133 results about "Multi-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 multimode optical fiber imaging method based on a double-encoder network and an attention mechanism. A parallel double-encoder structure is formed by combining a Transform encoder and a convolution encoder, and meanwhile, a CBAM attention mechanism is introduced, so that a DEANet network model is constructed. According to the method, a convolution encoder is adopted to capture local details, and meanwhile, a Transform encoder is utilized to establish global feature association and high-frequency feature distribution to make up for the problem that the sensing range is limited. In addition, collaborative extraction and fusion of multi-scale information of channels and spaces are performed in a feature space through an attention module (CBAM). Compared with a traditional convolutional network, the method has the advantages that local details and a global structure are considered, high-fidelity reconstruction of a complex target structure and edge details in multimode optical fiber imaging is realized, and good robustness is kept after system disturbance.

The invention discloses a multimode optical fiber anti-disturbance real-time imaging method based on a double-neural network architecture, which comprises the following steps: firstly, acquiring a speckle image of a target image subjected to multimode optical fiber scattering transmission under a multi-disturbance dynamic state, then extracting spatial domain and frequency domain information of the speckle image, and training through an SFNet classification network to obtain a disturbance dynamic state classification model; and training by using a U-Net imaging network to obtain a speckle imaging model. During testing, the multimode optical fiber disturbance state corresponding to the speckle image is judged by using the classification model, and then the speckle image is input into the speckle imaging model under the corresponding multimode optical fiber disturbance state for reconstruction. According to the method, accurate classification and high-quality reconstruction of the speckle image of the multimode optical fiber under the multi-disturbance condition are achieved, good real-time performance and anti-interference performance are achieved, and the method is suitable for dynamic optical fiber imaging in the complex environment.

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 an optical fiber coupling real-time correction method in a single-mode and multi-mode optical fiber endoscopic imaging system, which comprises the following steps of: firstly, manually adjusting reflectors M1 and M2 to an optimal multi-mode optical fiber coupling state, acquiring images of light spots at the near end and the far end of a laser beam in the state by using a CCD (charge coupled device) 1 and a CCD 2, and calculating the position of a central coordinate of the images; and collecting a speckle image formed by the light spot through the scattering medium by using a CCD3 (charge coupled device 3). The system monitors the center coordinates of near-end and far-end light spots at the current moment and the correlation coefficient of the current speckle image and the collimation state image in real time. The piezoelectric mirror bracket is fed back and adjusted in real time through the center coordinates of the two spot light spots and the correlation coefficient of the speckles, so that the correlation coefficient of the speckles is kept above a set threshold value, and automatic calibration of light beams is achieved. On the basis of the traditional thinking that two points determine one straight line, the correlation coefficient of using speckles is increased, the alignment precision is improved, and the method has certain practicability and application prospects.

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.

The present invention relates to a multispectrum endoscope and an endoscope system comprising same. The multispectrum endoscope of the present invention comprises: a first light source emitting infrared rays having a plurality of wavelengths; a plurality of multimode optical fibers for guiding the infrared rays emitted from the first light source toward a sample; a second light source emitting a visible ray; an optical fiber for guiding the visible ray emitted from the second light source toward the sample; a lens part for receiving a fluorescent signal emitted from the sample and a visible light signal reflected off the sample; and an optical fiber bundle for guiding the fluorescent signal and / or the visible light signal received by the lens part toward a multispectrum photodetector, wherein the optical fiber bundle is disposed so as to be surrounded by the plurality of multimode optical fibers, and the end portion of the multispectrum endoscope emitting the visible ray surrounds at least a portion of the plurality of multimode optical fibers.

