19 results about "Laser phase noise" patented technology

The invention discloses a laser phase noise compensation device and method for an optical frequency domain reflectometer, and relates to the technical field of distributed optical fiber sensing, and the compensation device comprises a sweep frequency laser source module which is used for outputting a first beam of sweep frequency laser and a second beam of sweep frequency laser; the main interferometer module is used for receiving the first beam of sweep frequency laser and generating a first beat frequency signal related to the scattering point position of the sensing optical fiber; the auxiliary interferometer module is used for receiving the second beam of frequency sweeping laser and generating a second beat frequency signal related to the weak reflection point position of the auxiliary optical fiber; and the signal processing module is used for acquiring the first beat frequency signal and the second beat frequency signal and respectively extracting phase terms of the sensing optical fiber and the auxiliary optical fiber so as to realize phase noise compensation. According to the compensation method, the function of the compensation device is achieved, namely phase noise compensation is achieved, then the frequency spectrum of compensation information is analyzed, and strain information along the sensing optical fiber is demodulated. According to the invention, uniform compensation of phase noise is realized, and the system measurement distance, the spatial resolution and the strain precision are improved.

According to the coherence-correlation optical time domain reflection detection method and system, a laser signal output by a laser is split into detection light and auxiliary light, and the detection light is injected into a detected optical fiber after being coded and modulated; processing the auxiliary light through an auxiliary light path, and detecting the phase noise of the laser in real time to obtain phase noise information; receiving a reflected signal returned by the detected optical fiber, generating a local reference signal which is homologous with the probe light code, and performing phase adjustment on the local reference signal according to the phase noise information to obtain a phase-compensated local reference signal; and performing sliding window correlation operation on the reflected signal and a local reference signal after phase compensation, realizing optical fiber link reflection characteristic measurement and fault positioning by using a correlation operation result, capturing laser phase noise in real time through an auxiliary optical path, and synchronously completing digital compensation. Related peak broadening and sidelobe lifting caused by phase noise are effectively suppressed, and the signal-to-noise ratio and the dynamic range of long-distance measurement of the system are improved.

The application discloses a laser phase noise measurement method based on delay self-heterodyne and digital demodulation, and relates to the technical field of laser measurement, and comprises the following contents: after being adjusted by a variable optical attenuator, to-be-measured laser is divided into a frequency shift arm and a delay arm, the frequency shift arm is frequency-shifted by an acousto-optic modulator, the delay arm is delayed by a delay optical fiber, and original electric beat frequency signals are obtained by a balanced photoelectric detector after the two arms are coupled; homologous and synchronous quadrature demodulation is carried out on the original electric beat frequency signals, envelope credibility judgment and abnormal sample repair are combined, and a continuous differential phase sequence is obtained; actual optical time delay is determined according to the beat frequency spectrum characteristics and the continuous differential phase sequence, and a differential phase power spectral density is formed; then, transmission relationship conversion is carried out according to the actual optical time delay, bounded spectrum compensation is implemented on a zero point neighborhood and a low credibility frequency point, and an intrinsic phase noise power spectral density is obtained. The application can improve the stability, continuity and result credibility of phase noise measurement under the condition of short delay.

The application relates to the technical field of photoelectric measurement, and discloses a mode-locked laser phase noise measurement system without dispersion management, which comprises a signal generation unit, a signal adjustment unit and a signal measurement unit. The signal generation unit comprises a mode-locked laser for generating a laser signal, a frequency doubling module connected to the output end of the mode-locked laser, and a signal extraction and screening module connected to the output end of the frequency doubling module. The signal adjustment unit is connected to the output end of the signal extraction module and comprises a signal frequency shift module and a signal extraction module connected in sequence. The signal measurement unit is connected to the output end of the signal extraction module and comprises a low-pass filter and a signal analyzer. The mode-locked laser phase noise measurement structure is newly constructed, the problem that an accurate dispersion management unit needs to be added when a traditional dual-wavelength delay self-heterodyne method is used to measure phase noise is solved, and the overall structure is simple, the measurement is accurate, and the efficiency is high.

