974 results about "Circulator" patented technology

The invention discloses a range gating anti-disturbance optical frequency domain reflection distributed measurement device and method. The device comprises a sweep frequency laser light source, a first optical coupler, a Mach-Zehnder modulator, a circulator, a detection optical fiber, a polarization controller, a second optical coupler, a balanced photoelectric detector and a data measurement unit. Wherein the Mach-Zehnder modulator is configured to perform BPSK modulation on the input probe light by using a pseudo-random spread spectrum coding technology. By means of the device and the method, the contradiction that long-distance measurement and fast frequency sweeping are difficult to achieve at the same time in a traditional OFDR is successfully solved.

The invention provides a frequency-modulated continuous wave laser ranging device based on frequency shift double optical combs, which integrates frequency-modulated continuous wave and double optical comb technologies and comprises an FMCW light source, a beam splitter, a detection and reference light channel, a beam combiner, a photoelectric detector and a processing module. The FMCW light source outputs linear frequency sweeping laser which is divided into two paths through the beam splitter, and the detection light channel detects a target through the first optical comb generator and the circulator. The frequency fFS of the reference optical channel is increased through a frequency shifter, optical combs with different comb tooth intervals are generated by a second optical comb generator, and the fFS and the repetition frequency difference delta fR are in a non-integer multiple relation, so that interference is effectively avoided. After being combined by the beam combiner, the two paths of signals are converted into beat frequency signals by the photoelectric detector, and then time domain signals are spliced by the processing module by using coherence, so that the distance measurement precision is improved. According to the invention, the frequency shift double-optical comb technology improves the precision and anti-interference performance; an efficient data processing algorithm ensures rapid measurement and a wide range of application.

The invention discloses a signal-to-noise ratio improvement method based on a multi-core optical fiber dual-channel distributed acoustic sensing system, and the method comprises the steps: carrying out the light splitting of light emitted by a narrow linewidth laser through a first coupler C1, enabling one path of light to generate a pulse signal through an acoustic optical modulator (AOM), enabling the other path of light to pass through a second coupler C2, and enabling the other path of light to pass through a second coupler C1; the pulse light is divided into two beams of transmission light, the two beams of transmission light are injected into a connected sensing optical fiber through two groups of erbium-doped optical fiber amplifiers (EDFA), two groups of filters, two groups of circulators and a fan-in coupler Fan-in Coupler, and the pulse light is subjected to backward Rayleigh scattering in the sensing optical fiber; based on a dual-channel DAS system, a multi-core optical fiber is used as a sensing optical fiber, three cores and four cores of the multi-core optical fiber are connected in series to form two sensing channels, seven-core space division signals are multiplexed, the equivalent self-noise pressure suppression effect of the seven-core space division signals is analyzed, after noise correlation is removed through a time domain dislocation-frequency domain phase shift method, the signal-to-noise ratio gain can be increased to 8.65 dB, and the signal-to-noise ratio gain can be increased to 8.65 dB. And the detection capability of the system on low-frequency weak signals can be improved.

The invention discloses an equivalent self-noise pressure suppression method and device based on a multi-core optical fiber space division multiplexing signal, light emitted by a narrow linewidth laser is split through a first coupler C1, one path of light passes through an acousto-optic modulator AOM to generate a pulse signal, and then the pulse signal passes through a second coupler C2 to generate a pulse signal; the pulse light is divided into two beams of transmission light, the two beams of transmission light are injected into a connected sensing optical fiber through two groups of erbium-doped optical fiber amplifiers (EDFA), two groups of filters, two groups of circulators and a fan-in coupler Fan-in Coupler, and the pulse light is subjected to backward Rayleigh scattering in the sensing optical fiber; based on the dual-channel DAS system, the multi-core optical fiber serves as the sensing optical fiber, three cores and four cores of the multi-core optical fiber are connected in series to form two sensing channels, seven-core space division signals are multiplexed, the equivalent self-noise suppression effect of the seven-core space division signals is analyzed, and the detection capacity of the system for low-frequency weak signals can be improved.