The invention discloses a laser synchronous transmission system and method based on a rotary motion mechanism and application, and belongs to the technical field of laser wireless energy transmission. The system comprises a static end and a rotary end of which the geometric centers are located on the same rotation axis; the static end is provided with a multimode optical fiber used for transmitting laser energy and a transmitting end single-mode optical fiber used for transmitting laser signals, the transmitting end single-mode optical fiber is provided with a transmitting end optical fiber collimator group, and the output of the multimode optical fiber is sequentially connected with a square optical fiber array and a lens array; the rotating end is provided with a laser cell panel for receiving laser energy, a receiving end optical fiber collimator for receiving laser signals and a receiving end single-mode optical fiber; and the square optical fiber array is connected to the transmitting end optical fiber collimator group. According to the invention, the stability and anti-interference performance of energy and signal cooperative transmission in the rotating mechanism are improved, the processing and assembling difficulty is reduced, the reliability of the system in a complex environment is improved, and long-term stable cooperative operation of higher-power laser and high-speed communication is supported.

The invention relates to the field of optical fiber sensing, in particular to a multichannel optical fiber surface plasma resonance sensing probe as well as a preparation method and application thereof. According to the multichannel optical fiber surface plasma resonance sensing probe, the sensing probe adopts an end face reflection type optical fiber sensing structure, and the end face reflection type structure is formed by welding a multimode optical fiber and a coreless optical fiber. A multimode-coreless optical fiber welded end face reflection type structure is adopted, SPR signals are excited through end face total reflection, the defect that a traditional lateral coupling type optical fiber SPR sensor is difficult to carry out directional detection in narrow spaces (such as blood vessels and tissue gaps) is overcome, miniaturized insertion type diagnosis with the minimum diameter being 300 micrometers is achieved, and the SPR sensor is suitable for in-situ monitoring of living tissue; according to the invention, through the nanocluster modification layers (0 / 2 / 4 layers) which are axially distributed at intervals, multi-channel functionalization can be completed only by a pulling method, traditional micro-nano processing and a complex film layer structure are not needed, and the preparation time of the multi-channel sensor is shortened from gt to gt; and the time is shortened from 6 hours to 1 hour.

The invention discloses an integrated distributed optical fiber sensing extra-high voltage live working sling on-line monitoring system, and relates to the technical field of electric power safety monitoring, and the system comprises a multilayer flexible insulating sling body with a spiral staggered optical fiber embedding channel; the multimode optical fiber sensing unit is embedded in the channel and comprises a Bragg grating array and a Brillouin scattering optical fiber; the stress identification module is used for constructing a heat-force coupling response matrix and identifying a stress concentration area; the digital twin modeling module is used for constructing a local finite element sub-model and outputting a fatigue trend curve; the diagnosis feedback module is used for generating a sling risk level signal and realizing remote control linkage; the system can monitor the stress evolution and fatigue damage conditions of the sling structure in real time, has the advantages of high strain identification precision, accurate fatigue trend prediction, timely remote response and the like, and improves the safety and intelligent management level of extra-high voltage live working.

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 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.

This invention relates to the field of cable technology and discloses a safety early warning cable with temperature sensing. The cable includes a wrapping layer containing multiple insulated power wire cores, a protective layer outside the wrapping layer, a first vibration sensing element within the protective layer, and an isolation layer between the wrapping layer and the protective layer. By incorporating a spiral metal sheath within each conductor, with thermally conductive silicone grease filling the space between the sheath's inner wall and the temperature-sensing optical fiber, rapid and direct monitoring of the conductor's core temperature is achieved. Simultaneously, heat is transferred through the conductor's copper wires in the spiral microgrooves, the thermally conductive metal strip on the surface of the insulation layer, and the thermally conductive material in the filling layer to the multimode optical fiber core in the multi-core sensing cable, forming redundant temperature measurement channels. When the temperature of a conductor is abnormal, the corresponding temperature-sensing optical fiber and the multimode optical fiber core can be cross-verified, effectively avoiding false alarms caused by single-point faults or poor local contact, significantly improving temperature measurement reliability and response speed.

The application discloses a kind of broadband fiber spectrometer based on phase modulation, including polarization maintaining optical fiber, fiber collimator A, phase modulation device, fiber collimator B, multimode optical fiber, CCD image sensor and computer that are sequentially arranged, fiber collimator A is set to the light outlet of polarization maintaining optical fiber, phase modulation device carries out phase modulation to the incident light from fiber collimator A, fiber collimator B is set to the light inlet of multimode optical fiber, the light outlet of multimode optical fiber is aligned with CCD image sensor, and CCD image sensor is electrically connected with computer.The application uses the above structure to overcome the problem that spectrum resolution and measurement bandwidth are mutually restricted in fiber spectrometer.

