506 results about "Single-mode optical fiber" patented technology

The invention discloses a polarization-state-based optical fiber vibration sensing system and application, and relates to the technical field of optical fiber sensing, and the polarization-state-based optical fiber vibration sensing system mainly comprises a transmitting end and a receiving end. The transmitting end comprises a laser diode, a first erbium-doped optical fiber amplifier, a first circulator, a polarization scrambler, a single-mode optical fiber link, a second circulator and a second erbium-doped optical fiber amplifier which are connected in sequence; and the receiving end comprises a polarization beam splitter, a first shunt module, a second shunt module, an optical mixer, a first balanced photoelectric detector, a second balanced photoelectric detector, a third balanced photoelectric detector and a polarization analysis module. According to the optical fiber vibration sensing system based on the polarization state and the application, the vibration monitoring performance and reliability in a long-distance and high-noise environment can be improved.

The invention discloses a fiber bragg grating femtosecond laser direct writing system and method based on light field regulation and control. The system comprises a femtosecond laser source, a polarization control module, a light beam expanding module, a light field modulation module, a 4f filtering imaging module, an oil immersed objective lens, a precision positioning and optical fiber clamping module, an observation module and a computer control module. The method comprises the following steps: firstly, fixing a standard single-mode optical fiber to be processed on a three-dimensional precision displacement platform; then programmable wavefront modulation is carried out on the femtosecond laser through a light field modulation module, and a multi-focus array is generated; then focusing the multi-focus array into the fiber core through an oil-immersed objective lens to realize one-time parallel inscribing of a plurality of refractive index modulation RIM regions; and finally, the computer control module controls the three-dimensional precision displacement platform to move at a constant speed in the axial direction of the optical fiber, and parallel integrated inscribing of a plurality of FBG structures is completed. According to the invention, the inscribing precision and inscribing efficiency of fiber bragg grating femtosecond laser direct writing are improved.

The invention relates to the technical field of coupling alignment of single-mode optical fibers, in particular to an optical fiber coupling alignment method and system based on wavefront aberration and a sensitivity matrix. The system comprises an optical measurement module, a processing and control module and a multi-axis precision adjustment platform, and the alignment method comprises the steps that firstly, an interference fringe image is obtained and processed through an interference light path, continuous wavefront is recovered through Fourier transform and phase unwrapping, and a Zernike coefficient for quantizing wavefront distortion is obtained through Zernike polynomial fitting. A sensitivity matrix representing the linear relation between the degree-of-freedom adjustment amount and Zernike coefficient changes is established and serves as a physical guide item to introduce a speed updating formula of a particle swarm optimization algorithm, an SG-PSO algorithm is formed, a particle swarm is guided to conduct directional intelligent search and rapidly output the optimal adjustment amount, and finally a multi-axis precision adjustment platform is driven to complete alignment. According to the method, optimization of wavefront sensing and physical model guiding is effectively fused, and the convergence speed, the alignment precision and the global search capability are remarkably improved.

The invention discloses an FPI and MZI optical fiber sensor based on a PDMS microcavity and application thereof, relates to the technical field of optical fiber sensors, and aims to solve the problem of lack of an optical fiber sensor with a double-effect cooperative regulation mechanism in the prior art. According to the technical key points, the FPI and MZI optical fiber sensor based on the PDMS microcavity is composed of a first single-mode optical fiber, a multimode optical fiber, the PDMS cavity and a second single-mode optical fiber which are connected in sequence, the first single-mode optical fiber and the multimode optical fiber are welded, the microcavity exists between the multimode optical fiber and the second single-mode optical fiber, PDMS is injected into the microcavity to form the PDMS cavity, and the PDMS cavity is connected with the PDMS microcavity. One end, far away from the PDMS cavity, of the second single-mode optical fiber is a cutting end surface; the critical surface of the multimode optical fiber and the PDMS cavity is a reflector 1, the critical surface of the second single-mode optical fiber and the PDMS cavity is a reflector 2, and the reflector 1 and the reflector 2 form a Fabry-Perot interferometer. The sensor combines the working principles of FPI and MZI, and can realize accurate measurement of temperature.

