Abstract: An optical communication line having a first control unit; an optical transmission fibre connected to the first control unit for transmitting an optical signal; and an optical amplification unit inserted along the optical transmission fibre for amplifying the optical signal. The optical amplification unit has an optical amplifier for amplifying the optical signal, a magneto-optical attenuator connected to the optical amplifier, and a control device for regulating the light transmissivity of the magneto-optical attenuator, wherein the first control unit has a magneto-optical attenuator and a control device for regulating the light transmissivity of the magneto-optical attenuator so as to superimpose service informations on the optical signal. In the optical amplification unit, the control device is suitable to regulate the light transmissivity of the magneto-optical attenuator so as to superimpose service informations on the optical signal.

Abstract: An optical communication system comprising a first apparatus for supplying at least three optical signals, each having a predetermined wavelength selected from a first range of wavelengths &Dgr;&lgr;; an optical transmission line, optically connected to the first apparatus, for the transmission of the at least three optical signals, the optical transmission line comprising in its turn i. at least one optical amplification system having a predetermined gain spectrum which, in the first range of wavelengths &Dgr;&lgr;, has a maximum and a minimum gain (expressed in dB), the difference between the maximum and minimum gain being &Dgr;Gtot, and ii.

Abstract: An optical communication system (1) comprising: a first apparatus for supplying at least three optical signals, each having a predetermined wavelength selected from a first range of wavelengths &Dgr;&lgr;; an optical transmission line (1000), optically connected to the said first apparatus, for the transmission of the said at least three optical signals, the said optical transmission line (1000) comprising in its turn; i. at least one optical amplification system (11) having a predetermined gain spectrum which, in the said first range of wavelengths &Dgr;&lgr;, has a maximum and a minimum gain (expressed in dB), the difference between the said maximum and minimum gain being &Dgr;Gtot; and ii.

Abstract: An underwater optical transmission system (1) comprises: a first (2) and a second (3) terminal transmission station; a branching unit (4) located between the said first and second terminal stations; a first line (5) connecting the said first station to the said branching unit, a second line (6) connecting the said branching unit to the said second terminal station; a third line (7) connecting the said branching unit to a third terminal station (8), having a first pair of optical fibers (71) connected at one end to the said branching unit.