LOW DIAMETER OPTICAL FIBER

• US 20140308015A1
• Filed: 04/15/2013
• Published: 10/16/2014
• Est. Priority Date: 04/15/2013
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Bookbinder, Dana Craig, Dawes, Steven Bruce, Kouzmina, Inna Igorevna, Li, Ming-Jun, Tandon, Pushkar, Ocampo, Manuela
• Granted Patent: US 9,057,817 B2
• Time in Patent Office: Days
• US Class Current: 385/124
• CPC Class Codes: C08F 222/1025 of aromatic dialcohols
• CPC Class Codes: C08F 222/1067 of alcohol terminated epoxy functional polymers, e.g. epoxy(meth)acrylates
• CPC Class Codes: G02B 6/02009 Large effective area or mode field radius, e.g. to reduce nonlinear effects in single mode fibres
• CPC Class Codes: G02B 6/02395 Glass optical fibre with a protective coating, e.g. two layer polymer coating deposited directly on a silica cladding surface during fibre manufacture G02B6/02052, G02B6/02057, G02B6/024, G02B6/032, G02B6/105, G02B6/14 take precedence; coating on fibre gratings G02B6/02104; multilayer core or cladding G02B6/036; reinforcing splice joints G02B6/2558; optical cables, i.e. comprising protective structures external to the protective coating such as a jacket or plural coated optical fibres G02B6/44; coating of glass to obtain optical fibres C03C25/104
• CPC Class Codes: G02B 6/028 with core or cladding having graded refractive index G02B6/02033, G02B6/02295 take precedence
• CPC Class Codes: G02B 6/0281 Graded index region forming part of the central core segment, e.g. alpha profile, triangular, trapezoidal core G02B6/0288, G02B6/0286 take precedence
• CPC Class Codes: G02B 6/0283 Graded index region external to the central core segment, e.g. sloping layer or triangular or trapezoidal layer G02B6/0288, G02B6/0286 take precedence
• CPC Class Codes: G02B 6/0286 Combination of graded index in the central core segment and a graded index layer external to the central core segment G02B6/0288 takes precedence
• CPC Class Codes: G02B 6/03627 arranged - +
• CPC Class Codes: G02B 6/0365 arranged - - +

Abstract

Small-radius coated optical fibers having large mode field diameter and low bending losses. The coated fiber may have an outer radius of 110 μm or less, while providing a mode field diameter of 9.0 μm or greater and a bending loss when wrapped about a 15 mm mandrel of 0.5 dB/km or less at wavelength of 1550 nm. The coated fiber may have a mode field diameter of 9.2 μm or greater and may have a bending loss at 1550 nm of 0.25 dB/km or less when wrapped about a 20 mm mandrel or a bending loss at 1550 nm of 0.02 dB/km or less when wrapped about a 30 mm mandrel.

Claims

1. An optical fiber comprising:

a core, said core having an outer radius r₁;

a cladding surrounding said core, said cladding having an outer radius r₄;

a primary coating surrounding said cladding, said primary coating having an outer radius r₅, said primary coating having an in situ modulus of 0.50 MPa or less; and

a secondary coating surrounding said primary coating, said secondary coating having an outer radius r₆, said secondary coating having an in situ modulus of 1500 MPa or greater;

wherein said outer radius r₆ is 110 μ

m or less and said fiber has a mode field diameter of 9 μ

m or greater at 1310 nm and exhibits a bend loss at a wavelength of 1550 nm, when turned about a mandrel having a diameter of 15 mm, of less than 0.5 dB/turn.

2. The fiber of claim 1,

wherein said cladding includes an inner cladding region having an outer radius r₃ and an outer cladding region surrounding said inner cladding region and having said outer radius r₄, said inner cladding region having a refractive index Δ

₃ with a minimum value Δ

_3MIN, said outer cladding region having a refractive index Δ

₄ with a minimum value Δ

_4MIN>

Δ

_3MIN.

3. The fiber of claim 2, wherein said inner cladding region is directly adjacent to said core and said refractive index Δ

₃ is substantially constant between said outer radius r₁ and said outer radius r₃.

4. The fiber of claim 2, wherein said inner cladding region is directly adjacent to said core, said refractive index Δ

₃ decreasing linearly between said outer radius r₁ and said outer radius r₃.