The invention discloses a dual-wavelength microsphere laser based on tri-doped rare earth ions and a preparation method thereof, the dual-wavelength microsphere laser based on tri-doped rare earth ions comprises a silica fiber, the middle part of the silica fiber is provided with a conical region; the pump light source is arranged at one end of the silica fiber; the erbium, holmium and ytterbium tri-doped tellurate glass microspheres are arranged in the conical region; pump light emitted by the pump light source is guided to the conical region through the single-mode optical fiber and is optically coupled with the erbium-holmium-ytterbium tri-doped tellurate glass microsphere; in the erbium-holmium-ytterbium triple-doped tellurate glass microspheres, infrared-transmitting tellurate glass is used as a matrix, and the doping amount of an erbium element is 0.11%, the doping amount of a holmium element is 0.22%, and the doping amount of an ytterbium element is 0.80% in percentage by mass. According to the dual-wavelength microsphere laser based on the three-doped rare earth ions, efficient and stable dual-wavelength laser output is achieved.

The invention discloses an optical fiber twinning controllable vernier hydrogen sensor and a detection method, and belongs to the technical field of optical fiber sensing, the optical fiber twinning controllable vernier hydrogen sensor comprises a single-mode optical fiber, a femtosecond laser direct writing grating, a Fabry-Perot interferometer and a Pd / WO3 hydrogen sensitive film; the single-mode optical fiber comprises an optical fiber core and an optical fiber cladding, the femtosecond laser direct writing grating is prepared in the optical fiber core, the Fabry-Perot interferometer is composed of a reflecting surface 1 and a reflecting surface 2 which are relatively parallel to each other, the Pd / WO3 hydrogen sensitive film is coated on the inner side of the reflecting surface 2, and the femtosecond laser direct writing grating and the Fabry-Perot interferometer are arranged in series; the optical path of the Fabry-Perot interferometer is modulated through the interaction of the Pd / WO3 hydrogen sensitive film and hydrogen, interference spectrum wavelength drift is triggered, temperature compensation is achieved in combination with the temperature response of the femtosecond laser direct writing grating, and hydrogen concentration sensing is completed. The method is suitable for hydrogen leakage detection in industrial environments, energy equipment and other scenes.

Quantum teleportation is essential for many quantum information technologies, including long-distance quantum networks. Using fiber-coupled devices, including state-of-the-art low-noise superconducting nanowire single-photon detectors and off-the-shelf optics, we achieve conditional quantum teleportation of time-bin qubits at the telecommunication wavelength of 1536.5 nm. We measure teleportation fidelities of ≥90% that are consistent with an analytical model of our system, which includes realistic imperfections. To demonstrate the compatibility of our setup with deployed quantum networks, we teleport qubits over 22 km of single-mode fiber while transmitting qubits over an additional 22 km of fiber. Our systems, which are compatible with emerging solid-state quantum devices, provide a realistic foundation for a high-fidelity quantum Internet with practical devices.

The invention provides an FPI optical fiber temperature sensor based on a PDMS filled capillary glass tube, which comprises a capillary glass tube, one end of the capillary glass tube is filled with cured polydimethylsiloxane, the other end of the capillary glass tube is inserted with a single-mode optical fiber, in the capillary glass tube, the end surface of the polydimethylsiloxane is a concave surface, and the end surface of the single-mode optical fiber is a convex surface. The end face of the single-mode optical fiber is a plane, the end face of the polydimethylsiloxane and the end face of the single-mode optical fiber form two reflecting faces of the Fabry-Perot cavity, light input is carried out in the single-mode optical fiber, and light output is carried out in the Fabry-Perot cavity. Displacement of the end face of the polydimethylsiloxane as a function of a temperature change causes an interference wavelength in the Fabry-Perot cavity to be adjusted to map the temperature change. The invention provides the PDMS-filled SCT-based micro-air cavity FPI optical fiber sensor which is simple in structure, easy to manufacture, low in cost, small in size and ultrahigh in precision, and is used for high-precision temperature detection.

