103 results about "Mode division multiplexing" patented technology

Aspects of the disclosure relate to wireless communication including mode division multiplexing of data and reference signals using different orbital angular momentum (OAM) modes. An OAM transmitter may transmit a reference signal (RS) configuration information to an OAM receiver that indicates radio resources for a plurality of OAM modes. The OAM transmitter may further transmit data on a first OAM mode of the plurality of OAM modes using first radio resources of the radio resources indicated by the RS configuration information. The OAM transmitter may further transmit a reference signal on a second OAM mode of the plurality of OAM modes using the first radio resources of the radio resources indicated by the RS configuration information. The OAM receiver may receive the data on the first OAM mode and the reference signal on the second OAM mode. Other aspects, embodiments, and features are also claimed and described.

The invention discloses a channel construction method for a passive optical network communication system, and belongs to the field of optical fiber communication. The implementation method of the invention is as follows: based on an M-QAM signal sequence after synchronization processing, a current M-QAM signal is regarded as real data. And the condition vector and the real data are combined to construct a training data set, and a TFPNet network model for channel construction of the passive optical network system is constructed. The TFPNet network model takes the combination of real data and conditional vectors as an input feature sequence for training, signal features are fully processed, when signal data at the current moment are processed, preorder signal data information in training data can be combined and utilized, serialized feature fusion can be performed on the signal data sequence, and the signal data sequence is subjected to feature fusion. And the nonlinear interference relationship between the current signal and the preorder signal can be better represented. According to the method, the calculation complexity is lower, data symbols transmitted in a mode division multiplexing system can be efficiently recovered, and linear damage and non-linear damage in a passive optical network optical communication system are compensated.

The invention discloses a wavelength division and mode division multiplexing multiply-adder which loads first data to be calculated on a first group of optical signals, and the first group of optical signals comprises a plurality of optical signals with different powers. The wavelength mode multiplexing module then converts the first set of optical signals into a first optical signal. The first optical signal is divided into a plurality of second optical signals through a power beam splitting module. Converting the plurality of second optical signals into a plurality of groups of second group optical signals through a mode demultiplexing module; then, the modulation module loaded with the partial data of the second data outputs a third group of optical signals after adjusting the light intensity of the second group of optical signals. And finally, combining the plurality of third groups of optical signals into a plurality of third optical signals through a beam combining module, wherein the product of the first group of data and the second group of data is indicated. According to the invention, the calculation power consumption can be saved, in addition, the optical signals are distinguished by using modes and wavelengths, the increase of calculation dimensions is facilitated, and large-scale matrix vector multiplication is realized.

The invention discloses a relay device and method for long-distance few-mode optical fiber communication, and belongs to the field of optical communication. According to the device, firstly, optical signals transmitted in a few-mode optical fiber are separated into a plurality of independent mode channels through a mode decomposition multiplexer; then, an adjustable light delay unit is configured in each channel, and compensation is carried out according to a difference mode group delay difference pre-calculated or actually measured by a few-mode optical fiber parameter; furthermore, a dimmable amplifier is used for amplifying the signal, power monitoring is carried out at the output end of the amplifier through an optical fiber beam splitter and a photoelectric detector, closed-loop feedback control is formed, and gain of each channel is adjusted in a self-adaptive mode to eliminate mode-dependent loss. According to the invention, signal distortion can be effectively suppressed in an optical domain, the complexity of digital signal processing of a receiving end is reduced, and the transmission distance and the transmission capacity of a few-mode optical fiber mode division multiplexing communication system are remarkably improved.

The invention discloses an all-fiber mode filter based on a multi-core fiber. The mode filter adopts an all-fiber structure of a multi-core fiber, and is an optical device for selecting or filtering light beams in a specific mode from input light beams containing different modes. The fiber core diameter, the fiber core distance and the refractive index of the multi-core optical fiber are adjusted and changed, mode filtering is achieved by finding out a proper transmission period among multiple modes, in a certain specific bandwidth, multi-mode signals can be efficiently and selectively filtered, the mode filtering function is achieved, operation is easy, and accuracy is high. The multi-core optical fiber structure provided by the invention can realize the functions of selecting a specific target mode and filtering a non-target mode, and has the characteristics of simple structure, small loss, high mode purity, stable performance and the like. The invention has wide application prospects in the fields of mode division multiplexing, optical fiber mode filters, optical fiber filters, optical fiber sensors, optical fiber lasers, optical fiber transmission systems and the like.

