Integrated etched multilayer grating based wavelength demultiplexer

• US 20070086703A1
• Filed: 10/19/2006
• Published: 04/19/2007
• Est. Priority Date: 10/19/2005
• Status: Active Grant

• Current Assignee: McGill University
• Original Assignee: McGill University
• Inventors: Kirk, Andrew, Bisaillon, Eric
• Granted Patent: US 7,447,403 B2
• Time in Patent Office: Days
• US Class Current: 385/37
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02B 6/124 Geodesic lenses or integrated gratings
• CPC Class Codes: G02B 6/29326 Diffractive elements having focusing properties, e.g. curved gratings Rowland circle spectrometers G01J3/20
• CPC Class Codes: G02B 6/29328 Diffractive elements operating in reflection
• CPC Class Codes: G02B 6/2938 for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM

Abstract

An integrated etched multilayer grating-based wavelength multiplexer/demultiplexer is disclosed wherein an etched multilayer grating structure is monolithically integrated within the optical waveguide stack of the multiplexer/demultiplexer to reflectively diffract an input optical beam. The multilayer grating structure is generally comprised of a series of etched diffractive elements and an etched multilayer reflector, the combined optical response of which providing the desired multiplexing/demultiplexing effect. The etched structures are generally comprised of shallow etch structures in a top surface of the multiplexer/demultiplexer waveguide stack. Monolithically integrated input and output ridge waveguides may also be provided, optionally fabricated in a same etching step as the etched multilayer grating.

Claims

1. An optical device for reflectively diffracting optical signals, comprising:

an input port for receiving an optical signal, the optical signal comprising light having wavelengths corresponding to a predetermined set of wavelength channels;

an optical medium, the optical medium comprising at least one of a plurality of waveguide layers and being characterised by a thickness, for guiding the optical signal within the optical device;

a grating structure disposed at a predetermined location within the optical medium, the grating structure comprising at least one of a plurality of diffractive elements and a plurality of multilayer reflector elements;

wherein,

the grating structure reflectively diffracts light in dependence upon a wavelength such that light having a wavelength corresponding to a first wavelength channel is directed to a first target location of the optical medium.

2. An optical device according to claim 1 wherein,

the optical medium comprises a planar waveguide, the planar waveguide providing one-dimensional confinement of the at least an optical signal.

3. An optical device according to claim 1 wherein,

the grating structure is provided by etching predetermined regions of the optical medium.

4. An optical device according to claim 1 wherein,

the grating structure is providing in predetermined regions of the optical medium an additional cladding layer after it'"'"'s formation.

5. An optical device according to claim 1 wherein,

the plurality of diffractive elements comprise

a first shallow structure being at least one of on and within the optical medium, the first shallow structure being characterised by a first depth corresponding to less than the thickness of the optical medium.

6. An optical device according to claim 5 wherein,

the first depth is between 1% and 60% of the thickness of the optical medium.

7. An optical device according to claim 1 wherein,

the plurality of multilayer reflector elements are comprised of a second shallow structure being at least one of on or within the optical medium, the second shallow structure being characterised by a second depth corresponding to less than the thickness of the optical medium.

8. An optical device according to claim 7 wherein,

the second depth is between 1% and 60% of the thickness of the optical medium.

9. An optical device according to claim 1 wherein,

the one of a plurality of diffractive elements and a plurality of multilayer reflector elements are comprised of a third shallow structure being at least one of on or within the optical medium, the third shallow structure being characterised by a third depth corresponding to less than the thickness of the optical medium.

10. An optical device according to claim 9 wherein,

the third depth is between 1%. and 60% of the thickness of the optical medium.

11. An optical device according to claim 1 wherein,

the plurality of waveguide layers are provided on a substrate.

12. An optical device according to claim 11 wherein,

the substrate is at least one of an undoped silicon wafer, a doped silicon wafer, gallium arsenide, indium phosphide, diamond, and fused silica.

13. An optical device according to claim 11 wherein;

at least one of the plurality of waveguide layers is silicon.

14. An optical device according to claim 1 wherein,

the one of a plurality of diffractive elements and a plurality of multilayer reflector elements are provided within the optical medium as a result of a single processing sequence of a manufacturing process.

15. An optical device according to claim 1 wherein,

the plurality of diffractive elements provide a transmissive diffraction grating.

16. An optical device according to claim 1 wherein,

the plurality of multilayer reflector elements provide a mirror.

17. An optical device according to claim 1 wherein,

the plurality of diffractive elements form an echelle grating.

