Liquid crystal adaptive coupler for steering a light beam relative to a light-receiving end of an optical waveguide

• US 20040067013A1
• Filed: 10/08/2002
• Published: 04/08/2004
• Est. Priority Date: 10/08/2002
• Status: Active Grant

• Current Assignee: Teledyne Scientific & Imaging, LLC (Teledyne Technologies Incorporated)
• Original Assignee: Innovative Technology Licensing LLC (Teledyne Technologies Incorporated)
• Inventors: Gu, Dong-Feng, Winker, Bruce K., Taber, Donald B.
• Granted Patent: US 6,832,028 B2
• Time in Patent Office: Days
• US Class Current: 385/31
• CPC Class Codes: G02B 6/32 having lens focusing means positioned between opposed fibre ends with lens being an integral part of the single fibre end G02B6/262
• CPC Class Codes: G02B 6/351 involving stationary waveguides with moving interposed optical elements G02B6/3538 takes precedence; interposed waveguides G02B6/3502
• CPC Class Codes: G02B 6/3556 NxM switch, i.e. regular arrays of switches elements of matrix type constellation
• CPC Class Codes: G02F 1/1392 using a field-induced sign-reversal of the dielectric anisotropy
• CPC Class Codes: G02F 1/292 by controlled diffraction or phased-array beam steering controlled diffraction for optical switching G02F1/31

Abstract

An apparatus for optically coupling a light source with a light-receiving end face of an optical waveguide comprises a lens for focusing a light beam emitted from the light source at a focal point on the light-receiving end face of the optical waveguide. An adaptive coupler, positioned in the optical path, is responsive to a beam steering control signal for steering and aligning the focal point relative to the light-receiving end face of the optical waveguide. In one form, the adaptive coupler comprises a pair of transparent substrates having confronting, parallel inner faces, the inner face of one of the pair of substrates carrying a beam intercepting, optically transparent, constant potential electrode and the inner face of the other of the pair of substrates carrying an electrically resistive, beam intercepting, optically transparent film. A pair of spaced apart electrodes in electrical contact with the film apply a linear voltage gradient along the film. An electro-optical phase shifting medium is disposed between the confronting inner faces of the substrates. The application of selected voltages to the electrodes creates a linear voltage gradient along the aforementioned film on the inner face of the one substrate resulting in a linearly varying electric field between that film and the constant potential electrode creating a corresponding linear variation in the refractive index of the liquid crystal medium and a linear wavefront tilt in the intercepting optical beam.

Claims

1. An apparatus for optically coupling a light source with a light-receiving end face of an output optical waveguide along an optical path, the apparatus comprising:

a lens positioned in the optical path for focusing a light beam emitted from the light source at a focal point on the light-receiving end face of the output optical waveguide; and

an adaptive coupler positioned in the optical path, the adaptive coupler being responsive to a beam steering control signal for steering the focal point relative to the light-receiving end face of the output optical waveguide to align the focal point with said light-receiving end face.

2. The apparatus of claim 1 in which:

the light source comprises a light-emitting end face of an input optical waveguide.

3. The apparatus of claim 2 in which:

the input and output optical waveguides comprise optical fibers.

4. The apparatus of claim 1 in which:

the adaptive coupler comprises a light beam-intercepting, electro-optical phase shifting medium responsive to said beam steering control signal.

5. The apparatus of claim 4 in which the adaptive coupler further comprises:

a pair of transparent substrates having confronting, parallel inner faces, the inner face of at least one of the pair of substrates carrying an electrically resistive, beam intercepting, optically transparent film;

a pair of spaced apart electrodes, responsive to said beam steering control signal, in electrical contact with said film for applying a beam steering potential gradient across said film; and

in which;

the electro-optical phase shifting medium is disposed between the confronting inner faces of said pair of substrates.

6. An adaptive coupler for steering an optical beam, the adaptive coupler comprising:

a pair of transparent substrates having confronting, parallel inner faces, the inner face of one of the pair of substrates carrying a beam intercepting, optically transparent, constant potential electrode and the inner face of the other of the pair of substrates carrying an electrically resistive, beam intercepting, optically transparent film;

a pair of spaced apart electrodes in electrical contact with said film for applying a potential gradient along said film; and

an electro-optical phase shifting medium disposed between the confronting inner faces of said pair of substrates.

7. The adaptive coupler defined in claim 6 in which:

the electro-optical phase shifting medium comprises a liquid crystal medium.

8. The adaptive coupler defined in claim 7 in which:

the liquid crystal medium comprises a dual frequency liquid crystal medium.

9. The adaptive coupler defined in claim 6 in which:

the potential gradient is linear.

10. The adaptive coupler defined in claim 6 in which:

the film comprises a material having a high electrical resistivity.