The invention discloses a broadband photonic filter based on a thin-film lithium niobate optical waveguide, and belongs to the technical field of integrated photoelectronics. The broadband photonic filter comprises a heat insulation filter, a multi-mode connection waveguide and a broadband mode converter, wherein the heat insulation filter and the broadband mode converter are both of an asymmetric directional coupler structure. The heat insulation filter selectively converts the input TE fundamental mode wavelength into a high-order TM mode, and the other TE fundamental modes are output from the straight-through end. And the high-order TM mode enters the broadband mode converter through the multi-mode connection waveguide, is completely converted into a TE fundamental mode and is output from the cross end. According to the invention, an asymmetric directional coupler structure commonly used in mode division multiplexing is creatively used as an optical filtering function, and the structure is simple. Based on a mode adiabatic evolution principle, the filter is suitable for being applied to broadband optical filtering operation, and has the advantages of being easy to design and process, low in loss and the like.

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

The invention provides a single-port input / output multi-state adjustable waveguide mode converter and a preparation method thereof, and belongs to the technical field of on-chip silicon-based polymer hybrid integrated waveguide mode converters. According to the invention, a double-layer MZI parallel combination structure is adopted, independent electrodes are configured at specific positions of interference arms, and corresponding modulation signals are applied, so that accurate regulation and control of an input light field are realized. When E00-mode signal light is input, the structure can dynamically realize the conversion function of three modes of E00 / E01 / E10 on the premise of keeping single-port output, and the mode conversion efficiency reaches 95%. And the device is compatible with a standard silicon-based CMOS (Complementary Metal-Oxide-Semiconductor Transistor) process, is beneficial to reducing the manufacturing cost and promoting large-scale integrated application, is suitable for the fields of a high-capacity mode division multiplexing system and multi-dimensional optical signal processing, and can meet the urgent requirements of modern optical communication on high-integration-level, reconfigurable operation and low-cost devices.

The long-distance frequency-broadening distributed optical fiber sensing system comprises a narrow linewidth laser, an optical fiber isolator, a dense wavelength division multiplexer, an optical fiber coupler, a continuous optical amplifier, a narrow-band filter, an acoustic optical modulator, an optical fiber circulator, a balance detector, an acquisition card and an upper computer, a segment of mode division multiplexing pulse sequence is obtained by selecting a narrow linewidth laser and controlling an arbitrary waveform generator. After the pulse sequence enters the to-be-measured optical fiber, a section of Rayleigh backscattered light is returned, and system original data is obtained after frequency beating with local light. And then signals are demodulated by using a compensation method, and undesired signals are suppressed successively, so that the problem of limited spurious-free dynamic range caused by phase mismatching of different modes is solved.

The invention relates to an underwater point cloud data transmission system and method based on vortex light mode division multiplexing, and the system comprises a point cloud data transmission module which is used for modulating the three-dimensional point cloud data of a measured target into two paths of laser signals, carrying out the first preprocessing of the two paths of laser signals, and transmitting an underwater space light signal; and the point cloud data receiving module is used for receiving the underwater space optical signal, performing second preprocessing on the underwater space optical signal, and generating user service data. According to the invention, a double-path vortex optical space division multiplexing technology is adopted, synchronization of target detection and data return is realized, and key technical problems of poor real-time performance, weak anti-interference capability and the like in the aspect of underwater three-dimensional point cloud data acquisition are effectively solved.

The invention discloses a mode division multiplexing optical fiber communication phase calibration method based on CNN-LSTM, and belongs to the technical field of optical fiber communication. By constructing a double-input CNN-LSTM hybrid neural network architecture, MIMO input signals and original target signals of mode division multiplexing optical fiber communication are obtained, data preprocessing is carried out, and the spatial feature extraction capability of a convolutional neural network and the time sequence modeling capability of a long-short-term memory network are combined, so that the MIMO input signals and the original target signals of mode division multiplexing optical fiber communication are obtained. Effective compensation of phase noise in long-distance strong-coupling mode division multiplexing optical fiber communication is realized, and a double-branch network comprising an image input layer, a convolutional layer, an LSTM layer, a deep connection layer and a user-defined phase calibration layer is constructed by separating complex MIMO signals into real and imaginary parts and generating a sliding window training sample. The problems that a traditional algorithm is limited in phase noise compensation capacity and poor in convergence performance under the strong coupling condition are effectively solved, and the balance performance and the transmission quality of a mode division multiplexing optical fiber communication system are remarkably improved.

