100 results about "Vernier effect" patented technology

A laser distance ranging method includes splitting two combs of dual comb radiation into a signal radiation portion and a local oscillator radiation portion. The signal radiation portions are, after separation, combined into a combined signal radiation and directed onto an object, the distance to which is to be measured. The signal thrown back from the object is split into a first and second signal portions. The first signal portion is superimposed with the second local oscillator radiation portion to generate a first measurement signal, and the second signal portion is superimposed with the first local oscillator radiation portion to generate a second measurement signal. The distance to the object is determined from the first and second measurement signals, and from reference signals obtained by the partial reflection, wherein the Vernier effect can be used to extend ambiguity by comparison of the first and second measurement signals.

The invention provides a detection system of a micro optical fiber coupler based on a bidirectional optical frequency comb vernier effect, which can be applied to the technical field of photoelectric detection. The system comprises: an optical frequency comb light source configured to emit detection light; the beam splitter is arranged to split the detection light into first sub-detection light and second sub-detection light; the reference sensing unit is arranged to guide the first sub detection light to interact with a reference solution through an evanescent field of the first micro optical fiber coupler so as to output first transmission light; the detection sensing unit is arranged to guide the second sub detection light to interact with the solution to be detected through an evanescent field of the second micro optical fiber coupler so as to output second transmission light; the beam combiner is set to combine the first transmission light and the second transmission light to obtain a combined light spectrum; the spectrum analyzer is set to collect the combined light and generate a vernier spectrum; and the processor is set to determine the concentration of the liquid to be detected according to the vernier spectrum.

The invention discloses a vernier effect and Sagnac ring-based dual-parameter optical fiber sensor, which belongs to the technical field of optical fiber sensors and comprises a broadband light source SLED (1), a coupler (2), a sensing structure A (3), a circulator (4), a sensing structure B (5) and a spectrum analyzer (6). The device comprises a first single-mode fiber (301), a polarization-maintaining photonic crystal fiber (302), a few-mode fiber (303), a fiber Bragg grating (304), a second single-mode fiber (501), a first hollow-core fiber (502) and a second hollow-core fiber (503). Parasitic interference is avoided by grinding the end face of the hollow-core optical fiber, and the reliability of the sensor is improved; two transmission peaks appear on the fiber bragg grating inscribed on the few-mode fiber through different mode numbers in the few-mode fiber, and gas concentration and temperature sensitivity of two signals can be calculated by observing drifting of the transmission peaks; an optical vernier effect can be formed through superposition of a Sagnac interferometer formed by polarization-maintaining photonic crystal fibers and an F-P interferometer formed by hollow core dislocation, and the gas concentration and the temperature sensitivity of the sensor are improved. The sensor has the characteristics of high sensitivity, wide measurement range, simple structure, small size and the like.

The invention discloses a Fabry-Perot interference type hydrogen detection device and method. The Fabry-Perot interference type hydrogen detection device comprises a broadband light source, a spectrograph, an optical fiber coupler, a sensing probe, a test gas chamber and a reference probe, the sensing probe and the reference probe are provided with sensor structures based on an optical fiber Fabry-Perot cavity, and the optical fiber coupler outputs input light emitted by the broadband light source to the sensing probe and the reference probe through a port A, a port B and a port C; light reflected by the optical fiber Fabry-Perot cavities of the sensing probe and the reference probe is output to a spectrograph through a D port, so that an interference spectrum is demodulated; hydrogen to be detected is mixed with air, then enters the test gas chamber through the gas flow rate controller, and is discharged from the outlet; the sensing probe adopts an anodic aluminum oxide / palladium film as a terminal reflector of a Fabry-Perot cavity, and an interference spectrum is detected through a spectrograph to obtain hydrogen concentration information in the environment; the reference probe adopts two single-mode optical fiber end faces to align in a sleeve and form an air Fabry-Perot cavity, and the reference probe only provides a stable reference spectrum to realize a vernier effect.

