34 results about "Laser phase noise" patented technology

The invention discloses a laser phase noise quantum random number generator which comprises a light source module, an unequal arm interference light path, a detection module, a sampling module, a control processing module and a driving module. The light source module generates light signals and outputs the light signals to the detection module through the unequal-arm interference light path, the detection module detects the intensity of the interference light signals, the sampling module carries out high-speed sampling on output results of the detection module, and sampling data of the sampling module is calculated and analyzed through the control processing module to obtain the size of phase drift. Then, an electric signal is generated through a driving module to load a compensation phase to the unequal arm interference light path to offset phase drift, so that the laser phase noise quantum random number generator reaches a stable state; and when the laser phase noise quantum random number generator reaches a stable state, the control processing module performs entropy evaluation and randomness extraction on the sampling data to generate a random sequence. Through the structural arrangement, the control precision and the feedback compensation speed are effectively improved.

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.

Embodiments herein describe spectroscopy systems that use an unmodulated reference optical signal to mitigate noise, or for other advantages. In one embodiment, the unmodulated reference optical signal is transmitted through the same vapor cell as a modulated pump optical signal. As such, the unmodulated reference optical signal experiences absorption by the vapor, which converts laser phase noise to amplitude noise like the other optical signals passing through the vapor cell. In one embodiment, the unmodulated reference optical signal has an optical path in the gas cell that is offset (or non-crossing) from the optical path of the modulated pump optical signal. The unmodulated reference optical signal allows removal or mitigation of the noise on the other optical signal.

The invention discloses a cavity ring-down spectral measurement system and method based on narrow linewidth single-frequency laser sideband scanning. The system comprises a computer, a radio frequency signal generator, a radio frequency signal amplification device, a laser, an electro-optical modulator, an optical switch, a resonant cavity, a threshold comparison circuit and the like. A computer controls a radio frequency signal generator to generate sinusoidal modulation signals with different frequencies and inputs the sinusoidal modulation signals into an electro-optical modulator, and light output by a laser passes through the electro-optical modulator, an optical switch, a lens and a reflector and then enters a ring-down cavity. The detector receives transmission light of the ring-down cavity and divides the transmission light into two paths for output, the first path is input to the threshold comparison circuit to generate a pulse signal to drive the optical switch, and the second path is collected by the collection card and then recorded and processed by the computer. The cavity ring-down spectrum measurement system and method have the advantages that the influence of laser phase noise on ring-down time stability can be avoided, the wavelength of a scanning spectrum point by point can be obtained by using the radio frequency signal frequency, integration is easy, and the like.

The invention discloses a laser phase noise measuring method. The method comprises the following steps: step 1, dividing an output optical signal of a laser into two paths, taking one path as signal light after time delay tau is introduced, and taking the other path as local oscillation light; step 2, mixing the signal light and the local oscillation light by using a 90-degree optical mixer, and selecting two paths of output optical signals with orthogonal phases from four paths of output optical signals of the 90-degree optical mixer to respectively perform photoelectric detection to obtain two paths of electric signals; 3, respectively carrying out analog-to-digital conversion on the two paths of electric signals to obtain two paths of corresponding digital signals VI (t) and VQ (t); and step 4, obtaining the phase noise L (fm) of the laser through digital signal processing, wherein # imgabs0 # S psi (fm) represents the power spectrum density of the digital signal # imgabs1 #. The invention further discloses a laser phase noise measuring device. Compared with the prior art, the measuring precision is higher, the system structure is simpler, and the measurement is faster and more convenient.

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 invention provides a quantum-enhanced laser phase noise filtering device and method, and belongs to the technical field of laser phase noise filtering. The technical problem to be solved is to provide the quantum-enhanced laser phase noise filtering device and method. According to the technical scheme, laser generated by a single-frequency laser sequentially passes through an acousto-optic modulator and a Faraday isolator and then is injected into a frequency doubling cavity; the frequency doubling cavity reflects fundamental frequency light in the received laser back to the Faraday isolator, and the fundamental frequency light is reflected to a mode cleaner locked in a semi-detuning state by a polarization beam splitter prism in the Faraday isolator and then is reflected to a second beam splitter by the mode cleaner; the second beam splitter divides the received optical signal into an inner ring feedback signal and an outer ring evaluation signal, and the divided inner ring signal is detected by the first photoelectric detector and then is output to the feedback controller for phase noise active control; the method is applied to laser phase noise filtering.

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.

