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Cedric Molucon

Frederic Guattari

Herve Lefevre

Eric Ducloux

Stephane Chouvin

Jean-Jacques Bonnefois

Pascal Simonpietri

Sebastien Ferrand

Joachin Honthaas

Karl Aubry

Disclosed is an optical fiber interferometric system including a light source (), a fiber optic coil (), a coil splitter (), a photodetector (), and a polarization filtering unit. According to an embodiment, the polarization filtering unit includes a first waveguide polarizer (), at least one second thin-plate polarizer () and an optical waveguide section (), the at least one second polarizer () being disposed in the Rayleigh zone between a first waveguide end () of the first polarizer () and a second waveguide end () of the optical waveguide section ().

Sagnac-ring fiber-optic interferometric system with Rayleigh length spaced polarizer

Interferometric measurement device includes a light source emitting a source signal and optical coupling elements receiving the source signal, directing part of the latter towards a measurement pathway including a Sagnac ring interferometer, of frequency f, producing a power output signal Ppolarized according to a first polarization direction, tapping off another part of the source signal towards a compensation pathway producing a return power compensation signal P, and directing the output and compensation signals towards detection elements. The compensation pathway includes polarization rotation elements producing the compensation signal according to a second cross-direction of polarization, and optical looping elements redirecting part of the compensation signal towards the measurement pathway; the detection elements include a single detector connected to the coupling elements for receiving the output signal and the compensation signal; the device further includes power equilibration elements equalizing the output power and/or return power are routed towards the detector.

Interferometric measurement device

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

Disclosed is a waveguide polarizing optical device, including a first waveguide polarizer (), a section of a second optical waveguide () and a second thin-plate polarizer () having a physical thickness T and a refractive index n, the second thin-plate polarizer () being disposed on the optical path between a waveguide end () of the first polarizer () and one end () of the second optical waveguide (), the physical distance d between the waveguide end () of the first polarizer () and the end () of the second optical waveguide () being less than or equal to twice the Rayleigh length and the physical thickness T of the second polarizer () being less than or equal to the physical distance d.

Waveguide polarizing optical device

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.

Interferometric measurement system with optical fibre and inertial guidance or navigation system including such an interferometric measurement system

An interferometric system includes a polarization separation element (), a first polarization conversion element (), a Mach-Zehnder interferometer () including a first () and second () arms connected to one another by a first () and second () ends in order for a first and second beams () having the same polarization to pass through the interferometer in a reciprocal manner in opposite directions of propagation, respectively, so as to form a first and second interferometric beam (), a second polarization conversion element () for obtaining an interferometric beam (), the polarization of which is converted, a polarization-combining element (), and a detection element () suitable for detecting an output beam ().

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Saint Germain-en-Laye, France

Cedric Molucon