Patent ID: 7233728

Claim:
A dispersion-compensated optical fiber, which, when operated in at least a wavelength which is selected from 1.53 μm to 1.63 μm, exhibits the following: a bending loss of 5 dB/m or lower with a 20-mm bending diameter, a wavelength dispersion of −120 ps/nm/km or lower, an absolute value of the wavelength dispersion per a unit loss is 200 ps/nm/dB or higher, a cut-off wavelength for used length and used condition is 1.53 μm or lower, an outer diameter of a cladding is 80 μm to 100 μm, an outer diameter of a coating of 160 μm to 200 μm, said dispersion, optical fiber comprising: a center core section; an intermediate core section, disposed on an outer periphery of the center core section; a ring core section, disposed on an outer periphery of the intermediate core section; and a cladding, disposed on an outer periphery of the ring core section; wherein the relative refractive index difference of the center core section with respect to the cladding is about 1.6% to 2.6%; a relative refractive index difference of the intermediate core section with respect to the cladding is about 0.30% to 1.4%; a relative refractive index of the ring core section with respect to the cladding is about 0.30% to 1.0%; a ratio of the outer radius of the intermediate core section to the outer radius of the center core section is about 1.5 to 3.5; a ratio of the outer radius of the ring core section to the outer radius of the intermediate core section is about 1.2 to 2.0, and the radius of the core is about 4 μm to 8 μm.