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

The invention belongs to the technical field of deformation measurement, and provides a distributed optical fiber sensing casing damage monitoring system and monitoring method based on an OFDR (Optical Frequency Domain Reflectometer) technology. An armored optical cable consisting of a multi-core single-mode optical fiber and two multi-mode optical fibers of which the tail ends are welded into a U shape is spirally wound on the outer wall of a casing; a single-channel DSS / dual-channel DTS modulation-demodulation system of a dynamic distributed optical fiber strain and temperature composite sensing technology is used for real-time acquisition of strain and temperature sensing data of the casing pipe under the action of ground stress, and a cylindrical casing pipe three-dimensional model reconstruction algorithm is combined to automatically generate a spiral line. The three-dimensional model of the cylindrical casing is in one-to-one correspondence with the position of the optical fiber on the real casing, casing damage possibly occurring to the underground casing under the action of ground stress is monitored and measured in real time for a long time, early warning and forecasting information about that the casing damage is about to occur or is occurring is issued in time, and well site operators can conveniently handle and repair the casing damage in time.

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 discloses a method of an optical anti-turbulence device for polarization multiplexing spatial optical communication. The mode demultiplexer is connected with the optical fiber; the single-mode optical fiber array is respectively coupled with each spatial intrinsic mode decomposed by the mode demultiplexer; the polarization CBC chip is connected with the other end of the single-mode optical fiber array; the driving control module is connected with the polarization CBC chip; the polarization multiplexing optical communication digital coherent receiver (Rx) is connected with the polarization CBC chip through a single-mode optical fiber; through the arrangement of the polarization CBC chip, the compatibility of a polarization multiplexing technology and a mode multiplexing coherent beam combination technology is realized, the problem of polarization dimension information loss or strong crosstalk caused by the use of a polarization state rotator (PSR) and a polarization maintaining optical fiber in the prior art is solved, modulation information of two orthogonal polarization dimensions is completely reserved, the communication bandwidth is improved, and the communication efficiency is improved. And the communication efficiency is greatly improved.

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 invention belongs to the technical field of pavement monitoring methods, and particularly discloses a distributed optical fiber permanent deformation monitoring method for an asphalt pavement under a moving load. The method comprises the following steps: laying a single-mode optical fiber in a test piece; laying a full-bridge strain gauge in the test piece; monitoring an optical fiber vibration signal of the test piece during the movement of a test wheel and a strain change of the test piece during the movement of the test wheel in real time through a strain acquisition instrument; processing the optical fiber vibration signal and the strain change by using matlab data analysis software; analyzing the data change trend according to the processed optical fiber vibration signal and the strain change, and establishing a mathematical relationship between the two; and according to the mathematical relationship, distributed monitoring of the permanent deformation of the asphalt pavement under the moving load by the optical fiber vibration signals is realized. By the adoption of the bituminous pavement distributed optical fiber permanent deformation monitoring method under the moving load, real-time, dynamic, large-range, long-distance and high-precision monitoring of bituminous pavement permanent deformation is achieved, and the defects in the prior art are overcome.

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 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 relates to the technical field of photoelectric composite cables, in particular to a cold-resistant tensile photoelectric composite cable and a rapid laying method thereof, and the cable comprises a conductor part, an insulating layer, an optical fiber unit, a filling layer and an outer sheath which are coaxially arranged from inside to outside and are sequentially wrapped. The conductor part is formed by twisting a plurality of strands of copper wires, a carbon fiber reinforced core is arranged in the conductor part, and the insulating layer is made of EAA and PEBA blending modified materials and contains nano boron nitride particles; the optical fiber unit is of a PBT loose tube structure, a plurality of single-mode optical fibers and special ointment are arranged in the PBT loose tube structure, micro-nano protrusions are arranged on the inner wall of a loose tube, and the surface of each micro-nano protrusion is covered with a silicon dioxide antireflection film. The cable integrates the functions of cold resistance, stretch resistance, electric conduction, insulation, communication, heat dissipation and protection. The insulating layer adopts EAA and PEBA blending modified materials to be combined with nano boron nitride particles, so that the cold resistance and the insulativity are improved; and the polyurethane elastomer of the filling layer is compounded with the glass beads, so that the structural stability and the comprehensive performance are enhanced.

