Claims
- 1. A method of making an optical fiber containing a fluorine doped region comprising:
heat treating a porous soot preform, the preform substantially devoid of any sintered glass layer, to a temperature of greater than about 1200° C.; and exposing the preform to an atmosphere comprising a fluorine containing compound, wherein the time and the temperature of said exposing step is controlled so that Φ comprises≧about 1 wherein Φ is defined as Rmax/(D/k)½, wherein Rmax is the outer radius of the preform, D is the diffusion coefficient of the fluorine containing compound into the preform, and k is the reaction rate constant of the reaction between the fluorine and the soot, thereby controlling the radial penetration of fluorine into the preform.
- 2. The method according to claim 1 wherein said heat treating step further comprises an atmosphere substantially devoid of any halide containing compound.
- 3. The method according to claim 1 wherein said Φ comprises≧about 2.
- 4. The method according to claim 1 wherein the soot preform is substantially devoid of a physical interface.
- 5. The method according to claim 1 wherein the pressure during said exposing comprises about atmospheric pressure.
- 6. The method according to claim 1 wherein said heat treating step results in an average reduction in pore size of at least about 25%.
- 7. The method according to claim 1 wherein said exposing step occurs at a temperature different than the temperature of said heat treating step.
- 8. The method according to claim 1 wherein the porous soot preform comprises at least two regions, a germanium doped first region when sintered having a Δ1 and a second region when sintered having a Δ2 which surrounds the first region, wherein Δ1 is ≧Δ2.
- 9. The method according to claim 1 wherein a time period for said heat treating comprises at least about 30 minutes.
- 10. The method according to claim 1 wherein said exposing occurs at a temperature that comprises at least about 1225° C.
- 11. The method according to claim 1 wherein a density of the porous soot preform comprises about 0.2 to about 1.2 g/cm.
- 12. The method according to claim 1 further comprising sintering the soot preform and drawing the sintered preform into a cane.
- 13. The method according to claim 1 wherein the soot preform is formed by depositing a first region of silica soot doped with a refractive index increasing dopant and a second region of undoped silica soot on a starting member.
- 14. A method of making an optical fiber containing a fluorine doped region comprising:
heat treating a porous soot preform, the preform substantially devoid of any sintered glass layer, to a temperature of at least about 1250° C.; and doping the soot blank with fluorine at a doping temperature of at least about 1300° C. such that a radial gradient of fluorine doping across the soot blank is great enough to result in a fiber having a change in delta, across a radial fluorine doped region, that is less than about −0.25% with respect to the cladding, where Δa−=(na2−nb2)/(2na2), na being the refractive index of the fluorine-doped glass and nb being the refractive index of the cladding.
- 15. The method according to claim 14 wherein the doping temperature comprises at least about 1320° C.
- 16. The method according to claim 14 wherein a thickness of the fluorine doped region comprises less than about 80% of the radius for the entire preform.
- 17. A method of making an optical fiber containing a fluorine doped region comprising:
depositing fluorine doped silica soot on a starting member to form a soot preform having at least one fluorine doped soot region; and heating the soot preform at a rate of more than about 10° C./min to a temperature of more than about 1300° C.
- 18. The method according to claim 17 wherein the temperature of said heating step comprises at least about 1350° C.
- 19. The method according to claim 17 wherein the rate comprises at least about 20° C./min.
- 20. The method according to claim 17 further comprising depositing at least one doped soot region on the starting member wherein the dopant is one selected from the group consisting of Ge, Sb, P, Bi, Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, and mixtures thereof.
- 21. The method according to claim 17 wherein an atmosphere of said heating step comprises at least one inert gas.
- 22. A method of making an optical fiber containing a fluorine doped region comprising:
heating a preform having at least one region of fluorine doped soot at a rate of more than about 10° C./min to a temperature of more than about 1400° C.
- 23. The method according to claim 22 wherein the temperature comprises more than about 1450° C.
- 24. The method according to claim 22 wherein an atmosphere of said heat treating comprises an atmosphere substantially devoid of any reactive material.
- 25. The method according to claim 22 wherein said heat treating comprises sintering the preform.
- 26. The method according to claim 22 further comprising depositing at least one doped soot region on a starting member wherein the dopant is one selected from the group consisting of Ge, Sb, P, Bi, Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, and mixtures thereof.
