39 results about "Optical frequencies" patented technology

The invention provides a terahertz frequency comb generation verification method and system based on an optical fiber microcavity optical frequency comb, and the method comprises the steps: injecting a continuous wave laser into an optical fiber microcavity resonator to generate a stable Kerr optical frequency comb, enabling the Kerr optical frequency comb to work in a single soliton state or a soliton crystal state, and obtaining an optical frequency reference with low phase noise. Furthermore, spectrum selection is performed on the optical frequency comb, multiple groups of optical comb tooth pairs comprising comb teeth of different orders are actively selected, and the optical frequency difference of each group of comb tooth pairs is directly converted into an electric signal in a terahertz frequency band by utilizing a beat frequency effect of a photoelectric detector. A plurality of terahertz electric signals generated by different comb tooth pairs are integrated to form a multi-channel terahertz frequency comb. The method allows a plurality of discrete and frequency-controllable terahertz signal channels to be generated in parallel on a single optical platform through one-time optical processing and photoelectric conversion, so that multichannel terahertz frequency comb generation is realized.

The invention discloses a coherent optical frequency signal regeneration amplification system based on optical fiber transmission. The coherent optical frequency signal regeneration amplification system comprises a local narrow linewidth laser which outputs narrow linewidth laser; the first optical fiber coupler couples the narrow linewidth laser to the first acoustic optical modulator and the second acoustic optical modulator respectively; the output of the first acousto-optic modulator and superior transmission light are jointly coupled into a photoelectric detector by a second optical fiber coupler to generate a beat frequency signal; the signal processing module samples the beat frequency signal after conditioning the beat frequency signal, performs phase discrimination on the sampled signal and the digital reference signal to generate an error signal, and generates a first feedback signal and a second feedback signal according to the error signal to be respectively used by the local narrow linewidth laser and the first acousto-optic modulator; performing real-time cycle slip detection on the error signal and repairing a phase abnormal point to generate a third feedback signal to be used by a second acousto-optic modulator; and the second acousto-optic modulator outputs amplified regenerated laser. According to the invention, high-precision optical frequency signal transmission can be realized in a complex and changeable optical fiber environment with large noise.

Optical frequency reference apparatus (10) comprising - an atomic vapor cell (1), containing a vapor of reference atoms, said atomic vapor cell (1) comprising a first end (41) having a first window (4) and a second end (61), - a laser source (11) for generating a laser probe beam (3) adapted to excite a two-photon optical transition of said reference atoms, - an optical detector (14), adapted to detect a fluorescence signal emitted by said reference atoms, and - at least one reflective element (5, 15) wherein the laser source (11), the atomic vapor cell (1) and the at least one reflective element (5, 15) are configured such that, in operation, the probe beam (3) enters the atomic vapor cell (1) through said first window (4) at said first end (41) and crosses said vapor of reference atoms until said second end (61) through a defined optical path in a first forward direction (3a), the probe beam (3) is reflected backwards by said at least one reflective element (5, 15) and crosses said vapor of reference atoms a second time through the same defined optical path, in a second direction (3b) opposite to the first forward direction (3a), characterized in that the optical frequency reference apparatus (10) further comprises means (7, 9) for absorbing the reflected laser probe beam (3) exiting from the atomic vapor cell (1) according to the second direction (3b).

An optical comb light source outputs an optical comb having a plurality of modes. The optical comb light source includes an optical comb generating section, an optical frequency changing section, and a mode optical frequency controlling section. The optical comb generating section generates the optical comb. The optical frequency changing section receives a reference wavelength light having a predetermined optical frequency and changes the optical frequency of the reference wavelength light for output. The mode optical frequency controlling section controls a mode optical frequency that is an optical frequency of one mode of the plurality of modes such that a difference between the mode optical frequency and a target optical frequency that is an optical frequency of an output from the optical frequency changing section has a predetermined value. The optical comb generating section changes optical frequencies of the plurality of modes according to the controlled mode optical frequency.

