44 results about "Mode purity" patented technology

The invention discloses an anti-turbulence free space optical communication method based on receiving and transmitting joint optimization, which balances the code length and the code rate through a Polar coding mode of an atmospheric turbulence channel, and ensures the coding and decoding overhead; meanwhile, a Transform model based on convolution enhancement is designed at a receiving end, learning of local features is enhanced through convolution, the relation between phase screen pixels is established, and a conjugate phase screen is given by the model for turbulence compensation. In order to solve the problem that in a free space optical transmission system, the atmospheric turbulence effect interferes with an OAM light beam, the influence of atmospheric turbulence interference on free space optical communication is relieved in a mode of joint optimization of the receiving end and the transmitting end. Error codes caused by atmospheric turbulence are corrected through Polar coding of the transmitting end, and the coupling efficiency of receiving light spots is improved after phase compensation of the receiving end, so that the mode purity obtained by corrected light spot images is improved, and the error rate of the system is reduced.

The invention relates to the technical field of semiconductor lasers, in particular to a DFB laser based on a top metal grating, and the DFB laser comprises a gain chip, the left end face of the gain chip is plated with a high-reflection HR film, and the right end face of the gain chip is plated with an anti-reflection AR film; the upper end face of the gain chip is provided with a ridge optical waveguide, and the upper end face of the ridge optical waveguide is provided with a metal Bragg reflection grating layer. A self-heterodyne interference method (the line width of a local oscillator is smaller than 500 Hz) is adopted, and the measured value of the 3dB line width is 50 Hz (the measured value of a traditional DFB is 125 kHz). The mode purity degree is verified through a Lorenzian fitting broadening factor 1.15; the wavelength drift is less than 0.05 pm / DEG C within the range of-40 DEG C to 85 DEG C after compensation of the temperature compensation circuit. The temperature tuning coefficient is 0.08 pm / DEG C, the current tuning coefficient is 0.05 pm / mA, and the tuning coverage range is 1530-1545 nm.

The invention discloses an underwater vortex optical communication anti-turbulence method based on a photoelectric hybrid deep neural network, and the method comprises the steps: carrying out the all-optical information compression at a front end through the diffraction deep neural network through the fusion of a diffraction deep neural network and a convolutional neural network, and transmitting the processed information to a rear end of the convolutional neural network, a model task is completed through training, a predicted coefficient of a Zernike polynomial is output, prediction and compensation of ocean turbulence are achieved, and the mode purity of vortex beams is improved. The front-end diffraction deep neural network is utilized to effectively improve the problem that the rear-end convolutional neural network is difficult to process massive information, the photoelectric hybrid deep neural network model is high in integration, high in operation speed and accurate in light field signal processing, the power overhead for achieving turbulence resistance through the machine learning technology is saved, operation is easy, implementation is easy, and the method is suitable for popularization and application. The method has a wide application prospect in the aspects of vortex beam underwater communication and the like.

The present disclosure provides a mode control system and method for controlling an output mode of a broadband light source including a photonic crystal fiber (PCF). The mode control system includes: at least one detection unit configured to measure one or more parameters of radiation emitted from a broadband light source to generate measurement data; and a processing unit configured to evaluate the mode purity of the radiation emitted from the broadband light source from the measurement data. Based on the evaluation, the mode control system is configured to generate a control signal for optimizing one or more pump coupling conditions of the broadband light source. The pump coupling condition relates to the coupling of a pump laser beam with respect to an optical fiber core of the photonic crystal fiber.

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 cylindrical vector optical fiber amplifier based on a rotary conical optical fiber. The cylindrical vector optical fiber amplifier comprises a cylindrical vector optical seed source; an isolator, a beam combiner, a rotary conical optical fiber and a cladding light pumping stripper are sequentially arranged in the column vector light transmission direction of the column vector light seed source, and a first pumping source is further welded to the input end of the beam combiner. The rotary conical optical fiber is adopted as the gain optical fiber, the stability of light polarization can be effectively kept in the cylindrical vector light amplification process, the sensitivity to temperature is reduced, and meanwhile the mode purity is improved.