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 discloses a double-core optical fiber integrated MZ interferometer based on thermal diffusion. The interferometer is mainly characterized in that a core structure of the interferometer is formed by sequentially welding an input optical fiber (1), a first double-cladding transition optical fiber (2), a double-core optical fiber (3), a second double-cladding transition optical fiber (4) and an output optical fiber (5). Thermal diffusion treatment is performed by long-term high-temperature heating in the welding regions (A) and (B). The thermal diffusion treatment enables fiber core doping elements to be diffused, a transition area is formed in the double-clad optical fiber, the coupling efficiency between the single-mode optical fiber and the double-core optical fiber is remarkably improved, and compared with a traditional tapering structure, the thermal diffusion area is higher in mechanical strength. The interferometer device is compact in structure, high in integration level and excellent in interference contrast, can realize high-precision phase sensitive sensing, is suitable for distributed measurement of physical quantities such as temperature, bending and refractive index, and can be widely applied to optical fiber sensing.

According to the recoverable self-adaptive traffic signal lamp control system, the traffic management level is remarkably improved. According to the system, through a multi-information acquisition layer, various sensors are deployed at key road sections, and traffic data are accurately acquired in combination with the Internet of Vehicles and a high-precision positioning technology. And the high-speed stable transmission layer is connected with 5G and 4G networks through a single-mode optical fiber, so that stable transmission of data is guaranteed. And the intelligent data processing layer applies 3D convolution, a CNN model of an attention mechanism and a data fusion algorithm to deeply analyze data and generate a congestion index. The optimization decision generation layer constructs a reward function according to the key indexes, generates an optimal timing scheme through a reinforcement learning algorithm, and gives consideration to the passage of special vehicles. And the precise control execution layer adjusts and controls the signal lamp by using gradient brightness. The intelligent energy management layer is powered by solar energy. Once a system fault occurs, the fault fast recovery layer switches the standby device in a short time, and the timing is recalculated based on the multi-source data. The system effectively relieves congestion, enhances stability and reliability, and also can reduce energy consumption.

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 provides a detection method of an end face integrated reflection type SPR optical fiber biosensor manufactured based on a 2PP technology. An experiment system mainly comprises a single-mode optical fiber, an optical fiber coupler, an SPR probe, a tungsten lamp light source, a sample pool, a spectrum analyzer and a computer. The method is characterized in that a volcanic three-dimensional microstructure is directly constructed on the end face of a single-mode fiber through a 2PP technology, a metal film with the thickness of about 50nm is deposited on the inner wall of the volcanic three-dimensional microstructure, and a stable and efficient SPR excitation structure is formed; the structural parameters are subjected to FDTD simulation optimization design, and have the characteristics of high quality factor and high sensitivity. The sensor can be used for AFP detection, the sensitivity reaches 0.684 nm / (ng / mL) within the linear range of 0-10 ng / mL, the normal and risk early warning concentration interval of human serum AFP is covered, and the sensor has good biological suitability and early hepatocellular carcinoma screening capacity; in addition, the probe structure is small in size, detection can be completed only by a few microliters of liquid to be detected, and the probe is suitable for a microfluidic platform with an extremely low sample size or a clinical sampling scene. Compared with the prior art, the device has the advantages of high structural integration, high sensitivity, low sample consumption, convenience in manufacturing, stability, reliability and the like.

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.

Expanded beam optical fibers, and methods of forming the same, are disclosed herein. In one example, an optical fiber includes a first optical fiber section with a photonic crystal fiber, a second optical fiber section with a mode field adapter fiber, and a third optical fiber section with a single mode fiber. The first optical fiber section is coupled to the second optical fiber section, and the second optical fiber section is coupled to the third optical fiber section.

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.