The invention provides a vernier effect-based micro-ring resonant cavity acoustic sensor, and belongs to the technical field of optical-acoustic sensors. Comprising a coupling unit; the light source is used for generating light signals; the cascade sensing ring unit comprises a front-stage sensing ring and a rear-stage reference ring, one end of the front-stage sensing ring is connected with a light path of the light source, and the other end of the front-stage sensing ring is connected with a light path of one end of the rear-stage reference ring through the coupling unit; wherein each of the front-stage sensing ring and the rear-stage reference ring comprises a hollow plate glass substrate, a first PDMS thin film, a micro-nano optical fiber knot and a second PDMS thin film which are sequentially stacked, and the two ends of the micro-nano optical fiber knot in the axial extension direction serve as the two ends of the sensing ring; the radius and the free spectral range of the micro-nano optical fiber junctions of the front-stage sensing ring and the rear-stage reference ring are different. The micro-nano optical fiber knot and the multi-stage sensing ring structure are adopted, the acoustic sensor can accurately detect weak acoustic pressure change, and the sensing ring is very sensitive to wavelength drift and acoustic pressure change.

The invention belongs to the technical field of optical communication, and particularly relates to a narrow linewidth laser based on a cascaded micro-ring resonant cavity. The laser comprises a semiconductor laser inner cavity module, a gain chip module, a phase shifter, a cascade micro-ring resonant cavity module, a thermal tuning module and an outer cavity reflector. The gain chip is combined with an III-V group material at the top of the silicon waveguide through heterogeneous integration, and adopts an InAlGaAs quantum well to provide high gain; the phase shifter is used for matching the lasing wavelength with the resonant wavelength; the cascaded micro-ring resonant cavity is formed by cascading three micro-rings, and tuning of the laser is realized based on a vernier effect; the thermal tuning module is composed of three semi-annular metal strips and a straight waveguide-shaped metal strip. The outer cavity reflector module adopts a Sagnac ring structure; the laser inner cavity, the gain chip, the cascade micro-ring resonant cavity and the outer cavity reflector are directly connected through silicon waveguides. The laser has the characteristics of narrow linewidth and wide tuning range, is easy to highly integrate and interconnect, and has important application value.

The invention discloses a high-sensitivity double Fabry-Perot interference hydrogen sensor resistant to temperature and humidity interference, and belongs to the technical field of optical fiber sensing. A modular integrated design is adopted, and the core comprises double Fabry-Perot interferometers which are connected in series and are respectively a temperature compensation unit FPI-1 and a hydrogen sensing unit FPI-2, and a matched software controllable vernier processing module; the FPI-1 realizes temperature real-time compensation by filling PDMS in an open microcavity, and the FPI-2 adopts a PDMS / Pd-WO3 composite material as a hydrogen sensitive layer, and has wide humidity range anti-interference capability through structural optimization; the weak hydrogen signal is amplified through Fourier transform filtering, sine function fitting, twin interference spectrum construction and vernier effect. According to the invention, precise detection of ultra-trace hydrogen in a complex temperature and humidity environment is realized, and the temperature and humidity interference resistance is high.

The invention relates to an optical radiation source. It is an object of the invention to enable the generation of laser radiation with (ultra) narrow linewidth and to provide an optical radiation source which is robust and simple to control. The optical radiation source of the invention comprises: a laser source having a gain medium and an internal cavity configured to generate laser radiation at multiple frequencies separated by a first free spectral range, at least one external cavity in optical communication with the laser source, the external cavity having a plurality of resonance modes within the gain bandwidth of the laser source, wherein the resonance modes are separated by a second free spectral range which is different from the first free spectral range, wherein the external cavity is configured to act as a frequency-selective reflector to selectively reflect laser radiation generated by the laser source back into the gain medium, thereby causing the gain medium to lase predominantly at only one frequency, and wherein the optical radiation source is configured to couple a portion of the generated laser radiation out from the internal cavity and / or from the external cavity.

The invention discloses a multi-parameter eye axis measurement and data processing system based on a self-mixing vernier effect, and relates to the field of optical fibers. The low-coherence light source is divided into optical fiber reference light and optical fiber measuring light through the first coupler; the optical fiber measuring light passes through a circulator and a collimator to output space measuring light, and different parts of an eyeball are scanned through a zoom lens; the optical fiber measuring light enters the optical fiber delay line through the circulator and the wavelength division multiplexer, and is output from the second circulator after being reflected; the high-coherence light source is reflected by the wavelength division multiplexer and the optical fiber delay line, self-mixing interference is generated at the phase shift grating, and the low-coherence peak spacing is calibrated; the reflected measuring light respectively outputs low-coherence light through a secondary circulator, generates interference in a second coupler and then is sent to a balanced photoelectric detector; and the spatial light reflected by the eyeballs is reflected to the Hartmann micro lens group and then is focused to collect a Hartmann array diagram to calculate the diopter. According to the scheme, the signal-to-noise ratio of data calibrated and measured by using the optical fiber and the self-mixing interference method is higher, and the data is more accurate.

