514 results about "Acousto-optic modulator" patented technology

The invention discloses a signal-to-noise ratio improvement method based on a multi-core optical fiber dual-channel distributed acoustic sensing system, and the method comprises the steps: carrying out the light splitting of light emitted by a narrow linewidth laser through a first coupler C1, enabling one path of light to generate a pulse signal through an acoustic optical modulator (AOM), enabling the other path of light to pass through a second coupler C2, and enabling the other path of light to pass through a second coupler C1; the pulse light is divided into two beams of transmission light, the two beams of transmission light are injected into a connected sensing optical fiber through two groups of erbium-doped optical fiber amplifiers (EDFA), two groups of filters, two groups of circulators and a fan-in coupler Fan-in Coupler, and the pulse light is subjected to backward Rayleigh scattering in the sensing optical fiber; based on a dual-channel DAS system, a multi-core optical fiber is used as a sensing optical fiber, three cores and four cores of the multi-core optical fiber are connected in series to form two sensing channels, seven-core space division signals are multiplexed, the equivalent self-noise pressure suppression effect of the seven-core space division signals is analyzed, after noise correlation is removed through a time domain dislocation-frequency domain phase shift method, the signal-to-noise ratio gain can be increased to 8.65 dB, and the signal-to-noise ratio gain can be increased to 8.65 dB. And the detection capability of the system on low-frequency weak signals can be improved.

The invention discloses an equivalent self-noise pressure suppression method and device based on a multi-core optical fiber space division multiplexing signal, light emitted by a narrow linewidth laser is split through a first coupler C1, one path of light passes through an acousto-optic modulator AOM to generate a pulse signal, and then the pulse signal passes through a second coupler C2 to generate a pulse signal; the pulse light is divided into two beams of transmission light, the two beams of transmission light are injected into a connected sensing optical fiber through two groups of erbium-doped optical fiber amplifiers (EDFA), two groups of filters, two groups of circulators and a fan-in coupler Fan-in Coupler, and the pulse light is subjected to backward Rayleigh scattering in the sensing optical fiber; based on the dual-channel DAS system, the multi-core optical fiber serves as the sensing optical fiber, three cores and four cores of the multi-core optical fiber are connected in series to form two sensing channels, seven-core space division signals are multiplexed, the equivalent self-noise suppression effect of the seven-core space division signals is analyzed, and the detection capacity of the system for low-frequency weak signals can be improved.

The invention discloses a 2 [mu] m nanosecond pulse fiber laser and a time domain waveform adjustment method thereof. The laser comprises a seed source module and an amplification module connected with the seed source module. The seed source module comprises a first high-reflectivity fiber bragg grating, an acoustic optical modulator, a first beam combiner, a first thulium-doped fiber, a 2 * 2 coupler and a second high-reflectivity fiber bragg grating which are connected in sequence, as well as a driving source connected with the acoustic optical modulator and a first pumping source connected with the first beam combiner; the amplification module comprises an online isolator, a second beam combiner, a second thulium-doped optical fiber and an output jumper which are connected in sequence, and a second pumping source connected with the second beam combiner; the rising edge time and the starting time of the acousto-optic modulator are subjected to parameter setting through a human-computer interface of the driving source; the wavelengths of lasers output by the first pumping source and the second pumping source are both 793 nanometers. According to the invention, the multi-peak phenomenon of the Q-switched pulse laser of the 2um waveband can be conveniently and effectively eliminated, the performance of the laser is improved, and the application requirements of low cost and mass production are met.

The invention discloses a differential nonlinear competitive super-resolution microscopy method and a differential nonlinear competitive super-resolution microscopy device. Light beams emitted by the same light source simultaneously irradiate the surface of a fluorescent sample. Wherein one light beam is focused on a sample after passing through a spatial light modulator to form a high-energy hollow light spot for generating a saturation effect; the other beam of light is modulated into time sequence light by an acousto-optic modulator, the time sequence light is focused on the sample to form a low-energy solid light spot, and signal light emitted by each scanning point of the sample is collected; and performing intensity control on the light intensity of the hollow light through a light intensity modulation device to obtain two nonlinear competition result images, and performing differential processing to obtain a super-resolution image. The device is simple and convenient to operate; on the basis of a competition mechanism of solid spots and hollow spots during sample fluorescence excitation, a high-resolution image can be obtained under low illumination light intensity by utilizing differential processing, and negative values of the differentiated image are greatly reduced.

