44 results about "Heterodyne detection" patented technology

An optical transmission apparatus includes an optical transmitter that generates an optical signal in an uplink direction by modulating output light of a laser that outputs light of a first frequency with a subcarrier on which transmission data is superimposed, a heterodyne detection unit that receives an optical signal in a downlink direction by heterodyne detection, a control unit that calculates a first intermediate frequency based on the frequency of the downlink signal received by the heterodyne detection and the first frequency of the laser, and controls the first frequency of the laser when there is a difference between the calculated first intermediate frequency and a reference second intermediate frequency by a threshold or more.

The invention provides a remote weak signal detection system and method based on weak measurement technology enhancement, and can be applied to the technical field of signal detection. The system comprises a light source for providing initial signal light; the first beam splitter is used for splitting the initial signal light into first local oscillator light, second local oscillator light and signal light; the long-distance signal transmission simulation unit obtains intermediate signal light; the second beam splitter divides the intermediate signal light into first sub-intermediate signal light and second sub-intermediate signal light; the first signal action unit modulates the first sub-intermediate signal light into first post-selection signal light, and performs heterodyne detection on the first post-selection signal light and the first local oscillation light to obtain a first heterodyne detection result; the second signal action unit modulates the second sub-intermediate signal light into second post-selection signal light, heterodyne detection is carried out on the second post-selection signal light and the second local oscillator light, a second heterodyne detection result is obtained, and the first post-selection angle and the second post-selection angle are opposite numbers; and the signal processing unit obtains the phase of the signal to be detected.

This invention provides a self-heterodyne detection system capable of stably and over long periods of time measuring broadband laser linewidths. [Solution] The present invention discloses a self-heterodyne detection system. The system may include a frequency comb light source that generates light, a photodetector that detects the light, an electrical spectrum analyzer connected to the photodetector that analyzes the frequency and wavelength of the light using the detection signal of the photodetector, an interferometer including an input coupler provided between the frequency comb light source and the photodetector to receive the light, a branch waveguide branched by the input coupler, and an output coupler connected to the branch waveguide, and a programmable filter provided in the branch waveguide to select the peak wavelength of the light.

This improves the degradation of the cross-correlation coefficient caused by the error between the set frequency and the actual frequency of the light source, and makes it possible to improve the degradation of the measurement accuracy of strain and temperature. [Solution] The light source unit has a frequency-stabilized wavelength-tunable laser that generates continuous light, and a first optical coupler splits the continuous light generated by the light source unit into two, sending one to a second optical coupler and the other to an optical frequency measurement unit. The optical frequency measurement unit measures the frequency of the continuous light generated by the light source unit, and the second optical coupler further splits the continuous light split by the first optical coupler into two, sending one as probe light to the optical pulse generation unit and the other as local light to a detection unit. The detection unit measures the frequency change Δf by means of coherent time domain reflectometry and a means for heterodyne detection of the Rayleigh scattered light and the local light resulting from Rayleigh scattering of pulsed light in the fiber under test. max and means for acquiring the

The application relates to the technical field of laser heterodyne atmospheric remote sensing, and discloses a laser heterodyne atmospheric remote sensing device and method applied to a ship, the device comprising a sun tracking module, a heterodyne light path module, a signal processing module and a computer device, wherein the sun tracking module comprises a sun tracking meter, a photoelectric detector and an optical switch, the heterodyne light path module comprises a laser, an optical attenuator, an optical fiber combiner and a photoelectric detector; the signal processing module comprises a radio frequency amplifier, a radio frequency filter, a power detector, a lock-in amplifier and a data collector. The laser heterodyne atmospheric remote sensing device applied to the ship can reduce the precision requirement of a sun tracking meter for laser heterodyne detection, and realizes spectral detection under the condition that the probability of the alignment precision being within the range of 0.1 degrees is greater than 50%.

