Ixblue

Eric Ducloux

Frederic Guattari

Cedric Molucon

Herve Lefevre

Joachin Honthaas

Jean-Jacques Bonnefois

Sebastien Ferrand

Cédric Molucon

Hervé Lefevre

Frédéric Guattari

Sébastien Ferrand

Disclosed is a system for the interferometric measurement of a physical parameter, including an amplified spontaneous emission light source, optically connected to a Sagnac ring interferometer, and two detectors, each supplying a measurement signal representative of the light output from the interferometer, and a reference signal representative of the light output emitted by the source, which is impaired by an excess relative intensity noise. This measurement is obtained from a difference between the measurement and reference signals, weighted by a weighting coefficient which is controlled to minimise the statistical deviation of an additional weighted difference between signals obtained by demodulating the measurement and reference signals by way of an additional digital demodulation sequential code insensitive to the parameter. Also disclosed is a gyroscope including such a measuring system.

Measuring system and gyrometer comprising such a system

An interferometric system with multi-axis optical fiber and a method for processing an interferometric signal in such a system, the multi-axis interferometric system includes a light source (); a plurality of N optical-fiber coils (), a first optical separation element () capable of splitting the source beam () into a first split beam () and a second split beam (); shared phase-modulation element (); a photodetector () and a signal-processing system (). The N optical-fiber coils () are connected in parallel, the coils having respective transit times T, T, . . . TN that all differ from one another, and the signal-processing system () is capable of processing the interferometric signal () detected by the shared photodetector () as a function of the respective transit times in the various coils.

Interferometric system with multiaxial optical fibre and method for processing an interferometric signal in such a system

An interferometric measurement device includes a broad-spectrum spontaneous emission light source; a measurement interferometer, receiving a light signal with input light power and delivering a modulated light signal with output light power, the modulated light signal being modulated at a modulation frequency, depending on a physical parameter to be measured and being proportional to the input light power; an optical radiation detector, receiving the modulated light signal exiting from the measurement interferometer and delivering a modulated electrical signal representative of the output light power; a filtering interferometer, insensitive to the physical parameter to be measured, having a free spectral range ISL and a finesse F selected such that an interval of frequencies, centerd around an optimal frequency fequal to (2k+1)ISL/2, k being a natural number, and of width &#x394;f equal to [0.9&#x2212;(3/2F)]ISL, includes the modulation frequency of the modulated light.

Interferometric measurement device comprising a filtering interferometer

A fiber-optic measurement device () includes a SAGNAC ring interferometer () having a proper frequency f, a detector () and a modulation chain () generating a phase-shift modulation &#x3c6;(t) between the two counter-propagating waves () propagating in the ring interferometer. The device aims to reduce measurement faults due to the linearity defects in the modulation chain of such a measurement device with optical fiber. For this reason, the fiber-optic measurement device reduces the amplitude of the phase-shift modulation &#x3c6;(t) which is the sum of a first biasing phase-shift modulation component &#x3c6;(t) and a first counter-reaction phase-shift modulation component &#x3c6;(t), the phase-shift modulation &#x3c6;(t) falling or rising by twice the amplitude of the first biasing phase-shift modulation component &#x3c6;(t). A rate gyro including such a measurement device and an inertial stabilization or navigation unit including at least one such rate gyro are also described.

Fibre-optic measurement device, rate gyro, and inertial stabilisation and navigation unit

A fiber-optic interferometric measurement device () intended to measure a physical parameter (QR), includes: a wide-spectrum light source (); a SAGNAC fiber-optic interferometer (), in which there propagate two counter-propagating light waves () including measurement elements () sensitive to the physical parameter that results in a non-reciprocal phase difference &#x394;&#x3c6;&#x3c1; between the two light waves; and a detector () delivering an electric signal representative of the physical parameter. The measurement elements include a ring resonator () in transmission mode including a first coupler () and a second coupler () respectively, which couple a first arm () and a second arm () respectively of the SAGNAC interferometer to the ring resonator, in such a way that the two light waves travel in opposing directions of travel (H,AH).

Fibre-optic interferometric measurement device comprising a ring resonator, gyrometer and inertial attitude or navigation unit comprising such a device

A fiber optic interferometric measurement system includes a light source; first and second optical transmission elements; first and second Sagnac-ring interferometers, respectively, including first and second fiber optic coils, and, respectively, having lengths Land L; and first and second individual integrated optical circuits, respectively, connected to the first and second optical transmission elements, and to the two ends of the first and second optic coils, respectively. The interferometric system includes a multiple integrated optical circuit integrating, on a single substrate, the first and second individual integrated optical circuits, and the difference &#x394;l between the optical length of the first optical transmission elements and the optical length of the second optical transmission elements is higher than the maximum of &#x394;Nb&#xd7;Land &#x394;NB&#xd7;L, in which &#x394;Nband &#x394;Nb, respectively, are the group birefringence index difference of the first and second fiber optic coils, respectively.

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Rueil Malmaison, France

Eric Ducloux