The invention discloses a frequency discrimination curve calibration system, method and device. A frequency locking technology is adopted, the output laser frequency of the seed laser is stably locked on an absorption peak of the atom / molecule absorption cell, and the problem of frequency drift of the seed laser is effectively solved. Meanwhile, two acousto-optic modulators are used for implementing accurate out-of-cavity passive frequency modulation on the seed laser, and the laser frequency is moved to a preset zero-speed frequency point of an optical frequency discriminator and a linear working area edge frequency point from an atom / molecule absorption peak position. In the calibration process, the telescope vertically points to the zenith, and atmospheric echoes with zero Doppler frequency shift are provided as reference. At the moment, the optical frequency discriminator measures and records the transmittance of a preset zero-speed frequency point in the center of the linear working area and the transmittance of an edge frequency point, and a new frequency discrimination curve can be derived based on the linear hypothesis of the frequency discrimination curve.

The invention provides an immersed laser direct-writing photoetching method and device. The immersed laser direct-writing photoetching device comprises a laser light source, a laser beam splitter, an acousto-optic modulator, a dichroscope-spectroscope module, an acousto-optic deflector, an objective lens, an immersion head and a motion platform, the motion platform is used for placing a wafer to be photoetched; the laser light source, the laser beam splitter, the acousto-optic modulator and the dichroscope-spectroscope module are sequentially arranged along a first straight line, the dichroscope-spectroscope module is arranged in a deflection mode relative to the first straight line, and the acousto-optic deflector, the objective lens, the immersion head and the motion platform are sequentially arranged along a second straight line; laser generated by the laser light source sequentially passes through the laser beam splitter and the acousto-optic modulator and is emitted to the dichroscope-spectroscope module, the dichroscope-spectroscope module selectively reflects laser with specific wavelength, and the reflected laser sequentially passes through the acousto-optic deflector, the objective lens and the immersion head and is emitted to a wafer to be photoetched. And high-speed and high-flux parallel laser scanning direct writing photoetching can be realized.

A 2-micron large-energy solid two-way amplifier based on a single-frequency pulse optical fiber preceding stage can make full use of the small signal amplification capacity of optical fiber laser and the energy extraction capacity of solid laser, and meanwhile the problem that energy is difficult to improve due to the stimulated Brillouin scattering effect in an optical fiber is solved. And high-stability, high-repetition-frequency and large-energy single-frequency pulse laser output can be realized. The all-fiber cascade amplifier comprises an all-fiber cascade amplifier and a solid two-way amplifier, according to the all-fiber cascade amplifier, a continuous narrow-linewidth fiber laser is adopted as a seed source, continuous light is modulated into pulse light through an acousto-optic modulator, and the waveform, the pulse width and the repetition frequency of output pulse laser are adjusted; the modulated pulse light adopts a main oscillation power amplification structure and is preliminarily amplified by a polarization maintaining optical fiber amplifier; the solid-state amplifier adopts a two-way amplification structure, and further high-efficiency amplification is realized through solid-state two-way amplification. The whole laser system is compact in structure, stable, adjustable in parameter and capable of meeting application requirements of different scenes.

Disclosed herein is an optical frequency comb generator for a distributed acoustic anomaly detection system. The system can include a continuous wave frequency modulated laser source configured to generate a laser signal. The system can include an acousto-optical modulator configured to modulate the laser signal by altering an amplitude and / or frequency of the laser signal based on an RF drive signal applied to the AOM, and to output an optical pulse with multiple frequency sidebands based on the modulation. The output can form an optical frequency comb usable detecting and locating acoustic anomalies within a structure under observation.

The invention discloses acousto-optic chalcogenide glass with a high laser damage threshold, the chemical composition formula of the acousto-optic chalcogenide glass is GexSySez, x, y and z respectively represent the mole fractions of Ge, S and Se, x = 10-30, y = 5-40, z = 40-70, x + y + z = 100, and the microscopic network structure of the acousto-optic chalcogenide glass contains a [GeSe4] tetrahedron, a [GeSSe3] tetrahedron, a [GeS2Se2] tetrahedron, a [GeS3Se] tetrahedron, a [GeS4] tetrahedron and a Se ring. The acousto-optic chalcogenide glass provided by the invention has a relatively high laser damage threshold Fth (9.72-15.58 J / cm < 2 > at1550 / 20ns / 5kHz), a relatively low thermo-optic coefficient dn / dT and good acousto-optic characteristics and mechanical properties, is high in near-infrared band transmittance, and has a relatively high laser damage threshold while ensuring a high acousto-optic quality factor. The material can be used as a material basis for developing high-performance and high-stability infrared acousto-optic modulation devices.