11. The adaptive coupler defined in claim 10 in which:

said high electrical resistivity material comprises zinc oxide.

12. The adaptive coupler defined in claim 11 in which:

the zinc oxide is doped with alumina.

13. The adaptive coupler defined in claim 6 which includes:

a second pair of transparent substrates having confronting, parallel inner faces, the second pair of substrates being disposed parallel with said first-mentioned pair of substrates, the inner face of one of the second pair of substrates carrying a beam intercepting, optically transparent, constant potential electrode and the inner face of the other of the second pair of substrates carrying an electrically resistive, beam intercepting, optically transparent film, a pair of spaced apart electrodes in contact with said film for applying a potential gradient along said film in a direction perpendicular to the direction of the first-mentioned potential gradient, and an electro-optical phase shifting medium disposed between the confronting faces of said second pair of substrates.

14. The adaptive coupler defined in claim 13 in which:

the electro-optical phase shifting medium disposed between the confronting inner faces of said second pair of substrates comprises a liquid crystal medium.

15. The adaptive coupler defined in claim 14 in which:

the liquid crystal medium comprises a dual frequency liquid crystal medium.

16. The adaptive coupler defined in claim 13 in which:

the potential gradient is linear.

17. The adaptive coupler defined in claim 13 in which:

the film carried by the inner face of the other of the second pair of substrates comprises a material having a high electrical resistivity.

18. The adaptive coupler defined in claim 17 in which:

said high electrical resistivity material comprises zinc oxide.

19. The adaptive coupler defined in claim 18 in which:

the zinc oxide is doped with alumina.

20. The adaptive coupler defined in claim 6 which includes:

a second pair of spaced apart electrodes in electrical contact with said film, the second pair of electrodes being substantially perpendicular to the first pair of spaced apart electrodes whereby, the application of selected voltages to said two pairs of electrodes produces a linear potential gradient at any selected angle in the plane of the film to provide 2-dimensional beam steering.

21. An adaptive coupler for steering an optical beam, the adaptive coupler comprising:

a first substrate having a flat surface carrying a first, beam intercepting, optically transparent film of material having an electrical resistivity;

spaced apart electrodes in contact with said first film for applying a potential gradient across said first transparent film;

a second substrate having a flat surface, the flat surface of said second substrate confronting the flat surface of said first substrate and disposed parallel thereto, said flat surface of said second substrate carrying a second beam intercepting, optically transparent film comprising a constant potential electrode; and

a dual frequency liquid crystal phase shifting medium disposed between said films on said confronting flat surfaces of said first and second substrates.

22. The adaptive coupler defined in claim 21 in which:

said first and second films comprising zinc oxide.

23. The adaptive coupler defined in claim 21 which includes:

a third substrate having a flat surface carrying a third beam intercepting, optically transparent film, the third film having an electrical resistivity and including spaced apart electrodes for applying a potential gradient across said third transparent film, said potential gradient applied across said third film extending in a direction perpendicular to the direction of the potential gradient across said first film;

a fourth substrate having a flat surface, the flat surface of said fourth substrate confronting the flat surface of said third substrate and disposed parallel thereto, said flat surface of said fourth substrate carrying a fourth beam intercepting, optically transparent film comprising a constant potential electrode, said third and fourth substrates being disposed parallel with and adjacent to the first and second substrates; and

a dual frequency liquid crystal phase shifting medium disposed between said third and fourth films on said confronting flat surfaces of said first and second substrates.

24. The adaptive coupler defined in claim 23 in which:

the third and fourth films comprise zinc oxide.

25. The adaptive coupler defined in claim 21 which includes:

a second pair of spaced apart electrodes in electrical contact with said film, the second pair of electrodes being substantially perpendicular to the first pair of spaced apart electrodes whereby, the application of selected voltages to said two pairs of electrodes produces a linear potential gradient at any selected angle in the plane of the film to provide 2-dimensional beam steering.

26. An optical switch for optically coupling the light-emitting end of a selected one of a plurality of input optical waveguides with the light-receiving end of a selected one of a plurality of output optical waveguides, the optical switch comprising:

a switch array for selectively deflecting a light beam from the light-emitting end of the selected one of said plurality of input optical waveguides to the light-receiving end of the selected one of said plurality of output optical waveguides;

a lens for focusing said light at a focal point on the light-receiving end of the selected one of said plurality of output optical waveguides; and

an adaptive coupler for steering said focal point relative to said light-receiving end of said selected one of said plurality of output optical waveguides to align said focal point with said light-receiving end.

27. The optical switch as defined in claim 26 in which:

said adaptive coupler comprises a pair of transparent substrates having confronting, parallel inner faces, the inner face of at least one of the pair of substrates carrying an electrically resistive, beam intercepting, optically transparent film;

a pair of spaced apart electrodes in electrical contact with said film for applying a potential gradient across said film; and

an electro-optical phase shifting medium disposed between the confronting inner faces of said pair of substrates.