18. An optical device according to claim 1 wherein,

the plurality of diffractive elements form an echelette grating.

19. An optical device according to claim 1 wherein,

the plurality of multilayer reflector elements are integrally disposed within the plurality of diffractive elements.

20. An optical device according to claim 1 wherein,

the plurality of multilayer reflector elements form a Bragg reflector.

21. An optical device according to claim 1 wherein,

the plurality of diffractive elements are disposed in at least one of a first linear and first arcurate pattern.

22. An optical device according to claim 21 wherein,

the first arcurate pattern is determined by at least a first equation.

23. An optical device according to claim 1 wherein,

the plurality of multilayer reflector elements are disposed in at least one of a second linear and second arcurate pattern.

24. An optical device according to claim 22 wherein,

the second arcurate pattern is determined by at least a second equation.

25. An optical device according to claim 1 further comprising:

a plurality of channel waveguides, the plurality of channel waveguides being formed within the optical medium;

wherein

each of the plurality of the channel waveguides is for guiding an optical signal.

26. An optical device according to claim 25 wherein,

the plurality of channel waveguides are for coupling optical signals with the grating structure.

27. An optical device according to claim 25 wherein,

the plurality of channel waveguides further comprise at least one of an optical switch, an optical attenuator, an optical amplifier, a photodetector, a laser diode, and a superluminescent diode.

28. An optical device according to claim 27 wherein,

the optical switch comprises a tunable mirror.

29. An optical device according to claim 27 wherein,

the optical switch selectively directing the optical signal between at least one of a channel waveguide and a second grating structure.

30. An optical device according to claim 29 wherein,

the second grating structure acting so as to multiplex optical signals.

31. An optical device according to claim 1 further comprising:

at least one of a plurality of optical elements, each optical element being at least one of a channel waveguide, an optical switch, an optical attenuator, an optical amplifier, a photodetector, a laser diode, and a superluminescent diode.

32. An optical device according to claim 31 wherein,

an optical element of the plurality of optical elements is for performing a process upon at least one optical signal having a predetermined characteristic wavelength channel of the plurality of optical signals.

33. An optical device according to claim 31 wherein,

an optical element is formed at a predetermined position within the optical device, the predetermined position being one such that a facet of the optical element is approximately positioned at a point along the focal plane of the grating structure.

34. An optical device according to claim 1 wherein;

the optical device functions as at least one of a wavelength multiplexer and a wavelength demultiplexer.

35. A method of directing optical signals comprising:

providing an optical medium, the optical medium comprising at least one of a plurality of waveguide layers and being characterised by a thickness, the optical medium for guiding optical signals;

coupling a plurality of optical signals to the optical medium, each optical signal of the plurality of optical signals having a characteristic wavelength corresponding to one of a plurality of predetermined wavelength channels;

providing a grating structure optically coupled to the optical medium, the grating structure comprising;

a plurality of diffracting elements and at least a multilayer reflective element, such that upon interacting with the grating structure a first optical signal corresponding to a first wavelength channel is directed to a first position of the optical medium and upon interacting with the grating structure a second optical signal corresponding to a second other wavelength channel is directed to a second other position of the optical medium; and

,

diffracting at least one of the plurality of optical signals by reflective diffraction using the grating structure.

36. A method according to claim 35 wherein,

providing the optical medium comprises providing a planar waveguide, the planar waveguide providing one-dimensional confinement of the at least an optical signal.

37. A method according to claim 35 wherein,

providing the grating structure comprises etching predetermined regions of the optical medium.

38. A method according to claim 35 wherein,

providing the grating structure comprises providing an additional cladding layer in predetermined regions of the optical medium.

39. A method according to claim 35 wherein,

providing the plurality of diffractive elements comprising providing a first shallow structure being at least one of on and within the optical medium, the first shallow structure being characterised by a first depth less than the thickness of the optical medium.

40. A method according to claim 39 wherein,

the first depth is between 1% and 60% of the thickness of the optical medium.

41. A method according to claim 35 wherein,

providing the grating structure comprises providing a second shallow structure being at least one of on and within the optical medium, the second shallow structure being characterised by a second depth less than the thickness of the optical medium.

42. A method according to claim 41 wherein,

the second depth is between 1% and 60% of the thickness of the optical medium.

43. A method according to claim 35 wherein,

providing the grating structure comprises providing a third shallow structure being at least one of on or within the optical medium, the third shallow structure being characterised by a third depth less than the thickness of the optical medium.