The application discloses a laser phase noise measuring device and method, comprising: a light source to be measured, a first optical coupler, a second optical coupler, an acousto-optic frequency shifter, a first single-mode optical fiber, a third optical coupler, a first polarization controller, a second single-mode optical fiber, a second polarization controller, a fourth optical coupler, a fifth optical coupler, a first balanced photodetector, a second balanced photodetector and a signal acquisition and processing unit. The technical scheme of the application overcomes the mutual restriction problem between sensitivity and bandwidth in the traditional delay interference method, and improves the sensitivity and bandwidth comprehensive performance of the laser phase noise measurement.

The application discloses a compensation device and method for laser phase noise of an optical frequency domain reflectometer, and relates to the technical field of distributed optical fiber sensing. The compensation device comprises a sweep laser source module, a main interferometer module, an auxiliary interferometer module and a signal processing module. The sweep laser source module is used for outputting a first sweep laser beam and a second sweep laser beam. The main interferometer module receives the first sweep laser beam and generates a first beat frequency signal related to the position of a scattering point of a sensing optical fiber. The auxiliary interferometer module receives the second sweep laser beam and generates a second beat frequency signal related to the position of a weak reflection point of an auxiliary optical fiber. The signal processing module collects the first beat frequency signal and the second beat frequency signal, extracts phase terms of the sensing optical fiber and the auxiliary optical fiber respectively, and realizes phase noise compensation. The compensation method realizes the function of the compensation device, that is, realizes phase noise compensation, analyzes the spectrum of compensation information again, and demodulates strain information along the sensing optical fiber. The application realizes uniform compensation of phase noise, and improves the system measurement distance, spatial resolution and strain accuracy.

The invention relates to the technical field of optics, and provides a compression-enhanced phase noise suppression system, which comprises an original laser generation module, a compressed light preparation module, a phase noise conversion module and a feedback control module, the original laser generation module is used for generating original laser and providing an original incident light source for the compressed light preparation module and the phase noise conversion module; the compressed light preparation module is used for generating a compressed light field, the phase noise conversion module is used for generating a reflected light field and converting phase noise of the reflected light field into intensity noise in a semi-detuning state, and the compressed light field and the reflected light field are coupled in a zero phase; and the feedback control module is used for feeding back the measured noise of the inner ring to the original laser generation module, realizing negative feedback of the phase noise and directly feeding back the noise to the outer ring. Light field phase noise is converted into amplitude noise through the half-detuning state of the narrow-linewidth over-coupling cavity, and laser phase noise is effectively suppressed in combination with compressed light injection.

The application provides a method for suppressing laser phase noise by using improved common mode lock arm technology, comprising: establishing three data streams of a satellite-borne GW detector; combining the three data streams to eliminate noise from optical platform motion; improving the principle of the lock arm, designing a lock arm controller, and using the output of one closed loop phase meter on the main spacecraft minus the output of another closed loop phase meter to further eliminate laser phase noise. The application has the beneficial effect that the output of one closed loop phase meter on the main spacecraft minus the output of another closed loop phase meter can further eliminate laser phase noise in real time. On the one hand, even under the arm lock closed loop, the phase meter output of each arm also contains the GW signal of the other arm, which means that the GW signal can be well preserved while eliminating the remaining noise. On the other hand, since the data at the phase meter output point is studied, the data can be processed in real time, and this method is easier to implement.

The invention discloses a correlation type optical time domain reflection signal processing method and system, and relates to the technical field of optical fiber sensing, and the method comprises the following steps: a transmitting end transmits a dual-polarization quadrature phase shift keying optical signal to an optical fiber; a receiving end obtains a coherent superposition signal of the dual-polarization quadrature phase shift keying optical signal reflected by each scattering point of the optical fiber through coherent detection; respectively calculating respective Jones vector inner products according to the dual-polarization quadrature phase shift keying optical signal and the coherent superposition signal, and performing preset correlation operation according to the Jones vector inner products of the dual-polarization quadrature phase shift keying optical signal and the coherent superposition signal to obtain a composite signal. Natural suppression of laser phase noise, obvious weakening of optical fiber front section common optical path disturbance and stable measurement insensitive to polarization state rotation can be realized.