The invention provides a heterogeneous integrated sub-wavelength structure end face coupler adaptive to a single-mode optical fiber and a preparation method of the heterogeneous integrated sub-wavelength structure end face coupler, and relates to the technical field of integrated optics. The coupler comprises a substrate, an insulating layer, a waveguide layer and a cladding from bottom to top. The waveguide layer comprises an upper lithium niobate ridge waveguide and a lower lithium niobate ridge waveguide, the lower waveguide is wider than the upper waveguide, and the upper waveguide is used for connecting an external waveguide; the heterogeneous integrated coupling region comprises a silicon nitride strip conical waveguide which forms directional coupling with the lower-layer lithium niobate waveguide, so that adiabatic transfer of a light field is realized; the sub-wavelength grating regulation and control region sequentially comprises a silicon nitride tapered waveguide and sub-wavelength grating combination section, a width gradually-changing grating section and an equal-width buffer grating section. The whole structure is symmetrical about the central axis. Through the multi-section adiabatic transformation and heterogeneous integration design, efficient expansion of a mode field is achieved, the coupling efficiency with a single-mode fiber is improved, and the advantages of being insensitive to polarization, good in process compatibility and suitable for high-density integration are achieved.

The invention belongs to the technical field of laser, and particularly discloses a beam shaping system and method based on prism pair orthogonality and cascade, and the system comprises a single-mode fiber, an aspherical lens, a first prism pair, a first parallel plate, a second prism pair and a second parallel plate which are sequentially arranged along the direction of an optical axis. A Gaussian beam emitted by a single-mode optical fiber is collimated by an aspherical lens to form a parallel beam, the beam is expanded or compressed in the X direction by a first prism pair, the beam is expanded in the Y direction by a second prism pair, and two inclined parallel plates are respectively used for compensating the beam offset in the X / Y direction; according to the invention, the circular Gaussian beam emitted by the single-mode fiber can be shaped, a large strip-shaped collimation light spot with an adjustable length-width ratio from 4: 1 to 20: 1 and a long axis size of 30mm can be realized, and the central positions of the input and output beams in the cross section are ensured to be unchanged.

The invention discloses an optical fiber sensor and a preparation method thereof, and belongs to the technical field of optical fiber sensing, and the optical fiber sensor comprises an optical fiber body adopting a splicing structure of a single-mode optical fiber, a tapering coreless optical fiber and a single-mode optical fiber; the cascaded F-P structure comprises a sensing cavity and a reference cavity which are arranged on the tapering coreless optical fiber; the metal enhancement layer comprises a silver film and a gold nanorod array which are sequentially arranged on the surface of the tapering coreless optical fiber, the thickness of the silver film is 30-50 nm, the length-diameter ratio of gold nanorods is 3: 1-5: 1, and the diameter of the gold nanorods is 40-60 nm; the sensitive material coating comprises a polydimethylsiloxane (PDMS) film coated on the surface of the sensing cavity and a polyvinyl alcohol (PVA) film coated on the surface of the gold nanorod array, the thickness of the PDMS film is 3-7 microns, and the concentration of the PVA film is 2-4 wt%; according to the optical fiber sensor and the preparation method thereof provided by the invention, a synergistically enhanced sensing system is formed, and high sensitivity, amplification and multi-parameter detection capability are considered at the same time.

The invention relates to the technical field of optical fiber sensing, and provides a micro-fluidic temperature and salt control two-parameter optical fiber sensor based on an anti-resonance effect and a preparation method and a test system thereof, the optical fiber sensor comprises a leading-in single-mode optical fiber, a hollow-core tubular optical fiber, a side single-hole double-core optical fiber and a leading-out single-mode optical fiber which are cascaded in sequence; a micro-groove is etched at the cladding of the fusion welding end of the introduction single-mode fiber and the hollow-core tubular fiber; the side wall of the hollow-core tubular optical fiber is etched with a micro-channel which vertically penetrates through the cladding of the hollow-core tubular optical fiber. The side single-hole double-core optical fiber is located between the hollow-core tubular optical fiber and the leading-out single-mode optical fiber, and an air hole parallel to the axial direction is formed in the side single-hole double-core optical fiber to form a fluid outflow channel; through the scheme, the response speed and the detection sensitivity are improved.

The invention provides a multi-core optical fiber, a parallel optical transmission optical module and an optical interconnection system, which can solve the problem of high operation and maintenance cost caused by coexistence of PSM and WDM optical modules and non-uniform optical module interface and optical fiber wiring in the prior art, the multi-core optical fiber comprises a multi-core optical fiber, the size of a central fiber core is the same as that of a single-mode optical fiber, and the optical interconnection system comprises a single-mode optical fiber and a single-mode optical fiber. The wavelength division multiplexing module is used for transmitting wavelength division multiplexing optical signals; the plurality of peripheral fiber cores are arranged around the central fiber core and are used for transmitting multiple paths of parallel optical signals; an optical interface of the parallel optical transmission optical module is connected with a peripheral fiber core of the multi-core optical fiber, and the parallel optical transmission optical module is used for transmitting multiple paths of parallel optical signals through the peripheral fiber core; the wavelength division multiplexing optical module is provided with a single-channel optical interface, and the single-channel optical interface is connected with the central fiber core of the multi-core optical fiber and used for transmitting wavelength division multiplexing optical signals through the central fiber core.