A fibre optic sensing apparatus (400) is described which has an optical output path (403, 405, 404) configured to repeatedly interrogate a sensing optical fibre (402) by launching coherent optical radiation into the sensing optical fibre. A detector (407) is configured to receive optical radiation that is Rayleigh backscattered from the sensing optical fibre and output a detected backscatter signal in response to each interrogation and a processor (408) processes the detected backscatter signal. The apparatus is operable in a frequency swept mode, in which the sensing optical fibre is interrogated with a first set of interrogations of coherent optical radiation having different optical frequencies from one another to acquire, for at least one sensing portion of the sensing optical fibre, a backscatter spectral profile (201) of a measurement value of the detected backscatter signal with frequency across a first frequency range. The processor is configured to combine a plurality of said backscatter spectral profiles (201, 202) to form a reference profile (203) with an effective frequency range greater than the first frequency range

The present application relates to the technical field of optical frequency transfer, and particularly relates to a relay system and method for realizing automatic phase locking of optical fiber optical frequency transfer, which comprises: an optical fiber beam splitter for splitting signal light into two parts; an acousto-optic modulator for frequency shifting; a relay laser for generating regenerative laser; a photodetector for beat frequency between signal light and regenerative laser; a signal processing and discrimination locking unit for processing beat frequency signals and discriminating whether to lock at a target frequency; a control unit for maintaining the locking state of the regenerative laser when it is discriminated that the frequency of the regenerative laser is locked; and outputting the locked regenerative laser to the next optical fiber link after frequency shifting by a third acousto-optic modulator; and the specific method is to realize automatic frequency locking and relocking of the regenerative laser through double beat frequency signal discrimination and feedback control, and to ensure stable relay of optical frequency signals. The present application improves the long-term stability and reliability of the relay system.

The invention provides an optical frequency scanning interference absolute distance measurement system and a stable reference construction method thereof. The optical frequency scanning interference absolute distance measurement system comprises a measurement interference module, an auxiliary interference module, a frequency stabilization laser reference module and a laser synchronous control and signal resolving assembly. The measurement interference module generates a beat frequency interference signal related to a to-be-measured space distance; the auxiliary interference module generates beat frequency interference signals related to instantaneous optical frequencies of the first tunable laser and the second tunable laser, monitors the optical frequencies of the first tunable laser and the second tunable laser in real time, and corrects frequency sweep nonlinear errors of the first tunable laser and the second tunable laser; a long fiber bragg grating string is arranged on a measuring arm of a Mach-Zehnder interferometer in the auxiliary interference module; the frequency stabilized laser reference module generates a beat frequency interference signal related to the optical path difference of the auxiliary interference module to compensate the optical path drift of the auxiliary interference module; the laser synchronous control and signal resolving assembly resolves a distance value to be measured according to interference signals generated by the three modules.

Ion optical frequency standard automatic control software adopts the design concept of system integration, the system is developed by adopting the LabVIEW language, the whole-process software and hardware control requirement in an ion optical frequency standard experiment is met, and automatic intelligent control is achieved. The method specifically comprises the steps of setting experimental parameters in an ion optical frequency standard experiment, controlling, detecting and reading experimental data of the ion optical frequency standard experiment, carrying out data processing and calculation work such as transition probability calculation and the like, controlling and adjusting the parameters by utilizing PID to realize system closed-loop locking, and storing the experimental data. And a man-machine interaction interface which is simple and beautiful and has high fault tolerance in an interaction mode is designed, so that the method is simple, convenient and easy to use, and the working complexity of an ion optical frequency standard experiment is effectively reduced.