- 27. A method of making an optical fiber containing a fluorine doped region comprising:
heat treating a porous soot preform, the preform substantially devoid of any sintered glass layer to a first temperature; and exposing the preform to an atmosphere comprising a fluorine containing compound at a second temperature, wherein the rate of reaction between the fluorine and the soot and the rate of diffusion of the fluorine compound into the preform are both temperature dependent and an increase in the rate of reaction as a function of increasing temperature comprises more than an increase in rate of diffusion as a function of increasing temperature, thereby controlling the radial penetration of fluorine into the preform.
- 28. The method according to claim 27 wherein the soot preform is substantially devoid of a physical interface.
- 29. The method according to claim 27 wherein the pressure during said exposing step comprises about atmospheric pressure.
- 30. The method according to claim 27 wherein said heat treating step results in an average reduction in pore size of at least about 25% of the pores of the porous preform.
- 31. The method according to claim 27 wherein the first temperature and the second temperature are different.
- 32. The method according to claim 27 wherein the first temperature and the second temperature are about the same.
- 33. The method according to claim 27 wherein the first temperature comprises a temperature of at least above about 1200° C. and said heat treating takes place for a time period of at least about 30 minutes.
- 34. The method according to claim 33 wherein said second temperature comprises at least about 1225° C.
- 35. The method according to claim 27 wherein the soot preform is formed by depositing a first region of silica soot doped with a refractive index increasing dopant and a second region of undoped silica soot on a starting member.
- 36. A method of making an optical fiber containing a fluorine doped region comprising:
depositing at least one region of fluorinated doped soot on a starting member forming a porous soot preform; heat treating the porous soot preform to a temperature of greater than about 1200° C. for a period of at least about twenty minutes, wherein the time and the temperature of said heat treating step is controlled so that Φ comprises≧about 1 wherein Φ is defined as Rmax/(D/k)½ wherein Rmax is the outer radius of the preform, D is the diffusion coefficient of the fluorine containing compound into the preform, and k is the reaction rate constant of the reaction between the fluorine and the soot, thereby controlling the radial penetration of fluorine into the preform.
- 37. The method according to claim 36 wherein said Φ comprises≧about 2.
- 38. The method according to claim 36 wherein said Φ comprises≧about 10.
- 39. The method according to claim 36 wherein the soot preform comprises a barrier layer.
- 40. The method according to claim 36 further comprising drying the soot preform with a drying gas that includes a chlorine containing compound including at least one silicon or germanium element.
- 41. The method according to claim 36 further comprising forming a barrier layer in the soot preform.
- 42. The method according to claim 36 further comprising depositing at least one region of silica soot doped with a refractive index increasing dopant and at least one region of undoped silica soot on the starting member, whereby the at least one region of undoped silica soot located between the at least one region of silica soot doped with the refractive index increasing dopant and the at least one region of fluorine doped silica soot.
- 43. The method according to claim 36 wherein said heat treating temperature comprises at least about 1225° C.
- 44. The method according to claim 36 wherein the soot preform comprises more than about 1 barrier layer.
- 45. The method according to claim 36 wherein said heat treating includes sintering the porous soot preform.
- 46. The method according to claim 36 further comprising sintering the perform.
- 47. The method according to claim 36 further comprising drawing the soot preform into a cane and depositing soot onto an outer surface of the cane.
- 48. A method of making an optical fiber containing at least one fluorine doped region comprising:
exposing a preform having at least one region of soot to a fluorine containing atmosphere in a furnace; and heating the soot preform in the fluorine containing atmosphere from a first temperature to a doping temperature at a rate of more than 10° C. per minute.
- 49. The method of claim 48 wherein the rate comprises at least about 20° C. per minute.
- 50. The method of claim 48 wherein the rate comprises at least about 25° C. per minute.
- 51. The method of claim 48 wherein a transition time period from the first temperature to the doping temperature comprises no more than about 30 minutes.
- 52. The method of claim 48 wherein the doping temperature comprises more than about 1225° C.
- 53. The method of claim 48 wherein the doping temperature comprises at least about 1250° C.
- 54. The method of claim 48 wherein the first temperature comprises no more than about 1100° C.
- 55. The method of claim 48 wherein the doping temperature comprises a temperature up to about 1450° C. and further comprising discharging the fluorine atmosphere from the furnace and maintaining the temperature at about 1450° C.
