Abstract: The optical fiber transmission line according to the present invention comprises first optical fibers having dispersion values greater than the average dispersion value D.sub.av over the entire transmission distance and second optical fibers having dispersion values less than the average dispersion value D.sub.av, wherein the average dispersion value D.sub.av over the entire transmission distance is in the anomalous dispersion region, the respective lengths L.sub.i and L.sub.i ' of the first and second optical fibers are shorter than the soliton length Z.sub.0 (wherein i is an arbitrary natural number), and the relationship between the lengths L.sub.i and L.sub.i ' and the larger of the respective differences D.sub.i and D.sub.i ' between the dispersion values of the first and second optical fibers and the average dispersion value D.sub.av satisfies the following condition:(L.sub.i +L.sub.i ')/Z.sub.0 <0.35/{1+0.20(the larger of D.sub.i and D.sub.i '/D.sub.

Abstract: In the method of measuring a distribution of zero dispersion wavelengths in an optical fiber in a longitudinal direction, an optical pulse and a pump light are launched into the optical fiber. A gain generation portion of the optical fiber which indicates that the optical pulse power is amplified based on modulation instability induced by the pump light is detected from a back-scattered light waveform of the optical pulse indicative of an optical pulse power distribution in the longitudinal direction of the optical fiber. A zero dispersion wavelength of the gain generation portion of the optical fiber is determined from the pump light wavelength.