Abstract: The present invention propose to use an optical multiplexer associated with an optical clock as a wavelength converter. Each RZ coded tributary will be carried by a single wavelength (channel) passively interleaved with the others without interferometric interaction hence achieving a not necessarily perfect OTDM. This input data stream as optical data signal composed of different wavelengths is then launched on at least one data access of said optical multiplexer used as a wavelength converter. An optical clock at the desired bit-rate is launched on the probe access of said optical multiplexer synchronously to the multi-wavelength data stream. At the output, the initial clock wavelength is converted on data signal using the gain conversion property of the optical multiplexer. In such a way, a data stream of substantially higher bit-rate is obtained while due to a very precise synchronization a lost of data is minimized.

Abstract: This invention relates to an electrolytic method for the selective recovery and recycling of silver from a nitric acid solution containing it in the form of Ag(I), this method comprising successive steps of electro-deposition of the silver in the form of silver metal Ag(0), and then of redissolution of the deposited silver Ag(0), to give a final solution of Ag(I) in which the step of electro-deposition is carried out at a prescribed current and the successive steps of electro-deposition of the silver and of redissolution of the deposited silver are carried out in the same apparatus. The invention is applicable particularly to the selective recovery of Ag(I) by reduction to Ag metal from nitric acid solutions arising from the processing of plutonium containing waste in plants for the reprocessing of nuclear fuels and to the redissolution of the silver metal to form Ag(I) with the purpose of recycling it to an upstream point of the method.

Abstract: A differential group delay generator includes a polarization splitter which splits an input signal into two components having orthogonal states of polarization, and an adjustable delay system for receiving one component. For high accuracy and a fast response, the adjustable delay system includes an adjustable phase modulator for applying phase modulation to the carrier wave of the component to supply an intermediate signal carried by a modified center wavelength, and a delaying dispersive component receiving the intermediate signal and supplying a delayed signal. Applications include polarization dispersion compensation in long-haul optical transmission, especially via standard fibers.

Abstract: The invention relates to an optical fiber transmission system using soliton signals with wavelength division multiplexing in which the wavelengths, &lgr;1 to &lgr;n, of the various channels of the multiplex are selected in such a manner that at least one point of the transmission system, the difference between the bit times of any two channels of the multiplex is substantially a submultiple T/N of the clock period. The invention proposes placing a synchronous modulator at said point to modulate the soliton signals at a frequency N/T which is a multiple of the soliton clock frequency 1/T. In a frequency allocation scheme that ensures that the bit times of the channels are synchronous at an interval ZR, this makes it possible to modulate all of the channels at intervals that are submultiples of ZR by using modulation frequencies that are multiples of the clock frequency.

Abstract: A synchronous optical regenerator applies intensity modulation and phase modulation. The phase modulation is effected after the intensity modulation by the crossed Kerr effect in a Kerr fiber. The clock used for the phase modulation is obtained by injecting a continuous wavelength into the intensity modulator. The regenerator therefore includes a multiplexer coupling continuous light with the signals transmitted, an intensity modulator modulating the signals transmitted and the continuous light, and a Kerr fiber phase modulating the transmitted signals by crossed phase modulation with the intensity-modulated continuous light. Applications include wavelength division multiplex transmission systems.

Abstract: To delay optical signals precisely and continuously in a very small dynamic range, a device for applying a time-delay to optical signals includes a first phase modulator to receive an input optical signal carried by an original center wavelength and to apply a first stage of phase modulation to the carrier wave of the input signal to supply a first intermediate signal carried by a modified center wavelength, a delaying dispersive member having chromatic dispersion to receive the first intermediate signal and to supply a second intermediate signal, and a second phase modulator to receive the second intermediate signal and to apply a second stage of phase modulation to the carrier wave of the second intermediate signal to supply an output signal carried by the original center wavelength. Applications include optical telecommunication systems, in particular converting wavelength division multiplexed signals into time division multiplexed signals and regenerating wavelength division multiplexed signals.

Abstract: The invention provides a method of repairing an optical fiber transmission system using soliton signals and wavelength division multiplexing, in which the various wavelengths, &lgr;1 to &lgr;n, of the multiplex are selected to ensure that over a given interval ZR, the relative slip between the various channels is substantially equal to a multiple of the bit time, the method comprising the following steps: inserting an additional length of optical fiber in the transmission system; and compensating for the effects of said additional length on the relative slip between the various channels of the multiplex. The invention also provides apparatus for repairing such an optical fiber transmission system using solution signals with wavelength division multiplexing. The invention prevents relative slip between the channels due to inserting an additional length of fiber into the transmission system.

Abstract: In a wavelength-division multiplex fiber optic soliton signal transmission system the wavelengths of the multiplex are chosen to assure a relative slippage between the channels at a given interval substantially equal to a multiple of the bit time. At one point of the transmission system at least, the soliton pulses of the various channels have a temporal offset relative to a given reference such that, on distributed optical modulation by a clock that is input at this point, for each channel, the extremum of the non-linear phase profile induced by the clock, integrated over the modulation length, coincides with the center of the bit time. In a system of this kind distributed optical modulation can be applied to all the channels of the multiplex by a single sinusoidal signal. The modulation can be effected in a non-linear optical loop mirror or in the transmission fiber itself.