- 56. A method of making an optical fiber containing at least one fluorine doped region comprising:
exposing a preform, having at least one region of soot, to a fluorine containing atmosphere in a furnace; and heating the soot preform in the fluorine containing atmosphere from a starting temperature to a doping temperature at a rate at least about 20° C. per minute.
- 57. The method of claim 56 wherein the rate comprises at least about 25° C. per minute.
- 58. The method of claim 56 wherein a transition time period from the first temperature to the doping temperature comprises no more than about 30 minutes.
- 59. The method of claim 56 wherein the doping temperature comprises more than about 1225° C.
- 60. The method of claim 56 wherein the doping temperature comprises at least about 1250° C.
- 61. The method of claim 56 wherein the first temperature comprises no more than about 1100° C.
- 62. The method of claim 56 wherein the doping temperature comprises a temperature up to about 1450° C. and further comprising discharging the fluorine atmosphere from the furnace and maintaining the temperature at about 1450° C.
- 63. A method of making an optical fiber containing at least one fluorine doped region comprising:
heat treating a porous soot preform, the preform substantially devoid of any sintered glass layer, from a first temperature to a second temperature, increasing the temperature from said first temperature to said second temperature at a rate of more than about 10° C. per minute; and doping at least one region of the preform with fluorine at a doping temperature of greater than about 1225° C.
- 64. The method according to claim 63 further comprising forming the porous soot preform by depositing at least one region of silica soot doped with germanium on a starting member and depositing at least one region of undoped silica soot on a starting member.
- 65. The method according to claim 63 wherein the second temperature and the doping temperature comprises the same numerical value.
- 66. The method according to claim 63 wherein said second temperature comprises a temperature of more than about 1225° C.
- 67. The method according to claim 64 further comprising sintering the preform and drawing the preform into a cane, wherein a plot of fluorine concentration of a cross section of the cane, in terms of fluorine weight percent and a normalized radius, exhibits at least one segment between the germanium doped region of the cane and the fluorine doped region of the cane having a slope with an absolute value of more than about 2.5 wt % F.
- 68. The method according to claim 67 wherein said slope comprises at least about 5.
- 69. The method according to claim 67 wherein said slope comprises at least about 16.
- 70. The method according to claim 63 wherein the second temperature and the doping temperature each comprise a temperature of more than about 1250° C.
- 71. The method according to claim 64 further comprising sintering the preform and drawing the preform into a fiber, wherein a plot of fluorine concentration of a cross section of the fiber, in terms of fluorine weight percent and a normalized radius, exhibits at least one segment between the germanium doped region of the fiber and the fluorine doped region of the fiber having a slope with an absolute value of more than about 2.5 wt % F.
- 72. The method according to claim 71 wherein said slope comprises at least about 5.
- 73. The method according to claim 71 wherein said slope comprises at least about 16.
- 74. A method of making an optical fiber containing at least one fluorine doped region comprising:
a first heating step of heating at least one region of a soot preform to a first temperature of more than about 1300° C. in a furnace; cooling the at least one region of the soot preform to a cooling temperature above 1100° C., wherein the cooling temperature comprises a temperature lower than the first temperature; exposing the soot preform to a fluorine containing atmosphere; and a second heating step of heating the soot preform in the fluorine containing atmosphere to a second temperature, said second temperature comprises a temperature higher than said cooling temperature.
- 75. The method according to claim 74 further comprising maintaining the temperature in the furnace at the first temperature for a sufficient period of time for the soot preform to reach an isothermal temperature of more than about 1225° C.
- 76. The method according to claim 75 wherein said time period comprises no more than about 30 minutes.
- 77. The method according to claim 75 wherein the isothermal temperature comprises the first temperature.
- 78. The method according to claim 74 wherein a rate of heating the preform from the cooling temperature to the second temperature comprises at least about 20° C. per minute.
- 79. The method according to claim 78 wherein the rate comprises at least about 25° C. per minute.
- 80. The method according to claim 74 wherein said first heating step comprises increasing the temperature to the first temperature at a rate of at least about 20° C. per minute.
- 81. The method according to claim 74 wherein said first heating step comprises increasing the temperature to the first temperature at a rate of at least about 30° C. per minute.
- 82. The method according to claim 74 wherein said cooling temperature comprises at least about 1200° C.
