75 results about "Multi-mode optical fiber" patented technology

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 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 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 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 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 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.

The invention relates to a conical cascaded spiral four-core optical fiber sensor and a preparation method thereof. The conical cascaded spiral four-core optical fiber sensor comprises a single-mode optical fiber, a multimode optical fiber and a four-core optical fiber, the single-mode optical fiber, the multimode optical fiber and the four-core optical fiber are sequentially cascaded according to the following sequence: the single-mode optical fiber, the multimode optical fiber, the four-core optical fiber and the single-mode optical fiber; an optical fiber core in the middle area of the four-core optical fiber is of a spiral structure. Cascade connection among the optical fibers uses a fusion splicer to perform discharge fusion splicing. The spiral structure is manufactured by using a special optical fiber fusion splicer, and spiral structures with different parameters are manufactured by adjusting a program of the fusion splicer. The sensor is mainly used for simultaneous detection of multi-parameter sensing, the special microstructure enables the sensor to respond to parameters such as temperature, strain, curvature, torsion and the like very sensitively, and particularly, the sensor can recognize the torsion direction. The sensor is compact in structure and simple in preparation method, and can be applied to the field of multi-parameter sensing.

The invention relates to the technical field of optical fiber optical measurement, in particular to a multimode optical fiber temperature and stress measurement and regional demodulating method and system.The single-frequency laser emitted by a tail fiber laser enters a measuring arm multimode optical fiber and a reference arm multimode optical fiber through a beam splitter, emergent light is collimated and polarized, then combined by a polarization beam combining crystal and modulated by a quarter-wave plate, and then the single-frequency laser and the reference arm multimode optical fiber are output. And finally, the interference fringes are recorded by the polarization mask camera. A wavefront phase image is reconstructed through a four-step phase shift algorithm, and two characteristic parameters of inclination angle change and wavefront phase distribution change of interference fringes are extracted. According to the invention, two-parameter decoupling is realized by utilizing the difference of wavefront response mechanisms of the multimode optical fiber under the action of temperature and stress, and the device has the advantages of high real-time performance, light intensity interference resistance and compact structure, and is suitable for temperature and stress integrated precision measurement in the fields of industrial monitoring and aerospace.

The application discloses a high-refractive-index glue reliability testing device and method. The testing device comprises a temperature detector, an optical power meter and sequentially fused light beam injection unit, a multimode optical fiber and a single-mode optical fiber. The multimode optical fiber and the single-mode optical fiber are provided with a high-refractive-index glue layer to be tested at a fusion point. The input end of the temperature detector is aligned with the high-refractive-index glue layer to be tested to monitor the temperature in real time. The optical power meter is arranged at the output end of the single-mode optical fiber to test the output power of the optical path. The reliability testing method is executed by the device. The device and method can test the reliability of the high-refractive-index glue to be tested in the laser field application process.

This invention provides a mode-division multiplexing (MDF) system, method, device, and storage medium, relating to the field of optical communication technology. The MDF system includes at least: multiple cascaded optical fiber transmission units across multiple spans and a central controller. Each optical fiber transmission unit includes multimode or few-mode fiber and a mode adjustment unit. The mode adjustment unit calculates the transmission parameters of the optical fiber transmission unit and sends these parameters to the central controller. The central controller acquires the transmission parameters of the optical fiber transmission units in each span, generates a target mode round-robin strategy for the corresponding span, and sends it to the mode adjustment unit to update the optical signal module. The central controller adaptively selects the target mode round-robin strategy based on the real-time transmission environment, adaptively adjusting each span to reduce differential mode group delay (DMD) and mode-dependent loss (MDL), adapting to different span lengths and different transmission environments, and improving the transmission performance of multimode or few-mode fiber.

The application discloses a graphene-coated surface saturable absorber device of a multimode optical fiber with an internal microstructure, which adopts a mixed structure of graphene and a graded-index multimode optical fiber. The saturable absorber device comprises a first single-mode optical fiber, a mixed structure based on a multimode optical fiber, and a second single-mode optical fiber. The mixed structure based on the multimode optical fiber is composed of a tapered graded-index multimode optical fiber with an internal microstructure and a single-layer graphene film. The graded-index multimode optical fiber is first subjected to a micro-tapering treatment, then a microstructure is inscribed in the core inside the taper waist, then the graphene film is coated on the surface of the taper waist of the optical fiber, and finally the single-mode optical fibers are fused at both ends of the multimode optical fiber. The saturable absorber combines the nonlinear multimode interference effect in the multimode optical fiber and the saturable absorption characteristics of graphene, can perform secondary compression on the pulse width of a high-energy pulse, and thus obtains an ultrashort pulse. The application has the advantages of a solid structure, strong stability, a high damage threshold and the like, and provides an effective technical means for obtaining a stable ultrashort pulse mode locking.