The corn fruit biological information detection device comprises a bottom plate, a waste liquid collection box and a U-shaped detection seat, a detection cavity is formed in an inner cavity of the U-shaped detection seat, a detection optical fiber is arranged on the inner wall of the detection cavity, and a light source, a spectrograph, a single-mode tail fiber and a multi-mode optical fiber are arranged at the two ends of the detection optical fiber respectively. Side frames are installed at the top ends of the outer walls of the two sides of the U-shaped detection base, a top beam is installed between the adjacent side frames, a controller and a flushing mechanism are arranged on the top beam, the flushing mechanism comprises a U-shaped walking frame, a spray head is installed at the bottom of the U-shaped walking frame, and two sets of tooth-shaped plugging plates are arranged at the bottom of the detection cavity; through the action of the light source, the single-mode tail fiber, the spectrograph, the multimode optical fiber and the detection optical fiber, rapid detection of corn fruit biological information is achieved, rapid washing of the detection cavity after detection is completed is achieved, the situation that residual corn fruit extracting solution affects the accuracy of next-time biological information detection is avoided, and the detection efficiency is improved.

The invention relates to an SMS structure Fabry-Perot ultrasonic sensor which comprises a packaging protection shell, a first single-mode fiber, a multimode fiber and a second single-mode fiber, the first single-mode fiber, the multimode fiber and the second single-mode fiber are sequentially arranged and welded, the welding area of the first single-mode fiber and the multimode fiber and the welding area of the second single-mode fiber and the multimode fiber form reflection end faces respectively, and a Fabry-Perot interference cavity is constructed. The cavity length of the Fabry-Perot interference cavity is the length of the multimode fiber; the packaging protection shell wraps the multimode fiber and the two welding areas and is connected to the first single-mode fiber and the second single-mode fiber. The packaging protective shell is provided with a sound transmission hole. A first single-mode fiber, a multi-mode fiber and a second single-mode fiber are sequentially arranged and welded to form a single-mode-multi-mode-single-mode (SMS) welding structure, a Fabry-Perot interference cavity is constructed by using the refractive index difference of a welding interface, the length of the multi-mode fiber is directly used as the cavity length, and the structure does not need to be additionally provided with a diaphragm or inscribe a grating through femtosecond laser.

The optical fiber type light spot homogenizer comprises a machine frame, a laser source is arranged at one end of the machine frame, a multimode optical fiber corresponding to the laser source is arranged at the other end of the machine frame, the laser source emits a laser beam, the multimode optical fiber receives the laser beam, and the multimode optical fiber is connected with the machine frame. The multi-mode fiber laser is characterized in that the relative refractive index difference section of the inner side of the sunken inner cladding of the multi-mode fiber is in a two-stage step decreasing shape, and the center line of the laser beam and the center of the end face of the multi-mode fiber are aligned and offset in parallel by a section of radial offset. The device is small in size, low in cost, compact in structure, good in homogenization effect and stable in performance, and can be directly seamlessly integrated with an input laser source and an output optical fiber system. The optical fiber type light spot homogenizer assembly and the laser beam shaping system can achieve efficient light spot homogenization within the centimeter-level distance. The system can be applied to a vehicle-mounted laser radar, a vehicle-mounted head-up display, a multimode PON optical splitter, laser medical equipment or laser material processing equipment and the like.

