Optical fiber illumination systems and methods

• US 8,591,087 B2
• Filed: 11/19/2010
• Issued: 11/26/2013
• Est. Priority Date: 11/20/2009
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Bickham, Scott Robertson, Bookbinder, Dana Craig, Fewkes, Edward John, Logunov, Stephan Lvovich
• Primary Examiner(s): CARIASO, ALAN B
• Application Number:
  US12/950,045
• Publication Number:
  US 20110122646A1
• Time in Patent Office: 1,103 Days
• Field of Search: 362/552, 362/558, 362/84, 362/560, 362/551, 362/582, 385/122, 359/326, 359/328, 372/22, 372/23
• US Class Current: 362/558
• CPC Class Codes: C03C 13/045 Silica-containing oxide glass compositions
• CPC Class Codes: C03C 25/105 Organic claddings
• CPC Class Codes: C03C 25/106 Single coatings
• CPC Class Codes: C03C 25/475 containing colouring agents
• CPC Class Codes: G02B 6/0003 the light guides being doped with fluorescent agents
• CPC Class Codes: G02B 6/001 the light being emitted along at least a portion of the lateral surface of the fibre
• CPC Class Codes: G02B 6/0229 characterised by nanostructures, i.e. structures of size less than 100 nm, e.g. quantum dots
• CPC Class Codes: G02B 6/02347 Longitudinal structures arranged to form a regular periodic lattice, e.g. triangular, square, honeycomb unit cell repeated throughout cladding
• CPC Class Codes: G02B 6/02361 Longitudinal structures forming multiple layers around the core, e.g. arranged in multiple rings with each ring having longitudinal elements at substantially the same radial distance from the core, having rotational symmetry about the fibre axis
• CPC Class Codes: G02B 6/02366 Single ring of structures, e.g. "air clad"

Abstract

An illumination system generating light having at least one wavelength within 200 nm to 2000 nm range. The system includes a light source and at least one light diffusing optical fiber with a plurality of nano-sized structures (e.g., voids). The optical fiber is coupled to the light source. The light diffusing optical fiber has a core and a cladding. The plurality of nano-sized structures is situated either within said core or at a core-cladding boundary. The optical fiber also includes an outer surface. The optical fiber is configured to scatter guided light via the nano-sized structures away from the core and through the outer surface, to form a light-source fiber portion having a length that emits substantially uniform radiation over its length, said fiber having a scattering-induced attenuation greater than 50 dB/km for the wavelength(s) within 200 nm to 2000 nm range.

Claims

1. An illumination system, comprising:

a light source that generates light having at least one wavelength between 200 nm and 2000 nm; and

at least one light diffusing optical fiber having a glass core, primary cladding, and a plurality of nano-sized voids situated within said core or at a core-cladding boundary, said optical fiber further including an outer surface, and an end optically coupled to the light source,

wherein the fiber is configured to scatter guided light via said nano-sized voids away from the core and through the outer surface, to form a light-source fiber portion having a length that emits substantially uniform radiation over its length, said fiber having a scattering-induced attenuation greater than 50 dB/km for said wavelength.

2. The illumination system of claim 1, wherein said fiber has a plurality of bends formed therein to preferentially scatter guided light via said nano-sized voids away from the core and through the outer surface.

3. The illumination system of claim 1, wherein said fiber radiation is substantially uniform, such that a difference between a maximum scattering illumination intensity and a minimum scattering illumination intensity is less than 30% of the maximum scattering illumination intensity.

4. The illumination system of claim 1, wherein said fiber having scattering-induced attenuation is 100 to 6000 dB/km for said wavelength.

5. The illumination system of claim 4, wherein said fiber has a length L of 0.5 m to 100 m and:

(i) said fiber scattering-induced attenuation is 300 dB/km to 6000 dB/km for said wavelength; and

/ or (ii) said fiber attenuation is greater than 3dB/L.

6. The illumination system of claim 1, wherein attenuation of the fiber due to scatter is 6000 dB/km to 20000 dB/km for said wavelength.

7. The illumination system of claim 1, comprising a plurality of light diffusing optical fibers, each having a glass core, cladding, and a plurality of nano-sized voids situated within said core or at a core-cladding boundary, each of said optical fibers further including an outer surface, and an end optically coupled to the light source, wherein each of said light diffusing fibers configured to scatter guided light via said nano-sized voids away from the core and through the outer surface, to form a light-source fiber portion having a length that emits substantially uniform radiation over its length, each of said light diffusing fibers having a scattering-induced attenuation greater than 50 dB/km for said wavelength.

