Patent ID: 7003205

Claim:
A wide-band dispersion controlled optical fiber, characterized in that a cut-off wavelength is substantially 1285 nm or less, dispersion values are −12 to −4 ps/nm/km in a wavelength region of substantially 1285 nm to 1330 nm and 8 to 14 ps/nm/km at substantially 1625 nm wavelength, a zero dispersion wavelength is positioned in a wavelength region below substantially 1430 nm, wherein the effective cross-section area of the optical fiber at substantially 1550 nm wavelength is less than 75 μm 2 , and wherein the difference of losses between the 1550 nm wavelength and the 1625 nm wavelength is substantially 0.03 dB/km or less, wherein the wide-band dispersion controlled optical fiber includes an internal core which has a diameter d 1 and a refractive index n 1 ; an external core which encloses the internal core and has a diameter d 2 , the refractive index n 2 of the external core gradually decreasing from n 1 in the direction away from the center of the internal core; an internal clad which encloses the external core and has a diameter d 3 and a refractive index n 3 ; and an external clad which encloses the internal clad and has a refractive index n 4 , and wherein the diameters meet with the relationships of 0≦d 1 /d 2 ≦0.8 and 0.1≦d 2 /d 3 ≦0.5 and the refractive indexes meet with the relationships of n 1 >n 2 ≧n 3 ≧n 4 , 0.0034≦(n 1 –n 4 )/n 1 ≦0.007, 0≦(n 2 –n 4 )/n 2 ≦0.0048, and 0≦(n 3 –n 4 )/n 3 ≦0.0014.