Broad-bandwidth multimode optical fiber having reduced bending losses

• US 8,565,568 B2
• Filed: 03/01/2011
• Issued: 10/22/2013
• Est. Priority Date: 03/02/2010
• Status: Active Grant

• Current Assignee: Draka-Comteq USA Incorporated (Draka-Comteq)
• Original Assignee: Draka-Comteq USA Incorporated (Draka-Comteq)
• Inventors: Bigot-Astruc, Marianne, Molin, Denis, Sillard, Pierre
• Primary Examiner(s): Petkovsek, Daniel
• Application Number:
  US13/037,943
• Publication Number:
  US 20110217012A1
• Time in Patent Office: 966 Days
• Field of Search: 385123-128
• US Class Current: 385/127
• CPC Class Codes: G02B 6/0288 Multimode fibre, e.g. graded index core for compensating modal dispersion
• CPC Class Codes: G02B 6/0365 arranged - - +
• CPC Class Codes: G02B 6/03666 arranged - + - +

Abstract

A multimode optical fiber includes a central core, an inner cladding, a buried trench, and an outer cladding (e.g., an outer optical cladding). Typically, the optical fiber'"'"'s central core is a glass-based central core having an alpha-index profile (i.e., a graded-index profile), an outer radius r₁, and a maximum refractive index difference Δn₁ with respect to the outer cladding. The central core'"'"'s alpha-index profile has a minimum refractive index at the central core'"'"'s outer radius r₁ that corresponds to a refractive index difference Δn_end with respect to the outer cladding. The inner cladding has an outer radius r₂, a width w₂, and a refractive index difference Δn₂ with respect to the outer cladding. The buried trench has an outer radius r_ext, a width w₃, and a refractive index difference Δn₃ with respect to the outer cladding. The multimode optical fiber typically has reduced bending losses, a high bandwidth at wavelengths of both 850 nanometers and 1300 nanometers, and a reduced cladding effect.

Claims

1. A multimode optical fiber, comprising:

a central core surrounded by an outer cladding, said central core having (i) an outer radius r₁ of about 25±

1.5 microns, (ii) an alpha-index profile, (iii) a maximum refractive index difference Δ

n₁ with respect to said outer cladding, and (iv) at said outer radius r₁, a refractive index difference Δ

n_end with respect to said outer cladding;

an inner cladding positioned between said central core and said outer cladding, said inner cladding having (i) an outer radius r₂, (ii) a width w₂, and (iii) a refractive index difference Δ

n₂ with respect to said outer cladding; and

a buried trench positioned between said inner cladding and said outer cladding, said buried trench having (i) an outer radius r_ext, (ii) a width w₃, (iii) a refractive index difference Δ

n₃ with respect to said outer cladding, and (iv) a volume v₃;

wherein, at a wavelength of 850 nanometers, the optical fiber has an outer DMD value (0-23 microns) of less than 0.20 ps/m as measured over 750 meters of the optical fiber; and

wherein said inner cladding'"'"'s refractive index difference Δ

n₂, said inner cladding'"'"'s width w₂, and said buried trench'"'"'s refractive index difference Δ

n₃ satisfy the following inequalities;

1000×

Δ

n₃>

A×

(1000×

Δ

n₂)²+B×

(1000×

Δ

n₂)+C; and

1000×

Δ

n₃<

D×

(1000×

Δ

n₂)²+E×

(1000×

Δ

n₂)+F;

where;

A=182.29×

w₂³−

550×

w₂²+545×

w₂−

177.32,

B=−

135.42×

w₂³+402×

w₂²−

399×

w₂+130.22,

C=15×

w₂³−

57.25×

w₂²+60.9×

w₂−

25.37,

D=−

83.137×

w₂³+235.06×

w₂²−

219.52×

w₂+66.66,

E=129.56×

w₂³−

388.67×

w₂²+378.13×

w₂−

121.11, and

F=−

48.28×

w₂³+137.84×

w₂²−

129.9×

w₂+38.97.

