Alcatel

Alcatel Lucent

Loïc Becouarn

Gabriel Charlet

Christian Simonneau

Georges Grandpierre

Thierry Boissau

A demodulator for a DPSK-modulated optical signal of bit frequency 1/T, comprises an interferometric structure () having an input port () for receiving the DPSK-modulated optical signal, an output port (), and first and second arms () extending from said input port () to said output port (), adjustment means () for fine tuning a propagation delay difference of said two arms () in a range comprising T, an optical/electrical converter () connected to the output port () of the interferometric structure (), and a bandpass filter () connected to an output of the optical/electrical converter (), the passband of which does not include 1/T. The adjustment means () is adapted to tune the propagation delay according to the output power level of the bandpass filter ().

DPSK demodulator and demodulating method

An optical amplifier assembly for submarine applications. The optical amplifier assembly comprises: a first and a second double stage fiber amplifier with respective first and second fiber amplifiers for amplifying optical signals (OS, OS') each propagated on a respective optical fibre, said optical fibres being operated in opposite operating directions (W-E, E-W), and a common pump source comprising a plurality of pump light sources, the common pump source being coupled via a coupler as a co-propagating pump to the first and second fiber amplifiers of the first and second double stage fiber amplifiers. The proposed optical amplifier assembly further comprises a gain flattening filter between the two fiber amplifiers of the first and second double stage fiber amplifiers. Thus the proposed optical amplifier assembly presents an increased efficiency with respect to an output power at a constant pump power and allows to adjust the pump power for maintaining a given output power without excessive NF degradation.

Optical transmission system and optical filter assembly for submarine applications

An optical wavelength division multiplex transmission system () for transmitting optical signals (S) on a plurality of wavelength channels has a transmitting terminal () and a receiving terminal () interconnected by a transmission line () with at least one, preferably a plurality of optical amplifiers (). Each of the optical amplifiers () comprises a Raman amplifier () with at least one pump light source (-) for pumping the transmission line () upstream the optical amplifier (). It is proposed that each optical amplifier () comprises a single tap coupler () arranged downstream of the Raman amplifier (). Optical receiving and transmitting means () may be connected to the transmission line () via the tap coupler () for communication of data (TX, Di) between at least the transmitting terminal () and the optical amplifiers () on an optical supervisory channel (OSC) with a given wavelength. Alternatively or in addition, monitoring means () for monitoring at least one optical transmission parameter may be connected to the transmission line via the tap coupler (). It is also possible to couple each optical amplifier () by means of its tap coupler () to a corresponding optical amplifier (') of a second substantially identical transmission system (&#x2032;) for transmitting optical signals (S&#x2032;) in an opposite direction via a transmission line (&#x2032;) of the second system (&#x2032;). The all-Raman optical transmission system thus obtained shows improved performance, in particular with respect to loss, noise, PMD, and PDL, while distinguishing itself from prior art systems by its simplicity and corresponding cost-effectiveness.

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Paris, France

Loïc Becouarn