The invention relates to a phase-sensitive optical time domain reflectometer based on multi-frequency reference switching. Continuous laser generated by a continuous laser is divided into a local path and a detection path through an optical coupler; the local path is input to the polarization coherent receiving module, the detection path is incident to a light intensity modulator driven by the signal generation circuit module, and the light intensity modulator is converted into a multi-frequency pulse laser sequence with intensity modulation; the multi-frequency pulse laser sequence enters the sensing optical fiber to be measured through the optical circulator; generated Rayleigh backscattered light and local continuous laser are subjected to beat frequency coherent receiving in a polarization coherent receiving module through a circulator; and the signal acquisition circuit adopts a demodulation algorithm to compensate phase drift and sensitivity difference of detection pulse demodulation signals with different frequencies so as to realize dynamic strain sensing. Compared with the prior art, the phase drift and the sensitivity difference between the frequencies are extracted to realize the compensation of the interleaved signals, and the method does not depend on the fixed reference frequency, so that the robustness and the adaptability of the system in a complex environment are remarkably enhanced.

The invention discloses a double-comb non-cooperative target ranging system based on single photon detection, which is characterized in that an optical pulse output by a first optical frequency comb is divided into two paths of light through a first beam splitter, the first path of light is combined with one of two paths of light divided by a second optical frequency comb through a second beam splitter, and the combined light is transmitted to a first nonlinear frequency up-conversion module; a sum frequency light pulse in the wave band of 780 nm is generated and detected by a base avalanche diode photoelectric detector, and then a time-dependent single photon counter is triggered to start counting; the second path of light is output to a beam expanding collimator through the circulator and irradiates a target to be measured through spatial propagation, the beam expanding collimator collects diffuse reflection light and returns the diffuse reflection light to a third port of the circulator along the original path, and the diffuse reflection light and the other path of light split by the second optical frequency comb through the second beam splitter are combined and transmitted to a second nonlinear frequency up-conversion module; the up-conversion light after sum frequency conversion passes through the optical filter group and then is recorded by a stop end of the single photon counting module, multi-cycle accumulative statistics is carried out by the time correlation single photon counter, and finally a photon counting waveform is reconstructed and the flight time difference of the to-be-measured target is calculated by the computer.

The invention provides a sensing system fusing optical fiber vibration and acoustic emission, a monitoring method and a device, and relates to the technical field of optical fiber sensing. The device comprises a light source module, a sensing optical fiber, a detection module and a controller, the light source module is used for respectively emitting modulation pulse light for vibration monitoring and continuous wave laser for acoustic emission monitoring; the sensing optical fiber is arranged along a monitored structure or area, and at least one optical fiber acoustic emission sensing head is connected to the optical fiber in series. The detection module collects Rayleigh scattering light and beat frequency signals at all positions in the sensing optical fiber through a circulator and a coherent light receiver, and optical signals are converted into electric signals; wherein the electric signals comprise vibration electric signals and acoustic emission electric signals; the signal processing unit carries out phase demodulation and envelope analysis processing on the collected vibration electric signals and acoustic emission electric signals so as to obtain vibration waveforms and acoustic emission event space-time information along all points of the optical fiber. According to the invention, a monitoring task fusing vibration and acoustic emission can be accurately completed.

The invention relates to the technical field of microwave ferrite devices, and discloses a double-section microstrip circulator which comprises a magnetic conductive sheet, a ferrite gyromagnet and a resistor, the ferrite gyromagnet and the resistor are arranged on the upper surface of the magnetic conductive sheet, a circuit is additionally arranged on the upper surface of the ferrite gyromagnet, and the circuit is connected with a microstrip filter; the ceramic chip is arranged on the upper surface of the circuit, and samarium cobalt is additionally arranged at the top end of the ceramic chip, according to the two-section microstrip circulator, through the arrangement of a combined structure of the magnetic conductive sheet, the ferrite gyromagnet, the circuit, the microstrip filter, the ceramic chip, the samarium cobalt and the resistor, the isolation degree can be effectively improved, and the requirement of a system for high isolation is met; the microstrip filter in circuit connection can improve the second harmonic characteristic and improve the problem that the second harmonic of a conventional microstrip circulator is poor; the ferrite gyromagnet is used as a gyromagnet material, and is combined with a double-section circuit, so that the characteristic of low emission loss can be realized, and the circulator is small in size, light in weight and relatively high in reliability due to the integral structural design.