2. A multimode optical fiber according to claim 1, wherein said inner cladding'"'"'s refractive index difference Δ

n₂, said inner cladding'"'"'s width w₂, and said buried trench'"'"'s refractive index difference Δ

n₃ satisfy the following inequality;

1000×

Δ

n₃<

G×

(1000×

Δ

n₂)²+H×

(1000×

Δ

n₂)+I;

where;

G=−

147.08×

w₂³+542×

w₂²−

678.78×

w₂+285.01,

H=472.92×

w₂³−

1771×

w₂²+2196.6×

w₂−

905.87, and

I=−

409.17×

w₂³+1476.5×

w₂²−

1778×

w₂+710.81.

3. A multimode optical fiber according to claim 1, wherein said inner cladding'"'"'s refractive index difference Δ

n₂, said inner cladding'"'"'s width w₂, and the optical fiber'"'"'s bending losses for two turns around a radius of curvature of 7.5 millimeters at a wavelength of 850 nanometers, designated PPC_{7.5 mm}, satisfy the following inequality;

J×

(1000×

Δ

n₂)+K<

PPC_{7.5 mm}<

L×

(1000×

Δ

n₂)+M,

where;

J=0.046×

w₂−

0.082,

K=−

0.206×

w₂+0.203,

L=−

0.030×

w₂−

0.221, and

M=−

0.339×

w₂+0.687.

4. A multimode optical fiber according to claim 1, wherein, for two turns around a radius of curvature of 7.5 millimeters at a wavelength of 850 nanometers, the optical fiber'"'"'s bending losses are less than 0.2 dB.

5. A multimode optical fiber according to claim 1, wherein, for two turns around a radius of curvature of 7.5 millimeters at a wavelength of 850 nanometers, the optical fiber'"'"'s bending losses are less than 0.01 dB.

6. A multimode optical fiber according to claim 1, wherein, for two turns around a radius of curvature of 7.5 millimeters at a wavelength of 1300 nanometers, the optical fiber'"'"'s bending losses are less than 0.5 dB.

7. A multimode optical fiber according to claim 1, wherein, for two turns around a radius of curvature of 7.5 millimeters at a wavelength of 1300 nanometers, the optical fiber'"'"'s bending losses are less than 0.3 dB.

8. A multimode optical fiber according to claim 1, wherein, for two turns around a radius of curvature of 7.5 millimeters at a wavelength of 1300 nanometers, the optical fiber'"'"'s bending losses are less than 0.05 dB.

9. A multimode optical fiber according to claim 1, wherein, at a wavelength of 850 nanometers, the optical fiber has an overfilled launch OFL) bandwidth of at least about 1,500 MHz·

km.

10. A multimode optical fiber according to claim 1, wherein, at a wavelength of 1300 nanometers, the optical fiber has an overfilled launch (OFL) bandwidth of at least about 500 MHz·

km.

11. A multimode optical fiber according to claim 1, wherein the optical fiber has a numerical aperture of between 0.185 and 0.215.

12. A multimode optical fiber according to claim 1, wherein said central core'"'"'s alpha-index profile has an alpha parameter of between 1.9 and 2.1.

13. A multimode optical fiber according to claim 1, wherein, at a wavelength of 850 nanometers, the optical fiber has an outer DMD value of less than 0.14 ps/m as measured over 750 meters of the optical fiber.

14. A multimode optical fiber according to claim 1, wherein said central core'"'"'s maximum refractive index difference Δ

n₁ is between about 11×

10<sup>−

3</sup> and 16×

10<sup>−

3</sup>.

15. A multimode optical fiber according to claim 1, wherein said inner cladding'"'"'s width w₂ is between about 0.5 micron and 2 microns.

16. A multimode optical fiber according to claim 1, wherein said inner cladding'"'"'s refractive index difference Δ

n₂ is between about −

0.6×

10<sup>−

3</sup> and 2×

10<sup>−

3</sup>.

17. A multimode optical fiber according to claim 1, wherein said inner cladding'"'"'s refractive index difference Δ

n₂ is at least about 0.8×

10<sup>−

3</sup>.

18. A multimode optical fiber according to claim 1, wherein said buried trench'"'"'s refractive index difference Δ

n₃ is between about −

15×

10<sup>−

3</sup> and −

3×

10<sup>−

3</sup>.

