The input of information by transmitters Tx1, Tx2 may be performed at wavelengths not included in the transmission wavelength band of network 1, since the transmitting transponders TxTs provide the signals with the correct wavelength (i.e., with the first wavelength ??x or the second wavelength ??y) Tx1, Tx2 may be, for example, a standard Sonet OC-48/SDH STM-16 terminal (produced for example by N