The invention relates to the technical field of optical fiber devices, and provides a hollow-core optical fiber power beam combiner, which comprises an optical fiber bundle and a hollow-core optical fiber, and is characterized in that the optical fiber bundle is formed by tapering and bunching n solid-core optical fibers; the input end of the optical fiber bundle is an optical fiber bundle large-head end, the output end of the optical fiber bundle is an optical fiber bundle small-head end, one of n solid optical fibers in the optical fiber bundle is located in the center and serves as a central optical fiber, and the rest n-1 optical fibers are distributed around the central optical fiber in a center surrounding mode; the hollow-core optical fiber is a nested anti-resonance hollow-core optical fiber and sequentially comprises an outer cladding layer, nested rings and a hollow-core area from inside to outside, and n-1 nested rings are distributed around the periphery of the hollow-core area; laser of the input optical fiber bundle is input into the hollow-core optical fiber through the small end of the optical fiber bundle, and long-distance transmission of the laser is achieved through the hollow-core optical fiber. The device is simple and compact in structure and high in coupling efficiency, can well maintain the mode purity of the light beam, and has great application value and potential advantages for high-power long-distance transmission of the fiber laser.

A laser transmission optical cable based on a hollow-core anti-resonance optical fiber is suitable for flexible transmission of ultrafast laser, and comprises an input laser beam, and a first optical window, a first air chamber, a first water chamber, a hollow-core capillary optical fiber, a hollow-core anti-resonance optical fiber, a second water chamber, a second air chamber and a second optical window which are sequentially arranged along the beam transmission direction, the hollow-core capillary optical fiber and the hollow-core anti-resonance optical fiber are glued to form a nested structure, and the ratio of the diameter of a cladding capillary of the hollow-core anti-resonance optical fiber to the diameter of a fiber core of the hollow-core anti-resonance optical fiber is 0.63-0.68. The hollow-core anti-resonance optical fiber has high single-mode purity, the problem that a laser mode is coupled to a high-order mode due to mechanical disturbance such as optical fiber bending and twisting can be solved, the hollow-core anti-resonance optical fiber has higher adaptability in a complex processing environment, the laser processing efficiency and stability are improved, and the optical fiber is suitable for large-scale production. And meanwhile, the influence of a heat effect under high power and a nonlinear effect caused by air in an ultrafast laser transmission process are considered.

The invention provides an all-fiber polarization-maintaining vortex light amplification system. The all-fiber polarization-maintaining vortex light amplification system comprises a polarization-maintaining seed laser output system, a polarization-maintaining mode conversion device, a fiber polarization controller, a mode matcher, a pumping signal beam combiner, a laser diode light source group, a few-mode polarization-maintaining ytterbium-doped fiber, a cladding mode filter and a water cooling plate. High-power and high-stability vortex light beam output is realized through an all-fiber structure, and a laser mode field of incident laser is controlled through the fiber polarization controller, so that eigenvector modes are superposed to generate a vortex light field; meanwhile, the amplified high-power vortex light field is output through the few-mode polarization-maintaining ytterbium-doped optical fiber, crosstalk between modes can be reduced through the few-mode polarization-maintaining ytterbium-doped optical fiber, the problem of polarization purity and mode purity degradation in the power amplification process is solved, and therefore high-power vortex light field output is achieved.

The invention discloses an OAM vortex communication system device and method of a silicon-based photon integrated micro-ring resonator array, and belongs to the technical field of wireless communication of the Internet of Things. The system comprises a silicon-based photon integrated micro-ring resonator array, and ultra-compact OAM beam generation is realized through thermo-optical tuning; according to the lightweight channel compensation architecture, a dual-branch DNN model is combined with NV color center quantum sensing to realize phase noise real-time calibration; and dynamic regulation and control of a heterogeneous multi-user access mechanism and fusion AI drive. The method solves the problems of beam divergence, channel time-varying sensitivity and multi-user interference of a traditional OAM technology in an Internet of Things scene, the mode purity under the millimeter wave (28GHz) frequency band reaches 99% or above, and the method is suitable for intensive Internet of Things scenes such as industry 4.0, automatic driving and intelligent agriculture.

