Abstract: A method for processing a signal from a coherent lidar comprising a periodically frequency-modulated coherent source (L), the method includes the following steps: A decomposing each modulation period indexed j into a plurality of intervals indexed i, and determining, for each interval Iij, an elementary power spectral density DSP(i,j) of the beat signal over the interval, B determining an average power spectral density over j DSP(i), C determining a lower frequency bound of the average power density DSP(i) and an upper frequency bound, D determining a distance dk(i) and a velocity of the fluid vk(i) from the lower and upper bounds.

Abstract: The invention relates to an optical reception device for receiving a signal from an antenna array comprising: a light source generating an optical carrier and M phased optical beams which are frequency-shifted relative to the optical carrier; a collection circuit comprising N paths connected to an antenna, and comprising a modulator of an incident signal; a beam-forming network connecting (M+1) first ports to N second ports connected to one path, M first ports being connected to the optical beams and a control port connected to the other ports so that a maximum optical intensity on the control port corresponds to phased signals on the N second ports.

Abstract: An elementary device for coherently recombining a first elementary beam and a second elementary beam, includes a first input and a second input, into which are respectively injected the first elementary beam and the second elementary beam to be recombined, an output that delivers an output beam corresponding to the coherent recombination of the first and second elementary beams, a delay line placed on one of the paths of said elementary beams and configured to induce a variable delay on said path, a variable coupler comprising a first 2×2 combiner, a phase modulator and a second 2×2 combiner, a control detector configured to generate, from the complementary beam, an error signal (?), a feedback loop configured to determine, from the error signal, the delay and the phase difference to be applied.

Abstract: The invention relates to an optical reception device for receiving a signal from an antenna array comprising: a light source generating an optical carrier and M phased optical beams which are frequency-shifted relative to the optical carrier; a collection circuit comprising N paths connected to an antenna, and comprising a modulator of an incident signal; a beam-forming network connecting (M+1) first ports to N second ports connected to one path, M first ports being connected to the optical beams and a control port connected to the other ports so that a maximum optical intensity on the control port corresponds to phased signals on the N second ports.

Abstract: An elementary device for coherently recombining a first elementary beam and a second elementary beam, includes a first input and a second input, into which are respectively injected the first elementary beam and the second elementary beam to be recombined, an output that delivers an output beam corresponding to the coherent recombination of the first and second elementary beams, a delay line placed on one of the paths of said elementary beams and configured to induce a variable delay on said path, a variable coupler comprising a first 2×2 combiner, a phase modulator and a second 2×2 combiner, a control detector configured to generate, from the complementary beam, an error signal (?), a feedback loop configured to determine, from the error signal, the delay and the phase difference to be applied.

Abstract: A laser-source assembly that is configured to illuminate a vacuum chamber containing atoms in the gaseous state so as to implement a cold-atom inertial sensor, the atoms having at least two fundamental levels that are separated by a fundamental frequency difference comprised between 1 and a few gigahertz, the assembly comprises: a master laser that emits a beam having a master frequency; a first control loop that is configured to stabilize the master frequency of the master laser on a frequency corresponding to half a set frequency of an atomic transition between a fundamental level and an excited level of the atoms; a slave laser that has a slave frequency; and a second control loop that is configured to stabilize the slave frequency of the slave laser with respect to the master frequency, the slave frequency being offset with respect to the master frequency successively, over time, by a first preset offset value, a second preset offset value, and a third preset offset value, the offset values being comprise

Abstract: A method for measuring the delay between N pulses having a duration less than 100 picoseconds comprises the steps: collimated emission of the pulses having the same repetition frequency, emission of a reference pulse having the same repetition frequency capable of producing interference fringes with each of the pulses, for each of the pulses, detection, by a detector, of the coherent sum of this pulse with the reference pulse, this sum producing the interference fringes, the fringes originating from each of the pulses being distinguishable from one another. The reference pulse is emitted with an adjustable delay, and the method further comprises: for each delay, simultaneous measurement for the pulses of N contrasts of the interference fringes, for each of the pulses, a delay value between this pulse and the reference pulse is determined by the delay corresponding to the maximum contrast.