Abstract: In a soliton transmission system, the invention proposes sending a signal constituted by a periodic series of solitons, each having a width lying in the range 0.20 times to 0.33 times the period of the signal. In such a signal, interaction between the solitons compensates the jitter caused by the Gordon-Haus effect. A signal is thus obtained that can be used as a clock, having an amplitude or a time Q-factor Q.sub.a or Q.sub.t that is high, over large distances z.

Abstract: It concerns a monomer, a polymer obtained from the monomer and a process for obtaining the said polymer. The monomer consists of a polyether containing at least 3 ether units and pyrrole or thiophene units bonded to the ends of the chains of this polyether via, for each of these heterocycic compounds, either their carbon atoms in the 3,3'-positions of their heterocycles or, as regards more particularly the pyrrole groups, via their respective nitrogen atoms, the 2- and 2'-positions of these heterocycles being, however, free of all substitutions or, at the very most, substituted by easily removable groups (protective groups, for example).Application to the purification and recovery of metal ions such as radioactive silver.

Abstract: The object of the invention enables wavelength division multiplexed solitons conveyed by an optical fiber to be regenerated synchronously. The method uses clock recovery from the WDM signal, and synchronous modulation of the solitons at the clock rate recovered in this way. The locations for the optical modulators are selected to be at a distance between the transmitter and the first modulator or between successive modulators along the optical link such that the signals at different wavelengths are synchronous. The apparatus of the invention regenerates solitons in-line by synchronously modulating said solitons using an optical modulator, clock recovery, and multichannel filtering at the output from the modulator. In a particular embodiment, the telecommunications system of the invention also includes fiber lengths having different dispersion relationships depending on their position within the link, so as to achieve "dispersion management" within the link.

Abstract: This process comprises; mixing (1) the solid residues with a solid reducing agent; treating (2) the mixture in a furnace at a temperature above 1000.degree. C. to obtain (3) a vitrified product rendered poor in metals and an emission of gas enriched in metallic elements in a vapour phase; air quenching (4) the gases rich in metals; filtering (5) the products resulting from the air quenching to obtain secondary ashes rich in metallic salts; at the end of the filtering operation, washing the smoke (6) for discharging it to the atmosphere; and subjecting the secondary ashes rich in metallic salts to a treatment for producing a product rich in valuable metals (7 to 10).

Abstract: It concerns a monomer, a polymer obtained from the monomer and a process for obtaining the said polymer. The monomer consists of a polyether containing at least 3 ether units and pyrrole or thiophene units bonded to the ends of the chains of this polyether via, for each of these heterocycic compounds, either their carbon atoms in the 3,3'-positions of their heterocycles or, as regards more particularly the pyrrole groups, via their respective nitrogen atoms, the 2- and 2'-positions of these heterocycles being, however, free of all substitutions or, at the very most, substituted by easily removable groups (protective groups, for example).Application to the purification and recovery of metal ions such as radioactive silver.

Abstract: It concerns a monomer, a polymer obtained from the monomer and a process for obtaining the said polymer. The monomer consists of a polyether containing at least 3 ether units and pyrrole or thiophene units bonded to the ends of the chains of this polyether via, for each of these heterocycic compounds, either their carbon atoms in the 3,3'-positions of their heterocycles or, as regards more particularly the pyrrole groups, via their respective nitrogen atoms, the 2- and 2'-positions of these heterocycles being, however, free of all substitutions or, at the very most, substituted by easily removable groups (protective groups, for example).Application to the purification and recovery of metal ions such as radioactive silver.

Abstract: It concerns a monomer, a polymer obtained from the monomer and a process for obtaining the said polymer. The monomer consists of a polyether containing at least 3 ether units and pyrrole or thiophene units bonded to the ends of the chains of this polyether via, for each of these heterocycic compounds, either their carbon atoms in the 3,3'-positions of their heterocycles or, as regards more particularly the pyrrole groups, via their respective nitrogen atoms, the 2- and 2'-positions of these heterocycles being, however, free of all substitutions or, at the very most, substituted by easily removable groups (protective groups, for example). Application to the purification and recovery of metal ions such as radioactive silver.

Abstract: An electrochemical installation for treating aqueous effluent containing a heavy metal, the installation comprising an electroplating reactor for the heavy metal, itself comprising a tank in which alternating electrodes of opposite polarity are placed, the cathodes being removable volume electrodes each constituted by a cassette in the form of two facing frames each supporting a wall that is permeable to said aqueous effluent, the permeable walls of a single cathode defining a space that is filled with an active granular material and in which a metal current-feed grid is disposed. According to the invention, the installation further comprises a regeneration electrochemical reactor for receiving the cathodes as anodes, the metal constituting the metal current-feed grids being selected from metals having an oxidation-reduction potential greater than that of the heavy metal to be electroplated and enabling the end of regeneration to be detected.