class Codes: G02B 6/12033 characterised by means for configuring the device, e.g. moveable element for wavelength tuning switching G02B6/35; thermo-optic devices G02F1/0147
• 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
• CPC Class Codes: G02B 6/124 : Geodesic lenses or integrated gratings
• CPC Class Codes: G02B 6/2861 : using fibre optic delay lines and optical elements associated with them, e.g. for use in signal processing, e.g. filtering delay lines in general H03H, H01P9/00; optical computing devices G06E
• CPC Class Codes: G02B 6/29349 : Michelson or Michelson/Gires-Tournois configuration, i.e. based on splitting and interferometrically combining relatively delayed signals at a single beamsplitter
• CPC Class Codes: G02B 6/29358 : Multiple beam interferometer external to a light guide, e.g. Fabry-Pérot, etalon, VIPA plate, OTDL plate, continuous interferometer, parallel plate resonator G02B6/29347, G02B6/29349, G02B6/2935, G02B6/29361 take precedence; resonator evanescently coupled to light guide G02B6/29335
• CPC Class Codes: G02B 6/34 : utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: G02B 6/4215 : the intermediate optical elements being wavelength selective optical elements, e.g. variable wavelength optical modules or wavelength lockers G02B6/4246 takes precedence
• CPC Class Codes: G02B 6/4232 : using the surface tension of fluid solder to align the elements, e.g. solder bump techniques flip-chip mounting techniques in assembly of semiconductor devices H01L24/81
• CPC Class Codes: G02B 6/43 : Arrangements comprising a plurality of opto-electronic elements and associated optical interconnections
• CPC Class Codes: G02F 1/0147 : based on thermo-optic effects G02F1/132 takes precedence
• CPC Class Codes: G02F 1/0152 : using free carrier effects, e.g. plasma effect
• CPC Class Codes: G02F 1/025 : in an optical waveguide structure G02F1/017, G02F1/2257 take precedence
• CPC Class Codes: G02F 1/295 : Analog deflection from or in an optical waveguide structure]
• CPC Class Codes: G02F 2201/20 : delay line
• CPC Class Codes: H01L 27/1203 : the substrate comprising an insulating body on a semiconductor body, e.g. SOI three-dimensional layout H01L27/0688

Abstract

A method for forming a hybrid active electronic and optical circuit using a lithography mask. The hybrid active electronic and optical circuit comprising an active electronic device and at least one optical device on a Silicon-On-Insulator (SOI) wafer. The SOI wafer including an insulator layer and an upper silicon layer. The upper silicon layer including at least one component of the active electronic device and at least one component of the optical device. The method comprising projecting the lithography mask onto the SOI waver in order to simultaneously pattern the component of the active electronic device and the component of the optical device on the SOI wafer.

Claims

1. An apparatus for coupling light into/from a hybrid active electronic and optical circuit disposed at least in part in a Silicon-On-Insulator (SOI) wafer, the SOI wafer including an insulator layer and an upper silicon layer which includes a slab dielectric waveguide, the hybrid active electronic and optical circuit including an active electronic device and at least one optical device each of which is disposed at least in part in the upper silicon layer, the apparatus for coupling light comprising:

an evanescent coupling region formed at least in part from a gap portion that couples an input/output light coupler using evanescent coupling to the slab dielectric waveguide;

wherein the input/output light coupler is disposed proximate to an outer surface of the wafer; and

wherein actuation of the electronic device varies a property of the at least one optical device which in turn varies an optical property of the slab dielectric waveguide.

2. The apparatus of claim 1, wherein the evanescent coupling region includes a tapered gap portion.

3. The apparatus of claim 2, wherein the tapered gap portion enhances coupling efficiency.

4. The apparatus of claim 1, wherein the evanescent coupling region includes a substantially constant thickness gap portion.

5. The apparatus of claim 1, wherein the evanescent coupling region is at least partially formed using an optically clear adhesive.

6. The apparatus of claim 5, wherein the optically clear adhesive secures the input/output light coupler to the evanescent coupling region.

7. The apparatus of claim 1, wherein the evanescent coupling region is at least partially formed including air.

8. The apparatus of claim 1, wherein a refractive index of an upper cladding of the slab dielectric waveguide is the same as that of the gap portion of the evanescent coupling region.

9. The apparatus of claim 8, wherein the evanescent coupling region and the cladding portion are at least partially formed of a glass.

10. The apparatus of claim 8, wherein the evanescent coupling region and the cladding portion are at least partially formed of a polyamide.