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 embodiments of the present application provide a method, device, and storage medium for measuring optical fiber temperature and / or strain, relating to the field of distributed optical fiber technology. The method comprises: obtaining a first high-frequency optical signal and a second low-frequency optical signal at any linear modulation frequency, and converting them into a first electrical signal and a second electrical signal; determining the average of the Brillouin attenuation and gain values ​​corresponding to the first electrical signal and the second electrical signal based on the central symmetry of BGS and BLS, and determining the measurement result of the temperature and / or strain of the optical fiber to be measured based on the Brillouin frequency shift determined from all the first average values. The present application utilizes the central symmetry of BGS and BLS to convert the high-frequency optical signal and the low-frequency optical signal obtained by the original SA-BOTDA into electrical signals and then average them, thereby suppressing the phase-to-intensity noise caused by the frequency shift of the high-frequency and low-frequency optical signals affected by the laser phase noise, and reconstructing the Brillouin gain spectrum, thereby reducing the impact of the laser linewidth on the signal-to-noise ratio.

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.

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.

Embodiments herein describe spectroscopy systems that use an unmodulated reference optical signal to mitigate noise, or for other advantages. In one embodiment, the unmodulated reference optical signal is transmitted through the same vapor cell as a modulated pump optical signal. As such, the unmodulated reference optical signal experiences absorption by the vapor, which converts laser phase noise to amplitude noise like the other optical signals passing through the vapor cell. The unmodulated reference optical signal has an optical path in the gas cell that is offset (or non-crossing) from the optical path of the modulated pump optical signal. The unmodulated reference optical signal allows removal or mitigation of the noise on the other optical signal.

The present invention discloses a novel laser phase noise quantum random number generation method and device. Based on real-time monitoring of changes in the average output light intensity of an interferometer to determine the real-time phase difference between the interferometer's two arms, the method dynamically adjusts the extraction ratio of the current original random number sequence to obtain quantum random numbers through online estimation of minimum entropy. This method eliminates the need for a phase stabilization structure and ensures that, regardless of the phase difference between the two arms, quantum random numbers can be generated and output while meeting randomness requirements. This simplifies the internal structure and process flow of the interferometer, reduces the system's requirements for feedback algorithms and hardware drivers, and facilitates the miniaturization, modularization, and chip-based development of existing quantum random number devices.

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 invention provides a magnetic resonance phase compensation method and system based on external signal compensation. The method comprises the following steps: multiplying sigRef and sigA to obtain a noise signal comprehensive sigNoise; the frequency of an externally applied signal is changed, and a noise signal consistent with sigNoise is added into the external magnetic field signal sigRef; through PID closed-loop control, the resolving signal error is suppressed to be a fixed value or 0; performing multiplication demodulation on the adjusted sigRef + sigNoise and an optical signal sigB so as to suppress sigNoise contained in the optical signal sigB, and at the moment, obtaining a resolving result as a signal of atomic nucleus spinning, namely, an actually required signal; and according to a result obtained by multiplying the optical signal sigA by the adjusted sigReff + sigNoise, controlling the output frequency of the detection laser through PID (Proportion Integration Differentiation) closed-loop control, and suppressing the phase noise of the detection laser. According to the technical scheme, the technical problems that in the prior art, a single method for forcing the output light intensity of the laser to be stable is single, the implementation means is tedious, and the method is inconsistent with the development trend of a sensor with the gradually-small size are solved.

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.

The invention discloses a photon wireless signal generation system capable of eliminating laser phase noise and a preparation method, and the technical key points are that the photon wireless signal generation system is integrated on an I nP-based photoelectric chip, the photon wireless signal generation system comprises a laser, the output end of the laser is connected with the input end of an RF modulation unit, the output end of the RF modulation unit is connected with the input end of a wavelength selection unit, and the wavelength selection unit is connected with the I nP-based photoelectric chip. The first output end of the wavelength selection unit is connected with the input end of the data modulation unit, the output end of the data modulation unit is connected with the first input end of the optical coupler, the second output end of the wavelength selection unit is connected with the second input end of the optical coupler, and the output end of the optical coupler is connected with the input end of the optical amplifier. The output end of the optical amplifier is in optical coupling connection with the photoelectric detector, and the output end of the photoelectric detector is connected with the input end of the antenna. The system is based on an I nP-based photoelectric platform, the system complexity is low, the integration level is high, preparation is easy, the performance and frequency stability of photon wireless signals are improved, and the error rate of a wireless communication system is reduced.

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 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 fiber, a third optical coupler, a first polarization controller, a second single-mode fiber, a second polarization controller, a fourth optical coupler, a fifth optical coupler, a first balanced photoelectric detector, a second balanced photoelectric detector and a signal acquisition and processing unit. By adopting the technical scheme of the invention, the problem of mutual restriction of sensitivity and bandwidth in a traditional delay interference method is overcome, and the sensitivity and bandwidth comprehensive performance of laser phase noise measurement is improved.