The invention relates to a phase-sensitive optical time domain reflectometer based on a parallel frequency division multiplexing sequence. Continuous laser is divided into a local path and a detection path through an optical coupler; the local path is input to the polarization coherent receiving module, the detection path is converted into a pulse laser sequence with intensity modulation through a light intensity modulator driven by a radio frequency signal provided by the signal generation circuit module, and the radio frequency signal is composed of two frequency division multiplexing sequences with difference; the pulse laser sequence enters the sensing link to be measured to generate Rayleigh backscattered light, and the Rayleigh backscattered light and local continuous laser are subjected to beat frequency coherent receiving through a circulator; and the signal acquisition circuit is used for sampling and analyzing the interference signal, and performing frequency domain comparison on an interleaving result of the two frequency division multiplexing pulse sequences to eliminate a harmonic frequency and retain a real strain signal frequency. Compared with the prior art, the non-harmonic strain signal measurement is realized, the high-frequency response performance and the high-precision strain measurement capability are excellent, and meanwhile, the long-distance coverage capability is also realized.

A distributed acoustic system (DAS) that may include two or more lasers that each transmit a continuous wave (CW) light, a pulser disposed after the two the two or more lasers and optically connected to each of the two or more lasers to receive the CW light from each of the two or more lasers and form a light pulse, and an optical amplifier, wherein the pulser is optically connected to the optical amplifier to receive the light pulse from the pulser as an input. The DAS may further include a splitter optically connected to the optical amplifier to optically split the light pulse into two or more light pulses for each output of the splitter a circulator optically connected to each output of the splitter, and a sensor fiber attached to each of the circulators as an output for each circulator.

An optical frequency domain reflectometer with environmental disturbance resistance and large strain measurement capability belongs to the field of distributed optical fiber sensing and comprises an opposite sweep frequency light frequency modulation continuous wave signal generation module, a light splitting device, a modulation device, a circulator, a polarization controller, an optical coupling device, a photoelectric conversion module and a data acquisition and processing module. An optical signal generated by an opposite sweep frequency light frequency modulation continuous wave signal generation module is divided into probe light and local oscillation light through a light splitting device, the probe light is modulated through a modulation device and sent to an optical fiber through a circulator, and a Rayleigh back scattering light signal generated by the optical fiber and the local oscillation light interfere in an optical coupling device to obtain interference light; the photoelectric conversion module mixes beat frequency signals of interference light, and the data acquisition and processing module analyzes and processes the beat frequency signals. According to the invention, the position information of the Rayleigh backscattering point is marked by using the modulated probe light, the Rayleigh scattering signal at the corresponding position is restored, crosstalk between channels is inhibited, and high-precision measurement in a large dynamic range and resistant to environmental disturbance is realized.

The invention discloses a rotor and stator axial clearance online measuring device and method based on optical carrier microwave interference. The measuring device comprises a broadband light source, a first polarization maintaining optical fiber, an electro-optical modulator, a second polarization maintaining optical fiber, an optical fiber circulator, a first single-mode optical fiber and a coated optical fiber probe which are connected in sequence, and the coated optical fiber probe directly faces the axial end face to be measured; a first port of the optical fiber circulator is connected with the second polarization maintaining optical fiber, a second port of the optical fiber circulator is connected with the first single-mode optical fiber, and a third port of the optical fiber circulator is sequentially connected with the second single-mode optical fiber, the photoelectric detector, the signal conditioning unit, the signal acquisition unit and the digital processing unit; the signal acquisition unit is connected with the micro-control unit, the micro-control unit is connected with the microwave frequency sweep signal generation unit, and the microwave frequency sweep signal generation unit is connected with the electro-optical modulator. According to the invention, non-contact on-line high-precision measurement of the axial clearance of the rotor and the stator of the aero-engine under the conditions of limited measurement space and complex signal leading-out path can be realized.