The application discloses a kind of optical frequency standard optical fiber precision transmission systems and methods of remote phase noise compensation, the system includes laser light source, optical fiber, first acoustooptic modulator, Raman amplifier, laser light source is used to simulate optical frequency standard signal, optical fiber is used to transmit optical frequency standard signal;First acoustooptic modulator is connected with laser light source by first optical fiber coupler, first optical isolator, for frequency shift to laser;Raman amplifier is connected with optical fiber, optical frequency standard signal enters optical fiber after first acoustooptic modulator, and the power of optical signal is amplified using Raman amplifier.The application obtains optical fiber phase noise signal by the light heterodyne detection of the phase-locked loop at the far end of optical fiber, and the working frequency of acoustooptic modulator is controlled by negative feedback to compensate optical fiber phase noise in real time, reduce the influence of phase noise on optical frequency standard signal frequency stability, solve the limitation of transmission end position of traditional method, and be applicable to the transmission of optical frequency standard of multiport output mode.

The invention discloses a high-wind-speed coherent laser wind-finding radar device, which comprises a seed laser, a plurality of cascaded acousto-optic frequency shift modules, a laser amplifier, a first optical switch, a laser transmitting and receiving detection module, a wind field inversion module and a wind speed identification and control unit, and is characterized in that the plurality of cascaded acousto-optic frequency shift modules realize frequency shift and beam splitting of the seed laser; the first optical switch selects the seed laser output by one acousto-optic frequency shift module as heterodyne detection seed laser; the wind field inversion module performs wind field inversion on the heterodyne beat frequency signal output by the balance detector to obtain a wind speed measurement result; the wind speed identification and control unit controls the frequency shift amount of the emitting seed laser and the frequency shift amount of the heterodyne detection seed laser, so that the difference value between the Doppler frequency shift amount caused by the wind speed and the frequency shift amount of the heterodyne detection seed laser is within the bandwidth range of the balance detector, and effective detection of the wind speed is achieved. According to the invention, the wind speed measurement range of the coherent wind lidar can be effectively improved, and the reduction of the wind speed measurement precision is not caused.

This invention discloses a bidirectional continuous-variable quantum key distribution method and system based on frequency division duplexing in a single-transceiver ring network. The method is based on a monolithically integrated silicon photonics transceiver chip. By pre-setting optical carrier frequency offsets for the forward and reverse links, it isolates the quantum signal from Rayleigh backscattering noise in the fiber in the frequency domain. The transmitting end generates a broadband waveform containing quantum signals and pilot signals, which is transmitted bidirectionally through a single optical fiber. The receiving end uses a laser source from the same chip as the local oscillator for coherent heterodyne detection. A digital signal processing module performs orthogonalization correction, phase recovery, and matched filtering to suppress noise and extract the quantum signal to generate a secure key. This invention solves the problems of inflexible networking, low fiber utilization, and severe scattering noise interference in bidirectional transmission over a single fiber caused by the separation of the transmitting and receiving ends in integrated continuous-variable quantum key distribution systems. It provides a low-cost and highly flexible solution for metropolitan quantum ring networks.

Transmitters, receivers, systems and methods for compensating for polarization drift caused by a communications channel are provided. One or more polarization reference signal(s) or sets of polarization reference signals may be transmitted in combination with a polarized communications signal. The combination may be via wavelength or time multiplexing. Polarization measurements of the one or more polarization reference signals or sets of polarization reference signals and subsequent heterodyne detections thereof may be used for compensation of the polarization drift of the combined signals which are received. The polarization compensation may be for a State of Polarization (SOP) of a polarized communications signal such as any one polarization basis. The polarization compensation may be for complete polarization channel compensation such as for three different polarization basis which are mutually unbiased.

This invention discloses a DC suppression circuit structure, a DC suppression method, and a terahertz heterodyne detection system. The DC suppression circuit structure includes a first nonlinear detection module, a second nonlinear detection module, a phase adjustment module, and a signal synthesis module. The phase adjustment module adjusts the phase of the mixing signal generated by the second nonlinear detection module. The signal synthesis module superimposes the phase-adjusted mixing signal with the mixing signal generated by the first nonlinear detection module. During the synthesis process, the self-mixing DC component is at least partially canceled out, and the intermediate frequency AC component is at least partially superimposed. This invention weakens or cancels the self-mixing DC component during the synthesis process, while allowing the intermediate frequency AC component to be superimposed and output, thereby effectively suppressing the self-mixing DC component in the output signal and improving the stability of the intermediate frequency signal.

