Thales

Centre National De La Recherche Scientifique

Université Nice Sophia Antipolis

Stéphanie Molin

Jean-Pierre Huignard

Daniel Dolfi

Martine Doisy

Umberto Bortolozzo

Stefania Residori

Arnaud Peigne

Jean-Paul Pocholle

Renaud Bouffaron

Loïc Morvan

A distributed optical fiber sensor of dynamic stress state comprises: an optical assembly configured to generate a series of optical pulses; an optical fiber of optical length L; an optical system configured to: inject through the first end at least the series of optical pulses; receive at the level of the end at least one series of output optical pulses, arising from the input pulses after propagation and retro-propagation in the fiber; generate at least one continuous reference beam or reference optical pulses on the basis of the optical assembly or of output optical pulses; produce a series of interference zones corresponding to the interference between the reference beam or a reference pulse and a signal optical pulse arising from an output optical pulse; a holographic detector comprising: a liquid-crystal light valve, the valve disposed so that it at least partially covers the interference zones, and producing holograms on the basis of the interference zones; at least one optical detector configured to detect output optical signals diffracted by the holograms.

Distributed optical fibre sensor for sensing stress state

A fiber optic sensor for detecting an excitation in proximity to a fiber optic assembly, the excitation inducing a modulation of the phase of an optical signal propagating in the fiber optic assembly, the sensor comprises: a laser assembly emitting at least one laser beam; a fiber optic assembly; an optical system configured to: inject at least one portion of the laser beam; generate at least one laser signal beam issued from the laser beam injected into and propagated in the fiber assembly; generate at least one reference beam from the laser beam or the signal beam; produce at least one interference zone corresponding to the interference between a portion of the reference beam and a portion of the interference signal beam corresponding to the interference between a portion of the reference beam and a portion of the signal beam; a digital holography assembly comprising: a liquid-crystal spatial light modulator; a video camera configured to receive the interference zone and to transcribe it electrically to the liquid-crystal spatial light modulator in order to create thereon a phase hologram corresponding thereto; at least one optical detector configured to detect an output optical signal beam.

Optical fiber sensor

An optical fiber sensor for locating an excitation in proximity to an optical fiber assembly comprises: a laser assembly configured to emit N laser beams indexed i with N&#x3e;1, of respective emission wavelength &#x3bb;i, an optical fiber assembly comprising N successive sections indexed i, an optical system configured to: inject the laser beams, receive N signal beams indexed i respectively of wavelengths &#x3bb;i, generate N reference beams indexed i respectively of wavelengths &#x3bb;i, produce N interference areas indexed i, a holographic detector comprising: a liquid crystal light valve that at least partially covers the interference areas, and is configured to produce N holograms indexed i from, respectively, N interference areas, at least one optical detector configured to detect N output optical signals indexed I, a processing unit adapted to identify the section of the fiber assembly situated in proximity to the excitation to be located.

Sensor with high-sensitivity optical fiber having a holographic detector comprising a liquid crystal light valve

The subject of the present invention is a dynamic sensor of physical quantities with optical waveguide with optically-pumped amplifier medium, which requires no interferometer or reference sensor and which makes it possible to obtain at least the same level of performance, in terms of sensitivity, as known sensors of this type, and this waveguide is linked at one end to a selective mirror, and comprises at its other end an interrogation laser, the reflection of which on the selective mirror produces a wave which, by interference with the incident wave, provokes the periodic saturation of the gain of the waveguide.

Dynamic sensor of physical quantities with optical waveguide with optically pumped amplifier medium

The general field of the invention is that of fiber-optic sensors comprising at least one measurement optical fiber having an optically pumped doped amplifying medium, the optical characteristics of which are sensitive to a physical quantity, the fiber having at least one Bragg grating. The fiber is designed so as to generate, in the amplifying medium, two optical waves having different optical frequencies that propagate in the same direction after reflection on the Bragg grating and are emitted by the amplifying medium, the two optical frequencies depending on the physical quantity. The two waves may be generated using either a birefringent polarization-maintaining fiber or a DBR (Distributed Bragg Reflector) laser cavity. Notably, this sensor may be used as a hydrophone.

Growing community of inventors

Draveil, France

Stéphanie Molin