The present invention relates to the technical field of optical fiber sensing, and particularly relates to an optical time-domain reflectometer, and a method for eliminating interference fading. The optical time-domain reflectometer comprises: a laser device, a frequency-division multiplexing modulator, a circulator and a signal processing apparatus, wherein the frequency-division multiplexing modulator comprises a first modulator, a second modulator, a first attenuator and a second attenuator; the laser device is used for generating a coherent light source, and the coherent light source sequentially passes through the first modulator and the first attenuator, so as to obtain a first pulsed light signal; the coherent light source sequentially passes through the first modulator and the second modulator, so as to obtain a second pulsed light signal; and the coherent light source sequentially passes through the second attenuator and the second modulator, so as to obtain a third pulsed light signal. Therefore, by means of different combinations of the first modulator, the second modulator, the first attenuator and the second attenuator, multiple pulsed light signals can be outputted; and compared with the prior art, hardware costs are saved.

The invention discloses a frequency modulation matching microwave plasma generator, which is characterized in that a circulator is connected between a microwave source and a plasma resonant cavity, microwaves are input from a port 1 of the circulator, and are output to the plasma resonant cavity from a port 2, so that the reflected microwaves are output from a port 3. Meanwhile, a matched load and a power meter are connected to a port 3 of the circulator, microwaves output by the port 3 of the circulator are absorbed by the matched load, most returned microwaves are absorbed by the matched load, a small part of the microwaves are reflected back to the port 3, the microwaves input by the port 3 are output at a port 1, the microwave power borne by the microwave source is reduced, and the stability and the service life of the microwave source are improved. The control system adjusts the output frequency of the microwave source according to the measured power, so that the output frequency of the microwave source is improved, and the output impedance of the microwave source is matched with the working impedance of the plasma resonant cavity again, so that the back-and-forth reflection loss of microwaves is avoided; and the impedance matching adjustment speed is greatly improved.

The invention relates to an arrangement for optical distance and / or speed measurement with a mode multiplexer in the coaxial transmission and reception path, wherein a different mode is used for transmission (i.e., light emission or the transmitter) than for the reception path. This eliminates the need for a circulator in the transmission path. The mode multiplexer thus assumes the function of branching the reception channel from the transmission channel and can be integrated as a PIC.

The invention discloses an equivalent self-noise pressure suppression method based on a dual-channel distributed acoustic sensing system, and the method comprises the steps: carrying out the light splitting of light emitted by a narrow-linewidth laser through a first coupler C1, enabling one path of light to generate a pulse signal through an acoustic optical modulator (AOM), enabling the other path of light to pass through a second coupler C2, and enabling the other path of light to pass through a second coupler C1; the pulse light is divided into two beams of transmission light, the two beams of transmission light are injected into a connected sensing optical fiber through two groups of erbium-doped optical fiber amplifiers (EDFA), two groups of filters, two groups of circulators and a fan-in coupler Fan-in Coupler, and the pulse light is subjected to backward Rayleigh scattering in the sensing optical fiber; according to the invention, based on a dual-channel DAS system, two fiber cores of the multi-core optical fiber are used as sensing optical fibers, and the space division signals of the two cores are multiplexed, so that the performance that the equivalent self-noise pressure drop is 2.54 dB in the frequency band of 100-1000Hz is realized under the condition that the noise correlation coefficient of the dual-core signals is 0.11, and the detection capability of the system on low-frequency weak signals can be improved.