The invention discloses a novel phi-OTDR (optical time domain reflectometry) system with low sampling rate requirement and polarization suppression, which belongs to the field of distributed optical fiber sensing and consists of a laser, three optical splitters, two acoustic optical modulators, three 3dB couplers, three balance detectors, a polarization controller, two polarization beam splitters, a data acquisition card and a computer. On the basis of a traditional phi-OTDR, a double-path AOM structure is introduced, and one path of optical signal is led out as a reference signal to participate in signal demodulation after light splitting and coupling, so that the requirement of a system on a DAQ sampling rate is reduced. And meanwhile, a polarization fading suppression structure is added in the system to adjust the optical signal, so that the output of two paths of cross-polarization signals is realized, and the influence of polarization fading is suppressed in combination with a phase optimal selection algorithm based on a time domain window. While the requirement of a traditional phi-OTDR system for the DAQ sampling rate is effectively reduced, the influence of polarization fading on phase extraction is suppressed, and the precision of system disturbance monitoring is improved.

The invention discloses a high-power picosecond pulse train laser with programmable sub-pulse energy and a method, and relates to the related technical field of lasers, the high-power picosecond pulse train laser comprises a mode-locked fiber laser, an acousto-optic modulator and a solid amplification chain which are sequentially arranged along an optical transmission path; the mode-locked fiber laser generates a mode-locked picosecond pulse sequence; the acousto-optic modulator performs pulse selection and pulse string grouping on the mode-locked picosecond pulse sequence, and performs pre-programming shaping on sub-pulse energy in a pulse string according to set intensity distribution to generate a pre-shaped pulse string; the solid amplification chain comprises at least one stage of solid amplifier, and the solid amplifier comprises a dichroscope, a laser gain crystal, a coupling optical assembly and an LD pumping source; and the dichroscope is used for focusing the pre-shaped pulse string amplified at the previous stage and the LD pump light transmitted by the coupling optical assembly into the laser gain crystal. Independent programmable regulation and control of the energy of each sub-pulse in the pulse string are realized, and the energy distribution of each sub-pulse in the pulse string can be flexibly adjusted.

According to the optical fiber interference sensor and the application method thereof, an electro-optical frequency comb is introduced to screen out two comb lines to form a photon-assisted millimeter wave light source, interference is carried out in two frequency spectral regions subsequently, common phase fluctuation is counteracted based on inherent phase coherence, and the strict requirement for the line width index of a laser is avoided. Meanwhile, the two acoustic optical modulators connected in parallel are introduced into the reference arm and the interference arm for frequency shift, the problem of co-frequency crosstalk caused by residual zero-order diffraction of the acoustic optical modulators is solved, and the sensing precision is substantially improved.

The invention discloses an equivalent self-noise pressure suppression method based on a dual-channel distributed acoustic sensing system, and the method comprises the steps: carrying out the light splitting of light emitted by a narrow-linewidth laser through a first coupler C1, enabling one path of light to generate a pulse signal through an acoustic optical modulator (AOM), enabling the other path of light to pass through a second coupler C2, and enabling the other path of light to pass through a second coupler C1; the pulse light is divided into two beams of transmission light, the two beams of transmission light are injected into a connected sensing optical fiber through two groups of erbium-doped optical fiber amplifiers (EDFA), two groups of filters, two groups of circulators and a fan-in coupler Fan-in Coupler, and the pulse light is subjected to backward Rayleigh scattering in the sensing optical fiber; according to the invention, based on a dual-channel DAS system, two fiber cores of the multi-core optical fiber are used as sensing optical fibers, and the space division signals of the two cores are multiplexed, so that the performance that the equivalent self-noise pressure drop is 2.54 dB in the frequency band of 100-1000Hz is realized under the condition that the noise correlation coefficient of the dual-core signals is 0.11, and the detection capability of the system on low-frequency weak signals can be improved.

