Patent ID: 7209654

Claim:
An optical transmission system in which optical repeaters are provided on a transmission line for transmitting signal light, comprising: a plurality of combined transmission line sections, each of which is composed of a first optical fiber with positive-dispersion and a second optical fiber with negative-dispersion that is located after the first optical fiber, the second optical fiber having a non-linear effect larger than the first optical fiber; and a plurality of optical repeaters, each of which is provided between an adjacent pair of the combined transmission line sections and each of which inputs pump light to an output end of the second optical fiber of a preceding combined transmission line section in the backward direction so as to obtain Raman gain in the second optical fiber, wherein the plurality of combined transmission line sections include a first combined transmission line section with positive accumulated wavelength dispersion and a second combined transmission line section with negative accumulated wavelength dispersion, and wherein the transmission line is constituted by repeating a basic pattern transmission line section, each of which is composed of one or more first combined transmission line sections and one or more second combined transmission line sections, and an accumulated wavelength dispersion of each said basic pattern transmission line section is substantially zero.