The application discloses a device and method for coexistence of bright-dark solitons based on a mode division multiplexing resonant cavity, and relates to the technical field of lasers.The device for coexistence of bright-dark solitons based on the mode division multiplexing resonant cavity comprises an erbium-doped fiber amplifier, a first optical coupler, an acousto-optic frequency shifter, a second optical coupler, a third optical coupler, a first mode selection coupler, a second mode selection coupler and a fiber ring resonant cavity, and the fiber ring resonant cavity is a non-uniform dispersion few-mode fiber.The device and method for coexistence of bright-dark solitons based on the mode division multiplexing resonant cavity can realize stable coexistence of bright-dark solitons.

The application discloses a mode division multiplexing all-optical regenerative device, which comprises a polarization controller, a few-mode amplifier, an optical coupler, a few-mode nonlinear optical fiber, an optical carrier extractor and an optical phase shifter. Mode division multiplexing signals of multi-level pulse amplitude modulation from different users can be simultaneously regenerated by the mode division multiplexing all-optical regenerative device, the regenerated mode division multiplexing signals are amplified and shaped, and the power transfer curve of each mode channel is not affected by the change of other mode levels.

The present invention discloses a multi-user quantum key distribution full-connection network system based on a multi-functional integrated optical quantum chip, including: a multi-degree-of-freedom integrated high-dimensional entangled photon pair source module at the network service provider side, a mode configuration module based on mode division multiplexing technology, a mode demultiplexing module, an encoding / decoding module, and a photon detection module at the user side. The present invention can further improve the key rate and also facilitate the construction of a quantum communication network based on the existing optical fiber communication network.

A mode insensitive 2x2 thermo-optic switch for mode division multiplexing system belongs to the technical field of planar optical waveguide devices. It is composed of a silicon substrate, a silicon dioxide lower cladding layer, a polymer core layer waveguide and a polymer upper cladding layer. The polymer core layer waveguide is composed of a first input straight waveguide and a second input straight waveguide, a first input S curved waveguide and a second input S curved waveguide, a first coupling arm straight waveguide, a second coupling arm straight waveguide and a third coupling arm straight waveguide, a first output S curved waveguide and a second output curved waveguide, and a first output straight waveguide and a second output straight waveguide. A metal modulation electrode is prepared on the polymer upper cladding layer corresponding to the second coupling arm straight waveguide. The present application realizes the channel switching of LP 01 , LP 11a and LP 11b three modes by adjusting the spacing and coupling length of the coupling arm straight waveguide and whether to apply the modulation electrode, which has important significance in the field of mode division multiplexing applications.

The invention discloses an apodized FBG circle-by-circle inscribing system and method based on a variable radius method, and relates to the technical field of optical fiber inscribing, and the system comprises a laser beam shaping module, an optical fiber track control module and an optical fiber real-time monitoring module. The laser beam shaping module generates laser and focuses the laser to form a refractive index modulation area; the optical fiber real-time monitoring module monitors the side mode rejection ratio and the reflectivity of a reflection spectrum in real time, observes the pose of the ring core optical fiber and adjusts the pose through the optical fiber track control module, and it is ensured that a modulation area is located on the fiber core all the time. The optical fiber track control module clamps the ring core optical fiber, controls the ring core optical fiber to move on the Y axis and the Z axis according to sine and cosine functions respectively to form an annular inscribing track and step along the X axis (axial direction) according to a preset grating period, and the radius of each annular track changes along the X axis according to Gaussian-like distribution to achieve apodization distribution. The system effectively improves the side mode suppression ratio to 20-25dB (optimal Gaussian distribution), keeps high reflectivity, remarkably improves the spectrum quality, and is suitable for the fields of mode division multiplexing, optical fiber sensing and the like.

