79 results about "Heterodyne detection" patented technology

The invention discloses a weak measurement sensing method, device and system based on a coherent state. Local oscillation light and coherent state signal light are obtained. And inputting the signal light into the weak measurement unit by taking a coherent state as a pointer state based on a to-be-measured signal to obtain a quantum state of the signal light. The carriers selected by the weak measurement system are enriched, and the application range of the weak measurement technology is expanded. Heterodyne detection is carried out on a quantum state by using local oscillation light, and secondary amplification is carried out on a signal to obtain a detection result, so that high-sensitivity sensing on a tiny signal is realized. And acquiring the variation of the to-be-detected signal based on the detection result, and calculating to obtain a detection signal according to the variation. According to the invention, high-sensitivity detection is carried out on tiny physical quantities by adopting quantum resources, the application of a quantum sensing technology on the premise of high measurement precision is supported, and the advantages of the quantum resources are fully exerted.

The invention provides an improved randomness evaluation method and system for a continuous variable source independent quantum random number generator based on heterodyne detection, and relates to the technical field of quantum information communication. According to the method, the influence of non-perfect ideal characteristics of an actual device at a measuring end is considered, and the safety problems of non-equilibrium heterodyne detection and the like caused by non-ideal characteristics of local oscillation light intensity fluctuation, the beam splitting ratio of a beam splitter and the detection efficiency of a detector are solved; the above imperfect characteristics are associated with the estimation of the measurement accuracy of the orthogonal component in the calibration process, and the measurement accuracy estimation formula of the orthogonal component is corrected, so that the randomness evaluation is corrected, the problem of security vulnerabilities introduced by local oscillation light intensity fluctuation under unbalanced heterodyne detection can be solved, and the accuracy of the measurement accuracy of the orthogonal component is improved. And the actual safety of the system is further improved.

The invention discloses a channel-associated local oscillator free space continuous variable quantum key distribution method, which comprises the following steps of: initializing a receiving end telescope and a transmitting end telescope, detecting the local oscillator light intensity of a receiving end, adjusting the telescopes to be in an optimal coupling efficiency state, and tracking the change of beacon light through a fine tracking and pointing system of the telescopes so as to maintain the stability of a communication link; a transmitting end performs heterodyne detection on 90% of thermal-state optical signals after polarization and beam splitting of a thermal-state light source, results X and P serve as local initial secret keys, the other 10% of thermal-state optical signals are attenuated and then combined with local oscillation light to be transmitted to a receiving end through a free space channel so as to perform homodyne or heterodyne detection, and corresponding initial continuous secret key data are obtained; and the receiving end performs data frame synchronization, phase compensation, parameter evaluation, error correction and confidentiality enhancement on the obtained initial continuous key data to obtain a binary bit key. The channel associated local oscillator free space CVQKD safe coding based on the thermal state source is realized, and the average key distribution rate under a-15dB attenuation channel reaches a thousand bps magnitude.

The invention relates to the technical field of quantum communication, and discloses a continuous variable quantum key distribution method and system based on a free space channel. The method is applied to each of two communication parties, and a traveling wave parameter amplifier is arranged in each of the two communication parties. Comprising the following steps: generating a microwave dual-mode compression state through a traveling wave parametric amplifier; heterodyne detection is applied to the microwave signal of one mode in the microwave dual-mode compression state, so that the microwave signal of the other mode is mapped to a coherent state, and a coherent state microwave signal is formed; the coherent state microwave signals are sent to a free space quantum channel, so that third-party equipment obtains the coherent state microwave signals corresponding to the two communication parties from the free space quantum channel, and continuous variable Bell detection is carried out after the coherent state microwave signals corresponding to the two communication parties are mixed; the continuous variable Bell detection result of the third-party device is obtained, the secret key is extracted from the continuous variable Bell detection result, and the method can be used for all-weather quantum communication.

The invention relates to a photoelectric integrated double-frequency laser for coherent wind measurement, which comprises a first light source module, a second light source module, a first coupler module, a second coupler module, a third coupler module, a first beam splitter module, a second beam splitter module, a third beam splitter module and a first balanced photoelectric detector module, a second balance photoelectric detector module, a modulator module, an optical phase-locked loop module and a transceiver. Based on the silicon-based optoelectronic chip technology and the photoelectric hybrid packaging technology on the structural level, the coupler, the beam splitter and the photoelectric detector are integrated on the silicon optical chip, and the silicon optical chip, the DFB chip, the coupling optical path, the electrical module and the like are packaged together by utilizing the photoelectric hybrid packaging technology, so that high-density integration is realized; a heterodyne digital optical phase-locked loop technology is applied to a system level, so that a specific frequency difference exists between output signal light and reference light, and pulse light with a high extinction ratio is generated in a modulator cascading mode. Compared with a conventional single-light-source system scheme, the heterodyne Doppler wind measurement laser radar system can greatly improve the integration level, reduce the power consumption and the cost, and is beneficial to mass production, and compared with a homodyne detection mode, heterodyne detection is higher in measurement speed, simpler in scheme and better in stability. The system has extremely high expansibility, and can be applied to systems of optical fiber sensing, laser remote sensing and cold atomic clocks through operations of replacing a transmitting-receiving device, modifying a control program and the like.

