Abstract: In a power feeding system for an optical transmission system used as an optical submarine cable system formed by at least two cable landing stations, a power feeding cable is provided between the cable landing stations, and a plurality of optical repeaters are provided at predetermined intervals on the optical submarine cable. The power feeding system includes at least one constant voltage source provided for one end or both ends of the power feeding cable to apply an electric potential between the power feeding cable and the ground, and another constant voltage source provided in the cable landing station. In addition, the power feeding system includes an optical repeater connected between the power feeding cable and the ground to utilize the electric potential as a supply voltage for the optical repeater itself.

Abstract: In an optical transmission line enabling definition of a fault point thereon and a method for defining the fault point, the optical transmission line includes: a plurality of optical fiber units connected in series in longitudinal direction so as to form the optical transmission line; and each of the optical fiber units having fibers with different parameters.