Optical fiber and method for fabricating same

Abstract

Disclosed is a method for fabricating an optical fiber having attenuation loss, in which non-uniformity of the attenuation loss in the lengthwise direction of the optical fiber is equal to or less than 0.05 dB/km in the wavelength band of 1383 nm and an average value of the attenuation loss is equal to or less than 0.35 dB/km. The method comprising the steps of (a) fabricating a soot preform while maintaining an average temperature of a core surface at a level equal to or less than 1000° C. and temperature variation of the core surface according to a growing length of the soot preform in a range of −10 to 10° C./cm, fabricating an optical fiber preform by dehydrating, consolidating and vitrifying the soot preform and (c) drawing the optical fiber from the optical fiber preform under a temperature range between 1900 to 2300° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1A is a graph illustrating the relationship between regional attenuation loss and average attenuation loss;

FIG. 1B is a graph illustrating the difference of regional attenuation loss obtained from the relationship between regional attenuation loss and average attenuation loss shown in FIG. 1a;

FIG. 2 is a graph illustrating the wave style non-straight line (P_wave);

FIG. 3 is a graph illustrating the step style non-straight line;

FIGS. 4A and 4B are graphs illustrating regional attenuation loss of optical fiber fabricated according to the present invention in a wavelength band of 1383 nm;

FIG. 5 is a graph illustrating the wave style non-straight line of optical fiber according to the present invention;

FIG. 6 is a view illustrating an apparatus and a method for fabricating a soot preform through vapor-phase axial deposition;

FIG. 7 is a view illustrating an apparatus and a method for fabricating a soot preform through outside vapor-phase axial deposition;

FIGS. 8A and 8B are graphs illustrating the surface temperature of a core of a soot preform measured along the length of the core of the soot preform, which is grown through vapor-phase axial deposition; and

FIG. 9 is a view illustrating the procedure of sintering and vitrifying a soot preform in the lengthwise direction of the soot preform through a zone sintering method.

Claims

1. An optical fiber, in which non-uniformity of attenuation loss in a lengthwise direction of the optical fiber is equal to or less than 0.05 dB/km at a wavelength band of 1383 nm and an average value of the attenuation loss is equal to or less than 0.35 dB/km.

2. The optical fiber as claimed in claim 1, wherein the non-uniformity of attenuation loss of the optical fiber includes a difference between regional attenuation loss and average attenuation loss of the optical fiber at a predetermined region in a lengthwise direction of the optical fiber.

3. The optical fiber as claimed in claim 1, wherein the non-uniformity in a lengthwise direction of the optical fiber includes a wave style non-straight line.

4. The optical fiber as claimed in claim 1, wherein the non-uniformity in a lengthwise direction of the optical fiber includes a step style non-straight line.

5. An optical fiber, in which non-uniformity of attenuation loss in a lengthwise direction of the optical fiber is equal to or less than 0.10 dB/km at a wavelength band of 1383 nm, an average value of the attenuation loss is equal to or less than 0.35 dB/km, a chromatic dispersion coefficient is in a range of 1.5 to 8.0 ps/nmkm, a maximum single mode cutoff wavelength is 1340 nm, and a maximum polarization mode dispersion is 0.20 ps/nmkm1/2 at a wavelength band of 1383 nm.

6. A method for fabricating an optical fiber, the method comprising the steps of: (a) fabricating a soot preform while maintaining an average temperature of a core surface at a level equal to or less than 1000° C. and temperature variation of the core surface according to a growing length of the soot preform in a range of −10 to 10° C./cm;(b) fabricating an optical fiber preform by dehydrating, consolidating and vitrifying the soot preform; and(c) drawing the optical fiber from the optical fiber preform under a temperature range between 1900 to 2300° C.

7. The method as claimed in claim 6, wherein, in step (b), the soot preform is dehydrated for 12 minutes to 6 hours under an inert gas atmosphere including 0.3 to 10 volume percent of Cl2 while maintaining an average temperature of the soot preform in a range of 900 to 1300° C., in which He is used as inert gas and density of oxygen is maintained at a level less than 30 ppm.

8. The method as claimed in claim 6, wherein, in step (b), the soot preform is consolidated and vitrified while maintaining a consolidation velocity at a level equal to or lower than 1/10th the diameter of the soot preform/min.

9. The method as claimed in claim 6, wherein, in step (b), the soot preform is consolidated and vitrified under a vacuum atmosphere of about 10 torr or less by uniformly applying heat over a whole area of the soot preform such that the whole area of the soot preform is simultaneously sintered in a lengthwise direction thereof while maintaining an average temperature of the soot preform in a range of 1100 to 1500° C. and the standard deviation of a temperature on the soot preform at a level equal to or less than 10° C. in the lengthwise direction of the soot preform.

10. A method for fabricating an optical fiber, the method comprising the steps of: (a) fabricating a soot preform while maintaining an average temperature of a core surface at a level equal to or less than 1000° C./cm and the standard deviation of a temperature on the core surface at a level equal to or less than 10° C. in a lengthwise direction of the core surface;(b) fabricating an optical fiber preform by dehydrating, consolidating and vitrifying the soot preform; and(c) drawing the optical fiber from the optical fiber preform under a temperature range between 1900 to 2300° C.