An optical communication system can include a multiplexer / demultiplexer. The multiplexer / demultiplexer can transfer a first optical data signal between a first single-mode fiber and a first propagation mode of a few-mode fiber. The first propagation mode can have a first effective refractive index. The multiplexer / demultiplexer can transfer a second optical data signal between a second single-mode fiber and a combination of a second propagation mode of the few-mode fiber and a third propagation mode of the few-mode fiber. The second propagation mode and the third propagation mode can have a same effective refractive index that differs from the first effective refractive index. During propagation within the few-mode fiber, the second optical data signal can couple bidirectionally between the second propagation mode and the third propagation mode, while being substantially isolated from the first optical data signal in the first propagation mode.

The utility model belongs to the technical field of optical fiber sensing application, and particularly relates to an optical fiber temperature sensor used in a strong magnetic field environment. The optical fiber temperature sensor is composed of a single-mode optical fiber and a corundum sleeve, the middle of the single-mode optical fiber is a double-cone-shaped section, an ellipsoidal microbubble is embedded in the middle concave position of the double-cone-shaped section, and the ellipsoidal microbubble and a fiber core are located on the same horizontal plane. The corundum sleeve is sleeved on the biconical section, and two ends of the corundum sleeve are fixedly adhered on the single-mode optical fiber through high-temperature-resistant inorganic glue. The transverse axis of the ellipsoidal microbubble is 71.42 [mu] m-73.42 [mu] m, the longitudinal axis of the ellipsoidal microbubble is 76.73 [mu] m-78.73 [mu] m, and the minimum wall thickness between the ellipsoidal microbubble and the middle recess of the biconical section is 1.2 [mu] m-3. 2 [mu] m. The optical fiber temperature sensor is high in magnetic interference resistance, high in precision and sensitivity, capable of being used for multi-point measurement and wide in application range.

The present invention relates to the technical field of optical fiber sensing. Disclosed are a multi-core grating sensor and a manufacturing method therefor, and a permafrost monitoring method. The multi-core grating sensor comprises a multi-core optical fiber grating, a strain gauge structure, and a demodulator, and the multi-core optical fiber grating comprises four uniformly and symmetrically distributed single-mode optical fibers, a cladding layer wrapping the four single-mode optical fibers, and a coating layer located between the single-mode optical fibers and the cladding layer; the strain gauge structure is attached to the outside of the multi-core optical fiber grating by means of glue bonding; and the demodulator is used for monitoring the dynamic change of the wavelength of the multi-core optical fiber grating, the demodulator comprises a broadband light source and a spectrum analyzer, an incident end of the multi-core optical fiber grating is connected to the broadband light source by means of the single-mode optical fibers, and an exit end thereof is connected to the spectrum analyzer by means of the single-mode optical fibers. Also disclosed in the present invention is a permafrost monitoring method. By means of comprehensive analysis and demodulation of fiber core wavelength variation amounts of a plurality of single-mode optical fibers on a single multi-core optical fiber grating, simultaneous measurement of multiple parameters is achieved, and the permafrost monitoring accuracy is improved.

The invention provides a dual-mode resonance optical fiber microcavity air pressure measurement system and method, and relates to the technical field of optical fiber microcavity air pressure measurement, and the system specifically comprises a sensing probe preparation module, a two-parameter sensitivity matrix calibration module, an optical fiber laser sensing system construction module, a real-time change monitoring module and a decoupling and output module. Femtosecond laser etching is combined with high-temperature tapering, an open type microcavity is manufactured on a single-mode optical fiber, a micro-nano cone area is formed, and the sensing probe with two resonance valleys with different temperature and air pressure response characteristics is obtained. A sensitivity coefficient matrix is obtained through calibration, a probe serves as a filter to be embedded into an annular optical fiber laser cavity, and an optical fiber laser with the laser wavelength locked by a resonance valley is constructed. Laser wavelength drift is caused by environmental change, real-time synchronous measurement of temperature and air pressure is realized by utilizing inverse matrix decoupling, and the method is suitable for high-precision and anti-interference monitoring of harsh industrial environments such as aero-engines and power transformers.