The invention provides a time stretching Fourier transform optical frequency comb morphology measurement system and method. The time stretching Fourier transform optical frequency comb morphology measurement system comprises an optical frequency comb OFC, an interferometer module, a dispersion optical fiber module, a signal detection module and a synchronous control module. An optical frequency comb (OFC) provides an incident light beam for the interferometer; the interferometer module obtains an interference signal of the measured object by adjusting the length of the single-mode optical fiber; the dispersion transmission module performs time stretching on the interference signal through a single-mode optical fiber to generate a time domain interference signal; a signal detection module captures the stretched time domain interference signal, and solves the morphology parameters of the measured object through a time-frequency transformation algorithm; the synchronous control module drives the two-dimensional displacement platform bearing the measured object through the motion control card and triggers synchronous acquisition and storage of three-dimensional shape data of the measured object. The method has enough high precision in morphology measurement, and the detection speed of the method can meet the requirements of industrial real-time detection.

To provide an optical fiber light source having high spectral wavelength flexibility and enabling incoherent continuous-wave output in a single transverse mode.SOLUTION: An optical fiber light source has: an optical fiber having a first end, a second end, and a tapered part positioned between the first and second ends, which is a single mode fiber; a wavelength conversion part; a light source for exciting the wavelength conversion part; and a support part. The first end outputs radiant light emitted from the excited wavelength conversion part. The tapered part includes: a constricted part; a first tapered region in which a diameter gradually decreases from the second end side toward the constricted part; and a second tapered region in which a diameter gradually increases from the constricted part toward the first end side. The constricted part has a diameter smaller than those of the first and second ends, and has a size of the wavelength or less of the radiant light. The wavelength conversion part is composed of liquid or gas and is disposed so as to surround at least an outer periphery of the constricted part of the tapered part. The light source simultaneously excites the outer peripheral portion surrounding the wavelength conversion part.SELECTED DRAWING: Figure 2

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 relates to the technical field of spacecraft structure micro stress detection, in particular to a spacecraft structure micro stress detection device and a use method thereof, and the spacecraft structure micro stress detection device comprises a displacement amplification structure, a single mode fiber, a reflector, a broadband light source and a spectrum analyzer. An optical resonant cavity formed by an optical fiber end face and a lens is combined with a displacement amplification structure, when stress acts on a spacecraft structure, the cavity length of the Fabry-Perot resonant cavity changes, so that phase movement of light is caused, and accurate measurement of the stress can be achieved by detecting the phase movement. The antenna has extremely high anti-electromagnetic interference capability, and can work stably in a complex space environment. Even under the condition of violent temperature change, high measurement accuracy can be kept, and detection of tiny stress can be achieved through the amplification effect of the displacement amplification structure. And the stress characteristic signal and the background noise can be effectively separated, so that the detection reliability is remarkably improved.

The invention discloses a service rearrangement method and device for a hybrid optical fiber network and a storage medium, and belongs to the technical field of frequency slot arrangement, and the method comprises the steps: constructing a service rearrangement task model according to the hybrid optical fiber network which comprises a standard single-mode optical fiber and a ULL optical fiber, the service rearrangement task model takes the minimum network blocking rate and the minimum frequency spectrum movement times as objective functions; constructing a same-fiber dissimilar spectrum and foreign-fiber dissimilar spectrum sorting mechanism; combining the same-fiber different-spectrum sorting mechanism and the different-fiber different-spectrum sorting mechanism, and combining a pre-constructed service migration trigger index and a service re-sorting selection strategy to obtain a spectrum fragment re-sorting algorithm; solving the service rearrangement task model by using a spectrum fragment rearrangement algorithm to obtain a plurality of service rearrangement schemes; and the scheme meeting the target is used as a final service rearrangement scheme, so that hybrid optical fiber network service rearrangement with high efficiency and high resource utilization rate can be realized.

