Alcatel

Thales

Alcatel Lucent

Dominique Annie Mongardien

Dominique Bayart

Thierry Zami

Catherine Martinelli

Eric Estebe

Philippe Richin

Eric Goutain

A method of adjusting Raman gain in an optical amplifier assembly (). The method comprises inputting a plurality (N) of optical signals (OS) on different wavelength channels to a backward-pumped Raman active medium () pumped by means of a Raman pump source (). 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 () is tuned depending on said change. In this way, fast and reliable Raman pump tuning can be achieved even in an optical amplifier assembly () and an optical transmission system, respectively, which suffer from channel adds/drops.

Method and an optical amplifier assembly for adjusting Raman gain

An optical signal amplifier comprises a Semiconductor Optical Amplifier SOA used as semiconductor Amplified Spontaneous Emission ASE source. This SOA produces optical pumping seed which has to be amplified to get a large pump power. With such large pump power, it will be possible to counteract the loss in a fiber link of optical signals transmitted through it by applying said amplified pumping seed as Raman amplification on the optical signals. The invention further relates to a method for amplifying an optical signal comprising the combination of a semiconductor ASE source together with a high-power pump source. Latter will be used to amplify optical pumping seed to be produced by the semi-conductor ASE source. Accordingly, the obtained amplified pumping seed will be used to act as a Raman amplification of optical signals.

Semiconductor optical amplifier based Raman pump

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.

Raman amplifying device and method for pump modulation

A two-stage Raman amplifier provides a gain control compensating for span loss variations and changing channel loading. A first amplifier stage (S) has a first amplifying medium (F) and a first pump light source (P, P, Pn), which is controlled and adjusted by a control unit (CU) to compensate for span loss variations. A second amplifier stage (S) has a second amplifying medium (F) and a second pump light source (P', P&#x2032;, P&#x2032;n), which is controlled and adjusted by the control unit (CU) to balance changing channel loading.

Raman amplifier with gain control

A Raman amplifier () including at least one amplifying fiber () and a coupler () for coupling at least first () and second () pump laser modules to the amplifying fiber (), the first pump laser module () including a frequency discriminator () 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 (). The first optical frequency is spaced apart from a local maximum () in optical power of the remaining optical frequencies, and the second pump laser module () emits at an optical frequency one Stokes-frequency above the frequency of the local maximum (). 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 fiberis broadened.

Raman amplifier and method for pumping a Raman amplifier

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&equals;1,2): n polarization switches CP , (1&lE;i&lE;n); n polarization splitters/recombiners SP (1&lE;i&lE;n); and n delay devices R (1&lE;i&lE;n).

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Antony, France

Dominique Annie Mongardien