The invention provides a dual-mode gravitational acceleration precision measurement system and method based on a light floating effect. According to the system, a 1064nm laser double-beam correlation structure is adopted, a strong focusing light trap is formed in a gravity orthogonal direction, and micron-sized silicon dioxide particles are stably captured. In the absolute measurement mode, the acousto-optic modulator is used for controlling the on-off of the laser, the high-speed position detection module is used for detecting and recording the free falling motion trail of the particles and the displacement amplitude showing the resonance state after re-capturing, and the absolute gravitational acceleration parameter is inverted. In a relative measurement mode, weak focusing 532nm laser is configured along the gravity direction to construct a gravity compensation light trap, and after absolute gravitational acceleration reference measurement is completed, the laser is modulated by an acoustic optical modulator to accurately balance the gravity of particles, so that the particles enter a quasi-balance state. When the external gravitational field changes slightly, the characteristic displacement of the particles in the gravity direction is extracted, and the change of the relative gravitational acceleration can be monitored continuously.

The invention provides a pulse laser frequency control device and method, and belongs to the technical field of pulse fiber lasers. Comprising a frequency measurement module used for acquiring the frequency of a first external control signal; the frequency selection and frequency division module generates and outputs a seed frequency signal and a frequency division coefficient according to the frequency of the first external control signal obtained by the frequency measurement module; the frequency generation module is used for receiving the seed frequency signal output by the frequency selection and division module and outputting a seed frequency trigger signal; the pulse generation module is used for acquiring the seed frequency trigger signal output by the frequency generation module and providing a seed pulse signal for the seed driver, and the seed driver outputs pulse light according to the input seed pulse signal; the current control module is used for receiving a second external control signal and providing a current driving signal for each pump driver; and the RAM controller is used for receiving a third external control signal and the frequency division coefficient output by the frequency selection and frequency division module, and controlling the acousto-optic modulator to work.

The invention discloses a handheld acousto-optic modulation device and a light scattering suppression method. When the handheld acousto-optic modulation device is used, the transparent film bonded on the upper surface is tightly attached to a medium, focused ultrasound acts on the medium, so that the local refractive index of the medium is changed, light is regulated and controlled by a focused sound field when penetrating through the medium, and concentration of light energy in the medium is promoted; the handheld acousto-optic modulation device comprises a handheld base, a handheld top cover, an ultrasonic transducer, an acoustic holographic lens, a transparent panel, a transparent film and a sealing gasket; the ultrasonic transducer and the acoustical holographic lens are fixed in the handheld base through a connecting piece; the handheld base and the handheld top cover are connected with each other in a screwing mode. The transparent panel is adhered to the lower surface of the handheld base; and the transparent film is adhered to the upper surface of the boss of the handheld top cover. According to the invention, an optical path can be regulated and controlled in situ in a medium, and the device is noninvasive, is simple to operate, and can be conveniently applied to light therapy.

The invention discloses a monitoring system for improving the anti-interference capability of converter transformer partial discharge ultrasonic monitoring. According to the system, a first coupler divides continuous narrow-band light emitted by a laser into a sensing light signal and a reference light signal; the sensing optical signal is reflected by the Faraday rotating mirror, then returns along an original optical path, and enters the second coupler through the circulator; a reference light signal generates a fixed frequency shift through an acousto-optic modulator and then enters a second coupler to interfere with the sensing light, two beams of interference light are converted by a balanced photoelectric detector for differential detection, and a measurement signal is output; the radio frequency driving signal is divided into a first driving signal and a second driving signal by the power divider, the first driving signal is used for driving the acousto-optic modulator, and the second driving signal enters the RF gain phase detector as an electrical synchronization reference signal; and the RF gain phase detector performs difference processing on the phase quantity of the measurement signal and the phase quantity of the electrical synchronous reference signal to obtain a partial discharge ultrasonic signal of the converter transformer, and outputs the partial discharge ultrasonic signal to the acquisition card system.

