Abstract: The invention relates to a light intensity modulator, in integrated optics and an integrated optical circuit comprising such a modulator.The modulator comprises a two-arm interferometer in which there is created by electro-optical effect, a phase shift controlled by a modulating voltage between the light waves propagated in the two arms. It is characterized by a feedback loop comprising a light separator placed on the output guide of the interferometer, and a photodiode collecting the fraction of output intensity from the separator and supplying an electric voltage which is superimposed in the interferometer on the modulating voltage. Thus linearization of the output intensity-modulating voltage response curve is obtained.

Abstract: The hydrophone has an interferometer structure incorporating a measuring arm in which is provided a very long monomodal optical fibre immersed in the interaction medium in which is propagated the acoustic wave. A phase displacement is induced on the optical wave by the elastooptical effect and said wave is propagated in the fibre by the acoustic wave which creates an acoustic pressure field in the medium. A reference arm establishes a reference optical path and the phase displacement linked with the acoustic wave is detected by interferometry between the two optical waves emerging from the two arms. The optical connections between the source, the optical fibre immersed in the interaction medium, the reference arm and the detector being provided in guided optics in a compact structure.

Abstract: A semiconductor laser particularly useful for frequency multiplexing in optical telecommunications having a distributed resonator supplying from a single etched grating, two or more radiations of different wavelengths. The laser comprises a junction formed by an n-type substrate, a p-type radiation-confinement region, and a surface region, a grating being etched at the interface between the confinement region and the surface region. Useful elementary bands of the junction for the attainment of the laser effect are fixed by proton implantation in the surface region of the junction. The elementary band-type regions are convergent and form, with the perpendicular to the grooves of the grating, angles that are determined so that the spacing along the various bands has a specified value linked directly to the wavelength of the corresponding emitted radiation.

Abstract: The invention relates to a light intensity modulator controlled by a "word" of n bits and an opto-electronic digital-analog converter.The modulator comprises a two-arm interferometer in whose length there is created, by opto-electrical effect, successive phase shifts controlled respectively by control bits and whose values, when the control bits are in state 1, conform to the successive powers of 2. The total phase shift obtained thus depends directly on the analog value of the control word and the emerging intensity is modulated as a function of this word. A digital-analog converter is constructed by adding a photodetector means whose output voltage depends on the analog value of the control word.

Abstract: The interferometric laser gyrometer according to the invention comprises a laser source, a wound monomode optical fibre an a detector, the optical coupling between the source and the two ends of the optical fibre in order that these two ends receive equal parts of the light emitted by the source contro-propagating in the fibre and the optical coupling between these two ends and the detector being effected by wave guides integrated on an electrooptical substrate at which the two ends of the fibre are rigidly coupled.

Abstract: A device for connecting a peripheral unit to an optical bus-line which comprises a substrate onto which are integrated a first optical waveguide for being inserted in the path of the bus-line, a second optical waveguide for being connected to the emitting circuit of the peripheral unit, a third optical waveguide for being connected to the receiving circuit of the peripheral unit, and three couplers for intercoupling these waveguides. A plurality of connections related to the peripheral unit are provided for controlling the couplers in order to control the emission or the reception of information on or from the bus-line.

Abstract: The invention relates to non-linear optical devices in which significant non-linear interactions are obtained by establishing a "quasi phase matching". The optical device according to the invention comprises on the surface of a substrate a periodic structure formed of zones in which the non-linear coefficient alternately assumes two values of opposite signal. The invention also relates to a process for producing this device. The invention allows generation of harmonics, frequency changing, parametric amplification or parametric oscillation.

Abstract: The invention relates to an integrated optical circuit intended to separate a plurality of optical waves of different wavelengths, comprising at least one basic cell formed of elements integrated on the same plate: a directional coupler adjusted to divide between two output branches the incident energy in one branch of the coupler; each of the output branches comprising a phase-shifter, an engraved network which reflects an optical carrier of a definite wavelength, a second phase-shifter; and a junction between the two output branches. The phase-shifters are adjusted so that the waves reflected by the networks are in phase-opposition at the input to the coupler and recombine in the fourth branch of the coupler, and so that the waves not reflected by the networks are in phase in the junction.

Abstract: A process designed for manufacturing an opto-electronic device comprising at least one light-guide integrated in a substrate with a control electrode constituted by a metallic band covering the light-guide and deposited onto the substrate, and an earth-plane integrated in the bottom of the substrate. The process comprises a preliminary step wherein the light-guide is created by doping the substrate for example in a channel adjacent to the upper side of the substrate. In the first step the material of the substrate (e.g. monocrystalline lithium niobate) is chemically reduced by hydrogen for rendering the whole substrate electrically conductive (and consequently opaque). After a second step of partial protective masking, a third step takes place wherein the upper part of the substrate is re-oxidized for restoring a transparent layer comprising the light-guide - the latter characterized by a higher refractive index - and an insulating medium in the upper part of the substrate.

Abstract: An electrically controlled light switch, which can also be used as a light modulator in integrated optical circuits is disclosed. The coupling length of a directional coupler is modified by applying a voltage between two electrodes positioned upon two rectilinear parallel waveguides made of an electro-optical material and arranged on a common substrate, thus generating a field distribution crossing the two waveguides in opposite directions and resulting in opposite signed refractive index variations thereof.

Abstract: The system according to the invention comprises at least one input and two output monomode waveguide branches connected to the input and the output of a multimode guide section. The input branch excites a combination of propagation modes in the multimode guide. This combination gives rise to energy distributions across the width of the multimode guide which are variable with the intensity of an electrical field.

Abstract: A method of manufacturing an electro-optical switch in which a metal layer is deposited on a substrate of ferroelectric material and etched to expose the substrate in the form of two channels disposed parallel over a given length. A second layer is then deposited upon the metal layer and the channels, with the diffusion into the substrate of the second layer forming two zones having optical refractive indices greater than that of the substrate. The assembly is then heated and a biasing voltage applied to create remnant electrical polarizations in opposite senses. After removal of the bias voltage, the assembly is cooled and the metal layer removed.

Abstract: The electro-optical switch according to the invention is formed by parts of two guides made of a ferro-electric material previously polarized in a suitable fashion, enclosed between two electrodes; the application of a voltage between the two electrodes has the effect of varying the refractive index of each of the guides in relation to the other and, consequently, of making it possible to enable or inhibit energy coupling between the two guides. Such a device is applicable in particular to integrated optical circuits.

Abstract: The invention relates to a coupling device for an optical waveguide, using a hologram recorded in a photoresist layer arranged on a face of the waveguide, and capable of coupling a wave having a predetermined wafe front and travelling outside the waveguide and a plane wave travelling inside the guide. The invention also describes a holographic method for manufacturing such a coupling device.