Alcatel

Alcatel N.v.

Alcatel Cit

Bertrand Desthieux

Dominique Bayart

Denis Penninckx

Laurent Gasca

Amaury Jourdan

Christian Le Sergent

Fran&ccedil;ois-Xavier Ollivier

Christophe Sinet

The present invention is a device to increase the bit rate and distance at which data can be transmitted by optical fiber. The device compensates the polarization dispersion of the line by processing a received optical signal with the use of a polarization controller, the generation of a differential group delay between two orthogonal polarization modes and a control unit for the polarization controller. The data that is sent is redundant to enable detection of errors affecting the data received and the control unit is adapted to minimize the error rate calculated in real time by using the redundant data. The application of the device is to long-haul optical transmission, in particular over stranded fibers.

Device for compensating polarization dispersion in an optical transmission system

The invention relates to optical fiber apparatus comprising an amplifier having optimal gain excursion over a given wavelength band for given input power, and a filter having a bell-shaped transfer function, with the center wavelength of the filter being tunable over a range that is sufficient to enable the gain excursion of the amplifier over said wavelength band to be reduced when the power received by the amplifier is different from said given input power. The invention makes it possible to match amplifier apparatuses to line losses while minimizing overall loss.

Optical amplifier with optimal gain excursion for different input powers

The invention relates to an optical fiber having a core based on silica with at least one fluorescent dopant distributed over the entire section of the core, a central zone co-doped with a co-dopant chosen from Al and P, and a peripheral zone co-doped with the other co-dopant chosen from Al and P. The invention can be used in an optical fiber amplifier, and it guarantees good amplifier gain flatness over a wavelength band suitable for WDM transmission.

Optical fiber for a flat-gain optical amplifier

To optimize the amplification in a device for extracting channels from a wavelength division multiplex, the following steps are carried out in succession: a first amplification step with a first gain, a wavelength selection step, and a second amplification step with a second gain. The first and second gains respectively confer upon the output optical signal a fixed signal to noise ratio and a particular optical power. Applications include optical transmission networks.

Method of and device for amplifying channels extracted from a wavelength

A method for equalizing power levels of channels of an optical frequency division multiplexed signal determines the power level of each channel of the optical frequency division multiplexed signal and introduces attenuation into the channels having high power levels corresponding to the difference between a level deduced from these high levels and a low reference level. The equalization system includes at least one optical equalizer module which measures the optical power levels of the channels of the signal to be monitored, a processor for implementing the method and variable attenuators controlled by the processor and operating separately on the power levels of the channels.

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Paris, France

Bertrand Desthieux