OPTICAL FIBER, OPTICAL TRANSMISSION SYSTEM, AND METHOD OF MAKING OPTICAL FIBER

• US 20130148934A1
• Filed: 12/06/2012
• Published: 06/13/2013
• Est. Priority Date: 12/09/2011
• Status: Active Grant

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: NAKANISHI, Tetsuya, KONISHI, Tatsuya, KUWAHARA, Kazuya
• Granted Patent: US 8,687,936 B2
• Time in Patent Office: Days
• US Class Current: 385/124
• CPC Class Codes: C03B 2201/075 Hydroxyl ion (OH)
• CPC Class Codes: C03B 2201/12 doped with fluorine C03B2201/14 takes precedence
• CPC Class Codes: C03B 2201/23 doped with hydroxyl groups
• CPC Class Codes: C03B 2205/56 Annealing or re-heating the drawn fibre prior to coating
• CPC Class Codes: C03B 37/02718 Thermal treatment of the fibre during the drawing process, e.g. cooling coating C03C25/10
• CPC Class Codes: C03B 37/02727 Annealing or re-heating
• CPC Class Codes: C03C 13/045 Silica-containing oxide glass compositions
• CPC Class Codes: C03C 13/046 Multicomponent glass compositions
• CPC Class Codes: G02B 6/028 with core or cladding having graded refractive index G02B6/02033, G02B6/02295 take precedence

Abstract

Provided is an inexpensive low-loss optical fiber suitably used in an optical transmission network. An optical fiber includes a core, an optical cladding, and a jacket. The core has a relative refractive index difference between 0.2% and 0.32% and has a refractive index volume between 9%·μm² and 18%·μm². The jacket has a relative refractive index difference between 0.03% and 0.20%. Glass constituting the core has a fictive temperature between 1400° C. and 1560° C. Stress remaining in the core is compressive stress. A cutoff wavelength measured on a fiber having a length of 2 m is 1300 nm or more and a cutoff wavelength measured on a fiber having a length of 100 m is 1500 nm or less. An effective area at a wavelength of 1550 nm is 110 μm² or more. A attenuation at a wavelength of 1550 nm is 0.19 dB/km or less.

Claims

1. A silica glass optical fiber comprising:

a core including the center axis;

an optical cladding surrounding the core; and

a jacket surrounding the optical cladding,

wherein the core contains GeO₂, a relative refractive index difference Δ

core of the core is greater than or equal to 0.2% and less than or equal to 0.32%, and a refractive index volume v of the core is greater than or equal to 9%·

μ

m² and less than or equal to 18%·

μ

m², the refractive index volume v being expressed by Eq. (1)

v=2∫

₀^aΔ

(r)·

r·

dr  

 

(1)

where Δ

(r) denotes the relative refractive index difference at a radial coordinate r and a denotes the diameter of the core,

wherein the jacket has a relative refractive index difference Δ

J greater than or equal to 0.03% and less than or equal to 0.20%,

wherein glass constituting the core has a fictive temperature greater than or equal to 1400°

C. and less than or equal to 1560°

C.,

wherein stress remaining in the core is compressive stress,

wherein a cutoff wavelength measured on a fiber having a length of 2 m is greater than or equal to 1300 nm,

wherein a cutoff wavelength measured on a fiber having a length of 100 m is less than or equal to 1500 nm,

wherein an effective area at a wavelength of 1550 nm is greater than or equal to 110 μ

m², and

wherein a attenuation at a wavelength of 1550 nm is less than or equal to 0.19 dB/km.

2. The optical fiber according to claim 1, wherein

the fictive temperature is less than or equal to 1530°

C.

3. The optical fiber according to claim 1,

wherein a attenuation at a wavelength of 1550 nm is less than or equal to 0.178 dB/km, and

wherein a attenuation at a wavelength of 1310 nm is less than or equal to 0.315 dB/km.

4. The optical fiber according to claim 1, wherein

stress in part of 50% or more of the cross-sectional area of the jacket in a cross section perpendicular to the axis of the fiber is compressive stress.

5. The optical fiber according to claim 1, wherein

the absolute value of stress remaining in the core is less than or equal to 30 MPa.

6. The optical fiber according to claim 1, wherein

an increment in attenuation due to OH groups at a wavelength of 1383 nm is less than or equal to 0.02 dB/km.

7. The optical fiber according to claim 1, wherein

the core contains fluorine.

8. The optical fiber according to claim 1, wherein

the jacket has a higher viscosity than the core by 0.3 poise or more at a temperature of 1300°

C.

9. The optical fiber according to claim 1, wherein

a change in relative refractive index difference of the core during annealing for one minute or more at a temperature of 1300°

C. after drawing is greater than or equal to 0.002% and less than or equal to 0.02%.

10. The optical fiber according to claim 1, wherein

the difference in stress between the core and the optical cladding is less than or equal to 20 MPa.

11. The optical fiber according to claim 1, wherein

the optical fiber has an attenuation α

, the attenuation α

being approximated by the equation α

=A·

exp(B/λ

) in a range of wavelengths greater than or equal to 1600 nm by using least squares, where λ

denotes a wavelength and A is less than or equal to 6.5×

10¹¹ and B is greater than or equal to 48.5.

12. The optical fiber according to claim 1, further comprising:

a primary coating and a secondary coating which surround the jacket,

wherein the secondary coating has a Young'"'"'s modulus greater than or equal to 800 MPa, and

wherein the primary coating has a Young'"'"'s modulus greater than or equal to 0.2 MPa and less than or equal to 1 MPa.

13. The optical fiber according to claim 1, wherein

the optical fiber with coating has an outside diameter greater than or equal to 240 μ

m and a secondary coating has a thickness greater than or equal to 10 μ

m.

14. An optical transmission system comprising:

two repeaters; and

an optical transmission line connecting the two repeaters,

wherein the optical transmission line has a length greater than or equal to 70 km, and

wherein a section of 90% or more of the optical transmission line includes the optical fiber according to any one of claims 1 to 13.

15. An optical transmission system comprising:

an optical transmission line including the optical fiber according to any one of claims 1 to 13,

wherein signal light is distributed-Raman-amplified in the optical fiber.

16. A method of making an optical fiber, comprising:

melting and drawing an optical fiber preform in a drawing furnace,

wherein the mean temperature in cross-section of the optical fiber at the time when the drawn optical fiber emerges from the drawing furnace is greater than or equal to 1200°

C. and less than or equal to 1550°

C.

17. The optical fiber making method according to claim 16, wherein

the drawn optical fiber is allowed to, while being at a temperature at or above 1000°

C., enter a heating furnace disposed downstream from the drawing furnace.

18. The optical fiber making method according to claim 16,

wherein the optical fiber preform includes a core including the center axis, an optical cladding surrounding the core, and a jacket surrounding the optical cladding, and

wherein the concentration of OH at the interface between the optical cladding and the jacket is less than or equal to 1000 wtppm.