Low bend loss optical fiber
An optical fiber having both low macrobend loss and low microbend loss. The fiber has a MAC number less than 7.0 and a zero dispersion wavelength less than 1450 nm. The optical fiber advantageously comprises a primary coating and a secondary coating. The primary coating has a Young's modulus of less than 1.0 MPa and a glass transition temperature of less than −25° C. The secondary coating surrounds the primary coating, and the secondary coating has a Young's modulus of greater than 1200 MPa. The macrobend loss as measured by a 20 mm diameter bend test at 1550 nm is not more than 5.0 dB/m. Optical fiber ribbon and optical fiber cable that include the optical fiber is also disclosed.
1. An optical fiber comprising:
a core region having a refractive index profile;
an outermost annular cladding region surrounding the core region;
a primary coating contacting and surrounding the outer annular cladding region, the primary coating having a Young's modulus of less than 1.0 MPa and a glass transition temperature of less than −25° C.;
a secondary coating surrounding the primary coating, the secondary coating having a Young's modulus of greater than 1200 MPa;
wherein the refractive index profile is selected to provide a MAC number of not more than 7.0, a zero dispersion wavelength of less than 1450 nm, and a 20 mm diameter bend loss at 1550 nm of not more than 5.0 dB/m.
2. The optical fiber of claim 1 wherein the primary coating is a cured product of a primary curable composition including an oligomer and at least one monomer.
3. The optical fiber of claim 2 wherein the total oligomer content of the primary curable composition is between about 40 wt % and about 60 wt %.
4. The optical fiber of claim 2 wherein the total monomer content of the primary curable composition is between about 35 wt % and about 55 wt %.
5. The optical fiber of claim 1 wherein the 20 mm diameter bend loss at 1550 nm is not more than 2.0 dB/m.
6. The optical fiber of claim 1 wherein the refractive index profile is selected to further provide a 2-m fiber cutoff of less than 1400 nm.
7. The optical fiber of claim 1 wherein the refractive index profile is selected to further provide a 2-m fiber cutoff of less than 1330 nm.
8. The optical fiber of claim 1 wherein the refractive index profile is selected to further provide a zero dispersion wavelength of less than 1325 nm.
9. The optical fiber of claim 1 wherein the refractive index profile is selected to further provide a zero dispersion wavelength of between 1300 and 1325 nm.
10. The optical fiber of claim 1 wherein the refractive index profile is selected to further provide a cabled cutoff of less than 1260 nm.
11. The optical fiber of claim 1 , wherein the refractive index profile is selected to further provide a mode field diameter at 1310 nm of less than 9.0 μm.
12. The optical fiber of claim 1 wherein the refractive index profile is selected to further provide a mode field diameter at 1310 nm of between 8.2 and 9.0 μm.
13. The optical fiber of claim 1 wherein the refractive index profile is selected to further provide a mode field diameter at 1310 nm of not more than 8.6 μm.
14. The optical fiber of claim 1 wherein the refractive index profile is selected to further provide a MAC number of between 6.2 and 7.0.
15. The optical fiber of claim 1 wherein the relative refractive index profile of the core relative to the outermost annular cladding region is non-negative.
16. The optical fiber of claim 1 wherein the optical fiber has a maximum hydrogen induced attenuation change of less than 0.03 dB/km at 1383 nm after being subjected to 0.01 atm partial pressure hydrogen for at least 144 hours.
17. The optical fiber of claim 1 wherein the optical fiber has an optical attenuation at 1383 nm which is not more than 0.10 dB/km above an optical attenuation at 1310 nm.
18. The optical fiber of claim 1 wherein the 20 mm diameter bend loss at 1550 nm is not more than 0.05 dB/m.
19. An optical fiber ribbon comprising the optical fiber of claim 1 .
20. An optical fiber cable comprising the optical fiber of claim 1 .