11. The apparatus of claim 8, wherein the evanescent coupling region and the cladding portion are at least partially formed of an electric insulator.

12. The apparatus of claim 11, wherein the electric insulator is also used to partially define active electronics in the hybrid active electronic and optical circuit.

13. The apparatus of claim 1, wherein altering an electric voltage applied to the active electronic device affects a free carrier distribution in a region of the at least one optical device, and thereby changes an effective mode index of the at least one optical device.

14. The apparatus of claim 13, wherein the at least one optical device is positioned at least in part in the dielectric slab waveguide.

15. The apparatus of claim 1, wherein the evanescent coupling region is at least partially formed from an optically clean polymer.

16. The apparatus of claim 1, wherein the evanescent coupling region has a thickness of less than 0.5μ

.

17. The apparatus of claim 2, wherein the tapered gap portion supports a first edge of the input/output light coupler at a height that is less than 100 microns above a second edge of the input/output coupler.

18. The apparatus of claim 17, wherein the second edge is in contact with the slab dielectric waveguide, and the first edge is out of contact with the slab dielectric waveguide.

19. The apparatus of claim 17, wherein both the first edge and the second edge are in contact with the slab dielectric waveguide.

20. The apparatus of claim 2, further comprising a ledge that supports the input/output light coupler above the tapered gap portion.

21. The apparatus of claim 20, wherein the ledge has a height that is less than 40 microns.

22. The apparatus of claim 21, wherein the ledge has a height of less than 3 microns.

23. The apparatus of claim 1, wherein the input/output light coupler includes a waveguide prism.

24. The apparatus of claim 2, wherein the input/output light coupler includes a waveguide prism.

25. The apparatus of claim 4, wherein the input/output light coupler includes a waveguide prism.

26. The apparatus of claim 25, wherein the at least one optical device is positioned at least in part in the dielectric slab waveguide, the input/output light coupler includes a base, and the base is positioned to be substantially parallel to an axis of the dielectric slab waveguide.

27. The apparatus of claim 26, wherein the hybrid circuit includes an on-chip electronics portion positioned in the dielectric slab waveguide.

28. The apparatus of claim 1, wherein the input/output light coupler includes a waveguide grating.

29. The apparatus of claim 2, wherein the input/output light coupler includes a waveguide grating.

30. The apparatus of claim 4, wherein the input/output light coupler includes a waveguide grating.

31. The apparatus of claim 30, wherein the at least one optical device is positioned at least in part in the dielectric slab waveguide, the input/output light coupler includes a base, and the base is positioned to be substantially parallel to an axis of the dielectric slab waveguide.

32. The apparatus of claim 1, wherein the input/output light coupler is at least partially formed on the wafer and disposed above the active electronic device and the at least one optical device.

33. The apparatus of claim 1, wherein the hybrid active electronic and optical circuit includes one from the group of a focusing mirror, a Fabry-Perot cavity, and a wavelength division multiplexer modulator.

34. The apparatus of claim 1, wherein the hybrid active electronic and optical circuit includes an evanescent coupler.

35. The apparatus of claim 1, wherein the hybrid active electronic and optical circuit includes a diode.

36. The apparatus of claim 1, wherein the hybrid active electronic and optical circuit includes a transistor.

37. The apparatus of claim 1, wherein the hybrid active electronic and optical circuit includes one from the group of a p-n device, a field plated device, a Schottky device, a MOSCAP, and a MOSFET.

63. The assembly of claim 29, wherein the assembly includes an on-chip electronics portion positioned at a height that is substantially the same as a height of the base.

64. The assembly of claim 29, wherein the input/output light coupler includes a waveguide grating.

65. The assembly of claim 30, wherein the input/output light coupler includes a waveguide grating.

66. The assembly of claim 29, wherein the at least one optical device includes one from the group of a p-n device, a field plated device, a Schottky device, a MOSCAP, and a MOSFET.

69. The assembly of claim 29, wherein the input/output light coupler is at least partially formed from the wafer and disposed above an active electronic device and the at least one optical device.

38. An apparatus for coupling light into/from a hybrid active electronic and optical circuit, the hybrid active electronic and optical circuit formed at least in part in a Silicon-On-Insulator (SOI) wafer, the SOI wafer including an insulator layer and an upper silicon layer, the hybrid active electronic and optical circuit including an active electronic device and at least one optical device each of which is disposed at least in part in the upper silicon layer, the apparatus for coupling light comprising:

an input/output light coupler disposed proximate to an outer surface of the wafer and associated with the at least one optical device; and

a tapered evanescent coupling region formed at least in part from a gap portion that couples the input/output light coupler to the at least one optical device using evanescent coupling.