The invention discloses a laser vibration meter series reciprocating type optical frequency modulation calibration method and device, and belongs to the field of photoelectric measurement. The calibration device is mainly composed of a calibrated laser vibration meter, a first acousto-optic modulator, a second acousto-optic modulator, a lens, a first sinusoidal signal source, a second sinusoidal signal source, an FM signal source and a plane mirror. Aiming at a laser signal emitted by the laser vibration meter, the reversibility characteristic of a light path is utilized, a straight-line-shaped light path structure is used, a secondary light frequency modulation mode of the same group of optical devices is combined with secondary light frequency translation to realize output frequency translation and modulation control of the laser vibration meter, and a laser Doppler effect caused by different vibration waveform magnitude values is simulated. And the modulated laser is completely returned to the calibrated laser vibration meter in the original path, so that the change waveform of the vibration velocity value is replaced by the change waveform of the frequency value, and the calibration of the laser vibration meter is realized. The device has the advantages of portability, wide frequency range, wide amplitude range calibration, high precision and good stability.

This invention relates to a Bragg light generation system and method suitable for Bragg-type atomic interferometers. The system includes: a laser for generating a first laser beam with a frequency in a preset atomic absorption peak band; an optical circulator for propagating the first laser beam to a cascaded acousto-optic modulator and receiving two third laser beams returned from the cascaded acousto-optic modulator; a cascaded acousto-optic modulator for diffracting the first laser beam into two second laser beams with opposite propagation directions through Bragg diffraction of two acousto-optic crystals; an optical assembly for performing secondary diffraction on the two second laser beams and reflecting the two mutually perpendicular second laser beams to the cascaded acousto-optic modulator; and an output module for splitting and sampling the two third laser beams and modulating the sampled third laser beams into Bragg laser beams in the target frequency band. This invention reduces the path separation of the two Bragg laser beams by using a quasi-common optical path, thereby reducing phase noise and improving measurement accuracy.

The utility model discloses a distributed sound wave sensing system for multi-frequency pulse modulation, and relates to the technical field of distributed sound wave sensing. The system comprises a narrow linewidth laser, an optical fiber coupler, a polarization-maintaining optical isolator, an acousto-optic modulator, a polarization-maintaining delay optical fiber, an erbium-doped optical fiber amplifier, a polarization-maintaining dense wavelength division multiplexer, an optical fiber circulator, an optical fiber Bragg grating, a piezoelectric transducer, a polarization controller, a photoelectric balance detector, a data acquisition card, an arbitrary waveform generator and the like. According to the utility model, the multi-frequency delay ring is utilized to carry out multi-frequency modulation, the frequency number of light waves is increased along with the circulation times of the light waves in the delay ring, and under the condition that the utilization of a large-bandwidth electro-optical modulator is not increased, the flexible modulation of the frequency is realized by utilizing a low-bandwidth acousto-optical modulator without being influenced by carrier frequency and sidebands of each order; the low-bandwidth acousto-optic modulator is used for frequency modulation in the multi-frequency delay ring, and compared with an electro-optical modulation or multi-acousto-optic / multi-light source modulation scheme, the modulation cost is effectively saved.

The invention discloses a rapid temperature measurement method and device based on micro-air-chamber double absorption spectrums, and belongs to the field of laser absorption spectrum sensing. The device comprises a light source module, a linear frequency sweep control module, a temperature measurement module and a signal acquisition and temperature calculation module. According to the invention, the scanning source, the optical fiber Mach-Zehnder interferometer and the feedback control circuit are utilized to ensure the optical frequency sweeping linearity, and two absorption spectral lines with known frequency difference and carrying temperature information are generated through the acousto-optic modulator. The method comprises the following steps: mapping an absorption spectrum from a time domain to a frequency domain on the basis that the time difference of the same absorption peak on two absorption spectrums with fixed frequency difference on a time domain corresponds to the driving frequency of an acoustic optical modulator, namely delta T = T1-T2 corresponds to the driving frequency f of the acoustic optical modulator, and then calculating by extracting parameters related to temperature on the absorption spectrum of the frequency domain to obtain the temperature of the air chamber. The invention can solve the problem of complexity of the traditional Doppler broadening temperature measurement system, and has the advantages of small measurement volume, low cost, high speed, high stability, strong adaptability and the like.

The invention relates to the technical field of grating interference type acceleration sensors, in particular to a high-resolution acceleration sensor based on a quasi-BIC metasurface and a measuring method. The problems that an existing grating interference type acceleration sensor is low in resolution ratio and large in ohmic loss are solved. The invention discloses a high-resolution acceleration sensor based on a quasi-BIC metasurface. The high-resolution acceleration sensor comprises a laser, a beam splitter, an acoustic optical modulator, an electro-optical modulator, an optical circulator, a packaging box, a balanced photoelectric detector, an amplifier and a digital instrument, a light-transmitting micropore is formed in the top wall of the packaging box in a penetrating manner; a sensing unit is packaged in an inner cavity of the packaging box; the sensing unit comprises two silicon supporting blocks, a silicon mass block, a distributed Bragg reflector, four columns of silicon nitride cantilever beams, a transparent substrate and a quasi-BIC metasurface structure. The method is suitable for measuring the acceleration signal.

