Super-large-effective-area (SLA) optical fiber and communication system incorporating the same

• US 6,904,218 B2
• Filed: 05/12/2003
• Issued: 06/07/2005
• Est. Priority Date: 05/12/2003
• Status: Active Grant

• Current Assignee: Furukawa Electric North America Incorporated (Furukawa Electric Company Limited)
• Original Assignee: Fitel USA Corporation
• Inventors: Sun, Yi, Wu, Fengqing, Peckham, David W.
• Primary Examiner(s): Ullah, Akm Enayet
• Assistant Examiner(s): Wood, Kevin S.
• Application Number:
  US10/435,855
• Publication Number:
  US 20040228593A1
• Time in Patent Office: 757 Days
• Field of Search: 385123-129
• US Class Current: 385/127
• CPC Class Codes: G02B 6/02014 Effective area greater than 60 square microns in the C band, i.e. 1530-1565 nm
• CPC Class Codes: G02B 6/02019 Effective area greater than 90 square microns in the C band, i.e. 1530-1565 nm
• CPC Class Codes: G02B 6/02266 Positive dispersion fibres at 1550 nm
• CPC Class Codes: G02B 6/0228 Characterised by the wavelength dispersion slope properties around 1550 nm G02B6/02228 takes 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 6/03611 Highest index adjacent to central axis region, e.g. annular core, coaxial ring, centreline depression affecting waveguiding
• CPC Class Codes: G02B 6/03627 arranged - +
• CPC Class Codes: G02B 6/0365 arranged - - +
• CPC Class Codes: G02B 6/03666 arranged - + - +

Abstract

A super-large-effective-area (SLA) optical fiber that is suitable for communicating over a wide wavelength range and that, because of its large effective area, suppresses nonlinear effects that typically result from interaction between signal channels. The effective area, A_eff, of the SLA fiber of the present invention preferably is equal to or greater than approximately 80 μm² at a wavelength window around 1310 nm. The cutoff wavelength of the SLA fiber of the present invention preferably is less than 1310 nm. Thus, the SLA fiber of the present invention has a very large effective area and a very low cutoff wavelength. In accordance with the present invention, a variety of SLA fibers are provided that all have very large effective areas and desirable transmission properties. The large effective areas of the SLA fibers of the present invention enable nonlinear effects to be suppressed, as well as Stimulated Brillouin Scattering in analog transmission. The large effective areas also enable attenuation to be reduced. The result of suppressing nonlinear effects and reducing attenuation enable signals to be transmitted over long distances and over a broad bandwidth.

Claims

1. An optical fiber communications system, comprising:

at least one source of optical energy;

an optical fiber cable comprising an optical fiber having a positive dispersion and a positive dispersion slope, the optical fiber cable being coupled to said at least one source of energy, the optical fiber having a core region and a cladding region surrounding the core region, the fiber having an effective area, A_eff, that is equal to or greater than approximately 80 micrometers squared (μ

m²) at a wavelength of approximately 1310 nm and having a cable cutoff wavelength less than or equal to approximately 1310 nm, wherein the core region is segmented into at least first and second refractive index portions, the first and second refractive index portions having first and second relative indexes of refraction n_1a and n_1b, respectively, that are different from each other, and wherein the first and second relative indexes of refraction are positive.

2. The optical fiber communications system of claim 1, wherein the optical fiber has an effective area, A_eff, that is equal to or greater than approximately 95 μ

m² at a wavelength of approximately 1550 nm.

3. The optical fiber communications system of claim 1, wherein the optical fiber further includes:

a trench region between the core region and the cladding region, the trench region having a negative relative index of refraction n₂.

4. The optical fiber communications system of claim 3, wherein the core region having the first and second refractive index portions has a relative refractive index profile defined by the equations:

$n_{1<br><br>a}<br><br>\left(0\le <br><br>r\le <br><br>a_1\right)={\left(\frac{r}{a_1}\right)}^{{\mathrm{\alpha <br><br>}}_1}\times <br><br>n_{\max }$$n_{1<br><br>b}<br><br>\left(a_1\le <br><br>r\le <br><br>\left(a_1+a_2\right)\right)=\left[1-{\left(\frac{r-a_1}{a_2}\right)}^{{\mathrm{\alpha <br><br>}}_2}\right]\times <br><br>n_{\max }$

where r is a radius position in micrometers, where n_max is the maximum relative refractive index of the core region, where a₁ is a radius of the first portion of the core region, where a₂ is a thickness of the second portion of the core region, where n_1a is a relative refractive index of the first portion of the segmented core region, where n_1b is a relative refractive index of the second portion of the segmented core region, where a₁+a₂ is a radius r of the core region, where a₃ is a width of the trench region, and where a₁+a₂+a₃ is a radius out to an outer edge of the trench region adjacent a beginning of the cladding region.

5. The optical fiber communications system of claim 4, wherein a₁≧

1 is an exponential that dictates the shape of the refractive index profile of the core region.