The invention relates to the technical field of optical fiber sensors, in particular to a double-parameter optical fiber sensor based on a double interference effect and a preparation method thereof.The sensor comprises a sensing unit 5 based on a Fabry-Perot interferometer and a sensing unit 6 based on a Mach-Zehnder interferometer, and the two sensing units form a cascade structure; mutual reference probes can be realized when different parameters are measured; according to the invention, an approximate free spectral range is obtained by controlling the cavity length, a remarkable vernier effect is formed, the air pressure and temperature sensitivity can be calculated by tracking the drift of the envelope, the measurement accuracy can be effectively improved, and the device has the advantages of simple structure and small volume.

The invention discloses a vernier-sensitized optical fiber microcavity magnetic field measuring device and method, and relates to the technical field of optical fiber magnetic field sensing. The device comprises a broadband light source, an optical fiber coupler, an optical fiber microcavity magnetic field sensor and a spectrum analyzer, the broadband light source is used for providing a detection light signal; the optical fiber coupler is used for transmitting the detection optical signal to the optical fiber microcavity magnetic field sensor; the optical fiber microcavity magnetic field sensor detects external magnetic field change information based on an optical fiber Fabry-Perot microcavity principle to obtain a total reflection light signal; the optical fiber coupler is also used for transmitting the total reflected light signal to the spectrum analyzer; the spectrum analyzer demodulates the total reflected light signal and realizes magnetic field measurement based on an optical vernier effect theory; the magnetic field intensity response is used for representing the relation between the wavelength drift amount enveloped by the vernier spectrum and the external magnetic field intensity. The invention aims to realize high-precision magnetic field measurement.

The invention discloses a narrow-linewidth thulium-doped fiber laser oscillator, which is characterized in that a saturable absorption fiber has certain absorption on signal light wavelength and is arranged between a first high-reflectivity fiber bragg grating and a second high-reflectivity fiber bragg grating, and when the laser gain exceeds the loss of a laser resonant cavity formed by the first high-reflectivity fiber bragg grating, the second high-reflectivity fiber bragg grating and a low-reflectivity fiber bragg grating, a thulium-doped fiber is generated; laser oscillation is formed and output through the low-reflection fiber bragg grating; the first and second high-reflectivity fiber gratings form an etalon effect; an etalon effect is formed between the second high-reflectivity fiber bragg grating and the low-reflectivity fiber bragg grating and between the first high-reflectivity fiber bragg grating and the low-reflectivity fiber bragg grating; signal light oscillated between the first high-reflectivity fiber bragg grating and the second high-reflectivity fiber bragg grating can form standing waves, and a dynamic grating is formed in the saturable absorption fiber. Under the action of the resonant cavity vernier effect and the saturable absorption dynamic optical fiber, signal light oscillates in a narrow linewidth mode between the first high-reflectivity fiber bragg grating and the second high-reflectivity fiber bragg grating, and the narrowed signal light is injected into the thulium-doped gain optical fiber through the second high-reflectivity fiber bragg grating, so that the laser maintains narrow spectral linewidth operation.

The invention discloses an ultrahigh repetition frequency adjustable ultrashort pulse cluster generator which comprises a mode-locked fiber laser, a first fiber coupler, a fiber delay line, a dispersion compensation fiber, a second fiber coupler, a fiber amplifier and an acousto-optic modulator. The first optical fiber coupler, the optical fiber delay line, the dispersion compensation optical fiber, the second optical fiber coupler and the optical fiber amplifier are sequentially connected end to end to form an optical fiber annular cavity, and the annular cavity is used as a frequency increasing device for pulse multiplication; the length difference between the optical fiber annular cavity and a mode-locked cavity in the mode-locked optical fiber laser is adjusted through the optical fiber delay line, and frequency increasing is carried out by using a vernier effect generated by time delay; the ultrahigh repetition frequency ultrashort pulse cluster laser output with adjustable parameters is realized through gain adjustment in the optical fiber annular cavity and synchronous pulse pickup outside the cavity. According to the technical scheme, the structural design is reasonable, the structure is simple, stability is good, sub-pulses are strictly equidistant, parameters are flexible and adjustable, and practicability is good.