A surgical robotic system includes a control tower having a first component configured to transmit and receive communication data, a first multimode fiber optic connection, a first single mode fiber optic connection and a first optical bulkhead connector coupled to the multimode fiber optic connection and the single mode fiber optic connection. The system also includes a surgeon console having a display configured to display video data, a second component configured to transmit and receive the communication data, a second multimode fiber optic connection, a second single mode fiber optic connection, a second optical bulkhead connector coupled to the second multimode fiber optic connection and the second single mode fiber optic connection. A main cable coupled to the first and second optical bulkhead connector, which interconnects the control tower and the surgeon console and is configured to transmit video data along with the communication data.

The application discloses a single-mode fiber to multi-mode fiber mode converter which comprises a single-mode fiber head assembly, a transmitting end C lens, a birefringent crystal sequence, a receiving end C lens and a multi-mode fiber head assembly arranged coaxially; an air gap is arranged between the light emitting end of the single-mode fiber head assembly and the transmitting end C lens, and an outer envelope tube of the transmitting end collimator is coaxially fixed to the outer circumferential side of the single-mode fiber head assembly and the transmitting end C lens; the single-mode fiber to multi-mode fiber mode converter can stably assemble each optical component and ensure the overall assembly precision by means of the outer envelope tubes of the transmitting end and receiving end collimators and the inner and outer envelope tubes of the crystal group; all the components are packaged by the overall outer envelope tube, the internal optical structure is effectively protected, and the firmness of the device structure is enhanced.

The application provides a kind of radiation resistant multimode optical fiber and its preparation method.The application provides a kind of radiation resistant multimode optical fiber, and the radiation resistant multimode optical fiber includes core layer, adjusting layer, fluorine-doped cladding layer and barrier layer and outer cladding layer.Core layer is located in the center of the optical fiber;Adjusting layer is wrapped outside the core layer;Fluorine-doped cladding layer and barrier layer are located outside the adjusting layer;Outer cladding layer is located outside the fluorine-doped cladding layer and the barrier layer.The absolute value of the refractive index difference between the core layer and the adjusting layer relative to the outer cladding layer gradually increases from the center of the core layer to the outside of the adjusting layer;The refractive index difference of the core layer relative to the outer cladding layer is a parabola from its center to its outside, the refractive index difference of the adjusting layer relative to the outer cladding layer is an inclined straight line, and the absolute value of the slope of the inclined straight line is less than the absolute value of the slope of the parabola endpoint.To solve the problem of high-order mode pulse shift caused by the diffusion of fluorine element at the core-cladding interface in the existing radiation resistant multimode optical fiber technology.

The invention provides a multimode optical fiber probe and a method and device for identifying the bending state of the multimode optical fiber probe, and relates to the technical field of optical fibers. The multimode optical fiber probe comprises a probe body, the probe body is twisted periodically at a preset angle in the optical axis direction, and the probe body is composed of a flexible multimode optical fiber; the side, close to the needle body, of the detection end can reflect detection light, and the detection end is connected with the needle body through a continuous multimode optical fiber; wherein after reaching the detection end along the needle body, the detection light carrying speckle light field information is reversely transmitted from the detection end along the needle body under the reflection effect of the detection end. According to the invention, real-time sensing of the bending form of the flexible optical fiber can be realized with high efficiency and high precision.

The invention discloses a high-brightness optical fiber beam combining device based on multimode optical fibers and a cascading method of the high-brightness optical fiber beam combining device. The device adopts a modular framework and comprises an input module, a beam combining module, a light beam optimizing module, a mode matching module and an output module which are connected in sequence. The core of the device is that the light beam optimization module is composed of one or more cascaded multimode optical fibers with parabolic or approximate parabolic refractive index distribution, a high-order mode can be effectively inhibited and a low-order mode can be enhanced through controlled mode coupling and energy redistribution after beam combination, so that synchronous improvement of output power and light beam brightness is realized. The device and the method disclosed by the invention are compatible with single-stage and multi-stage cascade application, are compact in structure and stable in performance, can effectively inhibit a nonlinear effect, and are suitable for meeting the requirements on high-brightness laser in the fields of industrial processing, optical communication, scientific research and the like.

The invention discloses a multimode optical fiber spot homogenizing device for a spherical optical interferometer, which comprises an ultrasonic oscillation cavity, the ultrasonic oscillation cavity is filled with coupling liquid, the temperature of the coupling liquid is adjusted through a temperature control device, a stress adjusting device is fixedly arranged in the ultrasonic oscillation cavity and is soaked in the coupling liquid, and the stress adjusting device is used for adjusting the temperature of the coupling liquid. The stress adjusting device adjusts mechanical stress borne by the multimode optical fiber, and the ultrasonic oscillation cavity is connected with the ultrasonic oscillator. The invention further discloses a multi-mode optical fiber light spot homogenizing method for the spherical optical interferometer, the refractive index of the multi-mode optical fiber is changed through microwave heating, and the output light spots of the multi-mode optical fiber are homogenized by combining the synergistic effect of mechanical stress and ultrasonic vibration. The device is simple in structure and convenient to operate, thermal damage to the multimode optical fiber is reduced, and long-term stable operation of equipment is facilitated.