The invention discloses a distributed optical fiber two-dimensional vector sensing system and method, the system uses an acousto-optic modulator group and an optical circulator group to ask a plurality of fiber cores of a multi-core optical fiber in parallel, heterodyne coherent detection uses local oscillator light to improve the signal-to-noise ratio, and through the relation between the fiber core position difference and the direction angle of a two-dimensional sound wave in the aspect of algorithm, the two-dimensional sound wave direction angle is obtained. According to the space division multiplexing distributed optical fiber acoustic sensing system, a two-dimensional vector signal is accurately restored, the measurement vector angle range of the space division multiplexing distributed optical fiber acoustic sensing system for two-dimensional sound waves is 0-360 degrees, the vector sensing range is larger than 50 km and far exceeds that of an existing system, and the detection capacity of the distributed optical fiber acoustic sensing system is greatly improved.

The invention discloses a Rydberg atom microwave electric field sensing system and method based on coupling light modulation, and belongs to the technical field of microwave electric field sensing. In the system, a Rydberg atom preparation module excites alkali metal atoms to a Rydberg state; the radio frequency module provides a local oscillator signal for the Rydberg atom preparation module; the coupling light modulation module modulates the broadband pulse signal to the coupling light through an acousto-optic modulator so as to change the intensity of the coupling light entering the Rydberg atom preparation module; the signal receiving and processing module collects transmission light signals passing through the Rydberg atom preparation module, matched filtering processing is carried out, microwave electric field information is extracted, and the transmission light signals are generated by alkali metal atoms under the combined action of to-be-detected signals, detection light, local oscillation signals and coupling light with changed intensity. According to the method, the measurement sensitivity and the signal-to-noise ratio are improved, higher environmental adaptability is achieved, and stable measurement performance can be kept under complex conditions.

The present invention relates to a high-speed, high-threshold acousto-optic modulator based on lithium niobate, belonging to the field of optoelectronics; the acousto-optic modulator comprises an acousto-optic medium, a bonding layer, a transducer and a surface electrode; the sound-transmitting surface of the acousto-optic medium is equipped with a transducer through the bonding layer, and the surface electrode is plated on the surface of the transducer; the acousto-optic medium is a lithium niobate crystal, the [100] axis of the lithium niobate crystal is perpendicular to the sound-transmitting surface of the acousto-optic medium, the [010] axis of the lithium niobate crystal is located within the sound-transmitting surface of the acousto-optic medium, and the angle between the [010] axis of the lithium niobate crystal and the incident light is 0.5°±0.3°. The present invention adopts lithium niobate crystal as the acousto-optic medium, improves the acousto-optic figure of merit of the lithium niobate crystal, and also improves the ability of the acousto-optic device to withstand high-power lasers; at the same time, the present invention also plates an anti-reflection film on the light-transmitting surface of the acousto-optic medium to improve the utilization rate of light energy by the acousto-optic device. Overall, the present invention can better meet the modulation requirements of high speed and high threshold.

The invention relates to a Bragg light generation system and method suitable for a Bragg atom interferometer, and the system comprises a laser device which is used for generating first laser with the frequency on a preset atomic absorption peak frequency band; the optical circulator is used for transmitting the first laser to the cascade acousto-optic modulator and receiving two beams of third laser returned by the cascade acousto-optic modulator; the cascade acousto-optic modulator is used for diffracting the first laser into two beams of second laser with opposite propagation directions through Bragg diffraction of the two acousto-optic crystals; the optical assembly is used for carrying out secondary diffraction on the two beams of second laser and reflecting the two beams of second laser which are obtained through diffraction and are perpendicular to each other to the cascade acousto-optic modulator; and the output module is used for carrying out light splitting sampling on the two beams of third laser and modulating the sampled third laser into Bragg laser of a target frequency band. According to the invention, path separation of the two Bragg laser beams is reduced through quasi-common-path, so that phase noise is reduced, and measurement precision is improved.