Abstract: A method for measuring the delay between N pulses having a duration less than 100 picoseconds comprises the steps: collimated emission of the pulses having the same repetition frequency, emission of a reference pulse having the same repetition frequency capable of producing interference fringes with each of the pulses, for each of the pulses, detection, by a detector, of the coherent sum of this pulse with the reference pulse, this sum producing the interference fringes, the fringes originating from each of the pulses being distinguishable from one another. The reference pulse is emitted with an adjustable delay, and the method further comprises: for each delay, simultaneous measurement for the pulses of N contrasts of the interference fringes, for each of the pulses, a delay value between this pulse and the reference pulse is determined by the delay corresponding to the maximum contrast.

Abstract: A laser-source assembly that is configured to illuminate a vacuum chamber containing atoms in the gaseous state so as to implement a cold-atom inertial sensor, the atoms having at least two fundamental levels that are separated by a fundamental frequency difference comprised between 1 and a few gigahertz, the assembly comprises: a master laser that emits a beam having a master frequency; a first control loop that is configured to stabilize the master frequency of the master laser on a frequency corresponding to half a set frequency of an atomic transition between a fundamental level and an excited level of the atoms; a slave laser that has a slave frequency; and a second control loop that is configured to stabilize the slave frequency of the slave laser with respect to the master frequency, the slave frequency being offset with respect to the master frequency successively, over time, by a first preset offset value, a second preset offset value, and a third preset offset value, the offset values being comprise

Abstract: A system based on recombination by superposition using a diffractive optical element DOE to combine the beams is provided. An optical diffractive assembly is placed upstream of a diffractive optical element to make it possible, via an appropriate imaging system, to optimize the combining efficiency in the ultra-short pulse regime.

Abstract: A system for phasing periodically configured laser sources, which comprises: means for collimating and directing the beams arising from the sources onto a combining diffractive optical element with a periodic phase grating, with an angle of incidence that differs from one beam to the next, these angles of incidence being determined according to the period of the grating; means for controlling the phases of the sources based on a negative feedback signal arising from the combined beams; means for drawing off a fraction of the combined beams; on the path of this fraction of the beams, a Fourier lens, with the combining diffractive optical element in its object plane; a matrix of detectors in the image plane of the Fourier lens, capable of detecting intensity distributions; means for calculating the negative feedback signal based on these intensity distributions.

Abstract: A system for phasing periodically configured laser sources, which comprises: means for collimating and directing the beams arising from the sources onto a combining diffractive optical element with a periodic phase grating, with an angle of incidence that differs from one beam to the next, these angles of incidence being determined according to the period of the grating; means for controlling the phases of the sources based on a negative feedback signal arising from the combined beams; means for drawing off a fraction of the combined beams; on the path of this fraction of the beams, a Fourier lens, with the combining diffractive optical element in its object plane; a matrix of detectors in the image plane of the Fourier lens, capable of detecting intensity distributions; means for calculating the negative feedback signal based on these intensity distributions.

Abstract: A system based on recombination by superposition using a diffractive optical element DOE to combine the beams is provided. An optical diffractive assembly is placed upstream of a diffractive optical element to make it possible, via an appropriate imaging system, to optimize the combining efficiency in the ultra-short pulse regime.

Abstract: The subject of the invention is a polarimetric imaging system exhibiting an optical axis, and comprising means (35) for the detection and analysis of the light backscattered by an object illuminated by a light source and at least one programmable waveplate (33), wherein the programmable waveplate comprises a material with an isotropic electrooptic tensor and a set of at least three electrodes disposed along the directions parallel to the optical axis of the imaging system.

Abstract: A laser source comprises N incident laser beams, N equal to two at least, N single-mode spatial beam propagation media, each forming a propagation channel (gi) for one laser beam, a system for coherent recombination at the exit of the N channels, in order to deliver a recombined laser beam (fR) at the exit, and a phase control device (D) comprising N programmable phase-shifter elements (di) under closed-loop feedback control, one at the entry of each channel (gi). The source also comprises a polarization control device (P) comprising N programmable polarization controllers (pi) under closed-loop feedback control, one per channel, each controller being disposed between the associated phase-shifter element and channel.