28. The optical switch defined in claim 27 in which:

the electro-optical phase shifting medium comprises a liquid crystal medium.

29. The optical switch defined in claim 28 in which:

the liquid crystal medium comprises a dual frequency liquid crystal medium.

30. The optical switch defined in claim 27 in which:

the film comprises a material having a high electrical resistivity.

31. The optical switch defined in claim 30 in which:

the high electrical resistivity material comprises zinc oxide.

32. The optical switch defined in claim 27 in which:

the inner face of the other of said pair of substrates carries an electrically conductive, beam intercepting, optically transparent film comprising a ground plane electrode.

33. The optical switch defined in claim 27 which includes:

a second pair of transparent substrates having confronting, parallel inner faces, the second pair of substrates being disposed parallel with said first-mentioned pair of substrates, the inner face of at least one of the second pair of substrates carrying an electrically resistive, beam intercepting, optically transparent film, a pair of spaced apart electrodes in contact with said film for applying a potential gradient across said film in a direction perpendicular to the direction of the first-mentioned potential gradient, and an electro-optical phase shifting medium disposed between the confronting faces of said second pair of substrates.

34. The optical switch defined in claim 33 in which:

the electro-optical phase shifting medium disposed between the confronting inner faces of said second pair of substrates comprises a liquid crystal medium.

35. The optical switch defined in claim 34 in which:

the liquid crystal medium comprises a dual frequency liquid crystal medium.

36. The optical switch defined in claim 33 in which:

said film carried by said inner face of said at least one of said second pair of substrates comprises a material having a high electrical resistivity.

37. The optical switch defined in claim 36 in which:

said high electrical resistivity material comprises zinc oxide.

38. The optical switch defined in claim 33 in which:

the inner face of the other of said second pair of substrates carries an electrically resistive, beam intercepting, optically transparent film comprising a ground plane electrode.

39. The optical switch defined in claim 27 which includes:

a second pair of spaced apart electrodes in electrical contact with said film, the second pair of electrodes being substantially perpendicular to the first pair of spaced apart electrodes whereby, the application of selected voltages to said two pairs of electrodes produces a linear potential gradient at any selected angle in the plane of the film to provide 2-dimensional beam steering.

40. An optical fiber coupling comprising:

a first array of optical fibers, each of the optical fibers of the first optical fiber array having a light-emitting end face;

a second array of optical fibers, each of the optical fibers of the second optical fiber array having a light-receiving end face;

a light deflector means responsive to control signals for directing a beam of light emitted from the light-emitting end face of a selected one of the optical fibers of the first optical fiber array along an optical path to the light-receiving end face of a selected one of the optical fibers of the second optical fiber array;

an array of lenses disposed between the light-emitting end faces of the first optical fiber array and the light-receiving end faces of the second optical fiber array, each lens of the lens array being associated with the light-receiving end face of one of the optical fibers of the second optical fiber array for focusing a beam of light emitted from a selected one of the optical fibers of the first optical fiber array at a focal point on the light-receiving end face of a selected one of the optical fibers of the second optical fiber array; and

an array of adaptive couplers disposed between the light-emitting end faces of the first optical fiber array and the light-receiving end faces of the second optical fiber array, each of the adaptive couplers of the adaptive coupler array being responsive to a beam steering control signal for steering a corresponding focal point of a beam of light emitted from a selected one of the optical fibers of the first optical fiber array relative to the light-receiving end face of a selected one of the optical fibers of the second optical fiber array to align said focal point with said light receiving end face.

41. The optical fiber coupling of claim 40 in which:

each of the optical fibers of the first array has a fixed end portion terminating at the light-emitting end face and extending along a longitudinal axis, the longitudinal axes of the fixed end portions of the first optical fiber array being parallel.

42. The optical fiber coupling of claim 40 in which:

each of the optical fibers of the second array has a fixed end portion terminating at the light-receiving end face and extending along a longitudinal axis, the longitudinal axes of the fixed end portions of the second optical fiber array being parallel.

43. The optical fiber coupling of claim 42 in which:

the longitudinal axes of the fixed end portions of the first and second optical fiber arrays are parallel.

44. The optical fiber coupling of claim 42 in which:

the light-receiving end face of each of the optical fibers of the second optical fiber array comprises a planar surface disposed perpendicular to the longitudinal axis.

45. The optical fiber coupling claim 40 in which each of the adaptive couplers of the adaptive coupler array comprises:

a pair of transparent substrates having confronting, parallel inner faces, the inner face of at least one of the pair of substrates carrying an electrically resistive, beam intercepting, optically transparent film;

a pair of spaced apart electrodes, responsive to said beam steering control signal, in electrical contact with said film for applying a beam steering potential gradient across said film; and

an electro-optical phase shifting medium disposed between the confronting inner faces of said pair of substrates.

