Low bend loss optical fiber
Disclosed herein are optical waveguide fibers comprising: (I) a core comprising an outer radius r 1 , a maximum refractive index delta percent Δ 1max and core alpha, α, of larger than 5; and (II) a cladding surrounding the core, the cladding comprising: (i) an inner cladding region having outer radius r 2 and refractive index delta percent Δ 2 , wherein Δ 1max >Δ 2 ; (ii) a trench region surrounding the inner cladding region, the trench region having an outer radius, r 3 where r 3 ≥10 microns and refractive index delta percent Δ 3 ; and (iii) an outer cladding region having chlorine concentration of ≥1.2 wt. % surrounding the trench region and comprising refractive index delta percent Δ 4 , wherein Δ 1max >Δ 4 and Δ 2 >Δ 3 , and Δ 4 >Δ 3 and wherein the difference between Δ 4 and Δ 3 is ≥0.12 percent.
1. A single mode optical fiber comprising:
(I) a core having outer radius r 1 , a maximum refractive index delta percent Δ 1max and core alpha>5;
(II) a cladding surrounding the core, the cladding comprising
(i) inner cladding region having outer radius r 2 and refractive index delta percent Δ 2 , wherein Δ 1max >Δ 2 ; and
(ii) a trench region surrounding the inner cladding region, the trench region having an outer radius r 3 >10 microns and refractive index delta percent Δ 3 ; and
(iii) an outer cladding region having chlorine concentration larger than 1.2 wt. % surrounding the trench region and comprising refractive index delta percent Δ 4 ; wherein Δ 1max >Δ 4 and Δ 2 >Δ 3 , and Δ 4 >Δ 3 and wherein the Δ 4 −Δ 3 ≥0.12 percent, and said fiber exhibits a MAC number ≥7.25 at 1310 nm wavelength, cable cutoff of less than 1260 nm, and bend loss at 1550 nm for a 15 mm diameter mandrel of less than 0.5 dB/turn, and 1300 nm≤λ 0 ≤1324 nm, where λ 0 is the zero dispersion wavelength.
2. The optical fiber of claim 1 , wherein the MAC number ≥7.6 at 1310 nm wavelength.
3. The optical fiber of claim 1 , wherein the MAC number ≥7.7 at 1310 nm wavelength.
4. The optical fiber of claim 1 , wherein the bend loss for a 30 mm mandrel diameter is less than 0.005 dB/turn at 1550 nm.
5. The optical fiber of claim 1 , wherein the bend loss for a 30 mm mandrel diameter is less than 0.003 dB/turn at 1550 nm.
6. The optical fiber of claim 1 , wherein a maximum refractive index delta percent Δ 1 <0.65%.
7. The optical fiber of claim 1 , wherein refractive index delta percent Δ 3 is between −0.4% and 0.1%.
8. The Optical fiber of claim 1 , wherein the trench region has a width W 1 between 4 microns and 22 microns.
9. The optical fiber of claim 1 , wherein the profile volume, |V 3 | of the trench region is at least 30% Δmicron 2 .
10. The optical fiber of claim 1 , wherein the profile volume, |V 3 | of the trench region is at least 45% Δmicron 2 .
11. The optical fiber of claim 1 , wherein Δ 4 −Δ 3 ≥0.15 percent.
12. The optical fiber of claim 1 , wherein Δ 1max −Δ 2 0.25 percent, and Δ 1max −Δ 3 ≥0.35; and Δ 2 −Δ 3 ≥0.08 percent.
13. The optical fiber of claim 12 , wherein 0.15%≤Δ 4 −Δ 3 ≤0.4% delta.
14. The optical fiber of claim 1 , wherein the core has less than 10 wt. % germania.
15. The optical fiber of claim 1 , wherein the maximum germania concentration in the core region, [Ge02] core-max , in weight percent is 4 wt. %≤[Ge02] core-max ≤13 wt. %.
