Optical fiber with macrobend loss mitigating layer

1. An optical fiber comprising:

(i) a core comprising silica and having a maximum relative refractive index delta Δ coreMAX ; and LP01 effective area >100 μm 2 at 1550 nm;

(ii) an annular inner cladding surrounding the core and having a minimum relative refractive index delta Δ 2MIN and Δ coreMAX >Δ 2MIN ;

(iii) an annular outer cladding surrounding the inner cladding and comprising

(a) a first outer cladding portion with a maximum refractive index Δ 3A such that Δ 3A >Δ 2MIN ; and

(b) another outer cladding portion surrounding the first outer cladding portion with a maximum refractive index delta Δ 3B wherein

Δ coreMAX >Δ 3B >Δ 3A , said another outer cladding portion being the outermost portion of the outer cladding; and

(iv) a coating layer surrounding the outer cladding, and in contact with said another outer cladding portion, the coating layer having a relative refractive index delta Δ C wherein Δ C >Δ 3B , wherein, wherein said inner cladding portion is in contact with said core,

−0.7%<Δ 2MIN <−0.2%, 3%>Δ C −Δ 3B ≧0.02% and said fiber has macrobend loss <0.03 dB/turn at 50 mm bend diameter, macrobend loss <0.003 dB/turn at 60 mm bend diameter, and macrobend loss of <0.001 dB/turn at 75 mm bend diameter.

2. The optical fiber of claim 1 , wherein −0.55%<Δ 2MIN <−0.35%.

3. An optical fiber comprising:

(i) a core comprising silica and having a maximum relative refractive index delta Δ coreMAX ; and LP01 effective area >100 μm 2 at 1550 nm;

(ii) an annular inner cladding surrounding the core and having a minimum relative refractive index delta Δ 2MIN , and Δ coreMAX >Δ 2MIN , wherein −0.7%<Δ 2MIN <−0.2%, measured relative to pure silica;

(iii) an annular outer cladding surrounding the inner cladding and comprising

a first outer cladding portion with a maximum refractive index Δ 3A such that Δ 3A −Δ 2MIN ≧0.02%; and

another outer cladding portion surrounding the first outer cladding portion with a maximum refractive index delta Δ 3B wherein Δ coreMAX >Δ 3B and

Δ 3B −Δ 3A ≧0.07%, said another outer cladding portion being the outermost portion of the outer cladding; and

(iv) a coating layer surrounding the outer cladding portion, and in contact with said another outer cladding portion, the coating layer having a relative refractive index delta Δ C wherein Δ C >Δ 3B , wherein said fiber has macrobend loss <0.03 dB/turn at 50 mm bend diameter, macrobend loss <0.003 dB/turn at 60 mm bend diameter, and macrobend loss of <0.001 dB/turn at 75 mm bend diameter.

4. The optical fiber of claim 3 , wherein the core comprises a maximum relative refractive index, Δ coreMAX relative to silica, from between −0.05% and 0.5%.

5. The optical fiber of claim 4 , wherein the core comprises essentially no germania.

6. The optical fiber of claim 5 , wherein the difference between the refractive index delta of the coating layer and said another outer cladding portion is 2.2%≧Δ C −Δ 3B ≧0.02%.

7. The optical fiber of claim 3 , wherein the core comprises less than 0.1 weight % germania.

8. The optical fiber of claim 3 , wherein the optical fiber has an attenuation of less than or equal to about 0.17 dB/km at a wavelength of 1550 nm.

9. The optical fiber of claim 3 , wherein said another outer cladding portion is the second outer cladding portion, and said second outer cladding portion has a radial thickness from greater than or equal to about 2 microns to less than or equal to about 25 microns and is situated in contact with the first outer cladding portion and the coating layer.

10. The optical fiber of claim 3 , wherein the core has a radial thickness from greater than or equal to about 3 microns to less than or equal to about 10 microns.

11. The optical fiber of claim 3 , wherein the inner cladding has a radial thickness from greater than or equal to about 5 microns.

12. The optical fiber of claim 3 , wherein the first outer cladding portion is surrounding the inner cladding, the first outer cladding portion has a relative refractive index Δ 3A , and Δ 3A −Δ 2MIN >0.05%.

13. The optical fiber of claim 12 , wherein the second outer cladding portion has a radial thickness from greater than or equal to about 2 microns to less than or equal to about 25 microns.

14. The optical fiber of claim 3 , wherein the refractive index of the coating is 1.45 to 1.5 at 1550 nm.

15. An optical fiber comprising:

(i) a core comprising silica and having a maximum relative refractive index delta Δ coreMAX ; and LP01 effective area >100 μm 2 at 1550 nm;

(ii) an annular inner cladding surrounding the core and having a minimum relative refractive index delta Δ 2MIN , and Δ coreMAX >Δ 2MIN , wherein −0.7% Δ 2MIN <−0.2%, measured relative to pure silica;

(iii) an annular outer cladding surrounding the inner cladding and comprising

a first outer cladding portion with a maximum refractive index Δ 3A such that Δ 3A −Δ 2MIN ≧0.02%; and

another outer cladding portion surrounding the first outer cladding portion with a maximum refractive index delta Δ 3B wherein Δ coreMAX >Δ 3B and

Δ 3B −Δ 3A ≧0.07%, said another outer cladding portion being the outermost portion of the outer cladding; and

(iv) a coating layer surrounding the outer cladding portion, and in contact with said another outer cladding portion, the coating layer having a relative refractive index delta Δ C wherein Δ C >Δ 3B , wherein the optical fiber has dispersion less than or equal to about 23 ps/nm·km at a wavelength of 1550 nm.