The present invention discloses a method for manufacturing an optical fiber magnetic field sensor composed of Terfenol-D powder and FPI. The method comprises the following steps: a first step of manufacturing a Fabry-Perot interferometer 1 (FPI1); a second step of uniformly coating the Terfenol-D powder on the surface of a large capillary of the FPI1 to form the FPI1 that is sensitive to a magnetic field; a third step of manufacturing a Fabry-Perot interferometer 2 (FPI2); and a fourth step of fusing the single-mode optical fiber ends of the FPI1 and the FPI2 together using a fusion splicer, with the two FPIs spaced 5 mm to 1 cm apart. The two FPIs are cascaded to form a first harmonic vernier effect sensor. The method of the present invention absorbs the advantages of existing sensors and overcomes their disadvantages. By utilizing a quartz capillary, a single-mode optical fiber, Terfenol-D powder, epoxy resin glue, ultraviolet glue, the FPI, and the first harmonic vernier effect, a compact optical fiber magnetic field sensor can be manufactured, which is easy to manufacture, easy to package, and highly sensitive. The sensor is suitable for measuring magnetic fields in confined spaces and has excellent practical application value.

The application belongs to the technical field of optical communication and relates to a frequency-shift-free microwave photonic channelized receiving device, which comprises a carrier light frequency comb generating unit, a local light frequency comb generating unit, an electro-optical modulation unit, an optical phase shift unit, a channel selection and spectrum processing unit and a plurality of photoelectric conversion units. The received broadband radio frequency signal is modulated on each comb tooth of the carrier light frequency comb through the electro-optical modulation unit, and the frequency alignment between the optical local oscillator and the required receiving sub-channel can be realized based on the "vernier" effect caused by the different free spectral ranges of the carrier light frequency comb and the local light frequency comb and the inherent frequency alignment of the same pump laser. The mirror image sub-channel suppression is realized based on the opposite optical phase shifts on both sides of the pump light. The application has a simple structure, omits the frequency shift and special modulation structure required for frequency alignment, effectively suppresses the inter-channel crosstalk problem in the channelized receiving process, and can flexibly increase the channelization quantity according to actual needs.

The present invention provides an optical fiber microcavity humidity sensor and a manufacturing method thereof. The optical fiber microcavity humidity sensor includes a silicon wafer, a moisture-sensitive material layer, a single-mode optical fiber and a sensor housing. The moisture-sensitive material layer is sputtered on the inner surface of the silicon wafer, and a silicon wafer cavity is formed between the moisture-sensitive material layer and the outer surface of the silicon wafer; the single-mode optical fiber extends toward and does not contact the moisture-sensitive material layer, and an air cavity is formed between the protruding end face of the single-mode optical fiber and the moisture-sensitive material layer; the sensor housing includes a first support platform for fixing the moisture-sensitive material layer and a second support platform for fixing the single-mode optical fiber, the single-mode optical fiber is passed through the second support platform and extends toward the first support platform, and is used to form the air cavity between the protruding end face of the single-mode optical fiber and the moisture-sensitive material layer; wherein the air cavity and the silicon wafer cavity are constructed into a cascade structure to achieve amplification of the sensor sensitivity by the optical vernier effect.

The invention discloses a vernier effect-based high-sensitivity double-dislocation optical fiber temperature sensor, which comprises an input optical fiber, a first dislocation optical fiber, a second dislocation optical fiber, an output optical fiber and a polymer microsphere which are connected in a dislocation manner, one end of the input optical fiber and one end of the first staggered optical fiber are welded in a staggered manner, and a first staggered welding surface is formed therebetween; the other end of the first staggered optical fiber and one end of the second staggered optical fiber are welded in a staggered manner to form a second staggered welding surface; the other end of the second dislocation optical fiber is in dislocation welding with one end of the output optical fiber to form a third dislocation welding surface; and the polymer microspheres are wrapped on a staggered cavity between the second staggered welding surface and the third staggered welding surface. According to the optical fiber temperature sensor, the staggered optical fiber pairs of the two Mach-Zehnder interferometers are formed, one staggered optical fiber is coated with the polymer, and therefore the vernier effect is achieved, and the optical fiber temperature sensor has the advantages of being high in temperature measurement sensitivity, easy to prepare and low in cost.