The application relates to a mode filter, a topology optimization method and an ultrasonic guided wave damage imaging artifact suppression method, relates to the field of ultrasonic detection and imaging, and the topology optimization method comprises the following steps: acquiring initial design parameters, generating an initial population, each chromosome individual in the initial population is coded by a binary logic matrix representing material distribution and meeting design constraints; a population is optimized by using a genetic algorithm, an adaptability function in the genetic algorithm is constructed based on a mode purity index and an energy transmission index, the mode purity index is the ratio of in-plane displacement integral in a transmission area in finite element simulation with the mode filter to total displacement integral, and the energy transmission index is the ratio of relative energy at a transmission end in the finite element simulation with the mode filter to relative energy of an S0 mode; and final optimized material distribution of the mode filter is output. Compared with the prior art, the application has the advantages of effectively suppressing background artifacts, giving consideration to mode regulation performance and substrate structure integrity and the like.

This invention proposes a complex optical system based on deep feature decoupling and an autonomous alignment and diagnostic method. The system includes a resonant cavity support system, a spot data acquisition system, and a preprocessing system. The method includes acquiring transmitted and reflected spot data from an F-P resonant cavity to construct a training dataset; preprocessing the training dataset to generate an average intensity projection feature map; inputting the average intensity projection feature map into a neural network feature decoupling and inference model to derive multi-degree-of-freedom adjustment parameters, achieving a fundamental mode purity of a first preset threshold; switching to an orthogonal serialized one-dimensional linear scanning fine-tuning mode, optimizing and locking extreme points dimension by dimension, achieving a fundamental mode purity of a second preset threshold, and completing closed-loop alignment; based on the adjustment data and principal component analysis, decoupling the system's sensitive dimensions, and outputting the optical system's sensitivity diagnostic results. This invention can diagnose the most sensitive and easily imbalanced key parts of the system, providing theoretical guidance for subsequent system maintenance and adjustment.

The present application relates to the technical field of acoustic metamaterials, and specifically relates to a multi-order asymmetric acoustic vortex generator and a generation method based on acoustic metamaterials, which comprises a phased structure I, a phased structure II, a three-dimensional mirror structure, a three-dimensional cylindrical waveguide base, a signal input structure and a quantitative evaluation structure; the phased structure I, the phased structure II and the three-dimensional mirror structure are coaxially arranged in the three-dimensional cylindrical waveguide base in sequence, the phased structure I and the phased structure II are sound wave incidence ends, and the three-dimensional mirror structure is a sound wave transmission end; the other end of the three-dimensional cylindrical waveguide base is provided with the quantitative evaluation structure, which is used for detecting the generation quality of the multi-order asymmetric acoustic vortex, and can realize the asymmetric generation of-2~+2 order acoustic vortexes in a wideband range, and has the characteristics of high mode purity, high acoustic energy transmission efficiency and structural integration, so as to solve the difficulties faced by the prior art in the collaborative realization of multi-order, wideband and asymmetric acoustic vortexes.

The application discloses an anti-turbulence free space optical communication method based on transceiving joint optimization, through a Polar coding mode of an atmospheric turbulence channel, balance code length and code rate, ensure the overhead of coding and decoding; at the same time, a convolution enhanced Transformer model is designed at the receiving end, the learning of local features is strengthened through convolution, and the connection between phase screen pixels is established, and the conjugate phase screen is given by the model to compensate the turbulence. The application aims at the problem that the atmospheric turbulence effect disturbs the OAM light beam in the free space optical transmission system, and utilizes the joint optimization mode of the transmitting end and the receiving end to relieve the influence of the atmospheric turbulence disturbance on the free space optical communication. After the Polar coding of the transmitting end corrects the error code caused by the atmospheric turbulence, and the phase compensation of the receiving end, the coupling efficiency of the received light spot is improved, so that the mode purity of the corrected light spot image is improved, and the system error rate is reduced.

