Methods of making an optical fiber, and optical fiber

Patent metadata

Field	Value
Publication number	US-9932260-B2
Application number	US-201615337591-A
Country	US
Kind code	B2
Filing date	Oct 28, 2016
Priority date	Oct 30, 2015
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

According to some embodiments a method of processing an optical fiber comprises the steps of: (i) drawing the fiber at a drawing rate of at least 30 m/sec; and (ii) cooling the drawn fiber in a gas at an average cooling rate less than 5000° C./s, such that said cooling reduces the temperature of the fiber from an entering temperature in the range between 1500° C. and 1700° C. to another temperature in the range between 1200° C. and 1400° C., the gas being at a temperature between 800° C. and 1500° C.; and the thermal conductivity κ of the gas being not greater than 1.5×10 −4 cal/cm-s-K for at least one temperature within a range of 800° C. to 1500° C. at one atm (atmosphere) pressure absolute.

First claim

What is claimed is:

1. A method of processing an optical fiber comprising the steps of:
(i) drawing the fiber at a drawing rate of at least 30 m/sec; and
(ii) cooling the fiber in a gas at an average cooling rate less than 5000° C./s, such that said cooling reduces the temperature of the fiber from an entering temperature in the range between 1500° C. and 1700° C. to another temperature in the range between 1200° C. and 1400° C., the gas being at a temperature between 800° C. and 1500° C.; and the thermal conductivity K of the gas being not greater than 1.5 ×10 −4 cal/cm-s-K for at least one temperature within a range of 800° C. to 1500° C. at 1 atm pressure absolute, and
(iii) further comprising: cooling said fiber at a first cooling rate, said first cooling rate greater than 5000° C./s, said cooling at said first cooling rate reducing said fiber temperature from a first temperature T 1 to a second temperature T 2 , such that T 2 <T 1 , said first temperature T 1 being in the range from 1800° C. to 2100° C. and said second temperature T 2 , being in the range from 1600° C. to 1800° C.

2. The method according to claim 1 , wherein:
the average thermal conductivity of the gas is not greater than 1.5×10 −4 cal/cm-s-K within a temperature range of 800° C. to 1500° C. at 1 atm pressure absolute.

3. The method according to claim 1 , wherein:
the thermal conductivity κ of the gas is not greater than 1.6×10 −4 cal/cm-s-K for all temperatures within a range of 800° C. to 1500° C. at 1atm pressure absolute.

4. The method of claim 3 , wherein the thermal conductivity κ of said gas at 1atm pressure absolute is not greater than 1.5×10 −4 cal/cm-s-K for all temperatures within a range of 800° C. to 1450° C.

5. The method of claim 1 , wherein the gas is being at: (i) the temperature that is between 1000° C. and 1300° C., and (ii) pressure 0.025 to 1 atm absolute.

6. The method of claim 1 , wherein the gas is Ar, Kr, Xe, or a mixture thereof; and the drawing rate is between 30 m/sec and 100 m/sec.

7. The method of claim 1 , wherein the gas is Ar, Kr, Xe, or a mixture thereof; and the drawing rate is 40 m/sec to 100 m/sec, and said cooling in said gas is performed at the average cooling rate that is between 1000° C./s and 4000° C./s, at a pressure 0.025 to 1 atm, absolute.

8. The method of claim 1 , wherein said entering temperature is higher than said another temperature by at least 100° C.

9. The method of claim 1 , wherein said entering temperature is higher than said another temperature by at least ≥200° C.

10. The method of claim 1 , wherein the drawing rate is between 40 m/sec and 100 m/sec.

11. The method of claim 1 , wherein the cooling the fiber between said entering temperature and said another temperature is performed for more than 0.1 seconds.

12. The method of claim 1 , wherein the cooling the fiber between said entering temperature and said another temperature is performed for more than 0.2 seconds.

13. The method of claim 1 , wherein cooling the fiber between said entering temperature and said another temperature is performed for more than 0.3 seconds.

14. The method of claim 1 , wherein the average cooling rate is between 1400° C./s and 3000° C./s.

15. The method of claim 1 , wherein cooling the fiber includes passing the fiber through a treatment region, said treatment region having a temperature between 800° C. and 1300° C.