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 relates to the technical field of quantum key distribution, in particular to a multi-ring discrete modulation quantum key distribution method and system based on zero photon catalysis. A sender prepares an EPR entangled state, the A state obtains two regular components of the A state through interference and heterodyne detection, and the B state outputs a B1 state through zero photon catalysis and interference and sends the B1 state to a receiver through a transmission channel. And the receiver receives a B2 state (i.e., a B1 state after channel transmission) and a B3 state obtained by interference with an H2 state in the locally generated EPR entangled state, and the obtained B3 state is subjected to homodyne or heterodyne detection to obtain optical signal information. And through post-processing, the receiver generates a security key consistent with the sender, and the process is repeated until the key quantity meeting the service requirement is accumulated. Zero photon catalysis operation is adopted to replace a traditional photon reduction scheme, the operation success probability is improved while similar operation logic is kept, the fidelity of signals in long-distance transmission is improved, and the problem that the efficiency of an existing photon reduction technology is limited in actual application is solved.

The invention relates to the technical field of optical fiber sensing and signal processing, and discloses an optical fiber positioning and common-mode noise suppression integrated device based on time-frequency joint coding, which comprises a time-frequency coding modulation module, a common-mode noise suppression module is mounted at the bottom of the time-frequency coding modulation module, and a common-mode noise suppression module is mounted at the bottom of the common-mode noise suppression module. An optical fiber sensing link is installed in the common-mode noise suppression module. According to the optical fiber positioning and common-mode noise suppression integrated device based on time-frequency joint coding, the time-frequency coding modulation module deeply fuses frequency hopping spread spectrum coding and a heterodyne detection technology, and the encoder encodes a positioning signal and a noise suppression signal into a composite waveform, so that the probability of being interfered is reduced, and the positioning precision is improved. Positioning signal transmission and common-mode noise suppression can be achieved through the same optical fiber, the common-mode noise suppression module can dynamically adjust the noise suppression ratio and the accurate positioning precision according to the environment, a learning-adjustment-optimization closed loop is achieved, and the reliability of the system in complex environments such as traffic, outdoor and mine environments is improved.

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

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 invention belongs to the technical field of laser radars, and particularly discloses a water body temperature profile coherent measurement system based on Brillouin scattering. Comprising a laser seed source, a first coupler, a pulse modulation and amplification module, an acousto-optic modulator, a sinusoidal signal generator, a collimator, a transmitter-telescope, a water body, a receiving telescope, a second coupler, a photoelectric detector, an AD acquisition card, a computer and a connection relation thereof. The invention further discloses a water body temperature profile coherent measurement method based on Brillouin scattering. The heterodyne detection technology is utilized, the system works under the conditions of wide pulse width and low peak power, and water body profile temperature information can be obtained with high sensitivity and high range resolution through coherent detection and a fast Fourier transform algorithm.

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.

The present invention relates to the technical field of quantum key distribution, and specifically to a multi-ring discrete modulation quantum key distribution method and system based on zero-photon catalysis. The sender prepares an EPR entangled state. Among them, the A state is subjected to interference and heterodyne detection to obtain two canonical components of the A state. The B state is subjected to zero-photon catalysis and interference to output the B1 state and is sent to the receiver through the transmission channel. The receiver receives the B2 state (i.e., the B1 state after transmission through the channel), and interferes with the B3 state obtained by interfering with the H2 state in the locally generated EPR entangled state. The obtained B3 state is subjected to homodyne or heterodyne detection to obtain the optical signal information. Through post-processing, the receiver generates a secure key consistent with the sender, and repeats this process until the key amount that meets the service requirements is accumulated. The present invention uses zero-photon catalysis operation to replace the traditional photon subtraction scheme, improves the operation success probability while maintaining a similar operation logic, enhances the fidelity of the signal in long-distance transmission, and solves the problem of limited efficiency of the existing photon subtraction technology in practical applications.

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.

The invention provides a heterodyne detection optical fiber vector hydrophone based on a weak reflection grating array and a demodulation system and method thereof, and the optical fiber vector hydrophone comprises a central mass block, and the six surfaces of the central mass block in the X-axis, Y-axis and Z-axis directions are all provided with sensing units. Each sensing unit comprises a clockwise changing cylinder structure installed on a central mass block, weak reflection optical gratings FBG are installed on the central mass block and the end portions of the six clockwise changing cylinder structures, and the weak reflection optical gratings FBG at the end portions of the six clockwise changing cylinder structures and the weak reflection optical gratings FBG located on the central mass block are arranged at equal intervals to form a weak reflection optical fiber grating array. And an optical fiber with the length of L is wound between the weak reflection grating FBG on the central mass block and the weak reflection grating FBG at the end part of the compliant cylinder. According to the optical fiber vector hydrophone, the grating is directly used as a reflection unit, the size problem caused by FRM is avoided, and meanwhile the excellent phase noise performance of the whole optical fiber vector hydrophone is guaranteed.

