Optical Fiber Illumination Systems and Methods

• US 20110122646A1
• Filed: 11/19/2010
• Published: 05/26/2011
• Est. Priority Date: 11/20/2009
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Logunov, Stephen Lvovich, Bookbinder, Dana Craig, Fewkes, Edward John, Bickham, Scott Robertson
• Granted Patent: US 8,591,087 B2
• Time in Patent Office: Days
• US Class Current: 362/554
• 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 a plurality of nano-sized structures (e.g., voids). The optical fiber 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 core, primary cladding, and a plurality of nano-sized structures 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 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 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 structures 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 the difference between the minimum and maximum 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 3 dB/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 core, cladding, and a plurality of nano-sized structures 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 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, 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 1 wherein said fiber is a multimode fiber, said fiber core further having:

(i) a core diameter greater than 50 μ

m and less than 500 μ

m; and

/or (ii) numerical aperture NA of said core, wherein NA>

0.2.

9. The illumination system of claim 1 wherein the core of said light diffusing fiber comprises silica and/or said nano-sized structures are situated in the core.

10. The illumination system of claim 9, wherein said nano-sized structures are situated in the core and said core has an outer diameter Rc, said core includes:

(i) a solid inner core section with an outer diameter R₁, such that 0.05 Rc>

R₁>

0.9 Rc;

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

W₂>

0.9 Rc; and

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

Ws>

0.9 Rc, wherein each section of said core comprised silica glass.

11. The illumination system of claim 10, wherein said core comprises silica doped with at least one of the following dopants:

Ge, F.

12. The illumination system of claim 9, wherein the entire core comprises nano-sized structures.

13. 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.

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

m; and

wherein said cladding diameter is at least 125 μ

m.

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

16. The illumination system of claim 3, 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.

17. The illumination system of claim 1, further comprising fluorescent and/or scattering species disposed in the light diffusing optical fiber coating to provide substantially uniform scattering intensity.

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 nanostructures 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, and/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. A method of making a light diffusing fiber with relatively uniform illumination along the fiber length wherein the minimum scattering illumination intensity is not less than 0.7 the maximum scattering illumination intensity and a scattering-induced attenuation greater than 50 dB/km at illumination wavelength, said method including the step of controlling fiber tension during draw process.

24. A light diffusing optical fiber comprising:

a core, a cladding, and a plurality of nano-sized structures 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 structures 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.

25. A light diffusing optical fiber comprising:

a core, a cladding, and a plurality of nano-sized structures 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 structures 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 structures.

26. The light diffusing optical fiber of claim 25, fiber including at least one coating such that either said cladding or said at least one coating includes phosphor or pigments.

27. A light diffusing optical fiber comprising:

a core, and a plurality of nano-sized structures situated within said core such that the entire core includes nano-structures, 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 said fiber does not include cladding.

28. The light diffusing optical fiber of claim 27, fiber including at least one coating such that either said cladding or said at least one coating includes phosphor or pigments.