The disclosure provides a weak measurement technology enhanced long-distance weak signal detection system and method, which can be applied to the technical field of signal detection. The system comprises: a light source providing initial signal light; a first beam splitter dividing the initial signal light into first local oscillator light, second local oscillator light and signal light; a long-distance signal transmission simulation unit obtaining intermediate signal light; a second beam splitter dividing the intermediate signal light into first intermediate signal light and second intermediate signal light; a first signal action unit modulating the first intermediate signal light into first post-selection signal light, performing heterodyne detection with the first local oscillator light, and obtaining a first heterodyne detection result; a second signal action unit modulating the second intermediate signal light into second post-selection signal light, performing heterodyne detection with the second local oscillator light, and obtaining a second heterodyne detection result, the first post-selection angle and the second post-selection angle being opposite numbers; and a signal processing unit obtaining the phase of the signal to be detected.

The invention provides a radar system for measuring wind and distance and a wind and distance measuring method, and relates to the technical field of laser radars. The system comprises a dual-band laser light source module used for outputting a first laser signal of a first wavelength and two paths of second laser signals of a second wavelength, which are emitted by the same laser and are separated; the optical antenna module is used for respectively transmitting the first laser signal and one path of second laser signal as anemometry laser, transmitting the other path of second laser signal as ranging laser, and receiving two kinds of anemometry echoes and ranging echoes; the photoelectric conversion module is used for performing heterodyne detection on the two wind measurement echoes to obtain a first wind measurement electric signal and a second wind measurement electric signal, and determining a distance measurement electric signal according to the distance measurement echoes; the identification module is used for identifying the wind speed according to the first and second wind measurement electric signals; and recognizing the clearance distance according to the ranging electric signal. According to the invention, continuity and reliability of wind measurement and distance measurement can be guaranteed, and multi-meteorological-scene monitoring requirements of wind power equipment are met.

The invention discloses a monopulse quantum laser radar device and an implementation method. The method comprises the following steps: firstly, generating phase locking seed light by using a single-frequency continuous wave laser, and respectively generating pulse quantum light and local reference light by the locking seed light through a pulse probe light source and an arbitrary waveform reference light source; transmitting the pulse quantum light to a target area by using a transmitting and receiving optical system, and receiving echoes scattered by the target area; meanwhile, after local reference light is delayed by an all-optical delayer, the local reference light serves as a local oscillation light field for balance heterodyne detection, optical balance beam combination is carried out on the local oscillation light field and received echoes, and therefore differential current is output; and finally, any waveform control and a spectrum analyzer are used for analyzing the spectrum so as to extract the quantum state of the echo and effective target information. Compared with the prior art, the quantum state information of the echo signal light can be reliably extracted.

The invention belongs to the technical field of laser radars, and discloses a low, small and slow single photon radar based on a detection array, which comprises a laser, a beam splitter, an acousto-optic modulator, a light amplification module, a receiving and transmitting light path, a turntable, an optical fiber array, a heterodyne detection array module and a data acquisition and processing module, and the data acquisition and processing module extracts fuselage vibration characteristic parameters of the unmanned aerial vehicle through a vibration characteristic extraction algorithm, and performs unmanned aerial vehicle target identification by using a target identification algorithm. Compared with the prior art, high-coherence laser is generated, large-range airspace laser projection and vibration signal receiving are achieved through the optical fiber array, the heterodyne detection array is combined to suppress environment noise and extract unmanned aerial vehicle fuselage vibration characteristics, and finally accurate detection and recognition of the unmanned aerial vehicle are completed through the signal processing and recognition module. The system has the advantages of being large in view field range, high in anti-interference capability, high in vibration signal extraction precision and the like, and remote, high-sensitivity and low-misjudgment-rate detection of the low-slow-small unmanned aerial vehicle can be achieved.

The invention discloses a dynamically prepared CV-MDI-QKD system and method, so that photoelectric devices such as an amplitude modulator (AM), a phase modulator (PM) and a quantum random number generator (QRNG) do not need to be arranged in an existing CV-MDI-QKD scheme any more, the system cost, the manufacturing time and the complexity are reduced, meanwhile, security vulnerabilities of a receiving end are allowed to be eliminated by means of an MDI scheme, and the system performance is improved. And heterodyne detection is carried out by adopting a high-bandwidth coherent detector in each sending end and each receiving end, so that the secret key rate is effectively improved, and the whole QKD system is more practical. Besides, for a dynamically prepared scheme, corresponding phase estimation compensation schemes are provided for different phase disturbance factors, the phase problem based on the dynamically prepared CV-MDI-QKD scheme is solved, and experimental verification and practical promotion of the CV-MDI-QKD scheme are facilitated.

