Abstract: A fiber-optic interferometer is designed to receive and propagate a first single-mode wave along a first optical path and, respectively, a second single-mode wave along a second optical path, the second optical path being the reverse of the first optical path, and to form a first output wave and, respectively, a second output wave, having a modulated phase difference ??m(t). According to the invention, the modulated phase difference ??m(t) is equal to sum of a first periodic phase difference ???(t) having a level equal to ±?, a second periodic phase difference ??alpha(t) having a level equal to ±alpha and a third periodic phase difference ??beta(t) having a variable level between ?beta and +beta, said modulated phase difference ??m(t) comprising per modulation period T at least eight modulation levels among twelve modulation levels and said modulated phase difference between such that: ??m(t+T/2)=???m(t).

Abstract: A fiber-optic interferometer is designed to receive and propagate a first single-mode wave along a first optical path and, respectively, a second single-mode wave along a second optical path, the second optical path being the reverse of the first optical path, and to form a first output wave and, respectively, a second output wave, having a modulated phase difference ??m(t). According to the invention, the modulated phase difference ??m(t) is equal to sum of a first periodic phase difference ???(t) having a level equal to ±?, a second periodic phase difference ??alpha(t) having a level equal to ±alpha and a third periodic phase difference ??beta(t) having a variable level between ?beta and +beta, said modulated phase difference ??m(t) comprising per modulation period T at least eight modulation levels among twelve modulation levels and said modulated phase difference between such that: ??m(t+T/2)=???m(t).

Abstract: 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.

Abstract: 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.

Abstract: 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 (1); a plurality of N optical-fiber coils (11, 12), a first optical separation element (3) capable of splitting the source beam (100) into a first split beam (140) and a second split beam (240); shared phase-modulation element (4); a photodetector (2) and a signal-processing system (800). The N optical-fiber coils (11, 12) are connected in parallel, the coils having respective transit times T1, T2, . . . TN that all differ from one another, and the signal-processing system (800) is capable of processing the interferometric signal (720) detected by the shared photodetector (2) as a function of the respective transit times in the various coils.

Abstract: 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 foptim equal to (2k+1)ISL/2, k being a natural number, and of width ?f equal to [0.9?(3/2F)]ISL, includes the modulation frequency of the modulated light.

Abstract: A fiber-optic measurement device (10) includes a SAGNAC ring interferometer (20) having a proper frequency fp, a detector (14) and a modulation chain (30) generating a phase-shift modulation ?m(t) between the two counter-propagating waves (24, 25) 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 ?m(t) which is the sum of a first biasing phase-shift modulation component ?b1(t) and a first counter-reaction phase-shift modulation component ?cr1(t), the phase-shift modulation ?m(t) falling or rising by twice the amplitude of the first biasing phase-shift modulation component ?b1(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.

Abstract: A fiber-optic interferometric measurement device (100) intended to measure a physical parameter (QR), includes: a wide-spectrum light source (103); a SAGNAC fiber-optic interferometer (110), in which there propagate two counter-propagating light waves (101, 102) including measurement elements (1140) sensitive to the physical parameter that results in a non-reciprocal phase difference ??? between the two light waves; and a detector (104) delivering an electric signal representative of the physical parameter. The measurement elements include a ring resonator (1143) in transmission mode including a first coupler (1141) and a second coupler (1142) respectively, which couple a first arm (111) and a second arm (112) respectively of the SAGNAC interferometer to the ring resonator, in such a way that the two light waves travel in opposing directions of travel (1143H, 1143AH).

Abstract: 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 L1 and L2; 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 ?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 ?Nb1×L1 and ?NB2×L2, in which ?Nb1 and ?Nb2, respectively, are the group birefringence index difference of the first and second fiber optic coils, respectively.

Abstract: 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 (1); a plurality of N optical-fiber coils (11, 12), a first optical separation element (3) capable of splitting the source beam (100) into a first split beam (140) and a second split beam (240); shared phase-modulation element (4); a photodetector (2) and a signal-processing system (800). The N optical-fiber coils (11, 12) are connected in parallel, the coils having respective transit times T1, T2, . . . TN that all differ from one another, and the signal-processing system (800) is capable of processing the interferometric signal (720) detected by the shared photodetector (2) as a function of the respective transit times in the various coils.

Abstract: A fibre-optic interferometric measurement device (100) intended to measure a physical parameter (QR), includes: a wide-spectrum light source (103); a SAGNAC fibre-optic interferometer (110), in which there propagate two counter-propagating light waves (101, 102) including measurement elements (1140) sensitive to the physical parameter that results in a non-reciprocal phase difference ??? between the two light waves; and a detector (104) delivering an electric signal representative of the physical parameter. The measurement elements include a ring resonator (1143) in transmission mode including a first coupler (1141) and a second coupler (1142) respectively, which couple a first arm (111) and a second arm (112) respectively of the SAGNAC interferometer to the ring resonator, in such a way that the two light waves travel in opposing directions of travel (1143H, 1143AH).

Abstract: An interferometric measurement device includes a broad-spectrum spontaneous emission light source; a measurement interferometer, receiving as input a light signal with input light power and delivering as output a modulated light signal with output light power, the modulated light signal being modulated at a modulation frequency, depending on a physical parameter (?R) 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, centred around an optimal frequency foptim equal to (2k+1) ISL/2, k being a natural number, and of width ?f equal to [0.9?(3/2F)] ISL, includes the modulation frequency of the modulated light.

Abstract: 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 L1 and L2; 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 ?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 ?Nb1×L1 and ?NB2×L2, in which ?Nb1 and ?Nb2, respectively, are the group birefringence index difference of the first and second fiber optic coils, respectively.

Abstract: A fibre-optic measurement device (10) includes a SAGNAC ring interferometer (20) having a proper frequency fp, a detector (14) and a modulation chain (30) generating a phase-shift modulation ?m(t) between the two counter-propagating waves (24, 25) 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 fibre. For this reason, the fibre-optic measurement device reduces the amplitude of the phase-shift modulation ?m(t) which is the sum of a first biasing phase-shift modulation component ?b1(t) and a first counter-reaction phase-shift modulation component ?cr1(t), the phase-shift modulation ?m(t) falling or rising by twice the amplitude of the first biasing phase-shift modulation component ?b1(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.

Abstract: A device for wide range continuous wavelength sweeping on a set of tunable laser sources over a predetermined global wavelength range, the device working with at least one functional pair of cooperating tunable lasers, each laser of the cooperating pair emitting over a sub range of the global wavelength range, the sub ranges of a functional pair partly overlapping each other in an overlapping wavelength zone, all the sub ranges being included within the global wavelength range and the sweeping of the output laser signal being done by the selection and tuning of one of the lasers of one of the functional pairs at a time. The device includes for a functional pair of cooperating tunable lasers an optical switch and an heterodyne optical detector.