Abstract: The invention relates to a process for producing layers made of oxide ceramic that conform to substrates having features in relief comprising: a step of depositing on said substrate a layer of a sol-gel solution that is a precursor of said ceramic; a heat treatment step of said layer with a view to converting it to the ceramic; said steps being optionally repeated one or more times, characterized in that the sol-gel solution that is a precursor of said ceramic is prepared by a process successively comprising the following steps: a) preparing a first solution by bringing the molecular precursor or precursors of the metals intended to be incorporated into the composition of the ceramic into contact with a medium comprising a diol solvent and optionally an aliphatic monoalcohol; b) leaving the solution obtained in a) to stand for a sufficient time needed to obtain a solution that has a substantially constant viscosity; c) diluting the solution obtained in b) to a predetermined amount with a dial solvent o

Abstract: The invention concerns a method for preparing a material based on piezoelectric ceramic oxide(s) comprising the following steps: a) wet deposition on at least one surface of a substrate of a layer of a dispersion comprising a piezoelectric ceramic oxide powder and a piezoelectric ceramic oxide precursor sol-gel solution identical to or different from the piezoelectric oxide constituting the powder; b) repeating a) once or several times, so as to obtain a stack of at least two layers; c) heat-treating said layers so as to transform them into corresponding ceramics; d) wet-shrink impregnation of the stack obtained at c) with a sol-gel solution identical to the one used in step a); e) optionally repeating step d) once or several times; f) heat-treating said stack, so as to transform the sol-gel impregnating the stack into the corresponding piezoelectric ceramics.

Abstract: The invention relates to a method of preparing a stable sol-gel solution as precursor of an oxide ceramic based on lead, titanium, zirconium and one or more lanthanides, comprising, in succession, the following steps: a) a sol-gel solution is prepared by bringing a lead-containing molecular precursor, a titanium-containing molecular precursor, a zirconium-containing molecular precursor and a lanthanide-metal-containing molecular precursor into contact with a medium comprising a diol solvent and optionally an aliphatic monoalcohol; b) the solution obtained in step a) is left to stand for a sufficient time needed to obtain a solution having an approximately constant viscosity; and c) the solution obtained in step b) is diluted to a predetermined amount with a diol solvent identical to that of step a) or a solvent miscible with this solvent. Application to the preparation of an oxide ceramic material comprising lead, a lanthanide metal, titanium and zirconium.

Abstract: The field of the invention is that of photodetectors (10), and more precisely so-called quantum well photodetectors operating in the medium infrared, known by the acronym QWIP standing for Quantum Well Infrared Photodetector. It is an object of the invention to increase the detectivity of the detectors by significantly reducing the surface area of the detection zone while conserving the incident flux. This result is obtained by arranging a structure (4) or grating on the active zone (31) of the photodetector (10), which couples the incident wave and confines it on the active zone (31). The major features of this structure (4) or this grating are that it comprises patterns or grooves having a first spatial frequency and a second spatial frequency, and also comprising a central defect.

Abstract: The invention relates to a detector comprising a multiple quantum well structure operating on interband or intersubband transitions by absorption of radiation having a wavelength ? having a polarization comprising a component perpendicular to the plane of the multiple quantum well structure, and comprising optical coupling means for coupling said radiation, wherein the coupling means comprise a set of first diffractive lamellar features that are distributed along at least a first direction and a set of second diffractive lamellar features that are distributed along at least a second direction, said first and second directions being mutually perpendicular and lying in a plane parallel to the plane of the multiple quantum well structure.

Abstract: The invention relates to an optical coupling structure intended to couple electromagnetic radiation to the surface of a photodetector, wherein a coupling surface paved along mutually perpendicular first and second directions by a set of N series (M1i, M2i, . . . Mni) of first features, second features, . . . nth features, the features being identical within any one series, the features being distributed along the first and second directions, the distance between the centers of two adjacent features or the inter-reticular distances between two adjacent features being variable. The subject of the invention is also a detector or a laser source comprising said coupling structure.

Abstract: A quantum well made out of a the stack of layers of III-V semiconductor materials comprises, in addition to the quantum well, an electron storage layer separated from the quantum well by a transfer barrier layer. The barrier layer has a thickness that is greater than the thickness of the quantum well by about one order of magnitude. This barrier thus enables the separation of the absorption function (in the quantum well) and the function of reading the photocarriers (in the storage layer) and therefore the limiting of the rate of recombination of the carriers, thus improving the performance characteristics of the detector.

Abstract: This optical polarimetric detector comprises: a first active detector element having a photoconductor (1) with which a first diffraction grating (3) is associated allowing incident light from a first specific polarization direction to be coupled in the first detector element and allowing the latter to detect the light having this first polarization direction; a second active detector element having a photoconductor (1′) with which a second diffraction grating (3′) is associated allowing incident light from a second polarization direction to be coupled in the second detector element and allowing the latter to detect the light having this second polarization direction. Furthermore, a detector (2) is provided making it possible to eliminate the background noise detected by previous detectors.