The invention discloses an acousto-optic modulator driving system with servo feedback. The system comprises a radio frequency generation module, a power control module, a radio frequency switch module, a power display module, a power amplification module, a sensor module and a servo feedback module. The radio frequency generation module generates a radio frequency signal and sends the radio frequency signal to the power control module; the power control module adjusts the attenuation degree of the radio frequency signal and then sends the radio frequency signal to the radio frequency switch module; the radio frequency switch module controls a radio frequency signal to enter the power amplification module or the power display module; the power display module displays the radio frequency power actually output by the power amplification module; the power amplification module amplifies the radio frequency signal and then outputs the radio frequency signal to the acousto-optic crystal; the sensor module receives the laser output by the acousto-optic crystal and outputs a photovoltage signal to the servo feedback module; the servo feedback module receives the photovoltage signal, compares the photovoltage signal with a preset value and then outputs a feedback control signal. The method can be used for optical power control and can also be used for light beam space stability control.

The invention discloses a GHz pulse train generation device and method, and relates to the technical field of laser, and the device comprises a seed light source, a first acousto-optic modulator, a 50: 50 coupler, an optical fiber loop, and a third acousto-optic modulator. Wherein the fiber loop comprises a second acousto-optic modulator, a first chirp long-period fiber grating, a polarization-maintaining double-clad fiber and a second chirp long-period fiber grating. By using the first chirp long-period fiber grating, the polarization-maintaining double-clad fiber and the second chirp long-period fiber grating, the dispersion effect in a fiber loop can be compensated, and the conversion rate of the chirp long-period fiber grating is relatively high, so that the transmission loss in the fiber loop can be reduced; group delay ripples of the chirp long-period fiber bragg grating and the optical fiber high-order LP0m mode are very low, the shape and the width of pulses in a GHz pulse string on a time domain can be controlled, and finally, the optical fiber of the chirp long-period fiber bragg grating is a polarization-maintaining double-clad optical fiber, so that the nonlinear effect can be effectively inhibited.

The present invention relates to a FreeTrig-based pulse output apparatus for an ultrafast laser, and a FreeTrig-based pulse output control method for an ultrafast laser. An output end of an optical fiber beam splitter is connected to an optical input end of a main acousto-optic modulator, and the other output end thereof is connected to an input end of an optical fiber collimator; an optical output end of the main acousto-optic modulator is connected to an input end of an optical fiber beam combiner; a control input end of the main acousto-optic modulator is connected to an output end of a control module; an output end of the optical fiber collimator is connected to an optical input end of an on-board auxiliary acousto-optic modulator, an output end of the on-board auxiliary acousto-optic modulator is connected to the input end of the optical fiber collimator, and a control input end of the on-board auxiliary acousto-optic modulator is connected to the output end of the control module; the output end of the optical fiber collimator is connected to the other input end of the optical fiber beam combiner; an output end of the optical fiber beam combiner is connected to an input end of an optical amplifier; an output end of the optical amplifier is connected to an optical input end of a free-space acousto-optic modulator; and a control input end of the free-space acousto-optic modulator is connected to the output end of the control module.

The invention provides a distributed optical fiber sound wave sensing system and device based on a frequency shift ring. The distributed optical fiber sound wave sensing system comprises a narrow linewidth laser source module, a sweep frequency optical pulse generation module, a radio frequency signal generation module, a circulator, a coherent receiving and photoelectric conversion module and a signal acquisition and processing module. The sweep frequency optical pulse generation module comprises an acousto-optic modulator, a frequency shift ring, an optical fiber coupler and an optical amplifier, the acousto-optic modulator generates narrow-bandwidth sweep frequency optical signals, the frequency shift ring is composed of an acousto-optic frequency shifter, a time delay optical fiber and the optical amplifier, the acousto-optic frequency shifter achieves frequency shift, the time delay optical fiber achieves time delay of the optical signals, and the optical amplifier compensates loss of the optical signals. And the spliced optical pulse enters a sensing optical fiber, returned Rayleigh backscattered light and local light are subjected to beat frequency, a matched filter generated by deconvolution is used for processing a beat product signal, and a vibration signal is demodulated. According to the invention, the frequency-shift ring is spliced to obtain a wide-bandwidth sweep-frequency optical signal, and high-spatial-resolution vibration detection is realized.