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.

The invention relates to the technical field of electron stimulated radiation, quantum amplification and quantum precision measurement, and discloses a quantum heterodyne detection method based on an organic molecule system, which comprises a receiving module, an organic molecule module, an excitation module and a detection module. Organic molecules form a spinning triplet state after being excited, and the energy level is matched with the used resonant cavity and is defined as the local frequency in the heterodyne detection method. After an input microwave field is mixed with a local oscillation frequency, different signals are output based on different input frequencies, and the output signals are processed by a subsequent detection module to realize detection of the microwave field. Compared with a traditional receiver, according to the quantum heterodyne detection method based on the organic molecule system, high-sensitivity heterodyne detection on weak signals can be achieved without using a traditional microwave source as a local oscillator signal by means of the frequency selectivity of the molecular spin energy level and the stimulated radiation principle.

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 present invention discloses a near-infrared diffuse coherent spectrum local cerebral blood flow speckle imaging device and a detection method thereof. The imaging device of the present invention comprises a light source module, an optical heterodyne detection module and an imaging acquisition module. The present invention is based on optical heterodyne detection technology and laser speckle imaging technology. The laser emitted by the laser is divided into two paths, namely, local oscillator light and excitation light, through an optical fiber beam splitter. The excitation light is transmitted to the surface of the local tissue of the brain of the biological being to be tested through a source optical fiber probe. Then, the probe optical fiber probe uses a multimode optical fiber to collect diffuse reflection signal light carrying local blood flow information. The optical fiber coupler and the local oscillator light are homodyne interfered to generate diffuse coherent light, and a laser speckle image is formed on the photosensitive surface of a CMOS camera. Finally, the near-infrared diffuse coherent spectrum speckle contrast analysis algorithm is used to extract the flow velocity characteristic value speckle contrast by computer processing, and the actual relative flow velocity of the local cerebral blood flow is reconstructed, so as to achieve the purpose of non-invasively and accurately detecting the local cerebral blood flow velocity and flow size.

The invention discloses an optical fiber distributed sound wave sensing system and method based on multi-frequency signal delay phase control, and the system comprises a dry light source, a first coupler, an acousto-optic modulator, a circulator, an electro-optic modulator, a second coupler, a balance detector, a drive circuit, and a data collection and signal processing module. A backscattering light signal returned by a sensing optical fiber is converted into a multi-frequency signal by modulation, and the phase shift amount is controlled by controlling the time delay of the signal to a balance detector by utilizing the characteristic that light with different frequencies is different in phase time delay after being transmitted through the same optical path. Therefore, signals with different frequencies after heterodyne detection have specific fixed phase delays, and signal detection and processing can be simplified. The method is characterized in that multi-channel same-frequency signals with set phase shift can be obtained through single-channel detection, and the phase shift amount can be adjusted.

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 present invention relates to the field of dual-beam digital coherent superposition, and particularly to an optical signal passive heterodyne detection and digital coherent superposition device and method. The first optical component of the device is arranged on the optical path between the target light source and the input end of the optical switch. The second optical component is arranged on the optical path between the local oscillator light source and the input end of the optical switch. The output end of the optical switch is connected to the input ends of the first mixer and the second mixer. The first balanced detector group is arranged on the optical path from the output end of the first mixer to the input end of the signal acquisition system. The second balanced detector group is arranged on the optical path from the output end of the second mixer to the input end of the signal acquisition system. The output end of the signal acquisition system is connected to the computer system, and the computer system is used for timing processing and outputs the first coherent signal and the second coherent signal obtained through coherent superposition. In this way, the time alignment of the dual beams can be achieved by using a digital method.

The invention discloses a broadband chaotic signal generation device and method based on delayed self-heterodyne, and relates to the technical field of microwave photonics. Comprising a master laser, an intensity modulator, a polarization controller, a circulator, a slave laser, a first optical fiber coupler, an adjustable optical fiber delay line, a second optical fiber coupler, a first photoelectric detector, a second photoelectric detector and a differential amplifier. A periodically changing driving electric signal is utilized to drive an intensity modulator to modulate a master laser to change the intensity of an output optical carrier signal, and a generated optical signal is injected into a slave laser, so that the slave laser enters a chaotic state and outputs two kinds of chaotic signals. One branch signal is delayed through an adjustable optical fiber delay line, self-heterodyne detection is carried out in the first photoelectric detector and the second photoelectric detector, and a chaotic signal is output. According to the invention, the optical heterodyne of two different chaotic signals is realized, the dominant role of eliminating relaxation oscillation is achieved, and the optical heterodyne relaxation oscillator has the advantages of simple structure, flexible operation and low cost.