A ray generating device and a control method thereof are provided. The ray generating device includes: an electronic beam generating device; a microwave generating device; a microwave circulator, having a power input port and at least two power output ports, the power input port being connected to the microwave generating device; a plurality of accelerating tubes respectively connected to at least two power output ports, configured to respectively receive a plurality of electronic beams, and accelerate electronic beams respectively through microwaves received from the at least two power output ports, and to respectively generate a plurality of rays having at least two different energies; and a controller, configured to perform chronological control on microwave power of the microwave generating device, and chronological control on beam loadings of the electronic beams generated by the electronic beam generating device and respectively corresponding to accelerating tubes.

The invention provides a BOTDR (Brillouin optical time domain reflectometry) system fusing Stokes-anti-Stokes light and a demodulation method, and belongs to the technical field of Brillouin distributed optical fiber sensing. The narrow linewidth laser is used for generating continuous optical signals; the input end of the coupler is connected with the laser, and the output end is connected with the pulse light branch and the local oscillator light branch. The pulsed light branch comprises a semiconductor optical amplifier, a random scrambler, a first erbium-doped optical fiber amplifier and a circulator which are connected in sequence; the local oscillator light branch comprises an electro-optical modulator, and the electro-optical modulator regulates and controls sideband frequency through a microwave module; the second erbium-doped optical fiber amplifier is used for extracting the Stokes light and the anti-Stokes light; the single-mode coupler mixes the double-sideband local oscillator light with the anti-Stokes light and the Stokes light; and the electrical beat frequency signals are acquired, filtered and enveloped and demodulated through an acquisition card. The detection capability of the Brillouin scattering signal is enhanced, the system structure is simplified, and the hardware cost and the maintenance difficulty are reduced.

The invention discloses a high-spatial-resolution distributed optical fiber sound wave sensing system based on FPGA real-time demodulation. The system comprises a narrow linewidth laser source module, a first coupler, a high-bandwidth sweep frequency signal modulation module, a circulator, a coherent receiving and photoelectric conversion module and an FPGA integrated module. A laser source emitted by the narrow linewidth laser source module is divided into about 10% of reference light and about 90% of detection light through the first coupler. The FPGA integrated module is connected with the high-bandwidth sweep frequency signal modulation module, and transmits a sweep frequency radio frequency pulse signal and a frequency shift radio frequency pulse signal to the high-bandwidth sweep frequency signal modulation module; the high-bandwidth sweep frequency signal modulation module is connected with the sensing optical fiber through the circulator so as to output sweep frequency optical pulses; the sensing optical fiber is connected with the coherent receiving and photoelectric conversion module through the circulator to transmit Rayleigh backscattered light; the coherent receiving and photoelectric conversion module is connected with the FPGA integrated module, and the FPGA integrated module carries out signal processing to obtain vibration information on the optical fiber.

A magnetless cryogenic circulator is developed that has three identical resonators in three branches. Each branch connects two ports and each resonator has a capacitor connected across a tunable inductor. A set of tunable inductors modulated with modulation signals that have a relative phase of 0°, 120° and 240° provided through a circuit. A microstrip delay line for providing the modulation signal to the three resonators, wherein the resonators are modulated in time such that the degeneracy of the two inherent counter-rotating modes is lifted, achieving a non-reciprocal signal routing. All capacitors and inductors are monolithically integrated and fabricated using a multi-layer Nb-based process with Nb / AlOx / Nb JJs.

Earthquake detection via fiber sensing is provided using using a supervisory path of submarine cables wherein the supervisory system / path of a submarine optical cable conveys portion(s) of an optical signal back to an origin location periodically—i.e., at every repeater location. Advantageously, since it is known where a returning signal is coming from, a resolution equivalent to an undersea span length may be determined—which is sufficient for wide area disturbances such as earthquakes. The returned signal is sufficiently strong such that the signal-to-noise ratio of a returned / received signal is not limited by the ASE noise of the amplifiers. The returned signal is much larger as compared to a normal distributed acoustic sensing (DAS) return signal since the return signal according to aspects of the present disclosure is directed backward via an optical coupler / reflector / circulator having a much larger coupling ratio as compared to normal Rayleigh back scattering utilized in DAS.

