Abstract: A decision system for a modulated electrical signal delivered by a converter in response to a received modulated optical signal compares the amplitude of the electrical signal to a reference level, measures an average amplitude of the electrical signal, and generates the reference level as a function of the result of such measurements so that the “reference level/average amplitude” ratio can be adjusted to a predetermined constant value different from 1. Applications include receivers for optical packet transmission systems.

Abstract: An optical switching device comprises i) a first stage comprising N first distribution modules each having a first input coupled to an optical fiber dedicated to the transport of multiplexes of channels of different wavelengths, and n first outputs each delivering at least one of the multiplexed channels received by the first input, ii) a second stage comprising Q second selection modules each having a second input receiving at least one channel of one wavelength, and q second outputs selectively delivering one of the multiplexed channels received by the second input, with Q?N×n, and iii) a third stage comprising a spatial switcher having, on the one hand, M third inputs and M? third outputs, with M??M, at least some of the first outputs being respectively coupled to third inputs and at least some of the second inputs being respectively coupled to third outputs, and, on the other hand, coupling means designed to couple each of the third inputs to one of the third outputs according to a chosen input/output com

Abstract: The device includes: an input stage (1) comprising broadcast modules (MD1-MD3) that provide duplicates of the same multiplex, an output stage (2) comprising programmable multiplexer modules (OWS1-OWS3) having inputs associated with respective broadcast modules, and an intermediate stage (3) connecting each programmable multiplexer module input that is associated with a broadcast module to an output of the associated broadcast module. Each broadcast module includes a programmable demultiplexer module (IWS1-IWS3) having a transit output (B1) and a selection output (B2) and a star coupler (SC1-SC3). The transit output (B1) is connected to a first input (C1) of the coupler and an input and an output of a processing device (RG, RG?) are respectively connected to a selection output (B2) and to a second input (C2) of the coupler. Application to semitransparent nodes of hybrid optical networks.

Abstract: A WDM network (R) comprises an optical fiber (F) connected to a hub (H) via an input of a demultiplexer (DX) having N outputs to communications stations (Si-Sn) able to deliver and/or receive spectral multiplexes of modulated optical signals with different wavelengths, via coupling means (CP, CP?, MXB). The communications stations (Sn?1) are adapted to deliver spectral multiplexes of modulated optical signals from a given one of P disjoint bands of wavelengths. At least one of the coupling means (MXB) is a 2×1 band multiplexer comprising i) an output connected to a downstream portion of the optical fiber (F), ii) a first input connected to one of the stations (then referred to as the “primary” station) and adapted to its band of wavelengths, and iii) a second input connected to an upstream portion of the optical fiber (F) and adapted to channels having wavelengths different from those of the channels passing through the first input.

Abstract: A selection module for use in an optical signal switch comprises a spatial selector comprising a plurality of inputs each receiving a wavelength division multiplexed optical signal comprising a plurality of channels each associated with a separate wavelength, an output delivering a single signal selected from the plurality of wavelength division multiplexed signals, and a plurality of spectral selectors each selecting a channel from a plurality of channels of the signal selected by the spatial selector.

Abstract: The switching system comprises a routing device having selection modules each having one input and a plurality of outputs adapted to switch spectral channels received selectively to respective outputs as a function of a command. The routing device comprises: a first stage comprising a plurality of modules whereof inputs constitute the input ports of the device, a second stage comprising at least one first selection module whereof the outputs constitute the output ports of the device, and an intermediate stage for coupling the input of the first selection module of the second stage both to a first output of a first selection module of the first stage and to a first output of a second selection module of the first stage. Application to interconnection panels in switching nodes for optical networks.

Abstract: Packets conveying data are received by a router via input ports which impose on them optical carrier waves whose wavelengths correspond to the ports. Respective time-delays are applied to the packets and they are broadcast to spatial selectors that transmit them to spectral selectors. Amplifiers are distributed over the paths of the packets and the paths are organized in such a manner as to limit the number of semiconductor optical switches in the selectors and to minimize noise and optical crosstalk affecting the packets.

Abstract: The network comprises an optical ring link (F) and a concentrator (HUB) that sends via one end of the link “downlink” optical signals carried by respective wavelengths and receives “uplink” optical signals via the other end of the link. The link is divided into a plurality of segments (FS1-FS4) separated by access nodes (AN1-AN3) for receivers (RX) of downlink optical signals and for senders (TX) of uplink optical signals. Each access node comprises coupling means that are not wavelength-selective for coupling the segment on the upstream side of the node to the segment on the downstream side and to the receivers and to couple the senders (TX) to the segment on the downstream side. The downlink optical signals are carried by wavelengths belonging to a set of predefined wavelengths. To optimize the use of spectral resources, a rejection filter (NF) is inserted into a segment to reject a portion of the wavelengths of said set of wavelengths.

Abstract: In order to reduce the effects of non-linear phenomena in WDM optical transmission networks, the optical carrier frequencies of the multiplex signals belong to a comb of frequencies that are spectrally spaced apart in irregular manner while nevertheless belonging to a chart of optical frequencies that are spectrally spaced apart in regular manner at a pitch df. These frequencies are selected in such a manner as to enable them to be dropped from the multiplexed signals by N respective periodic optical filtering operations having the same free spectrum interval (Df) equal to M.df, where M is an integer greater than or equal to N, the filtering operations enabling N consecutive frequencies to be dropped from the chart. In addition, the spacing between any pair of frequencies of the comb is different from any integer multiple greater than or equal to 1 of the free spectrum interval (Df).