The utility model relates to the field of optical fiber interference sensors, and discloses an M-Z interference sensor with a small excitation group velocity dispersion difference mode structure. Comprising a light injection single-mode optical fiber, a small-core-diameter step multimode optical fiber, a wide annular core optical fiber, an annular core optical fiber, a gradient refractive index multimode optical fiber, a large-core-diameter step multimode optical fiber and a light receiving single-mode optical fiber which are connected in sequence. The wide annular core optical fiber comprises a third quartz cladding and a third quartz fiber core, and the third quartz fiber core annularly wraps a third quartz layer; the annular core optical fiber comprises a fourth quartz inner wrapping layer, a fourth quartz fiber core and a fourth quartz outer wrapping layer, the fourth quartz inner wrapping layer is annularly wrapped by the fourth quartz fiber core, the fourth quartz fiber core is annularly wrapped by the fourth quartz outer wrapping layer, and the optical fiber radial refractive index distribution index of the gradient refractive index multimode optical fiber is 1.95-2. According to the scheme, the annular core optical fiber is used for injecting light to the gradient refractive index multimode optical fiber, two modes with smaller group velocity dispersion difference can be excited to interfere, and the sensitivity of the sensor is improved.

The invention relates to the technical field of wavelength division multiplexing passive optical network transmission optimization, in particular to a wavelength division multiplexing passive optical network transmission optimization method and system. Comprising the following steps: S1, constructing a network architecture through a plurality of pairs of wavelength stacked optical modules, dividing optical network units in the network architecture, and receiving and sending optical signals of a terminal through the optical network units; through the ONU architecture design of dense wavelength division multiplexing and transmitting-receiving separation, the capacity of a wavelength resource pool is further expanded, and in combination with the flexible branching ratio of 1: 8 to 1: 256 and the compatibility of single-mode and multi-mode optical fibers, it is ensured that the system can stably support 100 Gb / s total rate transmission under the scenes of different scales and different transmission distances; the problem that the wavelength resource utilization rate is low in a traditional static allocation mode is thoroughly solved.

The application discloses a kind of multi-mode optical fiber wavelength multiplexing wide field imaging quality promotion methods based on dynamic calibration.The method comprises the following steps: collecting the output speckle pattern corresponding to each wavelength after being transmitted by multi-mode optical fiber;The speckle patterns of different wavelengths are spatially registered and spliced to form a high-dimensional composite speckle vector;PCA is used to bidirectionally compress the dimension of input image and composite speckle vector group, and a linear wavelength multiplexing inverse transmission matrix (WITM) is dynamically estimated and updated in low-dimensional space, and real-time pre-reconstruction and continuous monitoring are realized;Set up optical fiber state monitoring module to analyze pre-reconstruction frame in real time, when structural disturbance or optical fiber deformation is detected, automatically trigger in situ dynamic calibration, realize the rapid adaptive update of WITM, without retraining network.The updated WITM will guide the diffusion neural network image optimizer to iteratively denoise and detail repair the pre-reconstruction result, significantly improve the image fidelity and structure restoration ability.

The invention provides a high-precision multi-plane optical converter installation and adjustment method and an optical converter, and belongs to the field of optical path installation and adjustment testing. The problems that an existing method is tedious in debugging step and long in time consumption and lacks an effective compensation mechanism for the multi-degree-of-freedom coupling error are solved. The method comprises the following steps: adjusting relative positions and postures of a reflector and a phase plate according to optical feedback, so that the reflector is parallel to the phase plate; adjusting the position of the collimation single-mode optical fiber array relative to the phase plate according to the auxiliary positioning optical fiber and the phase modulation; and adjusting the position of the collimation multimode optical fiber according to the output power maximization. The method is mainly used in the free space optical communication field.

The embodiment of the invention discloses a model training method, and the method comprises the steps: obtaining a sample image for a body tissue part of a sample user, and obtaining a corresponding initial sample speckle image based on the sample image through a target optical fiber; performing image quality enhancement and segmented adaptive normalization processing on the initial sample speckle image to obtain a target sample speckle image; training an initial image reconstruction model based on the target sample speckle image and the sample image to obtain a target image reconstruction model; wherein the target image reconstruction model comprises a feature extraction network; and the feature extraction network comprises a plurality of convolutional layers, so that the problem of insufficient image reconstruction quality in a complex multimode optical fiber imaging scene is solved. The embodiment of the invention further discloses an image determination method and device, equipment, a storage medium and a program product.