The invention belongs to the field of continuous variable quantum key distribution, and particularly relates to a modulation-free multi-state local oscillator continuous variable quantum key distribution method. In order to realize high-performance long-distance key transmission, an injection method is adopted to generate high-quality pulse signal light and pulse reference light. The pulse signal light and the pulse reference light respectively pass through a beam splitter, and heterodyne detection is carried out on each light beam. And the other beam of pulse signal light is attenuated into a quantum signal through a variable optical attenuator, and the quantum signal and the other beam of reference light are transmitted to an optical fiber polarization beam combiner together and are transmitted to a receiving end through a quantum transmission channel. And a receiving end adopts a dynamic polarization controller and an optical fiber polarization beam splitter to separate the quantum signal from the reference light. An electric signal output after a beam of light split from the reference light passes through a photoelectric detector can be used for a dynamic polarization controller and can also be used for synchronization of clocks at the transmitting end and the receiving end and alignment of data. Then, the quantum signal and the reference pulse interfere with the continuous local oscillation light, and heterodyne detection is carried out.

Dual comb radiation sources and heterodyne detection for overlay metrology are described. A dual comb radiation source is configured to irradiate a metrology target with first radiation and second radiation. The first radiation and the second radiation have different repetition rates so the radiation signals can pass through each other. A detector receives diffracted radiation and generates a detection signal. For overlay determination, the first radiation irradiates the metrology target and the second radiation is used as a reference. The detector performs heterodyne detection of interference between different corresponding portions of the first radiation diffracted by the metrology target and the second radiation to provide a spectral response of an amplitude and phase of the diffracted radiation.

The application provides a nano-air channel photodiode array, which comprises a three-layer structure, a first layer is a transparent substrate and a plurality of nano-air channel photodiodes located thereon, a second layer is a vertical interconnection metal column, and a third layer is a dielectric substrate and a circuit located thereon; the plurality of nano-air channel photodiodes in the first layer are photoelectric conversion elements, and the circuit in the third layer comprises a radio frequency circuit, an antenna array and a signal readout circuit; the nano-air channel photodiodes in the first layer and the circuit in the third layer are electrically interconnected through the vertical interconnection metal column in the second layer. The nano-air channel photodiode array provided by the application can overcome the limitation that the output power of a single device is small, better play the advantages of the nano-air channel photodiode, and can be used for heterodyne detection imaging of millimeter wave terahertz, and can also be used for optical focal plane imaging.

The invention belongs to the field of optical sensing, and particularly relates to an echo wall functionalized micro-flow cavity hydrogen sensing system based on a laser tracking technology. An ultrahigh-Q-value WGM optical micro-flow cavity is etched on the outer wall of a silicon dioxide capillary tube, a Pt / WO3 functionalized nano-film is deposited on the inner wall of the silicon dioxide capillary tube, a functionalized material is in indirect contact with the micro-flow cavity, hydrogen reacts with the Pt / WO3 material to release heat, and the optical characteristic change of the WGM optical micro-flow cavity is caused by heat conduction; and then the laser-trigger technology is adopted to ensure that the wavelength of the sensing laser tracks the resonance displacement of the microcavity, and photoelectric heterodyne detection is adopted to accurately measure the position and displacement of the resonance wavelength, so that the detection of the gas concentration is realized. The sensing system provided by the invention has a significant detection limit of 5ppb and large-range detection crossing five orders of magnitude, and realizes integration of high sensitivity, large dynamic range and real-time detection of hydrogen sensing; an advanced detection method is provided for microcavity sensing, and a good basis is provided for safe and large-scale application of hydrogen.

Dual comb radiation sources and heterodyne detection for alignment metrology are described. A dual comb radiation source is configured to irradiate a metrology target with first radiation and second radiation. The first radiation and the second radiation have different repetition rates so one comb samples the repetitive pulse train from the other comb. A detector receives diffracted radiation and generates a detection signal by analyzing heterodyne beating between different corresponding portions of the first radiation and the second radiation to distinguish relevant wavelength ranges in an optical spectrum of diffracted radiation.