The invention discloses an active mode demultiplexing module which comprises a mode converter, two optical circulators and a bidirectional semiconductor optical amplifier. The mode converter is used for converting a high-order mode into a fundamental mode to complete primary mode demultiplexing, fundamental mode signals after primary demultiplexing are injected into the bidirectional semiconductor optical amplifier through the two optical circulators from the positive direction and the negative direction respectively, and the signals after being shaped by the bidirectional semiconductor optical amplifier are output by the corresponding optical circulators. A bidirectional symmetrical injection structure is formed, different propagation is beneficial to separation of different signals, and mutual interference, namely mode crosstalk, between forward and reverse signals can be effectively reduced, so that a mode demultiplexing function is better completed, and an output signal has higher signal quality than a primary demultiplexing signal. Besides, by optimizing and adjusting the driving current of the bidirectional semiconductor optical amplifier or an auxiliary optical pumping mode, not only can the gain of the mode channel be dynamically adjusted, but also the power balance of the mode channel and the demultiplexing of a high extinction ratio mode can be realized; the method is especially suitable for receiving few-mode signals in a mode division multiplexing (MDM) optical transmission system and constructing optical switching nodes in a multi-dimensional multiplexing optical network.

The invention belongs to the technical field of optical fiber communication, and particularly relates to a seven-core seven-mode mode division multiplexer based on a mode coupling principle, which comprises a substrate material, a central few-mode fiber core and a peripheral single-mode fiber core, a high-refractive-index ring is arranged in the central few-mode fiber core; the peripheral single-mode fiber core comprises a first single-mode fiber core used for carrying out LP11 mode conversion on the central few-mode fiber core, a second single-mode fiber core used for carrying out LP31 mode conversion on the central few-mode fiber core, a third single-mode fiber core used for carrying out LP21a mode conversion on the central few-mode fiber core, and a fourth single-mode fiber core used for carrying out LP02 mode conversion on the central few-mode fiber core; the fifth single-mode fiber core is used for carrying out LP21b mode conversion on the central few-mode fiber core; and the sixth single-mode fiber core is used for carrying out LP12 mode conversion on the central few-mode fiber core. The invention has the characteristics of large number of conversion modes, high space utilization rate, low insertion loss, high flux and the like.

The invention discloses a signal-to-noise ratio and mode coupling joint estimation method and device for mode division multiplexing optical fiber communication and a storage medium, and the method comprises the steps: obtaining a plurality of groups of communication signals of the mode division multiplexing optical fiber communication, and obtaining a spectrum correlation function of the communication signals, determining a cyclic correlation function according to the spectrum correlation function, determining a signal-to-noise ratio and an optical fiber length according to the cyclic correlation function, and determining a power coupling coefficient value according to the signal-to-noise ratio and the optical fiber length corresponding to each group of communication signals. According to the method, the signal-to-noise ratio and mode coupling can be monitored at the same time, the communication quality can be evaluated more comprehensively through the combined monitoring capacity, and a complex data acquisition or synthesis process is not needed, so that implementation and operation of a monitoring system are simplified, real-time monitoring can be achieved, and reliability and timely detection of the communication system can be guaranteed. The method is widely applied to the technical field of optical communication.

The application relates to a mode conversion and multiplexer based on a zirconium oxide waveguide, which comprises a zirconium oxide waveguide layer, the zirconium oxide waveguide layer comprising a first waveguide, a second waveguide and a third waveguide, the first waveguide comprising a first input waveguide, a first coupling waveguide, a first straight waveguide, a second coupling waveguide and a first output waveguide; the second waveguide comprising a second input waveguide and a third coupling waveguide; the third waveguide comprising a third input waveguide and a fourth coupling waveguide; a coupling area formed by the first coupling waveguide and the third coupling waveguide converts fundamental mode light in the third coupling waveguide into second-order mode light, and the first straight waveguide transmits the second-order mode light and the fundamental mode light; a coupling area formed by the second coupling waveguide and the fourth coupling waveguide converts fundamental mode light in the fourth coupling waveguide into third-order mode light, and the first output waveguide transmits the third-order mode light, the fundamental mode light and the second-order mode light. The application can solve the problem of a relatively large size of a mode division multiplexer based on a polymer in the related art.