6. The optical fiber communications system of claim 4, wherein approximately 0≦

a₁≦

2.65, approximately 7.1≦

a₁+a₂≦

10, and approximately 3≦

a₃≦

25, where a₁, a₂ and a₃ are in units of micrometers.

7. The optical fiber communications system of claim 4, wherein approximately 0.25%≦

n_max≦

0.42%.

8. The optical fiber communications system of claim 4, wherein approximately −

0.4%≦

n₂≦

−

0.075%.

9. The optical fiber communications system of claim 1, wherein the optical fiber has a macrobending loss that is less than or equal to approximately 10 decibels per meter (dB/m).

10. The optical fiber communications system of claim 1, wherein the optical fiber has an attenuation loss that is less than or equal to approximately 0.19 decibels per kilometer (dB/km) at a wavelength of approximately 1550 nm and that is less than or equal to approximately 0.35 dB/km at a wavelength of approximately 1310 nm.

11. The optical fiber communications system of claim 1, wherein the optical fiber has a dispersion of approximately 20 picoseconds per kilometer.nanometer (ps/km.nm).

12. The optical fiber communications system of claim 1, wherein the optical fiber has a ratio of dispersion to dispersion slope (RDS) of approximately 0.0031 nm⁻

1.

13. A super-large effective area (SLA) optical fiber, the SLA fiber having a positive dispersion and a positive dispersion slope and having an effective area, A_eff, that is equal to or greater than approximately 80 μ

m² at a wavelength of approximately 1310 nm and having a cable cutoff wavelength less than or equal to approximately 1310 nm, the fiber having a core region and a cladding region surrounding the core region, wherein the core region is segmented into at least first and second refractive index portions, the first and second refractive index portions having first and second relative indexes of refraction n_1a and n_1b, respectively, that are different from each other, and wherein the first and second relative indexes of refraction are positive.

14. The optical fiber of claim 13, wherein the optical fiber has an effective area, A_eff, that is equal to or greater than approximately 95 micrometers squared (μ

m²) at a wavelength of approximately 1550 nm.

15. The optical fiber of claim 14, wherein the optical fiber further includes:

a trench region between the core region and the cladding region, the trench region having a negative relative index of refraction n₂.

16. The optical fiber of claim 15, wherein the core region having the first and second refractive index portions has a relative refractive index profile defined by the equations:

$n_{1<br><br>a}<br><br>\left(0\le <br><br>r\le <br><br>a_1\right)={\left(\frac{r}{a_1}\right)}^{{\mathrm{\alpha <br><br>}}_1}\times <br><br>n_{\max }$$n_{1<br><br>b}<br><br>\left(a_1\le <br><br>r\le <br><br>\left(a_1+a_2\right)\right)=\left[1-{\left(\frac{r-a_1}{a_2}\right)}^{{\mathrm{\alpha <br><br>}}_2}\right]\times <br><br>n_{\max }$

where r is a radius position in micrometers, where n_max is the maximum relative refractive index of the core region, where a₁ is a radius of the first portion of the core region, where a₂ is a thickness of the second portion of the core region, where n_1a is a relative refractive index of the first portion of the segmented core region, where n_1b is a relative refractive index of the second portion of the segmented core region, where a₁+a₂ is a radius r of the core region, where a₃ is a width of the trench region, and where a₁+a₂+a₃ is a radius out to an outer edge of the trench region adjacent a beginning of the cladding region.

17. The optical fiber of claim 16, wherein a₁≧

1 is an exponent that dictates the shape of the refractive index profile of the core region.

18. The optical fiber of claim 16, wherein approximately 0≦

a₁≦

2.65, approximately 7.1≦

a₁+a₂≦

10, and approximately 3≦

a₃≦

25, where a₁, a₂ and a₃ are in units of micrometers.

19. The optical fiber of claim 16, wherein approximately 0.25%≦

n_max≦

0.42%.

20. The optical fiber of claim 16, wherein approximately −

0.4%≦

n₂≦

−

0.075%.

21. The optical fiber of claim 13, wherein the optical fiber has a macrobending loss that is less than or equal to approximately 10 decibels per meter (dB/m).

22. The optical fiber of claim 13, wherein the optical fiber has an attenuation loss that is less than or equal to approximately 0.19 decibels per kilometer (dB/km) at a wavelength of approximately 1550 nm and that is less than or equal to approximately 0.35 dB/km at a wavelength of approximately 1310 nm.

23. The optical fiber of claim 13, wherein the optical fiber has a dispersion of approximately 20 picoseconds per kilometer.nanometer (ps/km.nm).

24. The optical fiber of claim 13, wherein the optical fiber has a ratio of dispersion to dispersion slope (RDS) of approximately 0.0031 nm⁻

1.