The utility model relates to the technical field of cables, in particular to a compression-resistant USB photoelectric composite wire, which comprises a four-core multimode optical fiber, four signal wires and a control wire, the four signal wires and the control wire are arranged on the periphery of the four-core multimode optical fiber, a wrapping tape is jointly extruded outside the four signal wires and the control wire, a special-shaped filling strip is arranged in the wrapping tape, and the special-shaped filling strip is arranged in the control wire. The special-shaped filling strip comprises a circular pipe strip which sleeves the four-core multimode optical fiber, five compression-resistant straight strips which are integrally formed on the outer wall of the circular pipe strip and are annularly arranged at intervals, and arc-shaped strips which are integrally formed on the compression-resistant straight strips, are far away from the end face of the circular pipe strip and abut against the inner wall of the wrapping tape. And lightening holes which extend along the radial direction of the four-core multimode optical fiber and are through front and back are formed in the compression-resistant straight strips. According to the utility model, the four-core multimode optical fiber, the signal line and the control line are separated by the special-shaped filling strips, so that the four-core multimode optical fiber, the signal line and the control line are mutually independent, and the special-shaped filling strips serve as inner skeletons of the composite line to ensure that the composite line has good roundness.

The application discloses an optical signal inner circulation delay system based on electro-optic polarization modulation, comprising a signal light source, a first polarization beam splitter prism, a first electro-optic polarization modulator, a second polarization beam splitter prism, a second electro-optic polarization modulator, a third polarization beam splitter prism, a first full reflection mirror, a first lens, a first optical fiber collimator, a single-mode / multi-mode optical fiber, a second lens, a second optical fiber collimator and a second full reflection mirror, forming a ring-shaped light path. The length of the single-mode / multi-mode optical fiber and the high level duration of the modulation electric signal are adjusted, the repetition frequency and the pulse width of the output optical signal can be changed respectively, and therefore the application can also be used for converting continuous light into controllable pulsed light. The number of times that the signal light circulates in the ring-shaped light path can be controlled through the loaded electric signal, the delay time is flexibly adjusted, and the delay time range is expanded.

The application discloses a special optical fiber bundle, an optical receiving system based on the special optical fiber bundle and a laser radar based on the optical receiving system, relates to the technical field of airborne water depth measuring laser radars, and the special optical fiber bundle comprises an input end, a first output end and a second output end; the input end is composed of a central multimode optical fiber and an annular multimode optical fiber bundle surrounding the central optical fiber; the first output end is the central multimode optical fiber; and the second output end is a circular optical fiber bundle synthesized by the annular multimode optical fiber bundle in the input end. The special optical fiber bundle provided by the application can separate a composite light echo signal into two parts of large and small fields of view, and can replace a split field of view optical reflector.

The invention discloses an optical fiber signal conversion device, which comprises a plurality of single-mode optical modules connected with a single-mode optical fiber connector for bidirectional signal transmission. And the multi-mode optical module is connected with the multi-mode optical fiber connector for bidirectional signal transmission, a receiving channel of the multi-mode optical module is connected with a sending channel of the single-mode optical module, and a sending channel of the multi-mode optical module is connected with a receiving channel of the single-mode optical module. And the VPX connector is connected with the multimode optical module. And the MCU main circuit performs work enabling on the optical module, communicates with the optical module, obtains the working state of the optical module, communicates with the outside through an I2C port, and reports the monitoring condition of the working state of the circuit. A VPX bus is selected as a high-speed serial bus, transmission of converting four pairs of single-mode double-fiber bidirectional optical signals into multimode optical fiber signals, transmission of converting two pairs of single-mode single-fiber bidirectional optical signals into multimode optical fiber signals and transmission of converting a group of single-mode four-path parallel optical receiving and transmitting integrated signals into multimode optical fiber signals are realized; and two pairs of high-speed differential SerDes signals are converted into multimode optical fiber signals for transmission.