The present disclosure proposes an opto-mechanical pressure measurement system for measuring an ambient pressure level, the system comprising: an optical fiber having a first optical fiber end and a second optical fiber end; an opto-mechanical cavity mounted at the first optical fiber end and composed of a first membrane element and a second membrane element spaced apart from each other, where the first membrane element contacts the first optical fiber end; at least one light beam generating device coupled to the second optical fiber end and configured to generate light beams and direct the light beams onto the opto-mechanical cavity via the optical fiber, each light beam having a particular optical frequency; and a light sensing member coupled to the second optical fiber end, where the at least one light beam generating device is configured to direct a first light beam having a first optical frequency onto the opto-mechanical cavity, where the first light beam is modulated at a modulation frequency within a bandwidth of a mechanical resonance frequency of the second membrane element, wherein the at least one light beam generating device is designed to direct a second light beam having a second optical frequency onto the optomechanical cavity; and wherein the light sensing member is configured to detect a portion of the second light beam reflected by the optomechanical cavity and to determine an ambient pressure around the optomechanical cavity based on a change in the amplitude of oscillation of the second membrane element.

The invention relates to a 2-halogen ethane sulfonate second-order nonlinear optical crystal and preparation and application thereof, the chemical formula of the crystal material is Na [SO3 (CH2) 2X] (H2O), X = Cl or Br, the crystalline material belongs to a monoclinic system, the space group is Pc, and the cell parameters are alpha = gamma = 90 degrees, beta = 91.86-92.86 degrees, and Z = 2. The powder frequency doubling effects of the non-linear optical crystals Na [SO3 (CH2) 2Cl] (H2O) and Na [SO3 (CH2) 2Br] (H2O) under 1064nm laser irradiation are respectively 0.6 and 0.8 times of that of KH2PO4 (KDP), the powder frequency doubling intensities of the non-linear optical crystals Na [SO3 (CH2) 2Cl] (H2O) under 532nm laser irradiation are respectively 0.1 and 0.2 times of that of beta-BaB2O4 (BBO) crystals, and phase matching can be realized. In addition, Na [SO3 (CH2) 2Cl] (H2O) and Na [SO3 (CH2) 2Br] (H2O) have moderate birefringence (0.09 at-546 nm and 0.106 at-546 nm) and short ultraviolet absorption cut-off edges (190 nm and 208 nm), and millimeter-level single crystals are easy to grow. The wavelength range of the coherent light source can be expanded through optical frequency conversion technologies such as second harmonic generation and optical parametric amplification, and important application value is shown in the fields such as laser frequency conversion and photoelectric information storage.

The optical frequency of one mode of an optical comb can be changed by more than half the repetition frequency of the optical comb. [Solution] The optical comb light source 1 outputs an optical comb having multiple modes. The optical comb light source 1 includes an optical comb generation unit 11 that generates an optical comb, an optical frequency change unit 14 that receives a reference wavelength light having a predetermined optical frequency νcw and changes the optical frequency νcw of the reference wavelength light to output, a mode optical frequency νm which is the optical frequency of one of the multiple modes, and a target optical frequency νcw+f which is the optical frequency of the output of the optical frequency change unit 14. AO The difference between this and the predetermined value (beat frequency) f beat The optical comb generation unit 11 includes a mode optical frequency control unit 18 that controls the mode optical frequency to achieve the desired result. The optical comb generation unit 11 changes the optical frequencies of multiple modes according to the controlled mode optical frequency νm to produce the output of the optical comb light source 1.

A gas-leak detection system includes a narrow-wavelength tunable laser, a beam scanner, a detector, a plurality of retroreflectors, and signal-processing electronics. The laser, beam scanner, and detector are co-located, and the plural retroreflectors are distributed throughout a facility. The laser is tuned so that its optical frequency is near to a frequency of an absorption line of a gas of interest, and modulated to create a controlled scan across the frequency of the absorption line. The beam scanner guides the laser beam towards some or all of the retroflectors, depending on the system’s operating mode. The retroreflectors return respective beams to the detector, where the respective intensities thereof are detected. The intensity of a return beam correlates to gas concentration. Since gas-concentration data is obtained at multiple locations, a gas leak and its location may be determined.