The invention relates to the technical field of bionic touch sensors, in particular to a touch pain sense sensor based on double-layer heterogeneous optical fiber sharpness perception and a preparation method. The touch pain sense sensor comprises an SGS-MZI structure which is formed by welding a single-mode optical fiber, a step type multimode optical fiber and a gradual change type multimode optical fiber and is used for realizing shallow touch pressure detection; the MNF structure is located under the SGS-MZI structure; the MNF structure is a non-adiabatic conical structure obtained by fused biconical taper of a single-mode fiber, and is used for realizing deep contact pressure and sharpness detection; the middle supporting layer is located between the SGS-MZI structure and the MNF structure; and the SGS-MZI structure and the MNF structure are fixedly arranged on the top surface and the bottom surface of the middle supporting layer respectively. According to the invention, through a double-layer heterogeneous structure based on the sandwich structure multimode fiber Mach-Zehnder interferometer (MZI) and the MNF, sharpness identification and touch pain perception functions are realized, so that the detection performance of the bionic touch sensor is improved.

The invention discloses an optical measurement device for an engine flow field, and relates to the technical field of optical measurement. The transmitting end module and the receiving end module are arranged on two walls of an engine to be tested and are provided with opposite lens type end caps; the transmitting end module comprises a built-in metal coating high-temperature single-mode optical fiber; one end of the single-mode optical fiber is connected with a lens type end cap of the transmitting end module to form an integrated laser transmitting probe; the receiving end module comprises a built-in metal coating high-temperature multimode optical fiber and a detector; one end of the multimode optical fiber is connected with a lens type end cap of the receiving end module to form an integrated laser coupling probe; and a receiving and transmitting light path pair penetrating through an engine combustion area is formed between the lens type end caps of the transmitting end module and the receiving end module. Water vapor between a window sheet and an optical probe collimating lens and between the collimating lens and an optical fiber core in a traditional measurement module is eliminated, and the measurement precision of an engine flow field combustion area is improved.

An apparatus and method for realizing photon pair emission and fiber output on the basis of quantum dots. The apparatus comprises: a single quantum dot (1), which is used for generating cascaded luminescence of single excitons and biexcitons, wherein an exciton state exhibits luminescence in two polarization states, i.e. H and V, and the two polarization states have an energy splitting; a microcavity (2), which is formed by a first Bragg reflector (3) and a second Bragg reflector (4), and is used for controlling the directional light emission of the single quantum dot (1); an optical fiber coupling component (6), which is prepared by means of vertically bonding a single-mode optical fiber (5) and encapsulated by means of curing, and is used for collecting the cascaded luminescence of single excitons and biexcitons generated by the single quantum dot (1); a local electric field, which is generated by a single dopant atom (22) in an adjacent modulation-doped layer (21), and is used for tuning the single quantum dot (1), so as to reduce exciton energy splitting and tune an exciton wave function; a luminescence output module, which is used for performing fluorescence collection on the single quantum dot (1) and outputting the collected cascaded luminescence of single excitons and biexcitons in the form of a Gaussian optical field; and a photon pair correlation test unit (11), which is used for filtering the cascaded luminescence of single excitons and biexcitons, and testing polarization correlation on the basis of filtered single excitons and biexcitons.

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 optical fiber sensing, and provides an optical fiber microstructure biosensor for detecting alpha fetoprotein and a preparation method thereof, and the method comprises the following steps: step 1, synthesizing a gold nanorod; 2, selecting a single-mode optical fiber for real-time monitoring, removing a coating layer, placing the single-mode optical fiber in a fusion splicer, drawing to obtain a micro-conical optical fiber, enabling CO2 laser to act on a conical waist area of the micro-conical optical fiber to manufacture a cone, taking out the optical fiber, and cooling and curing to obtain an optical fiber microstructure sensor; step 3, immersing a sensing area of the optical fiber microstructure sensor into NaOH, washing and drying, and immersing the sensing area into an MPTMS-ethanol solution; washing is carried out, and then the sensing area is immersed in a GNRs-PEG-COOH solution; washing and drying, immersing the sensing area in an EDC / NHS mixed solution for soaking, washing and drying, and putting the sensing area in an mAb solution for soaking; and washing and drying to obtain the optical fiber microstructure biosensor.

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.