Switchable optical components

• US 6,567,573 B1
• Filed: 08/13/1998
• Issued: 05/20/2003
• Est. Priority Date: 02/12/1997
• Status: Expired due to Fees

• Current Assignee: Hoya Corporation
• Original Assignee: DigiLens Inc
• Inventors: Little, Brent, Domash, Lawrence H.
• Primary Examiner(s): Sanghavi, Hemang
• Application Number:
  US09/133,524
• Time in Patent Office: 1,741 Days
• Field of Search: 385/16-23, 385/8-10, 385/37, 385/31, 385/40, 359/251, 359/252, 359/224, 359/203, 359/225, 359/291, 359/295, 359/573, 359/117, 359/130, 349/86, 349/92, 349/201, 349/202, 349/117, 349/141, 349/146
• US Class Current: 385/16
• CPC Class Codes: G02B 2006/12107 Grating
• CPC Class Codes: G02B 2006/12145 Switch
• CPC Class Codes: G02B 2006/12147 Coupler
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02B 6/2826 using mechanical machining means for shaping of the couplers, e.g. grinding or polishing grinding, polishing in general B24
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: G02F 1/011 in optical waveguides, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/13342 Holographic polymer dispersed liquid crystals
• CPC Class Codes: G02F 1/313 in an optical waveguide structure
• CPC Class Codes: G02F 2201/30 grating

Abstract

This invention relates to a number of components, devices and networks involving integrated optics and/or half coupler technology, all of which involve the use of electronically switchable Bragg grating devices and device geometries realized using holographic polymer/dispersed liquid crystal materials. Most of the components and devices are particularly adapted for use in wavelength division multiplexing (WDM) systems and in particular for use in switchable add/drop filtering (SADF) and wavelength selective crossconnect. Attenuators, outcouplers and a variety of other devices are also provided.

Claims

1. A component for selectively reconfiguring an optical signal on a guided wave optical path including:

at least one ESBG in optical contact with said path; and

electrodes for selectively applying at least a first and a second voltage across each said ESBG, there being no change in the optical signal for said path when said first voltage is across a said ESBG and there being a selected change in the optical signal on said path when said second voltage is across the ESBG.

2. A component as claimed in claim 1 wherein said optical signal is a multichannel WDM signal, and wherein a selected channel is dropped from said path when said second voltage is across the ESBG.

3. A component as claimed in claim 2 wherein said channel is dropped by being retroreflected back through said path.

4. A component as claimed in claim 3 wherein said channel is outcoupled from said path.

5. A component as claimed in claim 1 wherein said optical signal is a multichannel WDM signal, and including a second guided wave optical path optically coupled to a said ESBG, at least one selected channel being transferred between said paths when said second voltage is across said ESBG.

6. A component as claimed in claim 5 wherein a channel is dropped from said optical path by being transferred to said second optical path when said second voltage is across said ESBG.

7. A component as claimed in claim 5 wherein a channel is added to said path by being transferred to said path from said second path when said second voltage is across said ESBG.

8. A component as claimed in claim 5 wherein signals having WDM channels appear on both paths, and wherein a selected channel is transferred from one path to the other when a second voltage is across said ESBG.

9. A component as claimed in claim 5 wherein there are a plurality of ESBGs optically coupled to both paths, and wherein a different channel is transferred between paths by each ESBG when said second voltage is thereacross.

10. A component as claimed in claim 5 wherein there is an ESBG in optical contact with each of said paths, and including at least one optical path interconnecting said ESBGs.

11. A component as claimed in claim 10 wherein there are two optical paths interconnecting said ESBGs to form a ring.

12. A component as claimed in claim 11 wherein there is one of said rings between said paths for each channel to be transferred therebetween.

13. A component as claimed in claim 11 wherein the said optical path and second optical path have a first effective index, and wherein the optical paths for said ring have a second effective index different than first effective index.

14. A component as claimed in claim 13 wherein the optical paths for said ring are of a different size than the said optical path and second optical path.

15. A component as claimed in claim 5 wherein there are a plurality of ESBGs optically coupled to both paths, and wherein a different channel is transferred between paths by each ESBG when said second voltage is thereacross.

16. A component as claimed in claim 5 wherein said optical paths have different indexes.

17. A component as claimed in claim 16 wherein said optical paths are of different size.

18. A component as claimed in claim 16 wherein said ESBG has a grating with an index contrast Δ

n, and wherein the difference in the effective index of the optical paths is ≧

Δ

n.

