Abstract: A method for the servo control of an optical device includes a cavity exhibiting resonance around a center frequency ƒc, a laser and a phase modulator, the method being designed to servo-control the cavity to the laser or vice versa and to compensate for an amplitude modulation introduced by the phase modulator, the method comprising, inter alia, the following steps: A. varying a difference ?? between the optical frequency of the laser radiation and the center frequency, such that the optical frequency scans the resonance, the difference being controlled by a parameter of an element of the device, and for each difference ??i i. modulating, at a modulation frequency ƒmod, a phase of the laser radiation, through a modulation phase ?mod, with the phase modulator, ii. injecting the phase-modulated radiation into the cavity, iii. using a photodiode to detect radiation reflected or transmitted by the cavity and generating an electrical signal (St, Sr) representative of the intensity of the detected radiation, iv.

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 iterative method for determining scattering coefficients of the cavity of a laser gyro in operation supporting two counter-propagating modes, comprises steps of: determining a set of variables dependent on characteristic physical quantities of the laser gyro, one reference variable per dependency relationship being selected from the variables; measuring values of the characteristic physical quantities of the laser gyro in operation; determining measured values of the variables; estimating, via an iterative method, estimated values of the coefficients minimising a discrepancy between the measured values of the reference variables and estimated values of the reference variables, which are estimated from the values of the coefficients and the measured values of the variables other than the reference variables; and determining estimated values of the scattering coefficients from the estimated values of the coefficients.

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: A passive resonant optical gyroscope comprising a cavity and operating with three frequencies comprises: a first injecting laser to inject a first optical beam into the cavity in a first direction; a second injecting laser to inject a second optical beam into the cavity in an opposite direction; a third injecting laser to inject a third optical beam into the cavity in one of the aforementioned directions, one laser amongst the injecting lasers having a master frequency, the two other injecting lasers, called the first and second slave lasers, respectively having a first slave frequency and a second slave frequency; a master servocontrol device; a first servocontrol stage comprising first and second slave devices; and a second servocontrol stage comprising first and second optical phase-locking devices respectively comprising a first and second slave oscillator to generate a first radiofrequency offset signal and a second radiofrequency offset signal.

Abstract: The general field of the invention is that of passive resonator gyros comprising an injection laser emitting an initial optical beam at a first frequency and a fiber optic cavity. The gyro according to the invention operates with three optical beams at three different optical frequencies. A first beam is injected in a first direction of rotation, the second and the third beam are injected in the contrary direction. The gyro includes three slaving devices maintaining each optical frequency at a specific mode of resonance of the cavity. The gyro includes means for measuring the frequency differences existing between the different frequencies. Combined together, these differences are representative of the length of the cavity and the angular rotational velocity of the cavity along an axis perpendicular to its plane.

Abstract: A passive resonant optical gyroscope comprising a cavity and operating with three frequencies comprises: a first injecting laser to inject a first optical beam into the cavity in a first direction; a second injecting laser to inject a second optical beam into the cavity in an opposite direction; a third injecting laser to inject a third optical beam into the cavity in one of the aforementioned directions, one laser amongst the injecting lasers having a master frequency, the two other injecting lasers, called the first and second slave lasers, respectively having a first slave frequency and a second slave frequency; a master servocontrol device; a first servocontrol stage comprising first and second slave devices; and a second servocontrol stage comprising first and second optical phase-locking devices respectively comprising a first and second slave oscillator to generate a first radiofrequency offset signal and a second radiofrequency offset signal.

Abstract: An iterative method for determining scattering coefficients of the cavity of a laser gyro in operation supporting two counter-propagating modes, comprises steps of: determining a set of variables dependent on characteristic physical quantities of the laser gyro, one reference variable per dependency relationship being selected from the variables; measuring values of the characteristic physical quantities of the laser gyro in operation; determining measured values of the variables; estimating, via an iterative method, estimated values of the coefficients minimising a discrepancy between the measured values of the reference variables and estimated values of the reference variables, which are estimated from the values of the coefficients and the measured values of the variables other than the reference variables; and determining estimated values of the scattering coefficients from the estimated values of the coefficients.

Abstract: The general field of the invention is that of passive resonator gyros comprising an injection laser emitting an initial optical beam at a first frequency and a fibre optic cavity. The gyro according to the invention operates with three optical beams at three different optical frequencies. A first beam is injected in a first direction of rotation, the second and the third beam are injected in the contrary direction. The gyro includes three slaving devices maintaining each optical frequency at a specific mode of resonance of the cavity. The gyro includes means for measuring the frequency differences existing between the different frequencies. Combined together, these differences are representative of the length of the cavity and the angular rotational velocity of the cavity along an axis perpendicular to its plane.

Abstract: A laser gyro for measuring the angular velocity or the angular position relative to a defined rotation axis includes: an optical ring cavity; a solid-state amplifying medium; and a non-reciprocal magneto-optic device; which are arranged so that four linearly polarized propagation modes can propagate within the cavity, the magneto-optic device introducing a frequency bias between the modes propagating in a first direction and the modes propagating in the opposite direction. In the device, the cavity also includes a stabilizer device for stabilizing the intensity of the four propagation modes at substantially equivalent levels, said device comprising at least one optical element made of a non-linear crystal of the frequency-doubling type.