16. The method of claim 1 , wherein said entering temperature ≤T 2 .

17. A method of processing an optical fiber comprising:
(i) providing the fiber drawn at a draw rate greater than 30 m/sec;
(ii) cooling the fiber at a first cooling rate, said first cooling rate being greater than 5000° C./s, said cooling at the first cooling rate reducing fiber temperature from a first temperature T 1 to a second temperature T 2 , such that T 2 <T 1 , the first temperature T 1 being in the range from 1800° C. to 2100° C. and the second temperature T 2 , being in the range from 1600° C. to 1800° C.; and
(iii) cooling said fiber in a gas at a second cooling rate, at a gas temperature between 800° C. and 1500° C., the second cooling rate being less than 5000° C./s, said cooling at said second cooling rate reducing the temperature of said fiber from a third temperature T 3 to a fourth temperature T 4 , wherein T 3 ≤T 2 , the third temperature T 3 being in the range from 1500° C. to 1700° C. and the fourth temperature T 4 being in the range from 1200° C. to 1400° C.; and wherein the thermal conductivity κ of the gas is not greater than 1.6×10 −4 cal/cm-s-K, for all temperatures between 800° C. and 1500° C. at 1atm pressure absolute.

18. The method of manufacturing an optical fiber comprising:
(i) heating a fiber preform above its softening point,
(ii) drawing the optical fiber from the heated preform at a draw rate of at least 30 m/sec; and
(iii) passing the optical fiber through two treatment stages, such that
a. the fiber enters a first treatment stage at a temperature between 1800° C. and 2100° C. and experiences an average cooling rate greater than 5000 ° C./s in the first treatment stage;
b. the optical fiber exits the first treatment stage at a temperature between 1600° C. and 1800° C.;
c. the optical fiber enters a second treatment stage downstream from the first treatment stage at a temperature between 1500° C. and 1700° C. and experiences an average cooling rate less than 5000° C./s in the second treatment stage in a gas or gas mixture having
i. a temperature between 800° C. and 1500° C. and
ii. a thermal conductivity κ that is not greater than 1.6×10 −4 cal/cm-s-K for all temperatures within a range of 800° C. to 1500° C. at 1 atm pressure absolute, and

d. the optical fiber exits the second treatment stage at a temperature between 1200° C. and 1400° C.

19. The method of claim 18 further comprising: redirecting the fiber, after the fiber exits second treatment stage, with a fluid bearing device or an air-turn device.

20. The method of claim 18 , wherein the fiber comprises:
a silica based glass core containing at least one of: GeO 2 , Cl, K 2 O; the core having a relative refractive difference with respect to silica of 0.1% to 0.45%, the core having a residual stress that is a tensile stress with a value between 0 MPa and 15 MPa; and
(ii) a silica based glass cladding surrounding the core; and a polymeric coating surrounding the cladding.

21. The method of claim 18 , wherein said cladding has at least one region having a residual stress that is a tensile stress with a value between 5 MPa and 40 MPa.

22. The optical fiber made by the method of claim 18 , wherein the fiber comprises:
(i) a silica based glass core containing at least one of: GeO 2 , Cl, K 2 O; the core having a relative refractive difference with respect to silica of 0.1% to 0.45%, the core having a residual stress that is a tensile stress with a value between 0 and 15 MPA; and
(ii) a silica based glass cladding surrounding the core having at least one region having a residual stress that is a tensile stress with a value between 5 MPa and 40 MPa;
and a polymeric coating surrounding the cladding.

23. The optical fiber made by the method of claim 18 , having a mode field diameter at 1310 nm between 8.2 microns and 9.5 microns, cable cutoff of less than 1260 nm and attenuation at 1550 nm of less than 0.18 dB/km.

24. The optical fiber of claim 18 , comprising glass core containing at least one of: GeO 2 , Cl, K 2 O; and surrou

Assignees

• Corning Inc

Inventors

• Billings Kenneth Duane
• Bookbinder Dana Craig
• Chludzinski Paul Andrew
• Moore Robert Clark
• Tandon Pushkar

Classifications

• C03B2203/224

  Mismatching coefficients of thermal expansion [CTE] of glass layers · CPC title

• C03B2201/20

  doped with non-metals other than boron or fluorine · CPC title

• C03B2201/31

  doped with germanium · CPC title

• C03B37/029

  Furnaces therefor · CPC title

• G02B6/02009

  Large effective area or mode field radius, e.g. to reduce nonlinear effects in single mode fibres · CPC title