- 83. The method according to claim 74 wherein said cooling temperature comprises less than about 1300° C.
- 84. The method according to claim 74 further comprising sintering the soot preform in the fluorine containing atmosphere.
- 85. The method according to claim 74 further comprising drying the soot preform at a temperature of no more than about 1100° C. prior to said first heating step.
- 86. A method of making an optical fiber containing at least one fluorine doped region comprising:
a) a first heating step of heating at least one region of a soot preform to a first temperature in a furnace; b) cooling the at least one region of the soot preform to a cooling temperature, in an atmosphere substantially devoid of chlorine, the cooling temperature comprises a temperature of less than the first temperature; c) exposing the soot preform to a fluorine containing atmosphere; and d) a second heating step of heating the soot preform in the fluorine containing atmosphere to a second temperature, said second temperature comprises a temperature higher than cooling temperature.
- 87. The method according to claim 86 further comprising maintaining the temperature in the furnace at the first temperature for a sufficient period of time for the soot preform to reach an isothermal temperature.
- 88. The method according to claim 86 further comprising sintering the soot preform in the fluorine containing atmosphere.
- 89. The method according to claim 86 wherein the first temperature comprises at least about 1300° C.
- 90. The method according to claim 86 wherein the cooling temperature comprises more than 1100° C.
- 91. The method according to claim 86 further comprising repeating steps a and b at least once prior to said exposing step.
- 92. A method of making an optical fiber containing at least one fluorine doped region comprising:
a first heating step of heating at least one region of a soot preform to a first temperature of more than about 1300° C. in a furnace; maintaining the soot preform at a first temperature for a period of time sufficient for the soot preform to reach an isothermal temperature; cooling the soot preform for a time period of less than about 60 minutes, such that a temperature of the at least one region of the soot preform comprises a cooling temperature, wherein the cooling temperature comprises a temperature of less than the first temperature; exposing the soot preform to a fluorine containing atmosphere; and a second heating step of heating the soot preform in the fluorine containing atmosphere to a second temperature, said second heating step comprises increasing the temperature in the furnace from the cooling temperature to the second temperature at a rate of more than about 20° C. per minute.
- 93. The method according to claim 92 wherein said cooling temperature comprises about 1200° C. or more.
- 94. The method according to claim 92 wherein the rate comprises at least about 30° C. per minute.
- 95. The method according to claim 74 further comprising sintering the preform and drawing the preform into a cane having a central core region of undoped silica soot and a fluorine doped region, wherein a plot of fluorine weight percent of a cross section of the cane, in terms of wt % of Fluorine and a normalized radius, exhibits at least one segment between the central core region of the cane and the fluorine doped region of the cane having a slope with an absolute value of more than about 2.5 wt %.
- 96. The method according to claim 95 wherein the slope comprises more than about 5.0
- 97. The method according to claim 95 wherein the slope comprises more than about 16.0.
- 98. The method according to claim 86 further comprising sintering the preform and drawing the preform into a cane having a central core region of undoped silica soot and a fluorine doped region, wherein a refractive index profile of a cross section of the cane, in terms of delta percent and a normalized radius, exhibits at least one segment between the central core region of the cane and the fluorine doped region of the cane having a slope with an absolute value of more than about 2.5%.
- 99. The method according to claim 98 wherein the slope comprises more than about 5.0
- 100. The method according to claim 98 wherein the slope comprises more than about 16.0
- 101. The method according to claim 74 further comprising repeating said first heating step and said cooling step.
CROSS-REFERENCE To RELATED APPLICATIONS
[0001] The benefit of priority to the following applications, (1) U.S. patent application Ser. No. 60/257,341, filed Dec. 20, 2000 entitled Fluorine Doping A Soot Preform to Dawes et al., (2) U.S. patent application Ser. No. 60/274,803, filed Mar. 9, 2001 entitled Fluorine Doping A Soot Preform, and (3) U.S. patent application Ser. No. 60/295,360 filed Jun. 1, 2001 entitled Fluorine Doping A Soot Preform the content of which is relied upon and which are incorporated herein by reference in their entirety.
Provisional Applications (3)
|
Number |
Date |
Country |
|
60257341 |
Dec 2000 |
US |
|
60274803 |
Mar 2001 |
US |
|
60295360 |
Jun 2001 |
US |