An optical telecommunication system including a transmitting station and a receiving station for optical signals, connected with each other by an optical fiber line including optical line amplifiers having a rare-earth-doped active fiber and connected in series, in which the transmitting station includes signal generator for generating signals at several wavelengths, and connections for conveying the signals to a single optical fiber line. The optical signal receiving station includes apparatus for separating the signals. At least one of the optical line amplifiers has dopants, fiber length and pumping power capable of determining, at the input of the receiving station, an optical signal/noise ratio which for the different wavelengths has a difference less than 2 dB, and for each signal is greater than 15 dB.