The invention discloses a measurement type picometer-level displacement resolution generation method based on twin double cavities, and the method comprises the steps: employing a group of twin Fabry-Perot cavities with matched parameters, and the twin Fabry-Perot cavities comprise a measurement cavity and a reference cavity; based on the PDH technology, the lasers of the two lasers are locked to harmonic peaks of the measuring cavity and the reference cavity respectively, and then the resonant frequency is measured through an optical frequency comb to represent the displacement amount; a set frequency stepping signal is output through an optical phase-locked loop, the frequency stepping signal is converted into a voltage control signal to be loaded to a PZT of a measurement cavity, the PZT is driven to drive a reflector to move so as to change the cavity length, and a controllable picometer-scale standard displacement step is generated. According to the invention, on the basis of twin Fabry-Perot cavity resonant frequency differential mode detection, a common mode signal caused by Fabry-Perot cavity environment noise can be suppressed, the cavity length displacement is directly traced to an optical frequency standard, and absolute traceability and high-resolution measurement of a picometer-level displacement signal are realized.

Some embodiments in the present disclosure relate to a photon transduction device for transducing between microwave and optical frequencies including a superconducting element, and means for preventing optical frequency radiation from being absorbed by the superconducting element.

The application discloses an out-of-band noise-free alternate optical frequency transfer regenerative relay system and method, which can realize relay regeneration and amplification of the optical signal received by the upper link, and the regenerated signal continues to be transmitted to the next regenerative relay or user terminal output. The proposed relay structure can lock the regenerated light source. Meanwhile, the next stage actively compensates the phase noise introduced by the optical signal in the optical fiber link through a servo control module, so that the phase compensation of the received signal light is realized. Through the alternate repetition cascade of the proposed relay structure, the local optical frequency signal can be transmitted for a long distance, so that the user terminal obtains the phase-stable optical frequency signal. The application reduces the asymmetry of the transmission structure by adopting an online Faraday rotator, effectively avoids the influence of the out-of-band path noise, and has the advantages of simple system structure, low overall noise and long transmission distance without using a complex temperature control system.

A system for functionally integrating dual-frequency comb spectroscopy (DFCS) into and / or integrating with a mobile device. The system includes: an attachment device configured to couple to a mobile device; and DFCS enabling hardware configured to enable the mobile device to perform DFCS-based molecular analysis of a sample region including a sample, wherein the DFCS enabling hardware includes: a laser emitter configured to generate two optical frequency combs that emit laser light at uniformly spaced intervals across a broad spectrum of optical frequencies, wherein (i) the laser light is directed toward the sample region, and (ii) at least a portion of the laser light is received by at least one photodetector configured to: (a) receive at least a portion of the laser light after interaction with the sample, and (b) generate signal output data based on one or more wavelengths or absorption properties corresponding to a portion of the laser light.

The application discloses a chip active optical clock based on grating magneto-optical trap cooling and an implementation method thereof. Three saturated absorption spectrum frequency stabilization DBR lasers are used to generate cooling laser, re-pumping laser and pumping laser respectively, wherein the cooling laser and the re-pumping laser cooperate with the grating magneto-optical trap, are used for cooling and confining atoms, and form a cold atom group in an atom chamber; the pumping laser excites the cold atoms, and the generated stimulated radiation signal is directly used as an optical frequency standard signal output, and after frequency beating with a microcavity optical comb, a chip active optical clock is realized. Compared with a traditional cold atom optical clock, the application greatly reduces the volume of the system, can be integrated on a chip, and is suitable for a compact and portable device application scene; compared with a current chip microwave atomic clock, the stability index of the application is higher. The application has important application value, and can provide a long-time and high-precision frequency reference for a movable device.

An optical path length sensor for sensing a physical quantity of an external source includes a plurality of lasers, each having an optical resonator and a gain medium to produce a laser beam in the optical resonator. At least one of the optical resonators is configured to modulate the optical frequency of the laser beam when exposed to the external source. The sensor further includes a common carrier, in which the optical resonators are arranged, and a device configured to receive light from the plurality of lasers and to determine a difference between the optical frequencies of the laser beams. In another aspect the optical path length sensor includes a plurality of interferometers, each being an asymmetric Mach-Zehnder or an asymmetric Michelson interferometer, at least two of the plurality of interferometers having a different optical path length imbalance.