19. A component as claimed in claim 5 wherein said component is part of an integrated optics device.

20. A component as claimed in claim 19 wherein said optical paths have different indexes, and wherein said ESBG has a grating with an index contrast Δ

n, and wherein the difference in the effective index of the optical paths is ≧

Δ

n.

21. A component as claimed in claim 5 wherein said component is part of a coupler half device.

22. A component as claimed in claim 21 wherein said component is a switchable drop filter.

23. A component as claimed in claim 21 wherein said component is a switchable outcoupler.

24. A component as claimed in claim 21 wherein said component is an attenuator.

25. A component as claimed in claim 24 wherein said ESBG has a submicron grating.

26. A component as claimed in claim 5 wherein said ESBG is a resonator.

27. A component as claimed in claim 26 wherein said component is a channel drop filter, and including a first drop resonator and a second reflector resonator spaced from each other in the direction of travel of said optical signal on a said optical path by an integer number of wavelengths of a wavelength to be dropped plus a half wavelength.

28. A component as claimed in claim 27 wherein each resonator is a multipole resonator formed of resonator sections which are one of series coupled and parallel coupled.

29. A component as claimed in claim 26 wherein said component is a guide channel dropping filter, said ESBG being a resonator between the optical paths.

30. A component as claimed in claim 29 wherein said resonator is a split resonator having a phase delay section between split resonator sections.

31. A component as claimed in claim 5 wherein each said optical path has a core surrounded by cladding, and wherein said ESBG is in the cladding for both said optical paths.

32. A component as claimed in claim 31 wherein the cladding for said optical paths overlap, and wherein said ESBG is in the overlap of said cladding.

33. A component as claimed in claim 31 wherein said ESBG extends over both said optical paths.

34. A component as claimed in claim 5 wherein sidelobes are suppressed by apodization.

35. An integrated optics component for selectively reconfiguring an optical signal including:

a substrate;

at least one optical waveguide formed in said substrate, each said waveguide having a core with cladding therearound;

an ESBG in one of said core and said cladding for said waveguide; and

electrodes for selectively applying at least a first and a second voltage across said ESBG, there being no change in the optical signal when applied to the said waveguide if said first voltage is across the ESBG and there being a selected change in the optical signal if said second signal is across the ESBG.

36. A component as claimed in claim 35 wherein said optical signal is a multichannel WDM signal, and wherein a selected channel is dropped from said waveguide when said second voltage is across the ESBG.

37. A component as claimed in claim 35 wherein said optical signal is a multichannel WDM signal, and including a second guided wave optical waveguide optically coupled to a said ESBG, at least one selected channel being transferred between said waveguides when said second voltage is across said ESBG.

38. A component as claimed in claim 37 wherein a channel is dropped from said optical waveguide by being transferred to said second optical waveguide when said second voltage is across said ESBG.

39. A component as claimed in claim 37 wherein a channel is added to said waveguide by being transferred to said waveguide from said second waveguide when said second voltage is across said ESBG.

40. A component as claimed in claim 37 wherein signals having WDM channels appear on both waveguides , and wherein a selected channel is transferred from one waveguide to the other when a second voltage is across said ESBG.

41. A component as claimed in claim 37 wherein there are a plurality of ESBGs optically coupled to both waveguides , and wherein a different channel is transferred between waveguides by each ESBG when said second voltage is thereacross.

42. A component as claimed in claim 37 wherein there is an ESBG in optical contact with each of said waveguides , and including at least one optical waveguide interconnecting said ESBGs.

43. A component as claimed in claim 42 wherein there are two optical waveguides interconnecting said ESBGs to form a ring.

44. A component as claimed in claim 43 wherein there is one of said rings between said waveguides for each channel to be transferred therebetween.

45. A component as claimed in claim 43 wherein the said optical waveguide and second optical waveguide have a first effective index, and wherein the optical waveguides for said ring have a second effective index different than the first effective index.

46. A component as claimed in claim 45 wherein the optical waveguides for said ring are of a different size than the said optical waveguide and second optical waveguide.

47. A component as claimed in claim 37 wherein there are a plurality of ESBGs optically coupled to both waveguides , and wherein a different channel is transferred between waveguides by each ESBG when said second voltage is thereacross.