19. A multimode optical fiber according to claim 1, wherein said buried trench'"'"'s outer radius r_ext is about 32 microns or less.

20. A multimode optical fiber according to claim 1, wherein said buried trench'"'"'s width w₃ is between about 3 microns and 5 microns.

21. A multimode optical fiber according to claim 1, wherein said buried trench'"'"'s volume v₃ is between about 220%·

μ

m² and 1,200%·

μ

m².

22. A multimode optical fiber according to claim 1, wherein:

said buried trench'"'"'s width w₃ is between about 3 microns and 5 microns; and

said buried trench'"'"'s volume v₃ is between about 250%·

μ

m² and 750%·

μ

m².

23. A multimode optical system comprising at least a portion of the optical fiber according to claim 1.

24. A multimode optical fiber, comprising:

a central core surrounded by an outer cladding, said central core having (i) an outer radius r₁, (ii) an alpha-index profile, (iii) a maximum refractive index difference Δ

n₁ with respect to said outer cladding, and (iv) at said outer radius r₁, a refractive index difference Δ

_end with respect to said outer cladding;

an inner cladding positioned between said central core and said outer cladding, said inner cladding having (i) an outer radius r₂, (ii) a width w₂, and (iii) a refractive index difference Δ

n₂ with respect to said outer cladding; and

a buried trench positioned between said inner cladding and said outer cladding, said buried trench having (i) an outer radius r_ext of less than about 32 microns, (ii) a width w₃, (iii) a refractive index difference Δ

n₃ with respect to said outer cladding, and (iv) a volume v₃;

wherein, at a wavelength of 850 nanometers, the optical fiber has an outer DMD value (0-23 microns) of less than 0.20 ps/m as measured over 750 meters of the optical fiber;

wherein, at a wavelength of 1300 nanometers, the optical fiber has an overfilled launch (OFL) bandwidth of about 500 MHz·

km or greater;

wherein, for two turns around a radius of curvature of 7.5 millimeters at a wavelength of 850 nanometers, the optical fiber'"'"'s bending losses are less than 0.2 dB;

wherein, for two turns around a radius of curvature of 7.5 millimeters at a wavelength of 1300 nanometers, the optical fiber'"'"'s bending losses are less than 0.5 dB; and

wherein said inner cladding'"'"'s refractive index difference Δ

n₂, said inner cladding'"'"'s width w₂, and said buried trench'"'"'s refractive index difference Δ

n₃ satisfy the following inequalities;

1000×

Δ

n₃>

A×

(1000×

Δ

n₂)²+B×

(1000×

Δ

n₂)+C; and

1000×

Δ

n₃<

D×

(1000×

Δ

n₂)²+E×

(1000×

Δ

n₂)+F;

where;

A=182.29×

w₂³−

550×

w₂²+545×

w₂−

177.32,

B=−

135.42×

w₂³+402×

w₂²−

399×

w₂+130.22,

C=15×

w₂³−

57.25×

w₂²+60.9×

w₂−

25.37,

D=−

83.137×

w₂³+235.06×

w₂²−

219.52×

w₂+66.66,

E=129.56×

w₂³−

388.67×

w₂²+378.13×

w₂−

121.11, and

F=−

48.28×

w₂³+137.84×

w₂²−

129.9×

w₂+38.97.

25. A multimode optical fiber according to claim 24, wherein, for two turns around a radius of curvature of 7.5 millimeters at a wavelength of 850 nanometers, the optical fiber'"'"'s bending losses are less than 0.1 dB.

26. A multimode optical fiber according to claim 24, wherein, for two turns around a radius of curvature of 7.5 millimeters at a wavelength of 1300 nanometers, the optical fiber'"'"'s bending losses are less than 0.1 dB.

27. A multimode optical fiber according to claim 24, wherein, at a wavelength of 850 nanometers, the optical fiber has an overfilled launch (OFL) bandwidth of at least about 3,500 MHz·

km.