16. The optical fiber of claim 1 , wherein the maximum germania concentration in the core region, [Ge02] core-max , in weight percent is 6 wt. %≤[Ge02] core-max ≤12 wt %.
17. The optical fiber of claim 1 , wherein the maximum germania concentration in the core region, [Ge02] core-max ,in weight percent is 7 wt. %≤[Ge02] core-max ≤11 wt. %.
18. The optical fiber of claim 1 , wherein the maximum chlorine concentration in the core region, [Cl] core-max , in weight percent is 1 wt. %≤[Cl] core-max ≤7 wt. %.
19. The optical fiber of claim 1 , wherein the maximum chlorine concentration in the core region, [Cl] core-max , in weight percent is 1 wt. %≤[Cl] core-max ≤6 wt. %.
20. The optical fiber of claim 1 , wherein the maximum chlorine concentration in the core region, [Cl] core-max , in weight percent is 1.5 wt. %≤[Cl] core-max ≤6 wt. %.
21. The optical fiber of claim 1 , wherein the trench region contains 0 to 2 wt. % fluorine.
22. The optical fiber of claim 1 , wherein the outer cladding region comprises Cl concentration ≥1.5 weight percent.
23. The optical fiber of claim 1 , wherein the ratio of core radius to the inner cladding radius, 1.2<r 2 /r 1 <2.5.
24. The optical fiber of claim 1 , said fiber further exhibiting a wire mesh covered drum microbend loss at 1550 nm which is less than or equal to 0.05 dB/km.
25. The optical fiber of claim 1 , said fiber further exhibiting a wire mesh covered drum microbend loss at 1550 nm which is less than or equal to 0.01 dB/km.
26. The optical fiber of claim 1 , wherein the trench region is essentially free of fluorine and germania.
27. The optical fiber of claim 1 , wherein Δ 4 ≥Δ 2 for a radial position extending from r 3 to a radius of at least 30 microns.
28. The fiber of claim 1 , wherein said fiber exhibits an attenuation at 1550 nm which is less than or equal to 0.18 dB/km.
29. The fiber of claim 1 , wherein said fiber exhibits an attenuation at 1310 nm which is less than or equal to 0.32 dB/km.
30. The fiber of claim 1 , wherein the core alpha is greater than 10.
31. The optical fiber of claim 1 , wherein 9 microns<MFD at 1310 nm<9.5 microns.
32. The optical fiber of claim 1 , said fiber further exhibiting a basketweave microbend loss at −60° C. at 1550 nm which is less than or equal to 0.05 dB/km.
33. The optical fiber of claim 1 , said fiber further exhibiting a basketweave microbend loss at −60° C. at 1550 nm which is less than or equal to 0.01 dB/km.
34. The optical fiber of claim 1 , said fiber further is coated with primary and secondary coatings, wherein the outer diameter of the secondary coating is less than 250 microns.
35. The optical fiber of claim 34 , wherein the primary coating has Young's modulus of less than 1 MPa and the secondary coating has Young's modulus of greater than 1000 MPa.
36. The optical fiber of claim 1 , said fiber further is coated with primary and secondary coatings, wherein the outer diameter of the secondary coating is less than 210 microns.
37. The optical fiber of claim 36 , wherein the primary coating has Young's modulus of less than 1 MPa and the secondary coating has Young's modulus of greater than 1000 MPa.
38. The optical fiber of claim 1 , wherein the outer cladding region comprises a first outer cladding region with refractive index delta percent Δ4 and chlorine concentration larger than 1.2 wt. % ; and a second outer cladding region surrounding the first outer cladding region and comprising refractive index delta percent Δ5 such that Δ4>Δ5, the second outer cladding region having chlorine concentration of less than 0.5 wt. %.
39. The optical fiber of claim 38 , wherein viscosity of glass of said second outer cladding region is greater than the viscosity of glass of said first outer cladding region.