44. A method according to claim 43 wherein,

the third depth is between 1% and 60% of the thickness of the optical medium.

45. A method according to claim 35 wherein,

providing the plurality of waveguide layers comprises providing the layers on a single substrate.

46. A method according to claim 45 wherein,

the substrate is at least one of an undoped silicon wafer, a doped silicon wafer, gallium arsenide, indium phosphide, diamond, and fused silica.

47. A method according to claim 45 wherein;

at least one of the plurality of waveguide layers is silicon.

48. A method according to claim 35 wherein,

providing the grating structure comprises manufacturing the plurality of diffractive elements and plurality of multilayer reflector elements within the optical medium simultaneously.

49. A method according to claim 35 wherein,

providing the grating structure comprises providing a transmissive diffraction grating.

50. A method according to claim 35 wherein,

providing the grating structure comprises providing a mirror.

51. A method according to claim 35 wherein,

providing the grating structure comprises providing an echelle grating.

52. A method according to claim 35 wherein,

providing the grating structure comprises providing an echelette grating.

53. A method according to claim 35 wherein,

providing the grating structure comprises integrally disposing the plurality of multilayer reflector elements within the plurality of diffractive elements.

54. A method according to claim 35 wherein,

providing the grating structure comprises providing a Bragg reflector.

55. A method according to claim 35 wherein,

providing the grating structure comprises providing the plurality of diffractive elements in at least one of a first linear and first arcurate pattern.

56. A method according to claim 55 wherein,

providing the grating structure comprises providing first locales determined by at least a first equation.

57. A method according to claim 35 wherein,

providing the grating structure comprises providing the plurality of multilayer reflector elements in at least one of a second linear and second arcurate pattern.

58. A method according to claim 56 wherein,

providing the second arcurate pattern comprises providing second locales determined by at least a second equation.

59. A method according to claim 35 comprising:

providing at least one of a plurality of channel waveguides, the plurality of channel waveguides being formed within the optical medium;

wherein

each of the plurality of the channel waveguides is for guiding an optical signal.

60. A method according to claim 59 wherein,

providing the plurality of channel waveguides comprises providing at least one of an optical switch, an optical attenuator, an optical amplifier, a photodetector, a laser diode, and a superluminescent diode.

61. A method according to claim 60 wherein,

providing the optical switch comprises providing a tunable mirror.

62. A method according to claim 60 wherein the optical switch selectively couples at least an optical signal between at least one a channel waveguide and a second grating structure.

63. A method according to claim 62 wherein,

providing the second grating structure results in providing a multiplexer for the optical signals.

64. A method according to claim 35 further comprising,

providing at least one of a plurality of optical elements, wherein providing each optical element comprises providing at least one of a channel waveguide, an optical switch, an optical attenuator, an optical amplifier, a photodetector, a laser diode, and a superluminescent diode.

65. A method according to claim 35 wherein;

providing the optical medium and the grating structure results in providing an optical device functioning as at least one of a wavelength multiplexer and a wavelength demultiplexer.

66. A computer readable medium having stored therein data according to a predetermined computing device format, and upon execution of the data by a suitable computing device a design procedure for providing a design of optical device is provided, comprising:

providing an optical medium, the optical medium comprising at least one of a plurality of waveguide layers and being characterised by a thickness, the optical medium for guiding optical signals;

coupling a plurality of optical signals to the optical medium, each optical signal of the plurality of optical signals having a characteristic wavelength corresponding to one of a plurality of predetermined wavelength channels;

providing a grating structure optically coupled to the optical medium, the grating structure comprising;

a plurality of diffracting elements and at least a multiplayer reflective element, such that upon interacting with the grating structure a first optical signal corresponding to a first wavelength channel is directed to a first position of the optical medium and upon interacting with the grating structure a second optical signal corresponding to a second other wavelength channel is directed to a second other position of the optical medium; and

,

diffracting at least one of the plurality of optical signals by reflective diffraction using the grating structure.

67. A computer readable medium according to claim 66 further comprising,

providing at least one of a plurality of channel waveguides, the plurality of channel waveguides being formed within the optical medium;

wherein

each of the plurality of the channel waveguides is for guiding an optical signal.

68. A computer readable medium according to claim 66 further comprising,

providing at least one of a plurality of optical elements, wherein providing each optical element comprises providing at least one of a channel waveguide, an optical switch, an optical attenuator, an optical amplifier, a photodetector, a laser diode, and a superluminescent diode.