5. The fiber of claim 4, wherein said outer cladding region is directly adjacent said inner cladding region and said refractive index Δ

₄ is substantially constant between said outer radius r₃ and said outer radius r₄.

6. The fiber of claim 1, wherein said cladding includes a first inner cladding region having an outer radius r₂, a second inner cladding region surrounding said first inner cladding region and having an outer radius r₃, and an outer cladding region surrounding said second inner cladding region and having said outer radius r₄, said first inner cladding region having a refractive index Δ

₂ with a minimum value Δ

_2MIN, said second inner cladding region having a refractive index Δ

₃ with a minimum value Δ

_3MIN<

Δ

_2MIN, said outer cladding region having a refractive index Δ

₄ with a minimum value Δ

_4MIN>

Δ

_3MIN.

7. The fiber of claim 6, wherein second inner cladding region is directly adjacent said first inner cladding region and said refractive index Δ

₃ is substantially constant between said outer radius r₂ and said outer radius r₃.

8. The fiber of claim 6, wherein second inner cladding region is directly adjacent said first inner cladding region and said refractive index Δ

₃ decreases linearly between said outer radius r₂ and said outer radius r₃.

9. The fiber of claim 1, wherein said outer radius r₄ is at least 60 μ

m.

10. The fiber of claim 1, wherein said outer radius r₅ is 85 μ

m or less.

11. The fiber of claim 1, wherein said outer radius r₆ is 100 μ

m or less.

12. The fiber of claim 1, wherein said fiber exhibits a bend loss at a wavelength of 1550 nm, when turned about a mandrel having a diameter of 20 mm, of less than 0.25 dB/turn.

13. The fiber of claim 1, wherein said fiber has a cable cutoff wavelength of 1260 nm or less and a zero dispersion wavelength λ

₀ in the range 1300 nm≦

λ

₀≦

1324 nm.

14. The fiber of claim 1, wherein said cladding includes a depressed index region, said depressed index region having a moat volume with a magnitude between 30% μ

m² and 80% μ

m².

15. The fiber of claim 1, wherein said primary coating has an in situ modulus of 0.20 MPa or less.

16. The fiber of claim 1, wherein said secondary coating has an in situ modulus of 1800 MPa or greater.

17. The fiber of claim 1, wherein said primary coating has a glass transition temperature of less than −

15°

C.

18. The fiber of claim 1, wherein said primary coating has a glass transition temperature higher than −

50°

C.

19. The fiber of claim 1, wherein said primary coating has a glass transition temperature higher than −

60°

C.

20. The fiber of claim 1, wherein said primary coating is the cured product of a primary composition that includes a urethane acrylate oligomer and a monomer selected from the group consisting of (meth)acrylates, N-vinyl amides, and epoxy acrylates.

21. The fiber of claim 20, wherein said primary composition comprises one or more monofunctional (meth)acrylate monomers in an amount of from about 5 to 95% by weight;

an N-vinyl amide monomer in an amount of from about 0.1 to 40% by weight; and

one or more difunctional urethane acrylate oligomers which comprise a polyol and an isocyanate, said oligomer present in an amount of from about 5 to 95% by weight, wherein the polyol in said oligomer is a polypropylene glycol and the isocyanate in said oligomer is an aliphatic diisocyanate.

22. The fiber of claim 20, wherein said primary composition comprises one or more monofunctional (meth)acrylate monomers in an amount of from about 40 to 65% by weight;

an N-vinyl amide monomer in an amount of from about 2 to 10% by weight; and

one or more polypropylene glycol-based difunctional urethane acrylate oligomers in an amount of from about 35 to 60% by weight.

23. The fiber of claim 1, wherein said secondary coating is the cured product of a secondary composition that lacks urethane-containing oligomers.

24. The fiber of claim 23, wherein said secondary composition comprises a monomer selected from the group consisting of alkoxylated bisphenol-A diacrylate, alkylene glycol acrylate, and epoxy diacrylate.

25. The fiber of claim 24, wherein said secondary composition comprises:

about 40 to 80% by weight of ethoxylated (4) bisphenol A monomer;

from about 0 to about 30% by weight of ethoxylkated (10) bisphenol A monomer;

from about 0 to about 25% by weight of ethoxylated (30) bisphenol A monomer; and

from about 5 to 18% by weight of epoxy acrylate