Connection with amplifying optical fibers

Claim 1

A transmission line comprising: a plurality of optical fibers extending in succession along the length of said line to guide an optical carrier wave carrying a signal to be transmitted, said optical fibers being divided into groups having respective doping concentrations of a dopant, including at least a first group having a non-zero doping concentration for amplifying said carrier wave and said signal in response to a pump wave having a pump frequency that is different from said carrier frequency to thereby compensate for attenuation of said carrier wave and of said signal, a succession of pump injectors following one another along the length of said transmission line to thereby delimit sections of said transmission line, each said section including a respective said injector at one end of the respective section for injecting a respective said pump wave into said respective section, at least two of said optical fibers of said first group and collectively occupying a first fraction comprising more than 20% of the length of said each section, and at least one of said optical fibers of a second group of optical fibers each having a second said doping concentration lower than said first doping concentration and collectively occupying a second fraction comprising more than 10% of the length of said each section; wherein within each said section one optical fiber of the first group is directly coupled to said respective injector and is followed by an optical fiber of the second group that is indirectly coupled to said respective injector via said one optical fiber of the first group.