The invention discloses a multimode cladding pumping resonance space division multiplexing optical fiber amplifier and an implementation method thereof, and relates to the technical field of optical fiber amplifiers. The multimode cladding pumping resonance space division multiplexing optical fiber amplifier comprises a transmission optical fiber, an active optical fiber, a multimode pumping optical fiber and a resonant cavity; the active optical fiber is one of a multimode optical fiber, a multi-core optical fiber and a multi-core multimode optical fiber and is used for realizing stimulated radiation amplification of multichannel signal light; the multi-mode pumping optical fiber is coupled with the active optical fiber through a pumping coupling assembly to form a pumping injection path which is used for accessing an external multi-mode pumping source and injecting pumping light into a cladding of the active optical fiber; by constructing a resonant light path for pumping recycling, residual pumping is converted into reusable effective pumping, so that the residual pumping participates in the pumping effect on the active section for multiple times in the system, the equivalent pumping intensity and the accumulative absorption amount of the active section are improved under the condition that the rated power of an external pumping source is not remarkably increased, and the energy consumption of the active section is reduced. The purposes of improving the gain efficiency and reducing the thermal load are achieved.

The invention relates to a multi-layer film thickness high-precision measurement system and method based on low-coherence interference. According to the system, a low-coherence broadband light source, an optical fiber coupling module and one end of the forked end of a Y-type multimode optical fiber are sequentially and correspondingly arranged, the common end of the Y-type multimode optical fiber, a collimation module and an all-optical-fiber reflection type coaxial probe are sequentially and correspondingly arranged, the other end of the forked end of the Y-type multimode optical fiber is arranged corresponding to a spectrograph, and the spectrograph is connected with a data processing module; the all-fiber reflection type coaxial probe is used for vertically irradiating a collimated light beam to the surface of a tested multi-layer film structure sample and collecting reflected light of the tested multi-layer film structure sample, and the data processing module is used for carrying out Fourier transform on spectral data of the spectrograph and separating out optical path difference signals of all interfaces; and calculating the thickness information of the thin film in the measured multi-layer thin film structure sample. The structure is simple, the cost is low, rapid measurement can be achieved, the data analysis difficulty is low, and the thickness measurement accuracy and stability are high.

The purpose of the present invention is to provide an optical fiber testing device and a method therefor that enable stable measurement of crosstalk in an MCF and an MMF without being affected by noise.　An optical fiber testing device according to the present invention measures crosstalk of a space-division multiplexed optical fiber 50, and comprises: a light transmission unit 10 that causes modulated test light to enter one path of the space-division multiplexed optical fiber 50 from one end of the space-division multiplexed optical fiber 50; a light receiver 22 that receives transmitted light output from each path at the other end of the space-division multiplexed optical fiber 50 and outputs the transmitted light as a light reception signal; a signal processing unit 24 that demodulates each light reception signal and detects the light intensity of the respective transmitted light; and a calculation unit 30 that calculates crosstalk from the light intensity of the transmitted light.

The utility model relates to the field of optical fiber interference sensors, and discloses an M-Z interference sensor of a seven-core optical fiber cascaded graded-index multimode optical fiber, which comprises a light injection single-mode optical fiber, a step multimode optical fiber, a seven-core optical fiber, a graded-index multimode optical fiber and a light receiving single-mode optical fiber which are connected in sequence, the axis of the joint of the seven-core optical fiber and the gradient refractive index multimode optical fiber deviates by a preset offset; the outer side of a fiber core of the seven-core optical fiber is coated with a stress layer, and the radius of the fiber core of the step multimode optical fiber is larger than the radius of the stress layer of a central fiber core of the seven-core optical fiber and smaller than the minimum distance from the central fiber core of the seven-core optical fiber to the stress layer of the fiber core on the outer side of the seven-core optical fiber. The length of the seven-core optical fiber is far smaller than that of the gradient multimode optical fiber; and the refractive index of the stress layer material outside the fiber core of the seven-core optical fiber is smaller than that of the cladding material of the seven-core optical fiber. According to the scheme, the problems that the interference valley is too wide and the extinction ratio is too low in a gradient refractive index multimode optical fiber interference sensor can be solved while the high-sensitivity sensing characteristic is maintained.