The application discloses a fiber refractive index sensor based on a vernier effect, which comprises a broadband light source, an isolator, a first fiber ring resonant cavity, a second fiber ring resonant cavity, a refractive index sensitive unit, a spectrum analysis module and a data processing unit; the input end of the isolator is connected with the output end of the broadband light source; the input end of the first fiber ring resonant cavity is connected with the output end of the isolator; the input end of the second fiber ring resonant cavity is connected with the output end of the first fiber ring resonant cavity; the first fiber ring resonant cavity and the second fiber ring resonant cavity constitute a cascaded fiber ring resonant cavity; the refractive index sensitive unit is connected into the second fiber ring resonant cavity; the input end of the spectrum analysis module is connected with the output end of the second fiber ring resonant cavity; and the input port of the data processing unit is connected with the output port of the spectrum analysis module. The application has the characteristics of high sensitivity, simple structure, high demodulation precision and suitability for mass production.

The invention discloses an optical time delay calibration method of a broadband phased array. According to the method, the defect that a traditional optical time delay measurement method is only limited to a single measurement domain such as a time domain, a frequency domain or a phase domain is overcome, resources of multiple dimensions such as the time domain, the frequency domain and the polarization domain are reused, and the optical time delay measurement accuracy is improved based on the constructed optical domain vernier effect. By solving an indefinite equation formed by two optical pulse sequences in different polarization states, the measurable range of the optical time delay in a high-speed measurement scene is extended. The invention also discloses an optical time delay calibration device of the broadband phased array. Compared with the prior art, large-range, high-precision, multi-channel and rapid time delay measurement and calibration can be realized.

Permanent magnet synchronous joint motor, magnetic encoder and angle detection method, relate to motor angle detection technical field. The magnetic encoder contains a magnetic encoder module and an AMR sensor array. The magnetic encoder module is suitable for being installed at the motor shaft end. The magnetic encoder module includes coaxially arranged outer ring magnet and inner ring magnet. The absolute value of the difference between the pole pairs of the outer ring magnet and the inner ring magnet is 2. The AMR sensor array is suitable for being arranged in the magnetic field action area of the outer ring magnet and the inner ring magnet. The AMR sensor array includes two AMR sensors located on the same radius line of the magnetic field action area. Two AMR sensors correspond to the magnetic field area of the outer ring magnet and the inner ring magnet respectively, and are used for synchronously collecting the signals of the respective corresponding magnetic ring. The signals are suitable for realizing high-resolution detection of single-turn absolute angle through double-ring vernier effect and disambiguation algorithm.

The present invention discloses a watt-class linear cavity single-frequency fiber oscillator based on dynamic refractive index grating regulation. The oscillator comprises two sections of active optical fiber, which are pumped by two pump sources respectively. The two sections of active optical fiber fully absorb the pump power while still retaining unpumped portions. The standing wave effect in the linear cavity laser generates narrowband refractive index modulation gratings in the unpumped portions of the two sections of active optical fiber. Therefore, the two sections of active optical fiber serve as gain media to provide laser gain and as saturable absorbers to produce a frequency selection effect. The narrowband refractive index modulation gratings in the two sections of active optical fiber form a vernier effect, which enhances frequency selection and ensures that the power output level of the single-frequency fiber oscillator reaches the watt level.

The present invention relates to the technical field of fiber optic sensors. Disclosed are a differential vernier effect-based probe, a manufacturing method, and an ocean temperature sensor. In the present invention, a fiber optic cable is connected to a fiber optic coupler / splitter, the fiber optic coupler / splitter being further connected to sensing arm A and sensing arm B; sensing arm A extends into a temperature sensing tube fixed in a quartz tube; sensing arm B extends into the quartz tube; sensing arm B is located outside the temperature sensing tube; reflective film A and reflective film B are fixedly connected to the end of the temperature sensing tube away from the fiber optic coupler / splitter, reflective film A being located inside the temperature sensing tube; a cavity between sensing arm A and reflective film A forms a main scale cavity; reflective film B is located outside the temperature sensing tube, the ends of reflective film B and sensing arm B extending into the quartz tube being arranged opposite to each other; and a cavity between sensing arm B and reflective film B forms a vernier cavity. The probe further comprises an evacuated unit, the evacuated unit being fixed on a sensor base. The sensor probe of the present application can effectively improve the signal-to-noise ratio and sensitivity.