39. The apparatus of claim 38, wherein if the input/output light coupler is in an output light coupler configuration, then some of a substantially uniform concentration of light traversing the optical device will exit the input/output light coupler having a substantially Guassian configuration.

40. An assembly that couples light out of a hybrid active electronic and optical circuit disposed at least in part in a Silicon-On-Insulator (SOI) wafer having an upper silicon layer and a lower insulating layer, the apparatus comprising:

a device portion including at least one optical device formed at least in part on the upper silicon layer;

a light coupling portion producing a substantially Gaussian beam, thereby enhancing coupling efficiency to an external input or output light source; and

an evanescent coupling region that optically couples the light coupling portion to a waveguide disposed at least in part in the upper silicon layer, wherein an intensity of the light in the waveguide, in cross section, is substantially uniform; and

wherein the intensity of the light, in cross section, follows a substantially Gaussian curve as it exits said light coupling portion.

41. The assembly of claim 40, wherein the evanescent coupling region includes a tapered gap portion.

42. The assembly of claim 40, wherein the tapered gap portion enhances coupling efficiency.

43. The assembly of claim 42, wherein the evanescent coupling region is at least partially formed using an optically clear adhesive.

44. The assembly of claim 43, wherein the optically clear adhesive secures the input/output light coupler to the evanescent coupling region.

45. The assembly of claim 40, wherein the upper silicon layer of the SOI wafer includes a flip chip layer that includes the light coupling portion.

46. The assembly of claim 40, wherein the waveguide has an upper cladding, and the evanescent coupling region and the cladding are formed of the same material.

47. The assembly of claim 46, wherein the evanescent coupling region and the cladding portion are formed at least in part from glass.

48. The assembly of claim 46, wherein the evanescent coupling region and the cladding portion are formed at least in part from a polyamide.

49. The assembly of claim 46, wherein the evanescent coupling region and the cladding portion are formed at least in part from an electric insulator.

50. The assembly of claim 46, wherein an electric insulator is used to define, at least in part, active electronics in the hybrid circuit.

51. The assembly of claim 50, wherein altering an electric voltage applied to the active electronics affects a free carrier distribution in a region of the at least one optical device, and thereby changes an effective mode index of the optical device.

52. The assembly of claim 40, wherein the evanescent coupling region is at least partially formed from an optically clean polymer.

53. The assembly of claim 40, wherein the evanescent coupling region has a thickness of less than 0.5μ

.

54. The assembly of claim 41, wherein the tapered gap supports a first edge of the input/output light coupler at a height that is less than 100 microns above a second edge of the input/output coupler.

55. The assembly of claim 54, wherein the second edge is in contact with the waveguide, and the first edge is out of contact with the waveguide.

56. The assembly of claim 54, wherein both the first edge and the second edge are in contact with the waveguide.

57. The assembly of claim 41, further comprising a ledge that supports the input/output light coupler above the tapered gap portion.

58. The assembly of claim 57, wherein the ledge has a height that is less than 50 microns.

59. The assembly of claim 58, wherein the ledge has a height of less than 3 microns.

60. The assembly of claim 40, wherein the input/output light coupler includes a waveguide prism.

61. The assembly of claim 41, wherein the input/output light coupler includes a waveguide prism.

62. The assembly of claim 50, wherein the at least one optical device includes a waveguide, the input/output light coupler includes a base, and the base is positioned to be substantially parallel to an axis of the waveguide.

67. The assembly of claim 55, wherein the at least one optical device is positioned at least in part in the waveguide, the input/output light coupler includes a base, and the base is positioned to be substantially parallel to an axis of the waveguide.

68. The assembly of claim 56, wherein the hybrid circuit includes an on-chip electronics portion.

71. The assembly of claim 59, wherein the evanescent coupling region includes a tapered gap portion.

70. An assembly that couples light into a hybrid active electronic and optical circuit disposed at least in part in a Silicon-On-Insulator (SOI) wafer having an upper silicon layer and a lower insulating layer, the apparatus comprising:

a device portion including at least one optical device formed at least in part on the upper silicon layer;

a light coupling portion etched in the upper silicon layer, and

an evanescent coupling region that optically couples the light coupling portion to a waveguide disposed at least in part in the upper silicon layer, wherein the intensity of the light, in cross section, follows a substantially Gaussian curve as it enters said light coupling portion, and wherein an intensity of the light in the waveguide, in cross section, has a substantially uniform intensity.