The invention relates to the technical field of spectrum sensing and precision measurement, in particular to a photo-thermal gas detection device and method based on double-comb enhancement, and the photo-thermal gas detection device comprises a pumping laser module, a detection laser module, a hollow-core anti-resonance optical fiber and a data acquisition module, the pump light and a first optical comb generated by the detection laser module are transmitted in the same direction in the hollow-core anti-resonance optical fiber, and the phase of the first optical comb is modulated by a photothermal effect generated after gas absorbs the pump light; and performing optical beat frequency and demodulation on the modulated first optical comb and second optical comb in a data acquisition system to obtain a photo-thermal spectrum signal. According to the invention, the wide spectrum coverage capability of the double optical combs is utilized to realize rapid parallel detection of multi-component gas, and signals are transferred to a radio frequency domain through coherent heterodyne detection, so that various noises are effectively inhibited, and the detection sensitivity, the signal-to-noise ratio and the environmental adaptability are greatly improved.

The invention belongs to the field of optical fiber sensing, relates to a distributed optical fiber sensing technology, and particularly provides a time-frequency division multiplexing Brillouin time domain reflectometer based on pulse sequence coding, which is used for improving the system performance of the Brillouin time domain reflectometer. According to the method, the optical pulse string with the time domain separated from the frequency domain is generated through the frequency shift ring, then pulse time domain coding is carried out on the optical pulses of different channels, on the premise that the number of the channels is increased, increase of the optical peak power is avoided, meanwhile, heterodyne detection of single intrinsic light has feasibility due to the reasonable frequency interval, and the detection accuracy is improved. The intrinsic optical power is maximized, so that the heterodyne detection signal-to-noise ratio is maximized; moreover, the time domain pulse codes between different channels are not mutually aliasing, so that different groups of codes can be almost simultaneously input into the optical fiber to be measured and can be decoded simultaneously, and the limitation of long measurement time of the traditional codes is broken through. And finally, the signal-to-noise ratio, the detection speed, the detection precision and other system performances of the system are effectively improved.

One embodiment of the present invention is an optical communication instrument that uses heterodyne detection and comprises: a first polarization separator that separates a received optical signal into orthogonal polarization components; a second polarization separator that separates continuous light of a single wavelength into orthogonal polarization components; an optical splitter that splits each of the orthogonal polarization component separated by the first polarization separator and the orthogonal polarization component separated by the second polarization separator into two branches; and an optical receiver that converts eight polarization components, which are obtained by the optical splitter splitting into two branches, into an electric signal for each combination of the two branches and generates four beat components in total.

Described are systems and methods for generating two-dimensional spectra of liquid or gas samples. In examples, the disclosed systems and methods use frequency comb lasers for the pump and probe lasers, such as generated using fiber laser systems or electro-optic modulated laser systems, and employ enhancement cavities for the pump and probe lasers to increase laser intensity for interaction with the liquid or gaseous sample for generation of signals for use in generating two-dimensional spectra. In examples, heterodyne detection of generated signals using a detection laser is also employed.

The application discloses a self-evaluation quantum random number generation system and method based on heterodyne detection, which comprises the following steps: a heterodyne detection-based method is used to simultaneously extract two corresponding orthogonal component fluctuations of a quantum state as an entropy source of a random number generator; original data of a two-component measurement are randomly extracted based on a synchronous clock to reconstruct a quantum state phase space distribution in real time, so that the safety of the entropy source is comprehensively evaluated, and then the evaluation result is fed back to a hardware hash post-processing link, the size of a Toeplitz matrix constructed in an FPGA is adjusted in real time, and the real-time safety of the generated quantum random number is ensured; meanwhile, on the basis of simultaneously extracting two orthogonal component quantum fluctuations of a quantum state as an entropy source, multiple high-frequency quantum sideband modes in a balanced homodyne detection bandwidth are extracted as sub-entropy sources in parallel for the two orthogonal components, so that the quantum random number generation rate is doubled in a double-parallel quantum entropy source extraction mode.