Abstract: The invention relates to a method of preparing a sol of lead zirconium titanate, known as PZT, of formula PbZrxTi(1-x)O3 with 0.45≦x≦0.

Abstract: A bi-functional optical detector including a first active photoconduction detection element configured to detect light within first and second wavelength ranges, a first diffraction grating associated with the first detection element and configured to couple the light within the first wavelength range so that the first active photoconducting detection element detects the light in the first wavelength range, a second active photoconduction detection element configured to detect light within the first and second wavelength ranges, and a second diffraction grating associated with the second detection element and configured to couple the light within the second wavelength range so that the second active photoconduction detection element detects the light in the second wavelength range.

Abstract: This optical polarimetric detector comprises:

Abstract: The basic idea is as follows: operational simulations of subtractive focal planes, based on the French patent No. 2 756 666, have shown that the optimal subtraction rate should not be total in order to preserve the dynamic range of the system. In this case, the low-frequency fluctuations of the temperature of the focal plane of the bias voltages will be amplified and will give rise to a fluctuation of the mean gray level of the signal at output of the multiplexer. This variation can be corrected simply by: the making of several columns of subtractive pixels without diffraction grating, for which the integrated signal is directly the residual level of the thermal current; the integration of a comparator circuit at input of the electronic card to subtract the signal generated in the reference pixels from the signals integrated into the active pixels.

Abstract: The basic idea is as follows: operational simulations of subtractive focal planes, based on the French patent No. 2 756 666, have shown that the optimal subtraction rate should not be total in order to preserve the dynamic range of the system. In this case, the low-frequency fluctuations of the temperature of the focal plane of the bias voltages will be amplified and will give rise to a fluctuation of the mean gray level of the signal at output of the multiplexer.

Abstract: This bi-functional optical detector comprises:

Abstract: The disclosure relates to a bispectral electromagnetic wave detector including at least one first and one second overlaid plane active detector elements separated by a common layer, said first and second detector elements being sensitive to the different wavelengths; a first means of connection connected in common to said first and second detector elements, a second means of connection connected to said first detector element, and a third means of connection connected to said second detector element; means for applying successively a control voltage to each means of connection; and means connected to said first means of connection to detect a photoconduction current each time a control voltage is applied. The invention is used in applications requiring detection of electromagnetic waves in two bands of different wavelengths.

Abstract: An electromagnetic wave detector having a first detector element including an active photoconducting material capable of detecting a band of wavelength and a second detector element including an active photoconducting material capable of detecting the same band of wavelength. A common layer is positioned between the first and second detector elements. A first and second connectors are configured to connect to the first and second detector elements, respectively. A third connector is configured to connect in common to the first and second detector elements. The detector further includes contact mechanisms configured to apply control voltages where the voltage applied to the third connector has a value between the values applied to the first and second connectors. A reading circuit connected to the third connector reads a photoconduction current difference between the first and the second detector elements.

Abstract: Device for the detection and processing of optical radiations, comprising at least one quantum well having asymmetric composition, said well consisting of a stack of layers of materials having differing gaps.

Abstract: Semiconductor hybrid components, especially linear infrared detectors produced by hybridization. A main substrate has integrated thereon active elements which cannot be produced on a silicon substrate. The substrate is made, for example, of AsGa, InP, HgCdTe or PbTe. Several silicon chips are mounted on the main substrate, by hybridization using indium balls. These chips include the read and multiplexing circuits. The silicon chips remain of limited size (a few millimeters) so that the differential thermal expansion stresses are limited, but the detection array may be produced as one piece without butt-joining. It is therefore possible to produce arrays of great length (several centimeters) and of high resolution (at least a thousand points).

Abstract: Disclosed is an integrated direction finder that can be used to determine the direction of a light beam and, in particular, a laser beam. This direction finder has a substrate transparent to the light beam and means on the rear face to channel a part of the light flux received on this face to the front face which has several photodetector elements. Application to optical measurements.

Abstract: A photodetector arrangement capable of detecting high-power-light flux and including a set of elementary photodetectors each one of which is individually tested to determine that it has no defects. Each of the photodetectors which is found to be free of objectionable defects is connected in parallel to a common conducting line to thus produce a combined output when radiation impinges on the detector surface. The connection can be hard wired or provided through a set of transistors acting as connection control intermediaries between the good photodetectors and the common conducting line. The active areas of only good photodetectors are thus combined to form a large photodetector area of any desired shape or size without the usual reliability problems. The selective control of the transistors can further be provided by auxiliary control photodetectors to additionally automatically control the size of the active area in response to the area of light being detected or a control light beam.