8. The illumination system of claim 7, wherein:

(i) each light diffusing optical fiber is optically coupled to either the light source or a plurality of light sources, (ii) the plurality of light diffusing optical fibers is bundled together in at least one of;

a ribbon, ribbon stack, or a round bundle.

9. The illumination system of claim 1 wherein said fiber is a multimode fiber, wherein said fiber core has:

(i) a core diameter greater than 50 μ

m and less than 500 μ

m;

and (ii) a numerical aperture NA>

0.2.

10. The illumination system of claim 1 wherein the core of said light diffusing fiber comprises silica and said nano-sized voids are situated in the core.

11. The illumination system of claim 10, wherein said nano-sized voids are situated in the core and said core has an outer diameter Rc, said core includes:

(i) a solid inner core section with radius R₁, such that 0.1Rc<

R₁<

0.9Rc;

(ii) nano-structured region having a width W₂ wherein 0.05Rc<

W₂<

0.9Rc; and

(iii) outer solid core region having a width Ws between 0.1Rc<

Ws<

0.9Rc,

wherein each section of said core comprises silica glass.

12. The illumination system of claim 11, wherein said core comprises silica doped with at least one of the following dopants:

Ge, F.

13. The illumination system of claim 10, wherein the entire core comprises nano-sized voids.

14. The illumination system of claim 1, wherein:

(i) said cladding comprises either silica based glass or polymer, said cladding being at least 20 μ

m thick; and

/or (ii) at least one coating surrounding said cladding.

15. The illumination system of claim 1, wherein said plurality of nano-sized voids is situated at a core-cladding boundary and the nano- structured region including said nano-sized voids has a width of at least 7 μ

m; and

wherein said cladding diameter is at least 125 μ

m.

16. The illumination system of claim 1, wherein said nano-sized voids are gas filled voids with diameter of greater than 10 nm.

17. The illumination system of claim 1, further comprising a coating disposed on the outer surface of the optical fiber, wherein fluorescent species are disposed in the optical fiber coating.

18. The illumination system of claim 17, when said light source generates light in 200-500 nm wavelength range and fluorescent material in said coating generates either white, green, red, or NIR (near infrared) light.

19. The illumination system of claim 1 wherein said fiber has a glass core at least partially filled with nano-sized voids for scattering light, said core being surrounded by a either polymer or glass cladding, and at last one coating layer surrounding said cladding.

20. The illumination system of claim 19 wherein the cladding is surrounded by a primary and an optional secondary coating, or an ink layer.

21. The illumination system of claim 20 wherein the ink layer comprises:

pigments or phosphors, fluorescent material, UV absorbing material, hydrophilic material, light modifying material, or a combination thereof.

22. The illumination system of claim 20 wherein:

the cladding, and/or primary coating, and/or the secondary coating comprises at least one of;

pigment, phosphors, fluorescent material, UV absorbing material, hydrophilic material, light modifying material, or a combination thereof.

23. The illumination system of claim 1 comprising at least one multimode laser diode coupled to at least one fiber with a core radius of 30 μ

m to 400 μ

m.

24. The illumination system of claim 1 comprising a display screen, wherein said light diffusing fiber is coupled to a light source and is situated adjacent to perimeter of said display screen.

25. The illumination system of claim 1 wherein said at least one light diffusing optical fiber comprises a reflective coating.

26. The illumination system of claim 1 wherein said at least one light diffusing optical fiber comprises a reflective coating directing light in one direction.

27. An automobile comprising an illumination system of claim 1.

28. The illumination system of claim 1 wherein said light source is a UV light source, and said fiber transmits UV light.

29. The illumination system of claim 1 wherein:

said light source is a UV light source, and said light diffusing optical fiber (i) transmits UV light and (ii) has a coating that includes phosphor.

30. The illumination system of claim 29, wherein said fiber provides white light and through fluorescence, and the angular distribution of fluorescence white light is substantially uniform.

31. The illumination system of claim 1 wherein said light diffusing fiber has relatively uniform illumination along the fiber length such that the minimum scattering illumination intensity is not less than 0.7 the maximum scattering illumination intensity.

32. The illumination system of claim 1, wherein a cross-sectional size of the nano-sized voids is in the range from about 10 nm to about 1 μ

m.

33. The illumination system of claim 1, wherein a cross-section of the light diffusing optical fiber comprises the plurality of nano-sized voids.

34. The illumination system of claim 1, wherein a cross-section of the light diffusing optical fiber comprises at least 50 voids.