46. The optical fiber coupling of claim 40 in which:

the optical fiber coupling comprises an optical switch.

47. An optical fiber coupling comprising:

an array of input optical fibers, each of the optical fibers of the input optical fiber array having a light-emitting end face;

an output optical fiber having a light-receiving end face;

light deflector means responsive to control signals for directing a beam of light emitted from the light-emitting end face of a selected one of the input optical fibers along an optical path to the light-receiving end face of the output optical fiber;

a lens, disposed between the light-emitting end face of each of input optical fibers and the light-receiving end face of the output optical fiber, for focusing a beam of light emitted from a selected one of the input optical fibers at a focal point on the light-receiving end face of the output optical fiber; and

an adaptive coupler disposed between the light-emitting end face of each of the input optical fibers and the light-receiving end face of the output optical fiber, the adaptive coupler being responsive to a beam steering control signal for steering the focal point of a beam of light emitted from the selected one of the input optical fibers relative to the light-receiving end face of the output optical fiber to align said focal point with said light-receiving end face.

48. The optical fiber coupling of claim 47 in which:

each of input optical fibers has a fixed end portion terminating at the light-emitting end face, the fixed end portion extending along a longitudinal axis, the longitudinal axes of the fixed end portions of the input optical fiber array being parallel.

49. The optical fiber coupling of claim 47 in which:

the output optical fiber has a fixed end portion terminating at the light-receiving end face, the fixed end portion extending along a longitudinal axis.

50. The optical fiber coupling of claim 49 in which:

the longitudinal axes of the fixed end portions of the input and output optical fibers are parallel.

51. The optical fiber coupling of claim 49 in which:

the light-receiving end face of output optical fiber comprises a planar surface disposed perpendicular to the longitudinal axis.

52. The optical fiber coupling claim 47 in which each of the adaptive couplers comprises:

a pair of transparent substrates having confronting, parallel inner faces, the inner face of at least one of the pair of substrates carrying an electrically resistive, beam intercepting, optically transparent film;

a pair of spaced apart electrodes, responsive to said beam steering control signal, in electrical contact with said film for applying a beam steering potential gradient across said film; and

an electro-optical phase shifting medium disposed between the confronting inner faces of said pair of substrates.

53. The optical fiber coupling of claim 47 in which:

the optical fiber coupling comprises an optical switch.

54. An optical fiber coupling comprising:

an input optical fiber having a light-emitting end face;

an array of output optical fibers, each of the output optical fibers having a light-receiving end face;

light deflector means responsive to control signals for directing a beam of light emitted from the light-emitting end face of the input optical fiber along an optical path to the light-receiving end face of a selected one of the output optical fibers;

a lens, disposed between the light-emitting end face of the input optical fiber and the light-receiving end face of each of the output optical fibers, for focusing a beam of light emitted from the light-emitting end face of the input optical fiber at a focal point on the light-receiving end face of a selected one of the output optical fibers; and

an adaptive coupler disposed between the light-emitting end face of the input optical fiber and the light-receiving end face of each of the output optical fibers, the adaptive coupler being responsive to a beam steering control signal for steering the focal point of a beam of light emitted from the input optical fiber relative to the light-receiving end face of a selected one of the output optical fibers to align said focal point with said light receiving end face.

55. The optical fiber coupling of claim 54 in which:

the input optical fiber has a fixed end portion terminating at the light-emitting end face and extending along a longitudinal axis.

56. The optical fiber coupling of claim 54 in which:

each of the output optical fibers has a fixed end portion terminating at the light-receiving end face and extending along a longitudinal axis, the longitudinal axes of the fixed end portions of the output optical fibers being parallel.

57. The optical fiber coupling of claim 56 in which:

the longitudinal axes of the fixed end portions of the input and output optical fibers are parallel.

58. The optical fiber coupling of claim 56 in which:

the light-receiving end face of each of the output optical fibers comprises a planar surface disposed perpendicular to the longitudinal axis.

59. The optical fiber coupling claim 54 in which each of the adaptive couplers comprises:

a pair of transparent substrates having confronting, parallel inner faces, the inner face of at least one of the pair of substrates carrying an electrically resistive, beam intercepting, optically transparent film;

a pair of spaced apart electrodes, responsive to said beam steering control signal, in electrical contact with said film for applying a beam steering potential gradient across said film; and

an electro-optical phase shifting medium disposed between the confronting inner faces of said pair of substrates.

60. The optical fiber coupling of claim 54 in which:

the optical fiber coupling comprises an optical switch.