Thomson-csf

Office National D'etudes Et De Recherches Aerospatiales (onera)

Onera

Emmanuel Rosencher

Philippe Bois

Borge Vinter

Vincent Berger

Daniel Kaplan

Jean Massies

Riad Haïdar

Jean-Yves Duboz

Michel Lefebvre

Julien Nagle

Francedillaois Micheron

Jérôme Primot

Fran&ccedil;ois Micheron

Jéröme Primot

Aude Desormeaux

Paul Bois

Nicolas Grandjean

Gerard Neu

In a nonlinear optical medium such as the gallium arsenide, two collinear incident monochromatic waves are injected to generate a monochromatic wave. The medium induces between the three waves a propagation phase-shift that has a value &#x3c0; if the three waves travel a coherence length in the medium and that is compensated at the value 0 modulo 2&#x3c0; each time that the three waves have travelled a periodic distance in the medium. In order to significantly increase the conversion efficiency, the periodic distance between two successive bounces of total internal reflection of the waves in zig-zag is strictly less than the coherence length. The high conversion efficiency on a very short material length leads to product high-power coherent optical sources particularly with wavelengths of approximately 10 &#x3bc;m.

Wave generation by wave propagation phase-shift compensation in an non-linear optical medium

The oscillator comprises two resonant cavities in which a non-linear crystal () is situated. The incident pumping radiation Rfollows an emitting path across the crystal, the generated signal and complementary radiation carry out numerous emitted and return paths in the cavities, hence across the crystal and are thus converted into an inverse pumping radiation on the return paths thereof. According to the invention, a device () is incorporated in the oscillator for reflection of a fraction of the pumping radiation equivalent to the inverse pumping radiation in the absence of the device.

Doubly-resonant optical parametric oscillator with corresponding pump recycling

An infrared imaging device including a quantum device positioned and configured to detect infrared transmission at ambient temperature, a cooler thermally coupled to the quantum device, and controller for controlling the cooler based on a function of plural image-taking parameters as a command.

Infrared quantum structure imaging device working at ambient temperature

A laser made of a stack of laser diodes. The stack is inserted between two mirrors to create a laser cavity. The stack of diodes is produced by epitaxial growth of a set of semiconductor layers. The ohmic contact between two adjacent laser diodes is provided by an Esaki diode junction. The optical field of the mode created in the laser cavity is periodically cancelled at the Esaki diode junctions so as to create structures with small dimensions.

Laser comprising stacked laser diodes produced by epitaxial growth inserted between two bragg mirrors

A detector with quantum structure comprising a small-gap semiconductor material inserted between two large-gap semiconductor materials, the structure comprising a coupling grating between the wave to be detected and the detector zone constituted by the small-gap material. Under these conditions, the detector zone may have a very small thickness (typically of the order of 1,000 .ANG.) and lead to a detectivity, limited by the dark current, that is high.

Infrared detector with non-cooled quantum well structure

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.

Device for the detection of optical radiations

A frequency converter can be used, in particular, to generate optical waves in the medium infrared (3.12 .mu.m) range from optical sources in the near infrared range. It comprises a heterostructure semiconductor waveguide formed by an alternation of layers of material M.sub.I and M.sub.II, at least one of these materials being a non-linear semiconductor and the plane of the layers being parallel to the direction of propagation of the electromagnetic waves in the waveguide.

Frequency converter comprising a heterostructure semiconductor waveguide

Semiconductor hybrid component

An electromagnetic wave detector formed of semiconductor materials includes at least one quantum well in which there is provided a fine layer of a material with a gap width that is smaller than that of the quantum well layer. For example, in the case of a GaAlAs/GaAs/GaAlAs, there is provision for a fine layer of InAs. In this way, the difference of energy levels between the two permitted levels is increased and detection of short wavelengths may be accomplished.

Electromagnetic wave detector with quantum well structure

An electromagnetic wave detector comprises a stack of quantum wells included between an ohmic contact and a rectifier junction which may be a barrier (Al.sub.y Ga.sub.1-y As) with a forbidden band width that is greater than that of the barriers of the quantum wells.

Electromagnetic wave detector

A light intensity modulator with a predefined range of modulation wavelengths (preferably a narrow range) can be adjusted by a control signal. This modulator receives a light beam and retransmits a modulated light beam in which any wavelength within the modulation range is modulated. A light intensity detector receives this modulated beam and outputs an electrical signal which is a function of the luminous intensity detected. Such a device finds particular application as a spectrophotometer.

Spectrometer

An electronic bolometer comprises at least a quantum well between two barrier layers. It has an input side parallel to the quantum-well layer and receiving a beam at a quasi-normal incidence angle. Two electrodes disposed perpendicularly to the quantum-well layers allow to measure a change in the resistivity of said quantum well.

Quantum-well electronic bolometer and application to a radiation detector

A capacitive detector of electromagnetic waves, comprises three electron levels, wherein an internal barrier prevents a strong coupling between two levels of two neighboring wells. During an irradiation, the electrons are excited from a first level to a second level. The electrons then relax towards a third level until they relax, by tunnel effect, towards the first level. During the transition from the first level towards the third level, a dipole is created. This dipole can be detected by a detector, through the measurement of a potential difference at the terminals of the device.

Growing community of inventors

Bagneux, France

Emmanuel Rosencher