Thales

Commissariat a L'energie Atomique Et Aux Energies Alternatives

Mirsense

Societe Francaise De Detecteurs Infrarouges-Sofradir

Mathieu Carras

Alfredo De Rossi

Serge Gidon

Philippe Bois

Sergio Nicoletti

Philippe Andreucci

Mickaël Brun

Jean-Philippe Schnell

Xavier Marcadet

Guillaume Aoust

Simon Ferre

Bouzid Simozrag

Guy-Maël De Naurois

A photo-acoustic gas sensor using a method for modulating the wavelength of the laser radiation, the modulation being obtained via judicious use of an electric current, called the generation current, which pumps the one or more laser sources, and is configured to cause the one or more laser sources to operate in pulsed mode, and of a current, called the base current, which takes non-zero values between each laser pulse with a lower magnitude than the magnitude of the generation current, the magnitude of base current being modulated so that the one or more laser sources emit, into the cell, light radiation having a wavelength that varies periodically about a central wavelength so as to take, at regular intervals, a value specifically suitable for the excitation of a gas to be detected, whereby an interaction between the light radiation and the gas to be detected contained in the cell induces the generation of acoustic waves at a resonant frequency of the cell.

Photoacoustic gas sensor using a method for modulating the illumination wavelength

A photoacoustic detection device including a nanophotonic circuit including a plurality of semiconductor lasers capable of emitting a different frequencies; input couplers connected to optical waveguides; a multiplexer; an output optical waveguide, emerging into a recess; a tuning fork having its free arms arranged at the output of the output optical waveguide; and means for detecting the vibration of the tuning fork, all these elements being assembled in a monolithic component.

Photoacoustic gas detector

The field of the invention is that of photodetectors (), 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 () or grating on the active zone () of the photodetector (), which couples the incident wave and confines it on the active zone (). The major features of this structure () 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.

Photodetector having a near field concentration

An optical structure enabling properties of the surface plasmons to be used is defined from a substantially binary, parameterizable unit pattern M. The parameters a, b, c, d and hof the pattern are chosen so as to maximize the complex amplitudes of the first two harmonics of the complex Fourier series describing the pattern M. This structure is advantageously used in combination with a photodetector, an infrared or Terahertz optical wave emitter, or a field emission device.

Optical structure for localising an electromagnetic field and detector or emitter device including such a structure

The present invention relates to the field of distributed feedback semiconductor lasers. More specifically, the invention makes it possible to develop single-mode distributed feedback lasers with a production rate close to 100% using a simple and robust technology. To this end, the invention involves introducing radiative losses on just one of the two predominant modes of a DFB laser obtained by index modulation by defining a particular refractive index profile of the active area.

Single-mode distributed feedback semiconductor lasers

The present invention relates to a strong distributed feedback semiconductor laser. More specifically, the invention implements a top optical waveguide () for semiconductor lasers having a surface metallic grating () making it possible to obtain a stable and controlled distributed feedback, using a simple and robust technology. In the inventive laser, which comprises an active area () having an effective refractive index (neff) in which a light wave is propagated with a wavelength (&#x3bb;), the top waveguide () is made of a weakly-doped material and the periodic grating () depth (p) is plus or minus 50%, the low precision needed being one of the advantages of the inventive laser.

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Montrouge, France

Mathieu Carras