35. The illumination system of claim 1, wherein the nano-sized voids are nano-sized gas-filled voids, wherein a composition of the nano-sized gas-filled voids comprises SO₂, Kr, Ar, CO₂, N₂, O₂, or mixtures thereof.

36. The illumination system of claim 1, wherein a length of the nano-sized voids is in the range from about 1 mm to 50 m.

37. The illumination system of claim 1, wherein the nano-sized voids are nano-sized gas-filled voids.

38. A light diffusing optical fiber comprising:

a glass core, a cladding, and a plurality of nano-sized voids situated within said core or at a core-cladding boundary, said optical fiber further including an outer surface and is configured to (i) scatter guided light via said nano-sized voids away from the core and through the outer surface, (ii) have a scattering-induced attenuation greater than 50 dB/km at illumination wavelength; and

said fiber including at least one coating such that either said cladding or said at least one coating includes phosphor or pigments.

39. The light diffusing optical fiber of claim 38, wherein the nano-sized voids are nano-sized gas-filled voids.

40. A light diffusing optical fiber comprising:

a glass core, a cladding, and a plurality of nano-sized voids situated within said core, said optical fiber further including an outer surface and is configured to (i) scatter guided light via said nano-sized voids away from the core and through the outer surface, (ii) have a scattering-induced attenuation greater than 50 dB/km at illumination wavelength; and

wherein the entire core includes nano-sized voids.

41. The light diffusing optical fiber of claim 40, fiber including at least one coating such that either said cladding or said at least one coating includes phosphor or pigments.

42. The light diffusing optical fiber of claim 40, wherein the nano-sized voids are nano-sized gas-filled voids.

43. A light diffusing optical fiber comprising:

a glass core, and a plurality of nano-sized voids situated within said core such that the entire core includes nano-sized voids, said optical fiber further including an outer surface and is configured to (i) scatter guided light via said nano-sized voids away from the core and through the outer surface, (ii) have a scattering-induced attenuation greater than 50 dB/km at illumination wavelength wherein said fiber does not include cladding.

44. The light diffusing optical fiber of claim 43, the fiber including at least one coating such that said at least one coating includes phosphor or pigments.

45. The light diffusing optical fiber of claim 43, wherein the nano-sized voids are nano-sized gas-filled voids.

46. A light diffusing optical fiber comprising:

a glass core, and a plurality of nano-sized voids situated within said core, said optical fiber further including an outer surface and is configured to (i) scatter guided light via said nano-sized voids away from the core and through the outer surface, (ii) have a scattering-induced attenuation greater than 50 dB/km at illumination wavelength.

47. The light diffusing optical fiber of claim 46, the fiber including at least one coating such that said at least one coating includes phosphor or pigments.

48. The light diffusing optical fiber of claim 46, wherein the nano-sized voids are nano-sized gas-filled voids.

49. A light diffusing optical fiber comprising:

a glass core, and a plurality of nano-sized structures situated within said core, said optical fiber further including an outer surface and is configured to (i) scatter guided light via said nano-sized structures away from the core and through the outer surface, (ii) have a scattering-induced attenuation greater than 50 dB/km at illumination wavelength, wherein a cross-sectional size of the nano-sized structures is in the range from about 10 nm to about 1 μ

m and a length of the nano-sized structures is in the range from 1 mm to 50 m.

50. The light diffusing optical fiber of claim 49, wherein the cross-sectional size of the nano-sized structures is in the range from about 50 nm to about 500 nm.

51. The light diffusing optical fiber of claim 49, wherein the length of the nano-sized structures is in the range from about 2 mm to about 5 meters.

52. The light diffusing optical fiber of claim 51, wherein the length of the nano-sized structures is in the range from about 5 mm to about 1 meter.

53. A light diffusing optical fiber comprising:

a glass core, and a plurality of nano-sized structures situated within said core, said optical fiber further including an outer surface and is configured to (i) scatter guided light via said nano-sized structures away from the core and through the outer surface, (ii) have a scattering-induced attenuation greater than 50 dB/km at illumination wavelength, said optical fiber having length, wherein a scattering loss of the fiber does not vary more than 30% over the fiber length.

54. The light diffusing optical fiber of claim 53, wherein the scattering loss of the fiber does not vary more than 20% over the fiber length.

55. The light diffusing optical fiber of claim 53, wherein the scattering loss of the fiber does not vary more than 10% over the fiber length.