The invention discloses a multimode optical fiber endoscopic imaging device and method based on an adaptive alignment technology, and belongs to the technical field of optical fiber microscopic endoscopic imaging. Wherein the excitation module comprises a laser, a first lens and a second lens; the modulation coding module comprises a half-wave plate, a quarter-wave plate, a spatial light modulator and a beam splitter; the displacement coupling module comprises a first displacement objective lens coupling device and a multimode optical fiber; the transmission area array detection module comprises a second displacement objective lens coupling device, a linear polarizer, a reflector, a third lens and a first area array camera; the reflecting area array detection module comprises a first displacement objective lens coupling device, a beam splitter, a dichroscope, a fourth lens, a fifth lens and a second area array camera; and the total light intensity detection module comprises a photomultiplier connected with the dichroscope. Through the combination and cooperative work of the modules, the adaptive alignment technology is realized, and the imaging quality and precision of the multimode optical fiber endoscopic imaging system are remarkably improved.

The utility model discloses a plugging-resistant eight-core multi-mode stainless steel test insertion core, relates to the technical field of optical communication test connectors, and particularly relates to an improvement of the plugging-resistant eight-core stainless steel test insertion core suitable for multi-mode optical fiber connection. In order to achieve the purpose, the technical scheme adopted by the utility model is as follows: the insertion core comprises an insertion core body, the insertion core body is of a flat rectangular structure, and the insertion core body is a stainless steel insertion core; a plurality of optical fiber through holes which are arranged in parallel are arranged in the insertion core body, and the aperture of the optical fiber through holes is matched with a multimode optical fiber. And the coupling alignment precision during optical signal transmission is ensured. The overall structure is compact, and the connector has the characteristics of high strength and wear resistance, and adapts to frequent plugging scenes. And two circular positioning holes are formed in the insertion surface of the insertion core body. And the circular positioning hole is used for being matched with a positioning column in the test interface module, so that the insertion core is ensured to have good repeated positioning performance when being inserted. The problems that an existing plastic insertion core is short in service life, low in strength and not suitable for a high-frequency testing environment are solved, the overall structure is stable, and the compressive strength and the torsional strength are superior to those of a traditional plastic insertion core.

A hollow-core optical fiber for a fiber optic network is disclosed. The hollow-core optical fiber includes opposing end portions. A main portion extends between end portions. A tapered region is between an end portion and the main portion. One end portion has a reduced outer dimension. A cladding defines an inner surface of the main portion. The inner surface defines a hollow core. The cladding includes a doped layer. At least one end portion and tapered region has a solid core. The main portion has an outer diameter greater than 126 μm and one end portion has an outer diameter of 126 μm or less. A fiber optic cable assembly includes a hollow-core optical fiber, and optionally one or more single mode fibers (SMF) and / or multimode fibers (MMF), terminated by a fiber optic connector. A method of making such a hollow-core optical fiber and cable assembly is also disclosed.

The invention discloses an adiabatic low-loss vortex structure optical multiplexing and demultiplexing device and an optical communication system, and belongs to the field of optical communication, and the optical multiplexing and demultiplexing device comprises a plurality of optical fiber vortex mode selection couplers with different orders, which are respectively used for exciting vortex mode groups with different orders; the optical fiber vortex mode selection coupler is formed by parallel fused biconical taper of a multimode optical fiber with a transition cladding and a single-mode optical fiber subjected to pre-tapering, the multimode optical fiber and the single-mode optical fiber form a directional coupling structure, and a fundamental mode in the single-mode optical fiber is matched with a vortex mode group in the multimode optical fiber in phase; the multimode optical fiber with the transition claddings comprises a fiber core and a plurality of transition claddings, the width of each layer is gradually increased from the fiber core to the outermost transition cladding, and the refractive index difference between every two adjacent layers is gradually decreased; and a plurality of optical fiber vortex mode selection couplers with different orders are cascaded to form a multi-stage multiplexing and demultiplexing structure. The heat insulation loss of the optical fiber mode selection coupler can be reduced, so that the optical fiber mode selection coupler supports more vortex mode numbers.

The application discloses a hollow optical fiber light-heat spectrum gas sensor and a gas concentration detection system thereof, and relates to the technical field of optical fiber gas detection. The first sensor (00) is sequentially connected with a detection light (1), an incident detection light end single-mode optical fiber (2), a to-be-detected gas molecule (3), a Bragg hollow optical fiber (10), a multimode optical fiber (12), an incident pump light end single-mode optical fiber (13) and a pump light (14). The Bragg hollow optical fiber (10) is a hollow optical fiber with four high-refractive Bragg layers doped in a solid cladding. The application adopts a full optical fiber, naturally forms a gas passage in the optical fiber, and does not need to additionally introduce a complex gas interface structure. The sensor has the advantages of fast response speed, good stability, simple manufacturing process, low cost, avoidance of a tedious processing process such as femtosecond laser drilling, and avoidance of a bulky space alignment structure. The application provides a feasible technical path for realizing the application of the optical fiber gas sensor in multiple fields.