Alcatel

Societe Anonyme Dite: Alcatel Cit

Guy Balland

Alice Michaud

Emmanuel Rossi

Arnaud Bisson

Jacques Pochet

Claude Gauthier

Frank Bruyere

Christophe Trouiller

A method of automatic gain control for use in an optical amplification device comprising a variable optical attenuator and an optical amplifier connected downstream of the optical attenuator includes the steps of measuring the power at the input of the amplification device, determining the number of channels at the input of the amplification device as a function of the measured power knowing the attenuation value of a span upstream of the device, and modifying the gain of the amplifier as a function of the number of channels determined in this way.

Optical amplification device with automatic gain control

An optical device that measures and dynamically compensates power loss variations in an optical fiber based on supervisory signals. An injector injects supervisory signals having a predefined optical power downstream of the fiber entry end and a detector extracts the supervisory signals at the exit end of the fiber to detect their optical power. Based on the detected optical power and the predefined optical power, the optical power loss of the supervisory signals in the fiber is determined. The optical power loss and the nominal power loss in the fiber are compared to determine a variation in the power loss in the optical fiber. A controller coupled to the detector and to the exit end of the fiber modifies the power of primary signals delivered by the exit end of the fiber as a function of the detected variation in power loss.

Device for measuring and dynamically compensating variations in power loss in an optical transmission line with a supervisory channel, and an associated method

An optical system dynamically measures power loss in an optical fiber () having an entry end (E) adapted to receive optical signals and an exit end (S) adapted to deliver the signals. The system comprises modulation means () upstream from the entry end (E) and adapted to modulate the amplitude of the optical signals with a low-frequency modulation signal having a modulation index inversely proportional to the input power (Pe) of the optical signals, and detection means () downstream from the exit end (S) and adapted to extract from the modulated optical signals primary information representative of the output amplitude of the modulation signal and to deduce from the primary information secondary information representative of a variation in the power loss in the fiber.

System for measuring and/or dynamically controlling power loss in an optical transmission line, and an associated method

A current limiter circuit receiving an input current having a non-zero DC component whose value lies in a wide range of current values, and delivering a limited output current whose value lies in a narrower range of current values. The limiter comprises a series connection of a first asymmetrical conductivity element followed by a second asymmetrical conductivity element which is followed in turn by a resistive element, the series connection extending between two poles of a voltage source so that a bias current flows through the asymmetrical conductivity elements and makes them conductive. The input current is applied to the common point between the two asymmetrical conductivity elements and the current-limited output is taken from the common point between the second asymmetrical conductivity element and the resistive element. The direction of the input current flow is such that it splits into two fractions, with one of the fractions being subtracted from the bias current in the second asymmetrical conductivity element, while the other fraction is added to the bias current in the first asymmetrical conducitivity element, thereby increasing the dynamic resistance of the second asymmetrical conductivity element and reducing the dynamic resistance of the asymmetrical conductivity element, thus limiting the output current.

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Ste Genevieve des Bois, France

Guy Balland