Abstract: A bidirectional transmission system with identical laser components. The system features two identical assemblies. Each assembly is constituted by a laser structure able to operate as either an emitter or as a receiver. The system thus has a half-duplex operation. Such a system finds particular application to optical communications.

Abstract: A non-selective photoreceiver for frequency-modulated optical signals and optically using the receiver. The photoreceiver includes a laser operating under longitudinal multimode conditions, such as a FABRY-PEROT-type laser operating in a longitudinal multimode. The photoreceiver can function around any one of the longitudinal modes of the laser in overlapping frequency ranges, providing a wide overall band of operation. The plurality of modes reduces the selectively of the photoreceiver. The invention is also related to an optical link, which is either unidirectional using a photoreceiver as described above, or using two subassemblies each having a photoreceiver according to the invention, each photoreceiver being able to operate in an emission or a reception mode.

Abstract: Logic function generator using an optical transposition in a distributed feedback laser diode. It comprises sources (LD1, LD2) of synchronous digital optical signals having the same rate, an optical coupler (10) receiving said signals and supplying an optical signal, a distributed feedback laser diode (LD3) into which is injected said optical signal, means (24) for the electrical polarization of said laser diode enabling the latter to supply a signal, whose optical frequency varies as a function of the optical power of the injected signal, an optical filter (12) which receives said signal and which is frequency tunable and control means (28) for the said filter. The latter supplies a signal which is a logic function of the signals of the sources. Application to optical calculation.

Abstract: An integrated monolithic electrooptical component having an electrooptical modulator and a semiconductor laser on the same substrate. The modulator and laser are formed from a stack of semiconductor layers. The modulator includes one layer that is absorbent and the laser includes one layer that is active. Both absorbent and active layers are constituted by the same epitaxied structure of a highly coupled composition superlattice with alternation of semiconductor layers of different compositions. A forward voltage is applied to the laser layers that causes the active layer of the laser to emit a radiation which then traverses the absorbent layer of the modulator. A reverse voltage is applied to the modulator layers in order to modulate the absorption of the radiation traversing the modulator.

Abstract: A process for the transmission and reception of personalized programs. The program is constituted by personalized program elements containing an identification of the recipient or addressee, the access to each program element being reserved for a single recipient and is conditioned for the possession of an access title covering the access criteria to the service and the possession of an individual identification on the part of each recipient. The access title control message enables users of the service to calculate, on the basis of the single cryptogram of a root control word and the identification of the recipient, all the personalized control words which will enable each recipient and him alone to descramble the elements relating to him.

Abstract: This color display structure for color display purposes has a first and second spaced, transparent substrates, between which is interposed a liquid crystal film (6), the first substrate (2) essentially supporting color filters (124) resistant to high temperatures and separated by black matrixes (126), a first transparent, passivating layer (128) deposited on the entire surface occupied by the filters and the black matrixes, thin film transistors (8, 9), formed on the first passivating layer facing the black matrixes so as to be protected from the ambient light, first transparent capacitor plates (10) formed on the first passivating layer facing the color filters and connected to the transistors, electrode rows (14) and columns (12) for controlling these transistors and a second transparent passivating layer (20) covering the transistors, the first plates, the rows and the columns, the second substrate (4) essentially having the second transparent capacitor plate.

Abstract: Control protective circuit, in particular of liquid crystal display screen. The protective circuit includes three transistors making possible the transfer of the voltage to output pin, the resetting of middle point and the resetting of the output. Application to the control of liquid crystal display screens.

Abstract: The amplifier according to the invention comprises a shallow, narrow well (P1) in which amplification takes place and a deep, wide well (P2) for collecting the carriers at the end of excitation, said well being emptied by the laser effect.Application to optical telecommunications.

Abstract: The display of structured oriented graphs undergoing incremental modifications is locally updated by determining the area containing the modification and the affected areas surrounding the modification. The affected areas are shifted to accommodate the modification without the necessity of regenerating the entire display.

Abstract: A method for the automatic analysis of signals by segmentation and classification. To segment the signal, the method is carried out repeatedly by aggregating samples and merging adjacent pulses. Once segmentation has been obtained, classification is carried out. The method has particular application to the analysis of signals with a physiological origin.

Abstract: A truncated frequency discriminator according to the present invention features an amplifier (A), phase adjustment circuits (CAP1, CAP2) and circuitry (V1, V2) for very weakly forward polarizing Schottky diodes (DS1, DS2). Such a truncated frequency discriminator allows for a reduced noise and may find particular application in optical telecommunications receivers.

Abstract: A circuit for controlling the lines of a display screen and including a t means with a single output is disclosed. The test means includes a single test control line (LCT), a single test output line (LST) and a plurality of sample holders (CEBj) and associated gates (Pj) and switches (Ij). The output voltage of the sample holders is transmitted onto a test output block (ST).

Abstract: An antonomous container permits the vacuum transportation of any random small object and the performance of operations within a container (1) or lock (2), without it being necessary to transfer the object (10) into a working station (3). The container according to the invention is small and is provided with shielding windows (12). Therefore the object (10) can be observed within the container (1) during the operations performed within the said container (1). The latter can be transferred for supplementary operations with respect to the object (10) to the working station (3) by means of a manipulating rod (30). Application to the growth of integrated circuits in microelectronics.

Abstract: An optoelectronic device having an optical guide and photodetector integrated on a common substrate is provided with a light coupling means for increasing the absorption of light within the photodetector. This means consists of freeing the lower portion of the guide layer--opposite the photodetector--to bring it into contact with air. The use of air has the effect of repelling the light propagating through the guide layer towards the absorbent layer of the photodetector thereby increasing the photodetector efficiency.

Abstract: Sample and hold circuit for a liquid crystal display screen. The circuit comprises two stages, the first with switched capacitance the second with an amplifier device. Application to the control of liquid crystal display screens.

Abstract: Process for the local passivation of a substrate by a hydrogenated amorphous carbon layer and process for producing thin film transistors on said passivated substrate. The local passivation process consists of producing photosensitive resin patterns (3) on the substrate (1), subjecting the structure obtained to a radio-frequency plasma essentially constituted by a hydrocarbon for thus depositing a hydrogenated amorphous carbon layer (6) on the structure and dissolving the resin patterns (3) in order to eliminate the amorphous carbon deposited on the resin, the amorphous carbon deposited on the substrate constituting the said passivation.

Abstract: A process for exchange of rights between microprocessor cards, wherein multiple keys (K1, K2, . . . ) and varied keys (Ka5, Kb3) are used. A card to be debited calculates a voucher with varied key (Ka5) that the card to be credited reconstitutes. The process has application to electronic payment.

Abstract: A wavelength multiplexing device comprising a switching matrix (18) of the N to 1 type, which has several successive stages (18a,18b) of controllable optical couplers (20) interconnected to form a tree structure and modulating means (24) connected to the output of the switching matrix (18). The device further has N sources (10,12,14,16) each emitting a continuous light beam having a particular wavelength to an input of the matrix, and a control circuit (22) connected to the couplers and controlling the latter so as to select P wavelengths from among the N available wavelengths. The device allows efficient transmission of data through an optical network.

Abstract: Process for optical transmission by wavelength shifting and corresponding system. According to the invention, a wavelength hop corresponding to a mode hop of the laser is performed. The laser (20) is supplied by two currents, which fix the emission wavelengths (.lambda.1, .lambda.2).

Abstract: The method includes only two masking levels. During the second masking, capacitative lines (LC) (dedicated or merged with the addressing lines) are defined which overlap the pixels so as to form the storage capacitors (Cs).Application for display on flat liquid crystal screens.