Uniform white color light diffusing fiber

Abstract

Light diffusing optical fibers for use in illumination applications and which have a uniform color gradient that is angularly independent are disclosed herein along with methods for making such fibers. The light diffusing fibers are composed of a silica-based glass core that is coated with a number of layers including both a scattering layer and a phosphor layer.

We claim: 
     
       1. A light diffusing fiber for emitting white light comprising:
 a) a core formed from a silica-based glass; 
 b) a cladding in direct contact with the core; 
 c) a scattering layer in direct contact with the cladding; and 
 d) a phosphor layer surrounding and in direct contact with the scattering layer, wherein the a color of the light emitted, as measured by the CIE 1931 x, y chromacity space, comprises x from about 0.20 to about 0.30 and y from 0.26 to about 0.35; 
 wherein the scattering layer comprises a plurality of randomly distributed voids or microparticles or nanoparticles of a scattering material. 
 
     
     
       2. The light diffusing fiber of  claim 1 , wherein x is from about 0.23 to about 0.28 and y is from about 0.28 to about 0.33. 
     
     
       3. The light diffusing fiber of  claim 1 , wherein the color of the light emitted falls within the claimed CIE 1931 x, y values for all viewing angles from about 15° to about 170° relative to the direction of the light diffusing optical fiber. 
     
     
       4. The light diffusing fiber of  claim 1 , wherein the light diffusing optical fiber emits light having an intensity along the fiber that does not vary by more than about 20%. 
     
     
       5. The light diffusing fiber of  claim 1 , wherein the scattering induced attenuation loss comprises from about 0.1 dB/m to about 50 dB/m at a wavelength of 550 nm. 
     
     
       6. The light diffusing fiber of  claim 1 , wherein the core comprises a plurality of randomly distributed voids. 
     
     
       7. The light diffusing fiber of  claim 1 , wherein the cladding comprises a polymer. 
     
     
       8. The light diffusing fiber of  claim 7 , wherein the polymer comprises CPC6. 
     
     
       9. The light diffusing fiber of  claim 1 , wherein the scattering layer comprises a polymer. 
     
     
       10. The light diffusing fiber of  claim 9 , wherein the polymer comprises CPC6. 
     
     
       11. The light diffusing fiber of  claim 1 , wherein the scattering layer comprises a plurality of randomly distributed voids or microparticles or nanoparticles of a scattering material. 
     
     
       12. The light diffusing fiber of claim  11  1, wherein the microparticles or nanoparticles comprise TiO 2  or SiO 2 . 
     
     
       13. The light diffusing fiber of  claim 1 , further comprising a light emitting device that emits light with a wavelength from about 300 nm to about 450 nm into the core of the light diffusing fiber. 
     
     
       14. The light diffusing fiber of  claim 1 , wherein the phosphor layer comprises microparticles or nanoparticles of an inorganic phosphorescent or fluorescent material. 
     
     
       15. The light diffusing fiber of  claim 14 , wherein the inorganic phosphorescent or fluorescent material comprises CeYAG, NdYAG, quantum dots, or nanoparticles. 
     
     
       16. The light diffusing fiber of  claim 1 , further comprising a secondary layer in between the cladding and scattering layer. 
     
     
       17. A method of producing the light diffusing fiber of  claim 1  comprising:
 a) forming an optical fiber preform comprising a preform core; 
 b) drawing the optical fiber preform into an optical fiber; 
 c) coating the optical fiber with at least one cladding layer; 
 d) coating the optical fiber with at least one scattering layer; and 
 e) coating the optical fiber with at least one phosphor layer. 
 
     
     
       18. A light diffusing fiber for emitting white light comprising:
 a core formed from a silica-based glass;   a cladding in direct contact with the core;   a scattering layer in direct contact with the cladding; and   a phosphor layer surrounding and in direct contact with the scattering layer, wherein a color of the light emitted, as measured by the CIE 1931 x, y chromacity space, comprises y from about 0.26 to about 0.35;   wherein the scattering layer comprises a plurality of randomly distributed voids or microparticles or nanoparticles of a scattering material.   
     
     
       19. The light diffusing fiber of claim 18, wherein the color of the light emitted falls within the claimed CIE 1931 x, y values for all viewing angles from about 15° to about 170° relative to the direction of the light diffusing optical fiber. 
     
     
       20. The light diffusing fiber of claim 18, wherein the light diffusing optical fiber emits light having an intensity along the fiber that does not vary by more than about 30%. 
     