The application discloses a mode purity measurement method of a few-mode ring core fiber based on principal component prior information. First, all spatial modes supported by the few-mode ring core fiber to be measured are calculated to determine the highest order; second, a nonlinear equation set connecting the fiber output intensity mode spot and the complex amplitude of each spatial mode is listed, and an algorithm for solving the equation set by using the principal component order prior information is designed, so that the recovery of the complex amplitude of each mode and the measurement of the principal component mode purity are realized. Then, an optical device for detecting the fiber exit mode field is built. For the fiber near-field intensity mode spot at any time, the prior information of the principal component order is obtained through an interference pattern or the shape of the intensity mode spot, and the measurement of the mode purity can be realized by applying the above-mentioned algorithm. The application can accurately recover the mode purity of the few-mode ring core fiber from the fiber output near-field intensity mode spot only, and has strong applicability.

The present invention discloses a system and method for exchanging multiplexed orbital angular momentum modes based on controllable unitary transformation, comprising: a multiplexed pattern generation module for generating multiple coaxially transmitted multiplexed orbital angular momentum modes; a pattern exchange module for performing mode conversion between the multiple coaxially transmitted multiplexed orbital angular momentum modes; a pattern detection module for detecting the exchanged orbital angular momentum modes and outputting corresponding detection results; the pattern exchange module is arranged after the multiplexed pattern generation module and on the same optical axis as the multiplexed pattern generation module; and the pattern detection module is arranged after the pattern exchange module and on the same optical axis as the mode exchange module. The present invention can realize coaxial independent exchange of multiple input orbital angular momentum modes, and the exchanged modes have high mode purity. In addition, the mode coaxial exchange system has the characteristics of a large number of controllable modes, flexible functions, and independent modulation, and is suitable for all-optical mode information exchange in high-dimensional multiplexed communications.

The invention relates to a mode filter, a topological optimization method and an ultrasonic guided wave damage imaging artifact suppression method, and relates to the field of ultrasonic detection and imagines.The topological optimization method comprises the steps that initial design parameters are obtained, and an initial population is generated; each chromosome individual in the initial population is formed by coding a binary logic matrix which represents material distribution and meets design constraints; a genetic algorithm is adopted for population optimization, a fitness function in the genetic algorithm is constructed based on a mode purity index and an energy transmission index, and the mode purity index is a ratio of a transmission region in-plane displacement integral to a total displacement integral under finite element simulation added with a mode filter; the energy transmission index is a ratio of relative energy of a transmission end under finite element simulation added with a mode filter to relative energy of an S0 mode; and outputting the final optimized material distribution of the mode filter. Compared with the prior art, the method has the advantages that background artifacts are effectively inhibited, and the mode regulation and control performance and the matrix structure integrity are both considered.

The present invention relates to the field of satellite communication technologies, and discloses a method, a system, a device and a medium for evaluating the performance of an OAM inter-satellite optical communication system. The method includes: establishing an OAM inter-satellite optical communication system model to obtain the field strength distribution of the light beam emitted from the source satellite to the destination satellite under the influence of pointing error; representing the field strength distribution of the light beam under the influence of pointing error in the form of a spiral harmonic function expansion, and performing a radial integration on the expansion coefficients in the form of the spiral harmonic function expansion to obtain the energy of each OAM mode in the light beam; according to the energy of each OAM mode in the light beam and the total energy of the entire light beam, obtaining the purity of each OAM mode, and combining the purities of multiple OAM modes to construct a probability density function and a cumulative distribution function of the OAM mode purity in the OAM inter-satellite optical communication system, so as to evaluate the performance of the OAM inter-satellite optical communication system.

The invention discloses a method for calculating the mode purity of a high-quality factor TM010 over-mode cylindrical resonant cavity, and belongs to the field of electromagnetic field propagation. According to the method, structural details of a coupling hole, an end cover step and a fit clearance are covered in modeling; all possible competition modes are covered through functional region decomposition and electromagnetic field mode decomposition in combination with a mode excitation rule of an over-mode cavity; introducing power normalization processing, and establishing a unified amplitude comparison reference; based on the synergistic effect of scattering matrix cascading and electromagnetic field mode decomposition, the transmission, reflection and coupling processes of multiple modes in the cavity are completely described; according to the invention, the problems that only the mode purity of the port plane and the electromagnetic field distribution in the volume can be obtained and the mode purity of a specific mode in the volume of the resonant cavity cannot be accurately calculated in the prior art are solved; the method is applied to the core technologies of microwave communication, satellite load, particle acceleration, precision measurement and the like depending on high-quality factor resonant cavities to accurately calculate the TM010 mode purity in the volume of the resonant cavity.