28. A multimode optical fiber according to claim 24, wherein, at a wavelength of 850 nanometers, the optical fiber has an outer DMD value of less than 0.14 ps/m as measured over 750 meters of the optical fiber.

29. A multimode optical fiber according to claim 24, wherein said inner cladding'"'"'s refractive index difference Δ

n₂ is between about 0.2×

10<sup>−

3</sup> and 2×

10<sup>−

3</sup>.

30. A multimode optical fiber according to claim 24, wherein said buried trench'"'"'s volume v₃ is between about 250%·

μ

m² and 750%·

μ

m².

31. A multimode optical system comprising at least a portion of the optical fiber according to claim 24, wherein the system has a data rate of at least 10 Gb/s over a distance of about 100 meters.

32. A multimode optical fiber, comprising:

a central core surrounded by an outer cladding, said central core having (i) an outer radius r₁, (ii) an alpha-index profile, (iii) a maximum refractive index difference Δ

n₁ with respect to said outer cladding, and (iv) at said outer radius r₁, a refractive index difference Δ

n_end with respect to said outer cladding;

an inner cladding positioned between said central core and said outer cladding, said inner cladding having (i) an outer radius r₂, (ii) a width w₂, and (iii) a refractive index difference Δ

n₂ with respect to said outer cladding; and

a buried trench positioned between said inner cladding and said outer cladding, said buried trench having (i) an outer radius r_ext, (ii) a width w₃ between about 3 microns and 5 microns, (iii) a refractive index difference Δ

n₃ with respect to said outer cladding, and (iv) a volume v₃ between about 220%·

μ

m² and 1,200%·

μ

m²;

wherein, at a wavelength of 850 nanometers, the optical fiber has an outer DMD value (0-23 microns) of less than 0.20 ps/m as measured over 750 meters of the optical fiber; and

wherein said inner cladding'"'"'s refractive index difference Δ

n₂, said inner cladding'"'"'s width w₂, and said buried trench'"'"'s refractive index difference Δ

n₃ satisfy the following inequalities;

1000×

Δ

n₃>

A×

(1000×

Δ

n₂)²+B×

(1000×

Δ

n₂)+C; and

1000×

Δ

n₃<

D×

(1000×

Δ

n₂)²+E×

(1000×

Δ

n₂)+F;

where;

A=182.29×

w₂³−

550×

w₂²+545×

w₂−

177.32,

B=−

135.42×

w₂³+402×

w₂²−

399×

w₂+130.22,

C=15×

w₂³−

57.25×

w₂²+60.9×

w₂−

25.37,

D=−

83.137×

w₂³+235.06×

w₂²−

219.52×

w₂+66.66,

E=129.56×

w₂³−

388.67×

w₂²+378.13×

w₂31 121.11, and

F=−

48.28×

w₂³+137.84×

w₂²−

129.9×

w₂+38.97.

33. A multimode optical fiber according to claim 32, wherein, for two turns around a radius of curvature of 7.5 millimeters at a wavelength of 850 nanometers, the optical fiber'"'"'s bending losses are less than 0.05 dB.

34. A multimode optical fiber according to claim 32, wherein, for two turns around a radius of curvature of 7.5 millimeters at a wavelength of 1300 nanometers, the optical fiber'"'"'s bending losses are less than 0.2 dB.

35. A multimode optical fiber according to claim 32, wherein, at a wavelength of 850 nanometers, the optical fiber has an overfilled launch (OFL) bandwidth of at least about 3,500 MHz·

km.

36. A multimode optical fiber according to claim 32, wherein, at a wavelength of 1300 nanometers, the optical fiber has an overfilled launch (OFL) bandwidth of at least about 500 MHz·

km.

37. A multimode optical fiber according to claim 32, wherein said central core'"'"'s alpha-index profile has an alpha parameter of between 1.9 and 2.1.

38. A multimode optical fiber according to claim 32, wherein, at a wavelength of 850 nanometers, the optical fiber has an outer DMD value of less than 0.14 ps/m as measured over 750 meters of the optical fiber.

39. A multimode optical fiber according to claim 32, wherein said buried trench'"'"'s outer radius r_ext is about 30 microns or less.