The invention discloses a vernier effect-based high-sensitivity polymer micro-ring temperature and humidity optical waveguide sensor, and belongs to the technical field of planar optical waveguide integrated devices. The polymer electrolyte consists of a substrate layer, a polymer lower cladding, a polymer grooving layer, a polymer electrolyte core layer and a polymer upper cladding. The polymer electrolyte core layer is of a runway type MRR cascaded optical waveguide structure and is composed of a reference ring, a temperature sensing ring and a humidity sensing ring, a polymer electrolyte core layer material can adsorb water molecules in air, the free ion concentration can change along with the change of humidity and temperature, and then the refractive index of the material changes; the temperature and humidity dual-mode sensing device overcomes the defects of integration level, sensitivity and interference resistance of an existing temperature and humidity sensing device, ultra-compact and ultra-high-sensitivity temperature and humidity dual-mode sensing is achieved, the optical waveguide device is made of polymer materials, and the temperature and humidity dual-mode sensing device has the remarkable advantages of being good in flexibility, simple in process, low in cost, high in efficiency and the like. The method is suitable for various scenes requiring precise environment control or real-time monitoring of tiny changes.

This invention belongs to the field of fiber optic sensing application technology, specifically relating to a high-sensitivity air microbubble strain sensor based on the vernier effect and its fabrication method. The sensor consists of a parallel microbubble sensing cavity Fabry-Perot interferometer and an air reference cavity Fabry-Perot interferometer. The microbubble sensing cavity Fabry-Perot interferometer is made by fusion splicing two single-mode optical fibers, with an ellipsoidal microbubble embedded at the center of its conical region. The air reference cavity Fabry-Perot interferometer is made by fusion splicing two single-mode optical fibers through a hollow capillary tube, with the two single-mode fiber segments forming an air cavity within the capillary tube. When the microbubble sensing cavity and the air reference cavity are connected in parallel, their signals overlap, resulting in an envelope modulation effect. Compared to using the microbubble sensing cavity alone, this significantly amplifies the sensitivity, improves the sensor's sensing performance, and achieves high-sensitivity air microbubble strain sensing.

This invention discloses an alcohol detection chip and detection method based on a cascaded dual-ring resonator with dual-gradient curvature, belonging to the field of optical micro-nano sensing and integrated optics technology. This invention aims to solve the technical problems of low sensitivity, poor resolution, complex spectral analysis, and weak environmental adaptability in traditional micro-ring sensing devices, as well as the low detection accuracy of existing miniaturized equipment. The chip uses a silicon-based substrate and includes input and output waveguides, cascaded dual micro-rings, a coupling region, and two sets of miniature heating electrodes. The micro-rings employ dual-gradient waveguides with circular and Euler-circular curved structures for the inner and outer curves, respectively. The cascaded dual rings create a vernier effect, broadening the free spectral range. By adjusting the resonant wavelength through the heating electrodes, scanning detection is completed in the characteristic alcohol band around 1400nm, and high-precision alcohol measurement is achieved by combining transmission spectroscopy. This invention has a compact structure and low cost, and is suitable for rapid quantitative detection of alcohol in industrial monitoring, vehicle safety, food safety, and other scenarios.

The invention belongs to the technical field of temperature detection, and particularly relates to an enhanced vernier effect optical fiber temperature sensor, a preparation method thereof and a temperature sensing system. The invention provides an enhanced vernier effect optical fiber temperature sensor, which comprises a Fabry-Perot interferometer and a Liushu interferometer, and the Fabry-Perot interferometer and the Liushu interferometer are connected in parallel. The Fabry-Perot interferometer comprises a single-mode optical fiber and a hollow optical fiber fixedly connected with the single-mode optical fiber, and a cavity of the hollow optical fiber is filled with polydimethylsiloxane; the Liusu interferometer comprises an optical fiber polarizer and a second polarization maintaining optical fiber fixedly connected with a first polarization maintaining optical fiber of the optical fiber polarizer. The enhanced vernier effect optical fiber temperature sensor provided by the invention is simple in preparation process and can realize batch production; and moreover, the bandwidth utilization rate is higher, the sensitivity is higher, and the ultra-high-sensitivity use scene can be met. And high-sensitivity temperature monitoring can also be realized when the equipment condition is relatively poor. And the use threshold of the vernier sensor is obviously reduced.