The present application relates to a kind of based on heterodyne technique's hyperspectral detection method and the online hyperspectral detector using this method, belong to photoelectric detection technical field, solve the technical problem that the detection spectral range is limited.The method includes the following steps: after the optical collimation system collimation of the light signal to be measured, enter optical fiber and couple;Local light laser of the frequency band to be measured emits local light signal, and is divided into probe signal and reference signal by optical beam splitter.For the frequency band below wavelength 760nm, when the central wavelength of laser is not tunable, the present application utilizes the central frequency of band-pass filter to change, realizes the ultra-high resolution spectrum scanning of laser frequency band below 760nm.The present application changes from limited to possible for the heterodyne detection method of laser wavelength non-tunable range, and the implementation method is simple, the pressure of laser drive is changed into the implementation pressure of electronic filter, and digital control method is more flexible.

The application belongs to the technical field of laser radar, and discloses a low, slow and small single-photon radar based on a detection array, which comprises a laser, a beam splitter, an acousto-optic modulator, an optical amplification module, a transceiving light path, a rotary table, a fiber array, a heterodyne detection array module and a data acquisition and processing module; the data acquisition and processing module extracts the body vibration characteristic parameters of the unmanned aerial vehicle through a vibration characteristic extraction algorithm, and identifies the unmanned aerial vehicle target by using a target identification algorithm. Compared with the prior art, the application generates high-coherence laser, realizes laser projection and vibration signal reception in a large range of space through the fiber array, and then combines the heterodyne detection array to suppress environmental noise and extract the body vibration characteristics of the unmanned aerial vehicle, so that the precise detection and identification of the unmanned aerial vehicle are finally completed through a signal processing and identification module, and the application has the advantages of a large field of view, strong anti-interference capability, high vibration signal extraction precision and the like, and can realize the detection of the low, slow and small unmanned aerial vehicle at a long distance, high sensitivity and low misjudgment rate.

The invention discloses a microscopic system and method based on spontaneous Brillouin scattering. A microscopic system based on spontaneous Brillouin scattering may include a microscopic assembly and a detection assembly. The microscopic assembly is configured to receive first laser, and the first laser is pulse laser; and guiding the first laser to the sample to be tested to generate spontaneous Brillouin scattering light. The detection assembly is configured to: receive the spontaneous Brillouin scattering light and the second laser; heterodyne detection is carried out on the spontaneous Brillouin scattered light and the second laser to generate a detection result, and the detection result is processed to carry out Brillouin microscopic detection on the to-be-detected sample.

The invention provides a fast demodulation method, device and equipment for a heterodyne detection phi-OTDR signal, and belongs to the field of data processing, and the method comprises the steps: obtaining an original intermediate frequency signal according to a phase-sensitive optical time domain reflectometry phi-OTDR; demodulating the original intermediate frequency signal to obtain a baseband signal; performing primary filtering on the baseband signal through a preset cascade integrator comb CIC filter to obtain a baseband filtering signal; performing a vector rotation operation on the baseband filtering signal to obtain a frequency domain aliasing signal; performing low-pass filtering on the frequency domain aliasing signal through a preset low-pass filter to obtain a low-pass filtering signal; and obtaining target phase information in the optical fiber according to the low-pass filtering signal. The calculation amount and the storage amount can be reduced, meanwhile, the fading suppression efficiency and practicability of the phi-OTDR signal are improved, and the real-time processing cost of hardware is reduced.

This invention relates to an electromagnetic field scanning system for diamond NV centers based on heterodyne detection, belonging to the field of microwave quantum detection technology. It includes a laser pumping module, a fluorescence collection module, a microwave pumping module, a magnetic field control module, and a scanning detection module. The laser pumping module generates a laser to excite the diamond NV centers to emit fluorescence signals. The microwave pumping module generates an injection microwave signal and a reference microwave signal with similar frequencies. The injection microwave signal is injected into the microwave radiation device under test to generate the microwave signal to be measured. The reference microwave signal and the microwave signal to be measured generate a heterodyne mixing signal. The magnetic field control module applies a static magnetic field to the diamond, enabling the diamond NV centers to resonate with the microwave signal to be measured and emit fluorescence response signals. The fluorescence collection module collects the fluorescence signal and obtains the spectrum, which is sent to the control unit. The control unit calculates the microwave signal to be measured based on the spectrum information. This invention solves the problem of the lack of a system solution for applying heterodyne detection to the detection of diamond NV centers in the prior art.