The invention discloses a laser phase noise suppression system and method in distributed acoustic sensing. In the system, distributed acoustic sensing based on the Sagnac interferometer is realized, phase noise from a laser line broadband is suppressed by using a weak measurement technology, and the detection precision of acoustic sensing is improved. In the system, the first light splitting element and the optical fiber beam splitter are used for forming the structure of the Sagnac interferometer, so that the same optical path of the first polarized light and the second polarized light is ensured. By means of the characteristic that the transmission optical paths of the structure are the same, phase noise caused by the line width of the laser in the first back Rayleigh scattering light and the second back Rayleigh scattering light can be simply extracted as an overall phase, and the phase noise can be effectively removed during final phase change calculation by using light intensity detection of a weak measurement technology. Furthermore, the influence of phase noise caused by the line width of the laser on sound signal sensing is eliminated.

The invention discloses a laser phase noise elimination method and system for a phi-OTDR (Optical Time Domain Reflectometer), solves the problem of dependence of a phase-sensitive optical time domain reflectometer on a high-cost narrow-linewidth laser in the prior art, and realizes reduction of the influence of the phase noise of the laser in combination with a signal processing algorithm. Therefore, the requirement of the system on the line width of the laser is relaxed, the system cost is greatly reduced, and the compatibility of a sensing system and a communication system is improved; the method comprises the following steps: injecting a composite detection pulse into a to-be-detected optical fiber to obtain backscattered light; performing coherent beat frequency on the backscattered light and the local oscillation light to obtain a synthesized complex amplitude electric signal; processing and synthesizing the complex amplitude electric signal, and separating a scattering signal component corresponding to each sub-pulse through a frequency domain filtering or decoding mode; calculating an instantaneous phase difference between the at least one pair of scattered signal components to obtain a spatial differential phase; wherein the space differential phase eliminates common phase noise introduced by the local oscillation light.

Aspects of the subject disclosure may include, for example, deriving substantially orthogonal optical fields from an output of an optical source, implementing a delay on one of the substantially orthogonal optical fields, resulting in time delayed optical fields, performing coherent detection of the time-delayed optical fields, resolving electrical field signals based on the coherent detection, and causing the electrical field signals to be processed so as to estimate a property of the optical source, wherein estimation of the property facilitates disturbance detection and localization. Other embodiments are disclosed.

The application discloses a time delay interference laser phase noise compensation method and device for optical frequency domain reflection, and comprises the following steps: obtaining a linear sweep signal light based on a signal source; obtaining a first heterodyne signal through a measurement interferometer, and obtaining a second heterodyne signal through a reference interferometer; and processing the first heterodyne signal and the second heterodyne signal by using a time delay interference algorithm, so that direct compensation of laser phase noise is realized; and obtaining a strain signal based on the direct compensation of the laser phase noise. Through compensation of the laser phase noise, high-precision measurement of the strain signal can be realized at a distance far beyond the coherence length of the light source.

The device includes: a laser to be measured used to output an optical carrier; a phase modulator used to modulate a microwave signal onto the optical carrier, to output a phase-modulated optical signal; an optical notch filter used to filter the phase-modulated optical signal, to output an intensity-modulated optical signal; a photodetector used to detect the intensity-modulated optical signal to output a radio frequency signal; a radio frequency power splitter used to split the radio frequency signal to output at least two radio frequency signals; and a radio frequency phase noise measurement system used to perform phase noise measurement on one of at least two radio frequency signals, to obtain the phase noise of the laser to be measured. One of at least two radio frequency signals is modulated onto the optical carrier by using the phase modulator to output phase-modulated optical signal.

