France Telecom

Valerie Tholey

Mouhammad Jamil Chawki

Ivan Le Gac

Andre Hamel

Eric Delevaque

Jean Stoschek

This network, intended for the transmission of information in optical form, wavelength multiplexed, comprises nodes (N1, N2) linked to each other by at least one optical fiber (F1), at least one wavelength being treated in each node. The system comprises unit (OF1, OF2, OS1, OS2) for superimposing on the information, for at least one wavelength per node, a surveillance signal whose frequency is outside the transmission band and, in each node, a surveillance circuit (CS1, CS2) for sampling at least one part of the surveillance signals, elaborating surveillance information in function of this part and sending this information to the processing units of the network. Application in optical telecommunications.

Surveillance system of a multi-wavelength ring network

A method for the management of a one-directional optical management loop with optical frequency multiplexing. This method is characterized chiefly in that the central station (T) instructs a secondary station (Si) that it designates to tune its reception to a determined wavelength (.lambda.j), on the basis of a message broadcast permanently to all the secondary stations (S1-Sn) on all the channels of the frequency multiplex. This method can be applied to any type of telecommunications network.

Method for the management of wavelength-division-multiplexed optical

This multiplexer adds to a group of optical signals, whose wavelengths belong to a group of wavelengths (.lambda.1 . . . .lambda.N) and drop from said group of signals at least one optical signal having a given wavelength, chosen from within the wavelength group and comprises at least one optical circulator (C1, C2) having an input for receiving the group of signals and an output, an optical selection means (MS) coupled, on one side, to the circulator and which comprises at least one photoinduced Bragg grating (R1 . . . RN), said photoinduced Bragg grating being associated with the given wavelength and which can be in a first state, where it reflects the signal having said given wavelength and where it transits signals having a wavelength different from the given wavelength or optionally in a second state where it transmits all the signals, and a means (MC) for the control of said selection means (MS) for placing the grating in said second state, the selection means cooperating with each optical circulator for adding and dropping the optical signal or signals. Application to optical telecommunications.

Optical add-drop multiplexer using optical circulators and photoinduced

In a telecommunications network organized in wavelength-division-multiplexed optical loops, each loop has tunable reception means tuned as a function of the density of the network traffic, thus being capable of being reconfigured as a function of requirements. The disclosed system can be applied to public, private and data communication networks.

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Lannion, France

Valerie Tholey