The invention discloses a vernier effect-based phase modulation continuous wave distance measurement method and system. The vernier effect is utilized to enhance the distance measurement capability of phase modulation continuous waves. The method comprises the following steps: selecting two pseudo-random sequences of which the lengths are prime numbers for phase modulation; splicing the two sequences into a modulation sequence, and modulating the laser signal; transmitting a modulation signal to a measured target and receiving an echo; and processing echo signals, respectively measuring time delay by using two sequences, calculating normalized time delay in combination with a code length, solving actual time delay by using the Chinese remainder theorem, and further determining a target distance. The system comprises a laser, a beam splitter, a phase modulator, a signal generator, an acousto-optic frequency shifter, a transmitting / receiving device, a beam combiner, a photoelectric detector and a signal processing module, and realizes high-precision distance measurement. The vernier effect is utilized, the unambiguous measurement distance is effectively increased, the measurement speed is improved, and meanwhile the system complexity is reduced. By combining a precise signal processing algorithm, the actual distance between the measured target and the measuring device can be accurately and quickly calculated, and the method is suitable for high-precision and long-distance distance measurement requirements and has wide application prospects.

The invention belongs to the technical field of temperature sensing, and particularly relates to an optical fiber temperature sensor based on a double-FP parallel structure, which is characterized in that the optical fiber temperature sensor is formed by connecting a reference interferometer and a sensing interferometer in parallel, the reference interferometer is composed of a first single-mode optical fiber, a hollow-core optical fiber and a second single-mode optical fiber, and the sensing interferometer is composed of a second single-mode optical fiber and a third single-mode optical fiber. The sensing interferometer is composed of a third single-mode fiber, a PDMS cavity and a fourth single-mode fiber. Wherein the optical path lengths of the PDMS cavity and the hollow-core optical fiber are controlled to be close to each other but not equal to each other, so that the free spectral range of the sensing interferometer is close to each other but not equal to the free spectral range of the reference interferometer, and the vernier effect of an output spectrum is excited to form an envelope formed by fine stripes. The optical fiber temperature sensor has the advantages of being high in sensitivity and linearity, large in detection range, good in repeatability and good in reversibility, meanwhile, the size of the optical fiber sensing probe is in the micron dimension, and the optical fiber temperature sensor is suitable for temperature detection in a narrow space.

The invention discloses a vernier effect reconstruction-based signal processing method and related equipment, and the method comprises the steps: carrying out the cascading processing of an optical fiber core offset pair and a micro-nano optical fiber, obtaining a vernier effect optical fiber sensor, inputting a to-be-detected signal into the vernier effect optical fiber sensor, and obtaining an output signal, and performing vernier effect reconstruction processing on the output signal to obtain a reconstructed vernier envelope, and performing parameter measurement processing on the signal to be measured according to the reconstructed vernier envelope to obtain a measurement result. The embodiment of the invention can improve the measurement efficiency of the sensor, and can be widely applied to the technical field of data processing.

The invention provides a wooden ancient building multi-defense-area intrusion and fire danger integrated monitoring system, and belongs to the technical field of distributed optical fibers. The system comprises a broadband light source, laser emitted by the broadband light source is divided into two paths after passing through a first 1 * 2 coupler, the two paths of laser are input into two composite structure light paths respectively, each composite structure comprises an annular Sagnac interference structure and an MZ type interference structure which are parallel to each other, the annular Sagnac interference structures are used for monitoring the temperature in an arranged defense area, and the MZ type interference structures are used for monitoring the temperature in the defense area. Intrusion vibration events around the ancient building are monitored through an MZ type interference structure; according to the system, a Sagnac structure and an MZ structure are multiplexed in parallel, the vernier effect is ingeniously utilized, function integration on a single sensing optical fiber is achieved, and material consumption and installation complexity are remarkably reduced; besides, the panda type polarization maintaining optical fiber is integrated in the annular Sagnac structure, and the MZI made of the tapering single-mode optical fiber is combined, so that the sensitivity of temperature sensing and perimeter security protection is greatly improved, and the high-standard requirement of security protection of ancient buildings is met.