The present invention aims to enable seamless connection between high-frequency wireless communication and optical communication. A wireless reception device according to the present invention is a device for receiving a wireless signal modulated with an information signal, including a reception antenna, a laser emission element that outputs laser light with a predetermined wavelength, a micro-optical resonator that is excited by the laser light and generates an optical frequency comb with a repetition frequency different from a carrier frequency of the wireless signal by a difference frequency, an electro-optic conversion element that is provided at a reception portion of the reception antenna and optically modulates an arbitrary optical frequency mode within the optical frequency comb consisting of optical frequency modes, in accordance with the wireless signal, and an optical bandpass filter that separates a modulated component of the arbitrary optical frequency mode and an unmodulated component of an adjacent frequency mode spaced apart from the arbitrary optical frequency mode by the repetition frequency, the unmodulated component being most closely adjacent to the modulated component.

The invention provides a double-optical-comb signal optical frequency calibration system, and relates to the technical field of optical measurement. The system comprises a bias tee joint, a calibration signal generation module and a frequency resolving module, wherein the calibration signal generation module is composed of a laser, an optical loop and a double-optical-comb unit, and an optical reference signal and comb teeth of an optical frequency comb to be calibrated generate a radio frequency calibration signal in a beat frequency mode; and the frequency resolving module mixes the radio frequency calibration signal with the equidistant radio frequency reference signal generated by the comb signal generator through the mixer, and the optical frequency of the optical frequency comb to be calibrated is determined by the signal calculating unit in combination with the time domain pulse signal collected by the oscilloscope after the frequency is filtered by the band-pass filter. The optical frequency calibration device realizes high-precision and continuous-coverage optical frequency calibration of middle-infrared band double-optical-comb signals, is simple in structure and high in measurement precision, and is suitable for scenes of gas detection, environment monitoring, spectral analysis and the like.

The invention discloses a temperature-insensitive silicon-based hybrid integrated active optical frequency laser regeneration relay chip, which is suitable for a photon integrated optical frequency cascade transmission system. The chip can carry out on-chip regeneration amplification on a received previous-stage optical signal, and outputs an optical frequency signal with a stable phase to a next stage. According to the invention, the low-loss passive silicon-based waveguide is extremely low, and strict length matching is carried out on the out-of-band waveguide path in the chip, so that out-of-band phase noise caused by temperature change can be effectively inhibited, and the environmental adaptability of the chip is improved. Meanwhile, by means of advanced processes such as micro transfer printing, heterogeneous hybrid integration is carried out on a high-efficiency on-chip frequency shifter and a polarization controller which are realized on the basis of high-electro-optical coefficient materials such as thin-film lithium niobate, so that the on-chip optical frequency laser regeneration relay chip with complete functions is constructed. The chip has the advantages of being compact in structure, low in power consumption, high in environmental adaptability and the like, and is suitable for construction of a next-generation miniaturized optical frequency transfer network.

This invention discloses a cold atom two-photon transition physics device based on diffuse reflection cooling, comprising a glass chamber, a diffuse reflection coating, an optical unit, and a detection unit. The glass chamber is an ultra-high vacuum cavity sealed and connected to an external ultra-high vacuum system and an atomic source. Its outer wall is covered with a diffuse reflection coating, on which are formed apertures for cooling light, re-pumping light, excitation light, and fluorescence output. The optical unit includes cooling light, re-pumping light, and excitation light. The cooling light and re-pumping light form a global diffuse reflection cooling light field through the diffuse reflection coating, preparing three-dimensionally distributed cold atom clusters within the cavity. The excitation light passes through the cavity and is reflected back to form a bidirectional opposing light path, constituting a two-photon transition excitation light field. The detection unit collects, filters, and converges the fluorescence signal before outputting it through a photodetector. This invention features a simple structure, small size, and low power consumption, and can output clock transition spectra with high signal-to-noise ratio and narrow linewidth, providing a novel technical solution for small-scale, high-precision optical frequency standards.

