Abstract: A method of adjusting Raman gain in an optical amplifier assembly (1a). The method comprises inputting a plurality (N) of optical signals (OS) on different wavelength channels to a backward-pumped Raman active medium (4a) pumped by means of a Raman pump source (5). The proposed method is characterized in that a slope with respect to time in a quantity representative of a respective amplified optical signal (OS?) on at least one existing/surviving channel is determined in case of channel add/drop, and in that the Raman pump source (5) is tuned depending on said change. In this way, fast and reliable Raman pump tuning can be achieved even in an optical amplifier assembly (1a) and an optical transmission system, respectively, which suffer from channel adds/drops.

Abstract: A Raman-amplified optical transmission system (1) comprises at least one transmission fiber (4) for Raman amplifying of an optical signal (S), at least one corresponding pump (5, 5.1, 5.2, 5.3) for pumping the transmission fiber (4) at a plurality of pumping wavelengths (?P1, ?P2, ?P3), at least one Lumped Raman Amplifier LRA (9, 10, 11) for imparting an additional gain on the optical signal (S), and at least one corresponding LRA pump (10, 10.1) for pumping the lumped Raman amplifier LRA. According to the present invention the LRA pump (10, 10.1) is adapted to operate at a single LRA pumping wavelength (?P3), which is essentially equal to one of the pumping wavelengths (?P3) of the pump (5, 5.3) for pumping the transmission fiber (4).

Abstract: The invention is dealing with a Raman amplifying device comprising an optical path, pump sources for generating a plurality of Raman pump signals and means for coupling the plurality of Raman pump signals into the optical path for backward pumping. The plurality of optical Raman pump signals are time-division multiplexed by multiplexing controlling means and the controlling means apply a modulation frequency beyond the corner frequency of the co-propagating modulation transfer function. The method to modulate the time division multiplexed Raman signal gives a condition to avoid the increase of double Rayleigh scattering noise.

Abstract: A Raman amplifier (10) including at least one amplifying fiber (12) and a coupler (14) for coupling at least first (16) and second (18) pump laser modules to the amplifying fiber (12), the first pump laser module (16) including a frequency discriminator (24) for selecting an optical frequency to be emitted with an optical power exceeding an optical power of remaining optical frequencies that are also emitted by the first pump laser module (16). The first optical frequency is spaced apart from a local maximum (28; 36; 48) in optical power of the remaining optical frequencies, and the second pump laser module (18) emits at an optical frequency one Stokes-frequency above the frequency of the local maximum (28; 36; 48). The first optical frequency and the frequency of the local maximum are chosen on Stokes-frequency above the signal frequency range. As a consequence, the Raman gain provided in the Raman amplifying fiber 12 is broadened.

Abstract: A two-stage Raman amplifier provides a gain control compensating for span loss variations and changing channel loading. A first amplifier stage (S1) has a first amplifying medium (F1) and a first pump light source (P1, P2, Pn), which is controlled and adjusted by a control unit (CU) to compensate for span loss variations. A second amplifier stage (S2) has a second amplifying medium (F2) and a second pump light source (P?1, P?2, P?n), which is controlled and adjusted by the control unit (CU) to balance changing channel loading.

Abstract: The invention is dealing with a Raman amplifying device comprising an optical path, pump sources for generating a plurality of Raman pump signals and means for coupling the plurality of Raman pump signals into the optical path for backward pumping. The plurality of optical Raman pump signals are time-division multiplexed by multiplexing controlling means and the controlling means apply a modulation frequency beyond the corner frequency of the co-propagating modulation transfer function. The method to modulate the time division multiplexed Raman signal gives a condition to avoid the increase of double Rayleigh scattering noise.

Abstract: Disclosed is a Raman amplifier (10) comprising at least one length of fiber (12) and at least a coupler (14) for coupling at least a first pump laser module (16) and a second pump laser module (18) to said Raman amplifying fiber (12), the first pump laser module (16) comprising a frequency discriminator (24) for selecting an optical frequency to be emitted with an optical power exceeding an optical power of remaining optical frequencies that are also emitted by said first pump laser module (16). The first optical frequency is selected to be spaced apart from a local maximum (28; 36; 48) in optical power of said remaining optical frequencies, and the second pump laser module (18) emits at an optical frequency one Stokes-frequency above the frequency of said local maximum (28; 36; 48). The firts optical frequency and the frequency of said local maximum are chosen on Stokes-frquency above the signal frequency range. As a consequence, the Raman gain provided in Raman amplifying fiber 12 is broadened.

Abstract: A system including a first polarization element configured to linearly polarize at least one beam in open space, a processing device configured to receive linearly polarized beams at an input, downline from the first polarization element, a first polarization switch downline from said processing device, wherein the processing device carries out an identical processing on two states of a same input beam. The processing device includes a multiple delay creation device with polarization switches, and the multiple delay creation device includes, on two routes (j=1,2): n polarization switches CPi, (1≦i≦n); n polarization splitters/recombiners SPi j (1≦i≦n); and n delay devices Rij (1≦i≦n).

Abstract: The disclosure relates to any field of application using processing that necessitates the reception of linearly polarized beams. In particular, the invention can be used in array antenna beam-shaping and aiming systems that use delay generation with polarization switching. The proposed system does not call for the use of polarization maintaining elements upline from the processing device, necessitating the reception of linearly polarized beams at input. The proposed system comprises: an element for the splitting of polarizations in open space, placed upline with respect to said processing device, said processing device itself, a polarization switch placed downline with respect to said processing device, an element for the superposing of polarization in open space, downline from said polarization switch.

Abstract: A bidirectional optical amplification system which includes an optical amplifier having an input and an output and configured to amplify wavelengths lying within a range of wavelengths and an optical coupling device. The optical coupling device includes a first port configured to receive a first optical wave in a first subrange of wavelengths lying within a range of wavelengths, a second port configured to receive a second optical wave in a second subrange of wavelengths lying within the range of wavelengths, an optical coupling output coupled to the input of the optical amplifier, and an optical coupling input coupled to the output of the optical amplifier.