The invention discloses an ultra-wideband circulator based on a periodic modulation topology circuit, and belongs to the technical field of microwave and radio frequency nonreciprocal circuits. The working bandwidth range of the circulator is widened, and non-reciprocal transmission is achieved through non-magnetic materials. A time sequence control unit is respectively connected with a Floquet topology circuit layer, a clock signal driving module, a reset signal driving module and a start signal driving module; the Floquet topology circuit layer is respectively connected with a first coupling port, a second coupling port and a third coupling port; the other ends of the first coupling port, the second coupling port, the third coupling port, the clock signal driving module, the reset signal driving module and the starting signal driving module are respectively grounded; the Floquet topology circuit layer adopts a six-layer parallel network structure, and each layer of network structure comprises a coupling capacitor and three N-type MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) switches. The advantages of the switched capacitor structure are utilized, and the signal processing capacity which is high in integration level, small in size and capable of breaking through delay-bandwidth limitation is achieved.

A high-power single-frequency laser amplifier based on prepared YAG derivative optical fibers comprises a single-frequency optical fiber laser seed source, the output end of the single-frequency optical fiber laser seed source is connected with the input end of a first-stage pre-amplifier, and the output end of the first-stage pre-amplifier is connected with the input end of a second-stage pre-amplifier. The output end of the secondary preamplifier is connected with the input end of the high-power double-cladding circulator, and the output end of the high-power double-cladding circulator is connected with a signal light input port of the high-power pumping signal beam combiner. The output end of the high-power pumping signal beam combiner is connected with one end of a specially prepared large-mode-field low-NA double-cladding rare earth doped YAG derivative optical fiber, and the other end of the large-mode-field low-NA double-cladding rare earth doped YAG derivative optical fiber is connected with the input end of the cladding light filter. The problem that expansion and diffusion of a fiber core in the YAG derived optical fiber are not controlled is solved, and therefore the theoretical power limit of single-frequency optical fiber laser amplification conducted through a silica optical fiber at present is broken through.

The technology described herein is directed towards a reconfigurable intelligent surface (RIS) that harvests RF energy from incoming signals based on energy harvesting antennas and associated energy harvesting circuitry. At the same time RIS elements (unit cells) redirect the incoming signals towards a predetermined direction. The harvested energy is combined and converted to DC power using a harvesting circuit. In one implementation, a dual-mode energy harvesting circuit employs a higher power rectifier subcircuit and a lower power rectifier subcircuit, with a multiport circulator and switch that self-actuates to use one or the other rectifier subcircuit based on the combined RF input power captured by the energy harvesting antennas. A multiple battery approach is described, in which one battery is charging based on the converted DC power, another, previously-charged battery is powering the reconfigurable intelligent surface components.

The utility model relates to the technical field of linear actuating devices, in particular to a ball screw with a guide type circulating component, which comprises a screw and a nut coaxially sleeved on the screw, a spiral raceway is formed between the nut and the screw, and a return raceway is arranged in the nut along the axial direction of the nut; the circulator is arranged at the end part of the nut, and a guide channel connected with the spiral raceway is formed in the circulator and is used for guiding the balls to circulate; the sleeve is arranged on the circulator and inserted in the return raceway, a ball guide channel is arranged in the sleeve, the ball guide channel and the guide channel are communicated and matched with each other, and the inner diameter of one end, close to the guide channel, of the ball guide channel is smaller than that of other parts of the ball guide channel; and the balls are arranged in the spiral raceway, the return raceway, the guide channel and the ball guide channel in a rolling manner and circularly roll. The sleeve is arranged at the end part of the circulator, and the ball guide channel is arranged in the sleeve in a reducing manner, so that the impact point of the ball deviates towards the inner thick position, and the service life of a circulating part is prolonged.