     
       21. The light diffusing fiber of claim 18, further comprising a scattering induced attenuation loss from about 0.1 dB/m to about 50 dB/m at a wavelength of 550 nm. 
     
     
       22. The light diffusing fiber of claim 18, wherein the core comprises a plurality of randomly distributed voids. 
     
     
       23. The light diffusing fiber of claim 18, wherein the cladding comprises a polymer. 
     
     
       24. The light diffusing fiber of claim 23, wherein the polymer comprises CPC6. 
     
     
       25. The light diffusing fiber of claim 18, wherein the scattering layer comprises a polymer. 
     
     
       26. The light diffusing fiber of claim 25, wherein the polymer comprises CPC6. 
     
     
       27. The light diffusing fiber of claim 18, wherein the microparticles or nanoparticles comprise TiO2 or SiO2. 
     
     
       28. The light diffusing fiber of claim 18, further comprising a light emitting device that emits light with a wavelength from about 300 nm to about 450 nm into the core of the light diffusing fiber. 
     
     
       29. The light diffusing fiber of claim 18, wherein the phosphor layer comprises microparticles or nanoparticles of an inorganic phosphorescent or fluorescent material. 
     
     
       30. The light diffusing fiber of claim 29, wherein the inorganic phosphorescent or fluorescent material comprises CeYAG, NdYAG, quantum dots, or nanoparticles. 
     
     
       31. The light diffusing fiber of claim 18, further comprising a secondary layer in between the cladding and scattering layer. 
     
     
       32. A method of producing the light diffusing fiber of claim 18 comprising:
 forming an optical fiber preform comprising a preform core;   drawing the optical fiber preform into an optical fiber;   coating the optical fiber with at least one cladding layer; and   coating the optical fiber with at least one scattering layer.   
     
     
       33. A light diffusing fiber for emitting white light comprising:
 a core formed from a silica-based glass;   a cladding in direct contact with the core;   a scattering layer in direct contact with the cladding; and   a phosphor layer surrounding and in direct contact with the scattering layer,   wherein the emitted light comprises a combination of a scattered incident light and a scattered fluorescent or phosphorescent light, and has a uniform in color as a function of viewing angle;   wherein the scattering layer comprises a plurality of randomly distributed voids or microparticles or nanoparticles of a scattering material.   
     
     
       34. The light diffusing fiber of claim 33, wherein the scattered incident light comprises blue light. 
     
     
       35. The light diffusing fiber of claim 33, wherein the scattered incident light comprises UV light. 
     
     
       36. The light diffusing fiber of claim 33, wherein the color of the light emitted, as measured by the CIE 1931 x, y chromacity space, comprises y from about 0.26 to about 0.35, and wherein the color of the light emitted falls within the claimed CIE 1931 x, y values for all viewing angles from about 15° to about 170° relative to the direction of the light diffusing optical fiber. 
     
     
       37. The light diffusing fiber of claim 33, wherein the color of the light emitted, as measured by the CIE 1931 x, y chromacity space, comprises x from about 0.20 to about 0.30 and y from 0.26 to about 0.35. 
     
     
       38. The light diffusing fiber of claim 33, wherein the light diffusing optical fiber emits light having an intensity along the fiber that does not vary by more than about 20%. 
     
     
       39. The light diffusing fiber of claim 33, further comprising a scattering induced attenuation loss from about 0.1 dB/m to about 50 dB/m at a wavelength of 550 nm. 
     
     
       40. The light diffusing fiber of claim 33, wherein the core comprises a plurality of randomly distributed voids. 
     
     
       41. The light diffusing fiber of claim 33, wherein either one of or both the cladding and the scattering layer comprises a polymer. 
     
     
       42. The light diffusing fiber of claim 33, further comprising a light emitting device that emits light with a wavelength from about 300 nm to about 450 nm into the core of the light diffusing fiber. 
     
     
       43. The light diffusing fiber of claim 33, wherein the phosphor layer comprises microparticles or nanoparticles of an inorganic phosphorescent or fluorescent material. 
     
     
       44. The light diffusing fiber of claim 43, wherein the inorganic phosphorescent or fluorescent material comprises CeYAG, NdYAG, quantum dots, or nanoparticles. 
     
     
       45. The light diffusing fiber of claim 33, further comprising a secondary layer in between the cladding and scattering layer.