Abstract: System and method for dispersion compensation tuning for a WDM optical transmission system. A tunable dispersion compensation module (4) is located at or substantially close to a transmitting end of the optical transmission line (2) and at least one distributed Raman amplifier having an Raman pump (1) is coupled to the transmission line 2. The dispersion compensation is controlled by means of a signal derived from the Raman pump (1) which is fed through a control loop (3) to the tunable dispersion compensation module (4).

Abstract: System and method for dispersion compensation tuning for a WDM optical transmission system. A tunable dispersion compensation module (4) is located at or substantially close to a transmitting end of the optical transmission line (2) and at least one distributed Raman amplifier having an Raman pump (1) is coupled to the transmission line 2. The dispersion compensation is controlled by means of a signal derived from the Raman pump (1) which is fed through a control loop (3) to the tunable dispersion compensation module (4).

Abstract: An optical fiber amplifier is considered comprising a mono-mode core, a first cladding around said core and at least a further cladding around said first cladding while said first cladding includes a ring shaped active region doped with rare earth material surrounding said mono-mode core. Advantageously, the first cladding is designed with a radial refractive index following an almost continuous decreasing function for increasing radius. The use of a continuously decreasing refractive index for the cladding at the outer border of the ring shaped active medium optimize the efficiency of the coupling between the core and the cladding.

Abstract: An optical fiber amplifier is considered comprising a mono-mode core, a first cladding around said core and at least a further cladding around said first cladding while said first cladding includes a ring shaped active region doped with rare earth material surrounding said mono-mode core. Advantageously, the first cladding is designed with a radial refractive index following an almost continuous decreasing function for increasing radius. The use of a continuously decreasing refractive index for the cladding at the outer border of the ring shaped active medium optimize the efficiency of the coupling between the core and the cladding.

Abstract: Multiple wavelength source, in particular for optical communication employing a plurality of wavelength multiplexed channels, comprising a broadband light source (2) coupled to a discrete wavelength separator (3). The wavelength separator means (3) compromises cascaded refractive Bragg gratings (14, 15, 16, 17) each reflecting a discrete wavelength (&lgr;n, . . . , &lgr;3, &lgr;2, &lgr;1) to a source output (20).

Abstract: A C-band optical amplifier includes a fiber with a monomode core, a multimode internal cladding and an external cladding. It further includes a pump for pumping the fiber. The fiber is not doped with ytterbium and the multimode cladding has a diameter less than 55 &mgr;m. The amplifier can be used for amplifying C-band signals in wavelength division multiplex transmission systems.

Abstract: The apparatus includes a frequency-selective directing coupler (10) of the evanescent-wave type for injecting a low-frequency data-carrying wave and a high-frequency optical-pump wave that are guided by respective single-frequency waveguides (2, 4) into the same amplifying fiber (6). An isolation coupler (20) of the same type is inserted in series between the directing coupler (10) and at least one of the single-frequency waveguides (4) so as to transmit the corresponding wave selectively thereto. The invention applies in particular to making amplifiers for an optical-fiber transmission line.