A non-degenerate mode few-mode multiplexer / demultiplexer based on a four-core transmission main channel is characterized in that a transmission channel of the mode division multiplexer / demultiplexer is composed of an elliptical four-core super-mode fiber core FEC-SFC and three single-mode fiber cores, the elliptical four-core super-mode fiber core at the coordinate center serves as the transmission main channel, and the single-mode fiber cores SMF1, SMF2 and SMF3 are transmission coupling channels; the length of the transmission main channel FEC-SFC is 3.588 mm, and the lengths of the SMF1, the SMF2 and the SMF3 are respectively 3.588 mm, 1.658 mm and 1.808 mm; the mode field characteristics in the optical fiber can be changed by reasonably setting parameters such as the position, the size and the refractive index distribution of the fiber core; according to the ultra-mode fiber core, the advantages of a pure silicon dioxide fiber core, an elliptical core and an ultra-mode fiber core are fused, the mode degeneracy of LP11a / LP11b is broken, four ultra-mode multiplexing and demultiplexing of LP01, LP11a, LP11b and LP21b are achieved, the refractive index fiber core made of pure silicon dioxide is adopted, and the low-loss performance is achieved; a transmission channel with a large effective refractive index difference is adopted, and the position and the length of the transmission channel are reasonably set, so that the low-crosstalk and high-extinction-ratio performance is realized, and the low-crosstalk and high-extinction-ratio optical fiber can be used for MIMO-FREE operation.

The invention discloses a mode division multiplexing device based on topological optimization and a mode division multiplexing circulating system, and relates to the field of photon integration and optical communication. The manufacturing method of the mode division multiplexing device comprises the following steps: dispersing the whole design area into adjustable material pixels, wherein the design area is silicon on insulator; determining a target function of a mode division multiplexing device by taking maximization of mode conversion efficiency as a target; by taking the objective function as an optimization objective, automatically updating the distribution of material pixels in the whole design area to obtain a quasi-optimal structure; and optimizing the pixels which cannot meet the manufacturing requirements in the optimal structure until the manufacturing requirements can be met. When a mode division multiplexing device is manufactured, an optimal structure can be automatically searched in a continuous or discrete material parameter space, so that a complex geometrical shape which is difficult to intuitively conceal can be excavated, and ultra-compact, low-loss, low-crosstalk, broadband and robust mode division multiplexing multifunctional photonic devices and the like can be realized in an extremely small size.

The application discloses a compact fiber bundle and spatial vortex beam mode multiplexer and a diffraction optical element height distribution optimization method for the mode multiplexer, relates to the field of optoelectronics, and the mode multiplexer comprises a filter, a first diffraction optical element, a second diffraction optical element, a microlens array, a flange connector and a fiber bundle arranged in sequence from left to right along the light path direction, and an external sleeve; the first diffraction optical element and the second diffraction optical element are both annular structures, and the two constitute a diffraction neural network, realizing the multiplexing function and the demultiplexing function of the spatial vortex beam. The diffraction optical element height distribution optimization method comprises the following steps: determining the phase modulation amount of each region based on a phase distribution function, and determining the height distribution of each region based on the phase modulation amount. The application provides a feasible technical path for realizing a high-integration, low-crosstalk mode division multiplexing device, and has a wide application prospect.

The present invention discloses a broadband multi-mode end-face coupler based on a slit structure, and belongs to the field of optical interconnection communication devices. The multi-mode end-face coupler includes a substrate, a heterogeneous waveguide with two core layer materials, and a buried layer. The heterogeneous waveguide includes a strip waveguide formed by a first core layer material, and a multi-level adiabatic slow-changing inverted cone waveguide formed by a second core layer material, wherein the inverted cone waveguide is located in the strip waveguide; the multi-level adiabatic slow-changing inverted cone waveguide includes an input thin straight waveguide, a tapered strip waveguide, a multi-level slow-changing slit structure waveguide, and an output wide straight waveguide in sequence. Based on the principle of mode evolution, after multiple modes in a few-mode optical fiber are coupled to the multi-level adiabatic slow-changing inverted cone waveguide, they can be evolved into multi-mode waveguide modes on the chip, respectively, and have the characteristics of low loss, low crosstalk, and large bandwidth. The present invention realizes the application of mode division multiplexing technology in a fiber-chip optical interconnection system, which is of great significance for further improving the capacity of the fiber-chip interconnection system and other fields.

The invention provides a calculation implementation method of a mode division multiplexing and wavelength division multiplexing optical matrix-vector multiplication unit based on photosensitive silicon. Systems and methods for optical matrix-vector multiplication using mode division multiplexing and microring resonators are provided. Examples of the systems and methods disclosed herein include an array of structures based on mode division multiplexing and microring resonators, a phase change material, and a waveguide. An operation representing a matrix multiplied by a vector may be generated based on the optical power output from the array of microring resonator structures.