The utility model discloses a distributed sound wave sensing system for multi-frequency pulse modulation, and relates to the technical field of distributed sound wave sensing. The system comprises a narrow linewidth laser, an optical fiber coupler, a polarization-maintaining optical isolator, an acousto-optic modulator, a polarization-maintaining delay optical fiber, an erbium-doped optical fiber amplifier, a polarization-maintaining dense wavelength division multiplexer, an optical fiber circulator, an optical fiber Bragg grating, a piezoelectric transducer, a polarization controller, a photoelectric balance detector, a data acquisition card, an arbitrary waveform generator and the like. According to the utility model, the multi-frequency delay ring is utilized to carry out multi-frequency modulation, the frequency number of light waves is increased along with the circulation times of the light waves in the delay ring, and under the condition that the utilization of a large-bandwidth electro-optical modulator is not increased, the flexible modulation of the frequency is realized by utilizing a low-bandwidth acousto-optical modulator without being influenced by carrier frequency and sidebands of each order; the low-bandwidth acousto-optic modulator is used for frequency modulation in the multi-frequency delay ring, and compared with an electro-optical modulation or multi-acousto-optic / multi-light source modulation scheme, the modulation cost is effectively saved.

The waveguide carrying a nonlinear crystal with reflective interface, a pump photon source and a circulator define an optical parametric amplifier which uses optical power from the pump photons to boost incoming signal and idler photons which carry the encoded signal. The nonlinear crystal performs optical parametric amplification upon the incoming optical signal in a quantum photonic process that generates additional signal and idler photons to thereby boost the intensity of the incoming signal. A photodetector is coupled for communication with the third port and operative to convert the reflected optical signal into an electrical signal defining the output of the communications receiver.

The invention discloses a high-precision liquid level measuring device and method based on sweep frequency interference measurement, belongs to the technical field of optical-mechanical-electrical integrated measurement, and is used for high-precision liquid level measurement. The light path is composed of a frequency sweep correction light path and a measurement calibration light path. The device comprises a sweep-frequency light source, an optical fiber splitter, a high-speed acquisition card, a computer, an optical fiber circulator, an optical fiber reflector, a Fabry-Perot (FP) etalon, a balanced photoelectric detector (BPD), a liquid level measuring probe and the like. The FP etalon realizes a sweep frequency correction function, a measurement calibration light path switches channels through the one-to-two photoelectric switch, and high-speed signal acquisition is carried out through the BPD and the high-speed acquisition card. The measuring process is free of mechanical movement and has the advantage of being free of maintenance; the FP etalon is introduced for nonlinear frequency sweeping calibration, the measurement precision is improved, the micron-level measurement precision can be achieved under the better experiment condition, and the non-contact measurement method can meet the requirement for high-precision liquid level measurement in the fields of chemistry, chemical engineering and the like.

A system and method for locking laser frequency based on a hollow fiber FP resonant cavity are characterized in that the output end of a laser is connected with the first port of an optical fiber circulator, the second port of the optical fiber circulator is connected with the input end of an optical fiber coupler, and the first output end of the optical fiber coupler is connected with the input end of a polarization controller; a second output end of the optical fiber coupler is connected with an input end of the optical trap, an output end of the polarization controller is connected with an input end of the hollow-core optical fiber Fabry-Perot resonant cavity, and an output end of the hollow-core optical fiber Fabry-Perot resonant cavity is connected with a third port of the optical fiber circulator; the second output end of the optical fiber coupler is connected with the input end of the optical trap, the second output end of the optical fiber coupler is aligned with the input end of the optical trap, and optical signals output by the second output end of the optical fiber coupler directly enter the optical trap. The system is simple in structure, low in implementation cost, wide in locking range, high in anti-interference capability and high in integration degree.

A radio frequency power amplifier includes three amplification branches. Two amplification branches have narrow working frequency bands and respectively work on a frequency band A and a frequency band B. The other amplification branch works in a frequency band A and the frequency band B. The radio frequency power amplifier also includes an inter-frequency power division circuit and two circulators. The inter-frequency power division circuit performs inter-frequency power division on an output signal of a wideband amplification branch to output two paths of narrowband signals, and the two paths of narrowband signals are output after being subject to power combination with output signals of each narrowband amplification branch by the circulators.