The application discloses a kind of optical fiber optical frequency transmission relay system and method based on spread spectrum technology, the relay system includes receiving module, regenerative laser module and sending module;Receiving module is used to obtain demodulation optical signal by the spread spectrum optical signal demodulation according to second pseudo-random sequence;Spread spectrum optical signal is the signal that is spread spectrum to optical signal by front stage and is transmitted by optical fiber link;Regenerative laser module is used to lock the frequency of demodulation optical signal and generate regenerative optical signal, and its beam splitting obtains return optical signal and transmission optical signal;Receiving module is also modulated according to second pseudo-random sequence and is returned to front stage by return optical signal;Sending module is used to obtain demodulation return optical signal by the modulated return optical signal demodulation of rear stage, and transmission optical signal is transmitted to rear stage after noise suppression and spread spectrum by the demodulation return optical signal and third pseudo-random sequence.This application filters out second-order Rayleigh scattering signal by introducing spread spectrum technology, significantly improves the stability and reliability of system.

An optical comb light source outputs an optical comb with a multitude of modes. The optical comb light source comprises an optical comb generation section, an optical frequency modulation section, and a mode optical frequency control section. The optical comb generation section generates the optical comb. The optical frequency modulation section receives a reference wavelength light with a predetermined optical frequency and modulates the optical frequency of the reference wavelength light for output. The mode optical frequency control section controls a mode optical frequency, which is an optical frequency of one of the multiple modes, such that the difference between the mode optical frequency and a target optical frequency, which is an optical frequency of an output from the optical frequency modulation section, has a predetermined value.The optical comb generating section changes the optical frequencies of the multiple modes according to the controlled mode optical frequency.

The application discloses a phase noise compensation enhancement method and system for optical fiber optical frequency transmission, and relates to the technical field of optical communication and signal processing. The local high-precision laser source is transmitted to the remote end through an optical fiber, and frequency comparison is performed by beating with the remote laser source. Comparison data is obtained by measuring the beat signal through a phase counter. The local compensation radio frequency signal and the uncompensated signal are collected through a digital circuit, and the measurement time interval of the two signals is set. Then, the signals are connected to the phase counter for measurement. The compensation deviation data is obtained by subtracting the measured two-phase signals. The comparison data is subtracted by the compensation deviation data, so that the phase noise suppression enhancement is realized, the phase control bandwidth of the optical fiber optical frequency transmission is improved, and the transmission signal precision is improved.

The application relates to a 2-methyl imidazole germanium-based iodide second-order nonlinear optical crystal and preparation and application thereof. The chemical formula of the crystal material is (2-C4N2H7)GeI3, wherein 2 represents a substitution position of a methyl group on an imidazole ring, namely 2-methyl imidazole. The crystal material belongs to an orthorhombic system, a space group is Pna21, cell parameters are a=13.82~14.02 Å, b=9.47~9.67 Å, c=8.36~8.56 Å, alpha=beta=gamma=90 DEG, and Z=4. The powder frequency doubling effect of the nonlinear optical crystal (2-C4N2H7)GeI3 of the application under 1200 nm laser irradiation is about 5.8 times that of KH2PO4 (KDP), and phase matching can be realized. In addition, (2-C4N2H7)GeI3 has a large birefringence (0.38 @ 546 nm) and a large optical band gap (an absorption cutoff edge is about 420 nm, and an optical band gap size is 2.95 eV), and a millimeter-level single crystal is easy to grow. It can expand the wavelength range of a coherent light source through optical frequency conversion technologies such as second harmonic generation and optical parametric amplification, and exhibits important application values in the fields of laser frequency conversion and photoelectric information storage.