Abstract: In order to reduce the effects of non-linear phenomena in WDM optical transmission networks, the optical carrier frequencies of the multiplex signals belong to a comb of frequencies that are spectrally spaced apart in irregular manner while nevertheless belonging to a chart of optical frequencies that are spectrally spaced apart in regular manner at a pitch df. These frequencies are selected in such a manner as to enable them to be dropped from the multiplexed signals by N respective periodic optical filtering operations having the same free spectrum interval (Df) equal to M.df, where M is an integer greater than or equal to N, the filtering operations enabling N consecutive frequencies to be dropped from the chart. In addition, the spacing between any pair of frequencies of the comb is different from any integer multiple greater than or equal to 1 of the free spectrum interval (Df).

Abstract: A communications station (4-i) for a WDM ring network is adapted to insert into an optical fiber (2) packets of optical signals carried by at least one wavelength and having a propagation direction in common with at least one other communications station.

Abstract: A selection module for use in an optical signal switch comprises a spatial selector comprising a plurality of inputs each receiving a wavelength division multiplexed optical signal comprising a plurality of channels each associated with a separate wavelength, an output delivering a single signal selected from the plurality of wavelength division multiplexed signals, and a plurality of spectral selectors each selecting a channel from a plurality of channels of the signal selected by the spatial selector.

Abstract: The invention provides an optical modulator for transmitting data encoded in NRZ mode by modulating the intensity of a light signal, the modulator including means for shaping the light signal including shaping means for producing a signal of low bandwidth from an input control signal, and a laser modulator having a transfer function favoring the extinction time of the resulting light signal.

Abstract: The invention relates to a switch (112) for optical signals and which has a number of outputs at least equal to the number of inputs and include means whereby an input signal is routed to at least one of those outputs. Each input receives information modulating optical carriers at different wavelengths. The switch (112) includes means (12611, 12612, . . . , 126NB) for grouping all the carriers received into non-contiguous subsets of carriers (G11, . . . , G1B, . . . , GN1, . . . , GNB) and means (1291, 1292, . . . , 129NB) for selecting blocks of carriers from the same subset of carriers. The information corresponding to each subset of optical carriers is thus routed in blocks to the same subset output. Switching the carriers at the subset level improves the quality of the output signal and limits the number of components for the same total quantity of information switched.

Abstract: The present invention concerns a generator (G1) for generating at least M data carrier optical signals with selectable carrier wavelengths, where M is an integer greater than 1, said generator comprising N laser sources (Si) with constant and different wavelengths, where N is an integer greater than 1, and an optoelectronic modulator (Mod1) adapted to form one of said M optical data carrier signals,

Abstract: An optical system includes a first device for regenerating a plurality of electrical or optical signals (211, 213, 215, 217) in the form of a composite optical signal (235) including a plurality of wavelengths, the first device including a plurality of optical modulators (210, 212, 214 and 216) and a multiplexer (230) for multiplexing the signals supplied by the modulators, each of the modulators having an input (219) for the signals and a clock input (221), and a second device for regenerating the composite optical signal in the form of a plurality of electrical or optical signals, the second device including means for demultiplexing the plurality of wavelengths and a plurality of regenerators each having a clock input and a data output for reproducing an electrical signal. A first clock circuit (220) is common to all the clock inputs of the first device and a common second clock circuit is common to all the clock inputs of the second device.

Abstract: A decision system for a modulated electrical signal delivered by a converter in response to a received modulated optical signal compares the amplitude of the electrical signal to a reference level, measures an average amplitude of the electrical signal, and generates the reference level as a function of the result of such measurements so that the “reference level/average amplitude” ratio can be adjusted to a predetermined constant value different from 1. Applications include receivers for optical packet transmission systems.

Abstract: A multi-user optical fiber communications system uses spread spectrum code division multiple access techniques to achieve better bandwidth utilization. Each channel of the system is provided with light source that is temporally and spectrally modulated by an encoder. Modulation is accomplished by first passing the data through a pulse modifier to obtain a stream of shortened pulses with a reduced duty cycle. The modulated light is coupled to a fiber and data are recovered by the decoder. The source includes a superluminescent fiber source that is split multiple times and amplified in a hierarchical manner to produce a plurality of like sources. The like sources are decorrelated by adding delays to the different sources. Each of the encoders includes an encoding mask having a first code that encodes the optical signal. Light, spatially encoded by the mask and temporally modulated with data, is transmitted over a fiber link with the signals of other users and received by a decoder.

Abstract: In order to be able to use a semiconductor light amplifier of conventional type and operating under gain saturation conditions while nevertheless providing constant gain for an optical signal to be amplified, the device comprises means for producing a compensation light wave and coupling means for injecting the optical signal to be amplified and the compensation light wave into the amplifier. The compensation light wave presents amplitude modulation such that when combined with the optical signal to be amplified the overall amplitude modulation is eliminated or at least attenuated. The device is applicable to optical transmission systems operating at a single wavelength or with wavelength division multiplexing.

Abstract: Packets conveying data are received by a router via input ports which impose on them optical carrier waves whose wavelengths correspond to the ports. Respective time-delays are applied to the packets and they are broadcast to spatial selectors that transmit them to spectral selectors. Amplifiers are distributed over the paths of the packets and the paths are organized in such a manner as to limit the number of semiconductor optical switches in the selectors and to minimize noise and optical crosstalk affecting the packets.