The invention relates to a photoacoustic gas sensing probe and an optical detection system. The photoacoustic gas sensing probe comprises a ceramic packaging sleeve; a gas exchange channel is arranged on the side wall of the ceramic packaging sleeve; the single-mode optical fiber is used for transmitting incident light and receiving reflected light; the end face of one end of the single-mode optical fiber is coated to form an optical fiber end face coating layer; at least part of the single-mode optical fiber is arranged in the ceramic packaging sleeve in a nested mode, and the optical fiber end face coating layer is located in the ceramic packaging sleeve. The elastic reflecting film is used for generating deformation in response to sound pressure or a photoacoustic signal; the elastic reflecting film is arranged at one end of the ceramic packaging sleeve and is opposite to the optical fiber end face coating layer, so that an optical microcavity is formed between the optical fiber end face coating layer and the elastic reflecting film; wherein to-be-detected gas enters the optical microcavity through the gas exchange channel. According to the invention, integration and high sensitivity of gas detection and acoustic signal detection can be realized, so that the detection effect is improved.

The invention discloses a bolt washer sensor based on a fiber Bragg grating, which is characterized by comprising a double-layer composite washer, the double-layer composite washer comprises an inner ring and an outer ring, the inner ring is made of an FR4 epoxy resin material, and the outer ring is made of an aluminum alloy material; the strain body structures are symmetrically arranged on the two sides of the outer ring and comprise a positive strain body and a negative strain body, and the positive strain body and the negative strain body are both made of aluminum alloy materials; two fiber bragg gratings (FBG) with different central wavelengths are inscribed on the optical fiber, the two FBGs are respectively a first FBG (FBG1) and a second FBG (FBG2), the FBG1 is fixed at the central position of the positive strain body, and the FBG2 is fixed at the central position of the negative strain body. The gasket type sensor is compact in overall structure and resistant to corrosion, and has high repeatability, rapid dynamic response and long-term stability.

This invention discloses a doped and optimized ultra-low attenuation single-mode optical fiber, comprising a core, an inner cladding covering the core, and an outer cladding covering the inner cladding. The fiber fabrication method includes the following steps: 1) selecting a glass tube and a solid glass rod, and fitting the glass tube over the solid glass rod; 2) welding quartz rods to both ends of the glass tube; 3) placing the glass tube in a graphite furnace and doping the inner surface of the glass tube and the outer surface of the solid glass rod with alkali metals; 4) controlling the pressure and temperature inside the graphite furnace to fuse the glass tube and the solid glass rod into a single unit, forming the core; 5) forming an inner cladding around the core, followed by forming an outer cladding, to obtain the ultra-low attenuation single-mode optical fiber. The core obtained by this invention has the characteristics of large outer diameter, low hydroxyl content, high potassium concentration, and good longitudinal uniformity. By selecting appropriate inner and outer claddings to fabricate the optical fiber, the resulting fiber exhibits extremely superior ultra-low loss performance.

The invention is suitable for the technical field of wavelength measurement, and provides a speckle wavelength measurement device with miniaturization and strong anti-interference, which comprises a single-mode fiber, a dislocation welding multimode fiber, a CCD (Charge Coupled Device) camera and a computer which are sequentially arranged along a light path, the single-mode optical fiber is connected with the dislocation welding multimode optical fiber; the dislocation welding multimode optical fiber is formed by a first short multimode optical fiber and a second short multimode optical fiber through axial dislocation welding. The CCD camera is connected with the dislocation welding multimode optical fiber; and the computer is connected with the CCD camera and is used for processing the speckle pattern acquired by the CCD camera. The device is small in size, and the stability, the anti-interference performance and the resolution ratio of a measurement system can be effectively improved.