A frequency generator may include a coupled optical resonator coupled to a waveguide, where the coupled optical resonator includes three or more coupled individual resonators supporting three or more split-resonant frequencies distributed with a split-frequency spacing, and where the split-frequency spacing is determined by intracavity coupling between the three or more coupled individual resonators. The coupled optical resonator may receive pump light from the waveguide having optical frequencies corresponding to at least one of the three or more split-resonant frequencies and generates comb light having optical frequencies corresponding to the three or more split-resonant frequencies. A frequency generator may further include a photodetector, where the photodetector receives the comb light and generates an electrical signal having a frequency corresponding to the split-frequency spacing of the coupled optical resonator.

Synthetic aperture radar method for remote sensing of the Earth's surface (300), in which radar signals (RS) are emitted by a transmitter (100) moving above the Earth's surface (300) via a transmitting antenna (110) designed exclusively for transmitting, and radar echoes (RE) of the radar signals (RS) reflected on the Earth's surface (300) are received by at least one receiver (200) moving above the Earth's surface (300) and comprising a multi-channel receiving antenna (210) designed exclusively for receiving, wherein the transmitter (100) and the at least one receiver (200) are located on different platforms above the Earth's surface (300), wherein the transmitter (100) and the at least one receiver (200) as well as a signal processing unit (140, 150, 160) above the Earth's surface perform the following steps: a) The transmitter (100) generates signals in a base frequency band and performs a frequency conversion of these signals into a predetermined frequency band using oscillator signals of an oscillator (121) of the transmitter (100), wherein the converted signals are transmitted as the radar signals (RS); b) the at least one receiver (200) receives the radar echoes (RE) of the radar signals (RS) of the transmitter (100) and transforms the received radar echoes (RE) in real time by phase-preserving modulation from an electrical domain (201) into an optical domain (202), in which a number of receive beams (BR1-BR3) are generated from the received radar echoes (RE) and combined to form an optical signal (OS), wherein the optical signal (OS) contains the number of receive beams (BR1-BR3), each of which contains the signal of a beam with a different wavelength; c) the at least one receiver (200) sends the optical signal (OS) via a free-space optic (230) to the signal processing unit (140, 150, 160); d) The signal processing unit (140, 150, 160) processes the received optical signal (OS) by reconstructing the receive beams (BR1-BR3) from the optical signal (OS) and then transforming them from the optical domain (102) to the electrical domain (101); and e) The signal processing unit (140, 150, 160) demodulates the received modulated receive beams (BR1-BR3) and performs a frequency conversion of the demodulated signals into the base frequency band using oscillator signals from the oscillator (121) of the transmitter (100), thereby obtaining SAR raw data from which the signal processing unit (140, 150, 160) generates and stores digital data, wherein an optical frequency comb with a number of lines (T1-T3) with a respective optical frequency is generated in the optical domain (202), wherein the number of generated lines (T1-T3) corresponds at least to the number of receive beams (BR1-BR3), wherein an amplitude modulation of the respective optical frequency of the number of generated lines (T1-T3) with the received radar echoes (RE) of each receive channel (211-219) of the Multi-channel receiving antenna (210) using associated electro-optical modulators (241-249),which results in a modulated optical frequency comb channel (SBLiT1, SBRiT1 - SBLiT3, SBRiT3 (i = 1...N)) for each receiving channel (CH1-CH9).

The invention provides a laser frequency conversion device. The laser frequency conversion device comprises a transparent substrate; the single chiral carbon nanotube array film is fixed on the surface of the transparent substrate; an incident light source; incident light of the incident light source penetrates through the single chiral carbon nanotube array thin film and is converted into second harmonic light to be emitted. The axis of a carbon nanotube in the single chiral carbon nanotube array film, the incident light of the incident light source and the emergent second harmonic light are coplanar; the axis of a carbon nanotube in the single chiral carbon nanotube array film and the direction of incident light form an angle of 45 degrees. The device provided by the invention can output a frequency doubling optical signal with remarkable intensity, and high-efficiency optical frequency conversion is realized. Experimental results show that the 500nm output power of the laser frequency conversion device can reach the sub-milliwatt magnitude under the condition that the incident average power is 50mW, and the conversion efficiency is close to 1%.