16. An optical fiber comprising:

(i) a core comprising silica and having a maximum relative refractive index delta Δ coreMAX ; and LP01 effective area >100 μm 2 at 1550 nm;

(ii) an annular inner cladding surrounding the core and having a minimum relative refractive index delta Δ 2MIN , and Δ coreMAX >Δ 2MIN , wherein −0.7%<Δ 2MIN <−0.2%, measured relative to pure silica;

(iii) an annular outer cladding surrounding the inner cladding and comprising

a first outer cladding portion with a maximum refractive index Δ 3A such that Δ 3A −Δ 2MIN ≧0.02%; and

another outer cladding portion surrounding the first outer cladding portion with a maximum refractive index delta Δ 3B wherein Δ coreMAX >Δ 3B and

Δ 3B −Δ 3A ≧0.07%, said another outer cladding portion being the outermost portion of the outer cladding; and

(iv) a coating layer surrounding the outer cladding portion, and in contact with said another outer cladding portion, the coating layer having a relative refractive index delta Δ C wherein Δ C >Δ 3B , wherein the optical fiber is a single mode optical fiber and has cable cutoff <1530 nm.

17. An optical fiber comprising:

(i) a core comprising silica and having a maximum relative refractive index delta Δ coreMAX ; and LP01 effective area >100 μm 2 at 1550 nm;

(ii) an annular inner cladding surrounding the core and having a minimum relative refractive index delta Δ 2MIN , and Δ coreMAX >Δ 2MIN , wherein −0.7%<Δ 2MIN <−0.2%, measured relative to pure silica;

(iii) an annular outer cladding surrounding the inner cladding and comprising

a first outer cladding portion with a maximum refractive index Δ 3A such that Δ 3A −Δ 2MIN ≧0.02%; and

another outer cladding portion surrounding the first outer cladding portion with a maximum refractive index delta Δ 3B wherein Δ coreMAX >Δ 3B and

Δ 3B −Δ 3A ≧0.07%, said another outer cladding portion being the outermost portion of the outer cladding; and

(iv) a coating layer surrounding the outer cladding portion, and in contact with said another outer cladding portion, the coating layer having a relative refractive index delta Δ C wherein Δ C >→ 3B , wherein the difference between the refractive index delta of the coating layer and said another outer cladding portion is 0.9%>Δ C −Δ 3B ≧0.5%.

18. The optical fiber of claim 17 , wherein said fiber has macrobend loss <0.03 dB/turn at 50 mm bend diameter, macrobend loss <0.003 dB/turn at 60 mm bend diameter, and macrobend loss of <0.001 dB/turn at 75 mm bend diameter.

19. The optical fiber of claim 17 , wherein the difference between the refractive index delta of the coating layer and said another outer cladding portion is 0.85%≧Δ C −Δ 3B ≧0.6%.

20. An optical fiber comprising:

(i) a core comprising silica and having a maximum relative refractive index delta Δ coreMAX from between −0.05% and 0.5%; and LP01 effective area >100 μm 2 at 1550 nm;

(ii) an annular inner cladding surrounding the core and having a minimum relative refractive index delta Δ 2MIN , and Δ coreMAX >Δ 2MIN , wherein −0.7%<Δ 2MIN <−0.2%, measured relative to pure silica;

(iii) an annular outer cladding surrounding the inner cladding and comprising

a first outer cladding portion with a maximum refractive index Δ 3A such that Δ 3A −Δ 2MIN ≧0.02%; and

another outer cladding portion surrounding the first outer cladding portion with a maximum refractive index delta Δ 3B wherein Δ coreMAX >Δ 3B and

Δ 3B −Δ 3A ≧0.07%, said another outer cladding portion being the outermost portion of the outer cladding; and

(iv) a coating layer surrounding the outer cladding portion, and in contact with said another outer cladding portion, the coating layer having a relative refractive index delta Δ C wherein Δ C >Δ 3B , wherein the difference between the refractive index delta of the coating layer and said another outer cladding portion is 1.5%>Δ C −Δ 3B ≧0.5%; and the difference between the refractive index delta of the another outer cladding portion and said first outer cladding portion is 1.0%>Δ 3B −Δ 3A ≧0.05%.

21. An optical fiber comprising:

(i) a core comprising silica and having a maximum relative refractive index delta Δ coreMAX ; and LP01 effective area >100 μm 2 at 1550 nm;

(ii) an annular inner cladding surrounding the core and having a minimum relative refractive index delta Δ 2MIN , and Δ coreMAX >Δ 2MIN , wherein

−0.7%<Δ 2MIN <−0.2%, measured relative to pure silica;

(iii) an annular outer cladding surrounding the inner cladding and comprising

a first outer cladding portion with a maximum refractive index Δ 3A such that Δ 3A −Δ 2MIN ≧0.02%; and

another outer cladding portion surrounding the first outer cladding portion with a maximum refractive index delta Δ 3B wherein Δ coreMAX >Δ 3B and

Δ 3B −Δ 3A ≧0.07%, said another outer cladding portion being the outermost portion of the outer cladding; and

(iv) a coating layer surrounding the outer cladding portion, and in contact with said another outer cladding portion, the coating layer having a relative refractive index delta Δ C wherein Δ C >Δ 3B , wherein the core comprises a maximum relative refractive index, Δ coreMAX relative to silica, from between −0.05% and 0.5% and essentially no germania, and the refractive index of the coating layer is 1.45 to 1.51 at 1550 nm and wherein Δ C −Δ 3B ≧0.5%; and the difference between the refractive index delta of the another outer cladding portion and said first outer cladding portion is 1.0%≧Δ 3B −Δ 3A ≧0.05%.