This invention discloses an FBG strain sensor based on misaligned fusion spliced ​​coreless optical fiber and its fabrication method. The sensor comprises an input single-mode fiber, multiple segments of coreless optical fiber, and an output single-mode fiber connected sequentially. The input single-mode fiber is fused together with the first segment of the coreless fiber in a misaligned manner, and the next segment of the coreless fiber is fused together with the previous segment in a misaligned manner, with the misalignment direction of the next segment opposite to that of the previous segment, but the misalignment distance being the same. The output single-mode fiber and the last segment of the coreless fiber are fused together axially. The central axes of the input and output single-mode fibers are collinear, and the cores of the input and output single-mode fibers are connected by a photolithographically written straight waveguide. A fiber Bragg grating is then optically etched along the straight waveguide. This invention uses femtosecond lasers to fabricate the FBG on the misaligned fiber structure, increasing the structure's strain response and making the strain sensitivity of the FBG on this structure higher than that of an FBG fabricated on ordinary silica optical fiber.

This invention discloses a multi-wavelength Brillouin and Raman random fiber laser based on tunable broadband Raman pumping, comprising a 1.5μm Brillouin pump, a 1.45μm tunable broadband Raman pump, a wavelength division multiplexer (WDM) I, and a passive fiber. The 1.45μm tunable broadband Raman pump includes a wavelength-tunable cascaded random Raman fiber laser, a WDM II, and a single-mode fiber I. The wavelength-tunable cascaded random Raman fiber laser is injected into the single-mode fiber I through the WDM II. This multi-wavelength Brillouin and Raman random fiber laser based on tunable broadband Raman pumping provides a 1.45μm tunable broadband Raman pump source by back-Raman amplification of the broadband seed light. Working together with the 1.5μm Brillouin pump, it can achieve ultra-wideband multi-wavelength random fiber laser output. By simultaneously tuning the output wavelengths of the Brillouin pump and the Raman pump, wavelength tuning of the broadband multi-wavelength random fiber laser can be achieved.

This utility model discloses a broadband high-speed photodetector module, including: a housing and a driving circuit. The housing has an internal mounting cavity, a high-speed broadband response photodetector, and is fixed inside the housing via an SMA interface. An OLED display screen is embedded on the front of the housing and connected to the driving circuit via a flexible circuit board. The high-speed broadband response photodetector has a spectral response range of 800nm ​​to 1650nm, fully covering the wavelength requirements of multimode and single-mode optical fibers. It solves the limitations of traditional modules with single wavelength or narrow spectrum, significantly improves compatibility with different optical fiber systems, and is suitable for complex hybrid optical fiber network scenarios. Through the coordinated design of the cylindrical body on the side wall of the housing, the air outlet, and the heat dissipation components, the heat generated by the photodetector during operation can be quickly dissipated, avoiding performance degradation or device damage due to temperature rise, and ensuring long-term stable operation of the module under high-speed and high-load conditions.

The waveguide comprises an active optical fiber and a passive optical fiber, the active optical fiber comprises a fiber core and a polymer cladding, and the refractive index of the passive optical fiber is 3 * 10 <-3 > smaller than that of the active optical fiber cladding. The passive optical fiber has a larger diameter at the beginning of a segment and at the end of the segment than at the intermediate segment, and the active optical fiber has a smaller diameter at the beginning of the segment and at the end of the segment than at the intermediate segment, the active optical fiber is designed to be able to place a larger diameter section between a plurality of smaller diameter sections of the passive optical fiber, and an optical and mechanical contact is formed in an intermediate section of the optical fiber, making it flat, to transfer pump energy from the passive optical fiber to the active optical fiber, and to transfer pump energy from the passive optical fiber to the active optical fiber. The core of luminescent ions doped with rare earth elements is 50-90% of the core diameter, the concentration is 200-500 ppm, and the waveguide is designed to have the ability to generate radiation at a wavelength of 1040-1070 nm.

The invention discloses a micro double-arm vector sensor and a preparation method thereof, and belongs to the technical field of optical fiber sensing. According to the technical scheme, the micro double-arm vector sensor comprises a broadband light source, a first single-mode optical fiber, a second single-mode optical fiber, a first coupling point, an interference arm with a core shift structure, a sensing arm, a second coupling point, a third single-mode optical fiber, a fourth single-mode optical fiber and a spectrum analyzer. The Mach-Zehnder interferometer has the advantages that a micro-double-arm Mach-Zehnder interferometer is formed on the basis of a core shift structure, an asymmetric structure is formed, light transmitted in the asymmetric structure is more sensitive to changes of the bending size and direction, and the vector bending sensitivity is high. Meanwhile, an online Mach-Zehnder interferometer needs to introduce a special optical fiber with high price in order to monitor the vector bending, and the structure only needs a single-mode optical fiber with low price, and is more suitable for batch production.