25. A super-large effective area (SLA) optical fiber, the SLA fiber having a positive dispersion and a positive dispersion slope and having an effective area, A_eff, that is equal to or greater than approximately 90 μ

m² at a wavelength of approximately 1310 nm and having a cable cutoff wavelength less than or equal to approximately 1270 nm, the fiber having a core region and a cladding region surrounding the core region.

26. The optical fiber of claim 25, wherein the optical fiber has an effective area, A_eff, that is equal to or greater than approximately 95 micrometers squared (μ

m²) at a wavelength of approximately 1550 nm.

27. The optical fiber of claim 26, wherein the optical fiber further includes:

a trench region between the core region and the cladding region, the trench region having a negative relative index of refraction n₂.

28. The optical fiber of claim 27, wherein the trench region has a first trench portion and a second trench portion, the first and second trench portions having negative relative refractive indices which are different.

29. The optical fiber of claim 28, wherein the core region has a radius a₁ that extends from the center of the core region outwardly toward the cladding region approximately 6 micrometers, and wherein the first trench portion has a radius a₂ that extends outwardly from the center of the core region toward the cladding region of approximately 18 micrometers to approximately 24 micrometers, and wherein the second trench portion has a radius a₃ that extends outwardly from the center of the trench region toward the cladding region to approximately 30 micrometers to approximately 45 micrometers.

30. The optical fiber of claim 25, wherein the optical fiber has a macrobending loss at 20 millimeter diameter that is less than or equal to approximately 10 decibels per meter (dB/m).

31. The optical fiber of claim 25, wherein the optical fiber has a dispersion of approximately 18 to 20 picoseconds per kilometer.nanometer (ps/km.nm).

32. The optical fiber of claim 25, wherein the optical fiber has a dispersion slope of approximately 0.060 to approximately 0.065 picoseconds per nanometer squared.kilometer (ps/nm²/km).

33. The optical fiber of claim 25, wherein the optical fiber has a ratio of dispersion to dispersion slope (RDS) of approximately 0.003 nm⁻

1±

−

0.0005 nm<sup>−

1</sup>.

34. The optical fiber of claim 25, wherein the core region has a maximum relative refractive index of between approximately 0.25% and approximately 0.32%.

35. The optical fiber of claim 25, wherein the first portion of the trench region has a relative refractive index of approximately −

0.08% to approximately −

0.02%.

36. The optical fiber of claim 25, wherein the first portion of the trench region has a relative refractive index of approximately −

0.02% to approximately 0.08%.

37. A super-large effective area (SLA) optical fiber, the SLA fiber having a positive dispersion and a positive dispersion slope and having an effective area, A_eff, that is equal to or greater than approximately 90 μ

m² at a wavelength of approximately 1310 nm and having a cable cutoff wavelength less than or equal to approximately 1270 nm, the fiber having a core region and a cladding region surrounding the core region, the SLA fiber having a relatively low attenuation at a wavelength of approximately 1380 nm.

38. The optical fiber of claim 37, wherein the optical fiber has an effective area, A_eff, that is equal to or greater than approximately 95 micrometers squared (μ

m²) at a wavelength of approximately 1550 nm.

39. The optical fiber of claim 38, wherein the optical fiber further includes:

a trench region between the core region and the cladding region, the trench region having a negative relative index of refraction n₂.

40. The optical fiber of claim 39, wherein the trench region has a first trench portion and a second trench portion, the first and second trench portions having negative relative refractive indices which are different.

41. The optical fiber of claim 40, wherein the core region has a radius a₁ that extends from the center of the core region outwardly toward the cladding region approximately 6 micrometers, and wherein the first trench portion has a radius a₂ that extends outwardly from the center of the core region toward the cladding region of approximately 18 micrometers to approximately 24 micrometers, and wherein the second trench portion has a radius a₃ that extends outwardly from the center of the trench region toward the cladding region to approximately 30 micrometers to approximately 45 micrometers.

42. The optical fiber of claim 37, wherein the optical fiber has a macrobending loss at 20 millimeter diameter that is less than or equal to approximately 10 decibels per meter (dB/m).

43. The optical fiber of claim 37, wherein the optical fiber has a dispersion of approximately 18 to 20 picoseconds per kilometer.nanometer (ps/km.nm).

44. The optical fiber of claim 37, wherein the optical fiber has a dispersion slope of approximately 0.060 to approximately 0.065 picoseconds per nanometer squared.kilometer (ps/nm²/km).

45. The optical fiber of claim 37, wherein the optical fiber has a ratio of dispersion to dispersion slope (RDS) of approximately 0.003 nm⁻

1±

−

0.0005 nm<sup>−

1</sup>.

46. The optical fiber of claim 37, wherein the core region has a maximum relative refractive index of between approximately 0.25% and approximately 0.32%.

47. The optical fiber of claim 37, wherein the first portion of the trench region has a relative refractive index of approximately −

0.08% to approximately −

0.02%.

48. The optical fiber of claim 37, wherein the first portion of the trench region has a relative refractive index of approximately −

0.02% to approximately 0.08%.