The application provides an optical communication method applied to the field of optical communication. The optical communication method comprises the following steps: a first optical communication device acquires a first mode division multiplexing optical signal and a first wavelength division multiplexing optical signal. The first optical communication device performs beam combination on the first mode division multiplexing optical signal and the first wavelength division multiplexing optical signal to obtain a first multiplexing optical signal. The first optical communication device transmits the first multiplexing optical signal to a second optical communication device through a first optical fiber. The first optical fiber is a multimode optical fiber or a few-mode optical fiber. The wavelength of the first wavelength division multiplexing optical signal is greater than the cutoff wavelength of the first optical fiber. The wavelength of the first mode division multiplexing optical signal is less than the cutoff wavelength of the first optical fiber. In the application, the mode division multiplexing optical signal and the wavelength division multiplexing optical signal are transmitted through one optical fiber, so that the communication bandwidth can be improved.

The invention provides an optical chip for atom regulation and control and a regulation and control method, and belongs to the technical field of optical signal processing. The optical chip comprises a chip substrate, an optical waveguide integrated on the chip substrate, an acousto-optic modulator, an external port and a port facing an atomic array. The acousto-optic modulator generates sound waves through an interdigital transducer, and the sound waves interact with the optical signals in the acousto-optic interaction waveguide, so that at least one of the amplitude, the phase, the polarization, the frequency, the transverse mode and the transmission direction of the optical signals is accurately adjusted. The optical chip can also be integrated with a nonlinear optical frequency conversion module for changing the frequency of the optical signal; and the optical signal multiplexing module is used for performing beam splitting, filtering, frequency division or mode division multiplexing and the like on the optical signal. The external port is used for inputting / outputting optical signals, and the port facing the atom array outputs the optical signals to the atom array in a free space light beam mode and can collect the optical signals emitted by atoms.

The present invention discloses a four-mode mode division multiplexing / demultiplexing device based on Y-branching and multimode interference couplers. The device includes a four-mode multiplexer and a four-mode demultiplexer. The four-mode multiplexer and the four-mode demultiplexer multiplex four transmission modes through a four-mode bus waveguide. The four-mode multiplexer and the four-mode demultiplexer are mirror-symmetric structures, each composed of a dual-mode Y-waveguide, a four-mode Y-waveguide, a 2×2 single-mode input paired interferometer (MMI) type, and a 2×2 multimode input general interferometer (MMI) type basic unit. The present invention achieves four-mode multiplexing and demultiplexing by controlling the mode phase in the Y-waveguide and the MMI multimode coupler. The four-mode mode division multiplexer and demultiplexer have low loss, wide bandwidth, compact size, and wide manufacturing tolerance.

The invention discloses an optical fiber collimator, isolator and circulator in an orbital angular momentum mode, and belongs to the field of optoelectronic communication devices. Based on a special optical fiber collimator design scheme, the OAM optical fiber collimator which is simple in structure and excellent in performance is realized. On the basis of an OAM optical fiber collimator, an isolation core and an annular core are combined, and an OAM optical fiber isolator and an OAM optical fiber circulator which are low in cost, low in processing complexity, small in occupied size and excellent in performance are respectively realized through a special packaging process. The isolator and the circulator have the characteristics of low insertion loss, high isolation degree, high quality of a transmitted OAM mode and the like. The OAM optical fiber collimator, isolator and circulator realized by the invention can replace free space optical devices with consistent functions in systems such as an OAM mode optical fiber communication system, an OAM optical fiber amplifier and the like. The cost of the mode division multiplexing optical fiber communication system based on the OAM mode is reduced, the flexibility of the system is improved, and the method has important significance for promoting the practicability and miniaturization of the optical fiber communication system.

The invention provides a multi-core optical fiber type nine-mode mode division multiplexer with a high-refractive-index ring, and relates to the technical field of optical fiber communication. The multi-core optical fiber type nine-mode mode division multiplexer comprises a substrate material, a central few-mode fiber core and a peripheral single-mode side core, wherein the central few-mode fiber core and the peripheral single-mode side core are positioned in the substrate material; the central few-mode fiber core comprises a fiber core substrate and a high-refractive-index ring located in the fiber core substrate, and the axis of the fiber core substrate coincides with the axis of the high-refractive-index ring; the peripheral single-mode side core comprises single-mode fiber cores which convert an LP21a mode, an LP31a mode, an LP12 mode, an LP02 mode, an LP11b mode, an LP21b mode, an LP11a mode and an LP31b mode to the central few-mode fiber core, and the single-mode fiber cores are sequentially distributed on the periphery of the central few-mode fiber core. The signal transmission quality and stability can be improved.