The invention relates to the technical field of optical fiber adapters, in particular to a single-mode optical fiber adaptive connection protection structure of an SLD depolarization light source. The optical fiber adapter comprises an optical fiber adapter body and further comprises a protection tensile mechanism used for conducting overheating protection on the optical fiber adapter body and buffering when the optical fiber adapter body is stretched by external force. An outer connector is inserted into an outer connector, air bags I are extruded when the outer connector is inserted, so that air in the air bags I flows into an air bag II, the air bag II drives a limiting rod, clamping blocks I and an adjusting rod to vertically move through the interior of a driving block, and the two clamping blocks I are attached to a connecting line; the magnetic blocks fixedly installed in the two first clamping blocks provide magnetic force for auxiliary fixation, and the two second clamping blocks are clamped in the reserved grooves formed in the surface of the outer connector, so that the tensile resistance of the connection position of the optical fiber adapter is further improved, disconnection of the outer connector and the outer interface caused by external force is avoided, and the service life of the optical fiber adapter is prolonged. And the use stability of the optical fiber adapter is improved.

The invention discloses an aircraft composite material structure health monitoring system and method, and relates to the field of aircraft material health monitoring, and the system comprises a DAS integrated optical module which is used for generating and transmitting an optical pulse pair subjected to heterodyne phase modulation to a single-mode optical fiber sensing network, and converting backward Rayleigh scattering light into an electric signal; the single-mode optical fiber sensing network is arranged on the surface of the aircraft composite material structure and is used for converting an acoustic emission signal containing the physical change of the aircraft composite material structure into an optical phase change signal by utilizing a coherent Rayleigh scattering effect; the digital signal processing module is used for carrying out signal processing on the electric signal by utilizing a heterodyne phase modulation method based on instantaneous frequency tracking so as to identify and position the damage of the aircraft composite material structure; and the alarm output module is used for outputting a damage position, a damage degree grade and an alarm signal of the airplane composite material structure in real time when the structural damage is detected, so that full-distribution and wide-range online accurate monitoring is realized.

This invention belongs to the field of fiber optic sensing and relates to a method based on WS 2 A temperature sensor based on all-fiber fluorescence intensity comprises a single-mode fiber, a three-hole grapefruit fiber, and a multimode fiber connected in sequence; the three-hole grapefruit fiber has three air holes, in which WS is deposited. 2 The multimode fiber output end is equipped with a mounting base, on which a filter is mounted. This invention utilizes WS... 2 Assembled within a three-hole optical fiber, with single-mode and multi-mode fibers fused together at both ends, this sealed structure effectively isolates the sensor from external air, preventing contact between the outside air and the two-dimensional material on the inner wall of the fiber during heating. This slows down the decomposition of transition metal sulfides, significantly improving the fluorescent sensor's ability to detect high temperatures and extending its lifespan. The sensor itself and its detection system are coupled and output via optical fiber, eliminating the need for external spatial light or optical modulation.

The invention discloses a cascade seven-core optical fiber sensor applied to folic acid detection and a preparation method of the cascade seven-core optical fiber sensor, and belongs to the technical field of optical fiber sensing and biological analysis detection. The sensor comprises a first single-mode optical fiber, a seven-core optical fiber section and a second single-mode optical fiber, a double-microsphere-cavity structure is arranged at the optical fiber connecting position to form a cascade interference optical path, and tapering is conducted on the middle portion of the seven-core optical fiber section to form a sensing area. According to the invention, mode matching is improved through the microsphere cavity, an evanescent field is enhanced through tapering, and high-sensitivity specific detection of folic acid is realized in cooperation with the folic acid binding protein biological functional layer fixed on the surface; the sensor obtains stable linear response to a folic acid standard solution in the range of 0-50 ng / mL, a clinical serum sample verifies that the detection result of the sensor is highly consistent with that of a chemiluminescence method, the sensor has good reusability, and the sensor has the advantages of being easy to prepare in structure, rapid in response, high in sensitivity, capable of being matched with a complex matrix and the like, and has good application prospects. The method has huge potential in clinical folic acid quantitative detection.