High chlorine content low attenuation optical fiber

1. A single mode optical fiber comprising:

a core comprising silica and greater than or equal to 1.5wt % chlorine and less than 0.6 wt % F, said core having a refractive index Δ 1MAX , and a cladding region having refractive index Δ 2MIN surrounding the core, wherein Δ 2MIN is less than or equal to about −0.04% to greater than or equal to about −0.25%, where Δ 1MAX >Δ 2MIN , and wherein said fiber is single moded at 1550 nm.

2. The optical fiber of claim 1 , wherein said cladding region comprises fluorine, and the molar ratio of chlorine in the core to fluorine in the cladding is greater than 1.

3. The single mode fiber of claim 2 , wherein said cladding comprises an inner cladding comprising fluorine and an outer cladding region surrounding the inner cladding region, said outer cladding region having refractive index Δ 3 , wherein Δ 1MAX >Δ 1 >Δ 2MIN .

4. The single mode optical fiber of claim 3 , wherein the inner cladding has an outer radius greater than or equal to about 12 microns.

5. The single mode optical fiber of claim 3 , wherein said outer cladding comprises SiON.

6. The single mode optical fiber of claim 5 , wherein an inner radius of the outer cladding is positioned greater than or equal to about 12 microns.

7. The single mode optical fiber of claim 5 , wherein the inner radius of the outer cladding is positioned greater than or equal to about 12 microns to less than or equal to about 55 microns.

8. The single mode optical fiber of claim 3 , wherein the inner cladding has an outer radius greater than or equal to about 12 microns.

9. The single mode optical fiber of claim 2 , wherein said cladding comprises from greater than or equal to about 0.1 weight % fluorine to less than or equal to about 1 weight % fluorine.

10. The single mode optical fiber of claim 1 , wherein said core comprises greater than 2wt % chlorine.

11. The single mode optical fiber of claim 1 , wherein said core comprises greater than 3wt % chlorine.

12. The single mode optical fiber of claim 1 , wherein said core comprises greater than 4wt % chlorine.

13. The single mode optical fiber of claim 1 , wherein said fiber is free of fluorine.

14. The single mode optical fiber of claim 1 , wherein the core has a maximum relative refractive index, Δ 1MAX , from greater than or equal to about 0.15% to less than or equal to about 0.5%.

15. The single mode optical fiber of claim 14 , wherein the core has a radial thickness from greater than or equal to about 3 microns to less than or equal to about 7 microns.

16. The single mode optical fiber of claim 14 , wherein the core has a radial thickness from greater than or equal to about 3 microns to less than or equal to about 7 microns.

17. The single mode optical fiber of claim 1 , wherein the single mode optical fiber has an attenuation of less than or equal to about 0.18 dB/km at a wavelength of 1550 nm.

18. The single mode optical fiber of claim 1 , wherein the single mode optical fiber has an attenuation of less than or equal to about 0.17 dB/km at a wavelength of 1550 nm.

19. The single mode optical fiber of claim 1 , wherein the single mode optical fiber has an attenuation of less than or equal to about 0.16 dB/km at a wavelength of 1550 nm.

20. The single mode optical fiber of claim 1 , wherein the single mode optical fiber has an effective area at 1550 nm of greater than or equal to about 70 microns 2 .

21. The single mode optical fiber of claim 1 , wherein the single mode optical fiber has an effective area at 1550 nm of greater than or equal to about 90 microns 2 .

22. The single mode optical fiber of claim 1 , wherein the single mode optical fiber has an effective area at 1550 nm of greater than or equal to about 110 microns 2 .

23. The single mode optical fiber of claim 1 , wherein the single mode optical fiber has an effective area at 1550 nm of greater than or equal to about 130 microns 2 .

24. The single mode optical fiber of claim 1 , wherein the single mode optical fiber has an effective area at 1550 nm of between 70 and 90 microns 2 and a bend loss of less than 1 dB/turn at 1550 nm on a 20 mm diameter mandrel.

25. The single mode optical fiber of claim 1 , wherein the single mode optical fiber has an effective area at 1550 nm of between 70 and 90 microns 2 and a bend loss of less than 0.5 dB/turn at 1550 nm on a 20 mm diameter mandrel.

26. The single mode optical fiber of claim 1 , wherein the single mode optical fiber has an effective area at 1550 nm of between 90 and 110 microns 2 and a bend loss of less than 2 dB/turn at 1550 nm on a 20 mm diameter mandrel.

27. The single mode optical fiber of claim 1 , wherein 0.15%≦Δ 1MAX ≦0.5%.

28. The single mode optical fiber of claim 1 , wherein the core has a maximum relative refractive index, Δ 1MAX , from greater than or equal to about 0.15% to less than or equal to about 0.5%.

29. A single made optical fiber comprising:

a core comprising silica and greater than or equal to 1.5wt % chlorine and less than 0.6wt % F, said core having a refractive index Δ 1MAX , and a cladding region having refractive index Δ 2MIN surrounding the core, where Δ 1MAX >Δ 2MIN , and wherein said fiber is single moded at 1550 nm, wherein the single mode optical fiber has an effective area at 1550 nm of greater than or equal to about 110 microns 2 .

30. The optical fiber of claim 29 , wherein said cladding region comprises fluorine, and the molar ratio of chlorine in the core to fluorine in the cladding is greater than 1.

31. The single mode optical fiber of claim 29 , wherein said core comprises greater than 2 wt % chlorine.

32. The single mode optical fiber of claim 29 , wherein said core comprises greater than 3 wt % chlorine.

33. The single mode optical fiber of claim 29 , wherein said fiber is free of fluorine.

34. The single mode fiber of claim 29 , wherein said cladding comprises an inner cladding comprising fluorine and an outer cladding region surrounding the inner cladding region, said outer cladding region having refractive index Δ 3 , wherein Δ 1MAX >Δ 3 >Δ 2MIN .

35. The single mode optical fiber of claim 29 , wherein the core has a radial thickness from greater than or equal to about 3 microns to less than or equal to about 7 microns.

36. The single mode optical fiber of claim 29 , wherein the inner cladding has an outer radius greater than or equal about 12 microns.

37. A single mode optical fiber comprising:

a core comprising silica and greater than or equal to 3wt % chlorine and less than 0.6wt % F, said core having a refractive index Δ 1MAX and a cladding region having refractive index Δ 2MIN surrounding the core, where Δ 1MAX >Δ 2MIN , and wherein said fiber is single moded at 1550 nm.

38. The optical fiber of claim 37 , wherein said cladding region comprises fluorine, and the molar ratio of chlorine in the core to fluorine in the cladding is greater than 1.

39. The single mode optical fiber of claim 37 , wherein said core comprises greater than 4 wt % chlorine.

40. The single mode optical fiber of claim 37 , wherein said fiber is free of fluorine.

41. The single mode fiber of claim 37 , wherein said cladding comprises an inner cladding comprising fluorine and an outer cladding region surrounding the inner cladding region, said outer cladding region having refractive index Δ 3 , wherein Δ 1MAX >Δ 2 >Δ 2MIN .

42. The single mode optical fiber of claim 37 , wherein said cladding comprises from greater than or equal to about 0.1 weight % fluorine to less than or equal to about 1 weight % fluorine.