56. A light diffusing optical fiber comprising:

a glass core, and a plurality of nano-sized structures situated within said core, said optical fiber further including an outer surface and is configured to (i) scatter guided light via said nano-sized structures away from the core and through the outer surface, (ii) have a scattering-induced attenuation greater than 50 dB/km at illumination wavelength, said optical fiber including a segment having length, wherein a scattering loss of the fiber does not vary more than 30% over the segment length.

57. The light diffusing optical fiber of claim 56, wherein the scattering loss of the fiber does not vary more than 20% over the segment length.

58. The light diffusing optical fiber of claim 56, wherein the scattering loss of the fiber does not vary more than 10% over the segment length.

59. The light diffusing optical fiber of claim 56, wherein the segment length is 0.2 m.

60. The light diffusing optical fiber of claim 56, wherein the segment length is 0.05 m.

61. The light diffusing optical fiber of claim 56, wherein the segment length is 0.01 m.

62. The light diffusing optical fiber of claim 61, wherein the scattering loss of the fiber does not vary more than 20% over the segment length.

63. The light diffusing optical fiber of claim 61, wherein the scattering loss of the fiber does not vary more than 10% over the segment length.

64. A light diffusing optical fiber comprising:

a glass core, and a plurality of nano-sized structures situated within said core, said optical fiber further including an outer surface and is configured to (i) scatter guided light via said nano-sized structures away from the core and through the outer surface, (ii) have a scattering-induced attenuation greater than 50 dB/km at illumination wavelength, wherein the fiber emits light having a substantially uniform angular distribution relative to an axis of the fiber.

65. The light diffusing optical fiber of claim 64, wherein the angular distribution of emitted light is substantially uniform when an axial scattering intensity of light scattering axially from the outer surface varies less than 50% from a mean scattering intensity of the fiber.

66. The light diffusing optical fiber of claim 64, wherein the angular distribution of emitted light is substantially uniform when an axial scattering intensity of light scattering axially from the outer surface varies less than 30% from a mean scattering intensity of the fiber.

67. The light diffusing optical fiber of claim 64, wherein the angular distribution of emitted light is substantially uniform when an axial scattering intensity of light scattering axially from the outer surface varies less than 20% from a mean scattering intensity of the fiber.

68. The light diffusing optical fiber of claim 64, wherein the angular distribution of emitted light is substantially uniform when an axial scattering intensity of light scattering axially from the outer surface varies less than 10% from a mean scattering intensity of the fiber.

69. The light diffusing optical fiber of claim 64, wherein the fiber has a forward scattering intensity, a 90 degree scattering intensity, and a backward scattering intensity, wherein the angular distribution of emitted light is substantially uniform when:

(i) the forward scattering intensity is within 30% of the 90 degree scattering intensity;

(ii) the forward scattering intensity is within 30% of the backward scattering intensity; and

(iii) the 90 degree scattering intensity is within 30% of the backward scattering intensity.

70. The light diffusing optical fiber of claim 69, wherein the angular distribution of emitted light is substantially uniform when:

(i) the forward scattering intensity is within 20% of the 90 degree scattering intensity;

(ii) the forward scattering intensity is within 20% of the backward scattering intensity; and

(iii) the 90 degree scattering intensity is within 20% of the backward scattering intensity.

71. An illumination system comprising the light diffusing optical fiber of claim 64 and a reflective minor, wherein the reflective mirror is optically coupled to an end of the fiber.

72. The light diffusing optical fiber of claim 64, the fiber further comprising a coating.

73. The light diffusing optical fiber of claim 72, wherein the coating is an ink based coating.

74. A light diffusing optical fiber comprising a glass core and an outer surface, wherein the core comprises:

a nano-structured glass region including a plurality of nano-sized structures configured to scatter guided light via the nano-sized structures away from the core and through the outer surface, such that the light diffusing optical fiber has a scattering-induced attenuation greater than 50 dB/km at an illumination wavelength; and

an outer solid glass region surrounding the nano-structured region.

75. The light diffusing optical fiber of claim 74, wherein the core further comprises an inner solid glass region, wherein the nano-structured glass region is a nano-structured ring surrounding the inner solid glass region.

76. The light diffusing optical fiber of claim 75, wherein:

the core has a radius Rc;

the inner solid glass region has a radius R₁, such that 0.1Rc<

R₁<

0.9R;

the nano-structured glass region has a width W₂, such that 0.05Rc<

W₂<

0.9R; and

the outer solid glass region has a width Ws, such that 0.1Rc<

Ws<

0.9Rc.