48. A component as claimed in claim 37 wherein said optical waveguides have different indexes.

49. A component as claimed in claim 48 wherein said optical waveguides are of different size.

50. A component as claimed in claim 48 wherein said ESBG has a grating with an index contrast Δ

n, and wherein the difference in the effective index of the optical waveguides is ≧

Δ

n.

51. A component as claimed in claim 37 wherein said ESBG has a submicron grating.

52. A component as claimed in claim 51 wherein said ESBG is a resonator.

53. A component as claimed in claim 52 wherein said component is a channel drop filter, and including a first drop resonator and a second reflector resonator spaced from each other in the direction of travel of said optical signal on a said optical waveguide by an integer number of wavelengths of a wavelength to be dropped, plus a half wavelength.

54. A component as claimed in claim 51 wherein said component is a guide channel dropping filter, said ESBG being a resonator between the channels.

55. A component as claimed in claim 54 wherein said resonator is a split resonator having a phase delay section between split resonator sections.

56. A component as claimed in claim 37 wherein each said optical waveguide has a core surrounded by cladding, and wherein said ESBG is in the cladding for both said optical waveguides.

57. A component as claimed in claim 56 wherein the cladding for said optical waveguides overlap, and wherein said ESBG is in the overlap of said cladding.

58. A component as claimed in claim 56 wherein said ESBG extends over both said optical waveguides.

59. A component as claimed in claim 37 wherein sidelobes are suppressed by apodization.

60. A coupler half component for selectively reconfiguring an optical signal including:

an optical fiber having a core with cladding therearound, the core having an index n₁, the cladding having an index n₂, and the effective index of the fiber being n_e, the cladding being at least partially removed in a selected region;

an ESBG mounted to said fiber in said region, said ESBG having an index n_B when in a first state, where n_B is substantially equal to n₂; and

electrical elements including electrodes for selectively applying a voltage across said ESBG, the effect which the ESBG has on light applied to the ESBG varying as the voltage thereacross changes, thereby changing the state of the ESBG.

61. A component as claimed in claim 60 wherein light applied to said optical fiber is substantially unaffected by said ESBG when the ESBG is in said first state.

62. A component as claimed in claim 61 wherein said ESBG is in said first state when the mechanism applies substantially no voltage across to said ESBG.

63. A component as claimed in claim 61 wherein variations in n_B as a result of voltage changes across the ESBG results in selective attenuation of light applied to said fiber.

64. A component as claimed in claim 63 wherein said light is multichannel light at different wavelengths, and wherein said attenuation is substantially independent of channel.

65. A component as claimed in claim 61 wherein said light is a multichannel multiwavelength signal, and wherein said ESBG causes light at one or more selected wavelengths to be coupled through the ESBG in at least one direction to or from said fiber as the voltage across of said ESBG is varied from a voltage causing the ESBG to be in said first state.

66. A component as claimed in claim 61 wherein said ESBG has a grating period which causes light at one or more selected wavelengths of a multiwavelength light signal to be reflected back along said fiber, thereby filtering said one or more selected wavelengths from the light propagating in said fiber.

67. A component as claimed in claim 61 wherein there are two of said fibers with the said region of the fibers being adjacent, and with said ESBG being mounted between the fibers in both said regions, all light on one of said fibers passing unchanged through the ESBG to the other fiber when the ESBG has a selected index.

68. A component as claimed in claim 67 wherein the fibers have substantially the same indexes, and wherein when said ESBG is in its first state substantially all light applied to one of said fibers is transferred through the ESBG to the other fiber.

69. A component as claimed in claim 68 wherein said ESBG has a selected grating period, said ESBG, when in a second state as a result of the voltage applied theracross, blocking light of at least one selected wavelength from a multiwavlength optical signal, determined by the period of the ESBG grating, from passing through the ESBG, light at such at least one wavelength continuing to propagate in its original path.

70. A component as claimed in claim 67 wherein the fibers have different indexes, wherein said ESBG has a selected grating period Λ

, wherein the propagation constants for the two fibers are β

_ι

and β

′

_ι

respectively, and wherein for at least one wavelength of a multiwavelength light signal, the condition 2π

/Λ

=β

_ι

−

β

′

_ι

is satisfied, there being no coupling between fibers through the ESBG except for the at least one wavelength for which said condition is satisfied.

71. A component as claimed in claim 67 wherein the fibers have different indexes, wherein said ESBG has a gating with an index contrast Δ

n, and wherein the difference in the effective index of the fibers is ≧

Δ

n.