The application provides a magnetic resonance phase compensation method and system based on external signal compensation, and the method comprises the following steps: multiplying sigRef and sigA to obtain a noise signal sigNoise; changing the frequency of an externally applied signal, adding a noise signal consistent with sigNoise to the external magnetic field signal sigRef; through PID closed loop control, the error of the calculation signal is suppressed to a fixed value or 0; multiplying the adjusted sigRef+sigNoise and the optical signal sigB to demodulate, so as to suppress the sigNoise contained in the optical signal sigB, and the result of the calculation at this time is the signal of the atomic nucleus spin, that is, the actual required signal; according to the multiplication result of the optical signal sigA and the adjusted sigRef+sigNoise, the output frequency of the detection laser is controlled through PID closed loop control, and the phase noise of the detection laser is suppressed. The technical scheme of the application is used to solve the technical problems that the single forced laser output light intensity stabilization method in the prior art is relatively single, the implementation means is relatively complicated, and the development trend of the sensor is small in size.

This invention provides a single-frequency fiber laser with a wide range of finely adjustable linewidth, comprising a single-frequency fiber laser resonator, a pump source, a wavelength division multiplexer, an integrated fiber isolation coupling device, a monitoring-feedback module, and a phase modulation unit. The wavelength division multiplexer couples the pump light output from the pump source into the single-frequency fiber laser resonator and outputs the generated single-frequency fiber laser. The integrated fiber isolation coupling device splits the single-frequency fiber laser beam and inputs it to the main optical path and the monitoring-feedback module respectively. The monitoring-feedback module acquires the phase fluctuation information of the single-frequency fiber laser in real time and generates a phase modulation signal according to the preset linewidth control requirements. The phase modulation unit compensates for or superimposes the phase fluctuation of the single-frequency fiber laser transmitted on the main optical path according to the phase modulation signal output by the monitoring-feedback module, thereby achieving the effect of suppressing or increasing laser phase noise and realizing the function of finely controlling the linewidth of the fiber laser over a wide range.

The invention discloses a DAS data background noise simulation method and device, electronic equipment and a medium. The method can comprise the following steps: acquiring DAS demodulation equipment parameters; simulating laser phase noise in DAS data; and coherent fading influence in the DAS data is simulated, and finally simulated DAS background noise is output. According to the invention, through effective simulation of the background noise of the DAS data, influence factor analysis of the background noise of the DAS data, parameter optimization of DAS demodulation equipment, background noise removal of the DAS data and the like are guided.

The invention discloses a light quantum random number generation device and method based on laser phase noise, and belongs to the field of quantum random number generators, the device comprises a light source module, a detection module and a data sampling and post-processing module, and the light source module, the detection module and the data sampling and post-processing module are connected in sequence; the light source module comprises a laser, a first coupler BS1, a delay optical fiber and a second coupler BS2; the detection module comprises a photoelectric detector PD1 and a photoelectric detector PD2; or the light source module comprises a laser, a circulator, a third coupler BS, a delay optical fiber and a Faraday rotating mirror; the detection module comprises a photoelectric detector PD1 and a photoelectric detector PD2. The problem that an existing phase noise QRNG scheme needs a phase stabilization device and a complex feedback algorithm is solved, no complex feedback algorithm or device is needed for phase stabilization, and the method has the advantages of being easy to implement, low in cost and the like.

A method and apparatus for estimating laser phase noise power spectral density (PN-PSD) utilize multi-laser interferometry. The method performs three or more interferometric measurements and solves a matrix equation to isolate the individual noise profile of a laser of interest from reference lasers. To improve sub-Hz estimation accuracy, the invention employs a block-processing phase reconstruction algorithm that tracks instantaneous aliased beat frequencies. This enables severe sub-Nyquist sampling of beat products, significantly reducing memory requirements and allowing for longer data capture periods required for low-frequency characterization. The individual PN-PSD of each laser is obtained through digital signal processing, which may include quadratic programming to account for measurement noise