Abstract: A laser gyro having a solid-state amplifying medium and an optical ring cavity includes an assembly encompassing the optical cavity and able to experience an oscillating rotational motion, as well as at least one external optical device for longitudinal injection of energy into the solid-state amplifying medium. The laser gyro also includes a fixing assembly adapted for translationally and rotationally binding said assembly encompassing the optical cavity and said external optical device for longitudinal injection of energy.

Abstract: The general field of the invention is that of gyrolasers comprising at least one ring-shaped optical cavity comprising at least three mirrors, a solid state amplifying medium pumped by a laser diode whose optical emission power is determined by a current supply source, the cavity and the amplifying medium being such that two so-called contra-rotating optical modes propagate in opposite directions to each other within the said optical cavity, the gyrolaser being a class B gyrolaser, the gyrolaser also comprising means of measuring the difference in optical frequency existing between the two optical modes. The gyrolaser comprises means of measuring the total optical power circulating in the optical cavity and first means of control of the current delivered by the supply source in such a way as to maintain the total optical power substantially constant in a narrow spectral band centred on the relaxation frequency of the laser.

Abstract: Solid-state gyrolaser having a device for stabilizing the intensities making it possible to maintain equilibrium of the two counter-propagating modes having at least a means for calculating a rotation measurement (?, I?) of the gyrolaser on the basis of the counter-propagating modes having a frequency difference (??mes) between them, by assuming that the frequency difference (??mes) between the two counter-propagating modes is induced only by the rotation of the cavity.

Abstract: A laser gyro for measuring the angular velocity or the angular position relative to a defined rotation axis includes: an optical ring cavity; a solid-state amplifying medium; and a non-reciprocal magneto-optic device; which are arranged so that four linearly polarized propagation modes can propagate within the cavity, the magneto-optic device introducing a frequency bias between the modes propagating in a first direction and the modes propagating in the opposite direction. In the device, the cavity also includes a stabilizer device for stabilizing the intensity of the four propagation modes at substantially equivalent levels, said device comprising at least one optical element made of a non-linear crystal of the frequency-doubling type.

Abstract: The field of the invention is that of solid-state laser gyros used for the measurements of rotation speed or relative angular positions. This type of equipment is notably used for aeronautical applications. The object of the invention is to complete the optical devices necessary to control the instability of lasers by specific optical devices enabling elimination of the dead zone and of population inversion gratings exiting in the amplifying medium. An “all optical” solid-state laser is hence obtained without moveable parts, stable and without a dead zone. To this end, the laser gyro according to the invention comprises notably and optical assembly enabling a nonreciprocal optical phase-shift to be introduced between the counterpropagating modes; and control means allowing the phase-shift amplitude to be varied periodically around a mean value that is very approximately zero.

Abstract: A laser gyro having a solid-state amplifying medium and an optical ring cavity includes an assembly encompassing the optical cavity and able to experience an oscillating rotational motion, as well as at least one external optical device for longitudinal injection of energy into the solid-state amplifying medium. The laser gyro also includes a fixing assembly adapted for translationally and rotationally binding said assembly encompassing the optical cavity and said external optical device for longitudinal injection of energy.

Abstract: The field of the invention is that of solid-state laser gyros used for the measurements of rotation speed or relative angular positions. This type of equipment is notably used for aeronautical applications. The object of the invention is to complete the optical devices necessary to control the instability of lasers by specific optical devices enabling elimination of the dead zone and of population inversion gratings exiting in the amplifying medium. An “all optical” solid-state laser is hence obtained without moveable parts, stable and without a dead zone. To this end, the laser gyro according to the invention comprises notably and optical assembly enabling a nonreciprocal optical phase-shift to be introduced between the counterpropagating modes; and control means allowing the phase-shift amplitude to be varied periodically around a mean value that is very approximately zero.

Abstract: Solid-state gyrolaser having a device for stabilizing the intensities making it possible to maintain equilibrium of the two counter-propagating modes having at least a means for calculating a rotation measurement (?, I?) of the gyrolaser on the basis of the counter-propagating modes having a frequency difference (??mes) between them, by assuming that the frequency difference (??mes) between the two counter-propagating modes is induced only by the rotation of the cavity.

Abstract: A multioscillator ring laser gyro includes an optical ring cavity, a solid-state amplifying medium and a measurement device arranged in such a way that a first linearly polarized propagation mode and a second linearly polarized propagation mode, perpendicular to the first mode, propagate in a first direction in the cavity and in such a way that a third linearly polarized propagation mode parallel to the first mode and a fourth linearly polarized propagation mode parallel to the second mode propagate in the opposite direction. The amplifying medium is a crystal of cubic symmetry having an entry face and an exit face, the crystal being cut so that said faces are approximately perpendicular to the <100> crystallographic direction, the various modes propagating in directions approximately perpendicular to said faces.

Abstract: The general field of the invention is that of gyrolasers comprising at least one ring-shaped optical cavity comprising at least three mirrors, a solid state amplifying medium pumped by a laser diode whose optical emission power is determined by a current supply source, the cavity and the amplifying medium being such that two so-called contra-rotating optical modes propagate in opposite directions to each other within the said optical cavity, the gyrolaser being a class B gyrolaser, the gyrolaser also comprising means of measuring the difference in optical frequency existing between the two optical modes. The gyrolaser comprises means of measuring the total optical power circulating in the optical cavity and first means of control of the current delivered by the supply source in such a way as to maintain the total optical power substantially constant in a narrow spectral band centred on the relaxation frequency of the laser.