A mode control system and method for controlling an output mode of a broadband radiation source including a photonic crystal fiber (PCF). The mode control system includes at least one detection unit configured to measure one or more parameters of radiation emitted from the broadband radiation source to generate measurement data, and a processing unit configured to evaluate mode purity of the radiation emitted from the broadband radiation source, from the measurement data. Based on the evaluation, the mode control system is configured to generate a control signal for optimization of one or more pump coupling conditions of the broadband radiation source. The one or more pump coupling conditions relate to the coupling of a pump laser beam with respect to a fiber core of the photonic crystal fiber.

The application relates to a rotating Doppler signal optimization method based on non-complete vortex light correction. Non-complete vortex beams are very common in actual rotating Doppler speed measurement, can be used for obtaining object parameters or carrying out rotating Doppler basic research, but the mode purity of the non-complete vortex beams is reduced due to diffraction in transmission, and the experimental results are affected. Based on the diffraction characteristics of vortex beams, a rotating Doppler signal optimization method based on non-complete vortex light correction is provided. First, a superposition state vortex light distribution carrying positive and negative topological charges is subjected to phase offset angles with equal size and opposite direction, and a corrected vortex beam is obtained. After transmitting for a certain distance, the deflection of the light beam can compensate the influence of diffraction, improve the mode purity, and improve the signal-to-noise ratio of the echo signal. The method is flexible and simple to operate, can effectively overcome the influence of diffraction, improve the speed measurement accuracy and speed detection distance, and has great application value in remote sensing detection.

The present invention relates to a terahertz vector vortex quantum cascade laser, comprising a substrate, a bonding metal layer located above the substrate, a seed laser region and a bus waveguide arranged along the length direction of the laser and connected to each other are arranged above the bonding metal layer, a resonant ring and a transition electrode arranged along the length direction of the laser and spaced apart from each other are arranged on one side of the bus waveguide, a metal air bridge is set between the resonant ring and the transition electrode, and an absorption boundary is set at the end of the seed laser region and the end of the bus waveguide. The present invention also provides a method for preparing a terahertz vector vortex quantum cascade laser, which can directly emit a terahertz vector vortex laser with a high mode purity, can realize a hollow annular far-field light spot, and the emitted vector vortex light can be decomposed into left-handed and right-handed circularly polarized light carrying orbital angular momentum, and the polarization characteristic is angular polarization, which has the advantages of high stability, high excitation efficiency, narrow line width, and high side mode suppression ratio.

The present invention relates to a terahertz scalar vortex quantum cascade laser, comprising a substrate and a bonding metal layer located above the substrate, wherein a seed laser region, a gradual amplification region, an insulating region, and an emission region are arranged in sequence along the length direction of the laser above the bonding metal layer, a first absorption region is provided on the side of the seed laser region opposite to the gradual amplification region, and a second absorption region is provided on the surrounding side of the emission region; the width of the gradual amplification region gradually increases from the seed laser region to the insulating region, and the width of the insulating region gradually increases from the gradual amplification region to the emission region. The present invention also provides a method for preparing a terahertz scalar vortex quantum cascade laser, which can directly emit a terahertz scalar vortex laser with a high mode purity, can realize a hollow annular far-field light spot, and the phase is spirally carried with orbital angular momentum, can realize a specific topological charge, and has linear polarization characteristics, high stability, high excitation efficiency, narrow line width, and high side mode suppression ratio.

The invention relates to the technical field of resonant cavities, in particular to a quasi-optical cavity-based powder material dielectric property separation type cylindrical resonant cavity, which comprises a box body, an upper cavity, a sample bin and a lower cavity are arranged in the box body, the upper cavity is of a cylindrical structure, the sample bin is made of flexible polytetrafluoroethylene, the top and the bottom of the sample bin are respectively provided with a magnetic attraction point, and the magnetic attraction points are arranged in the lower cavity. The top of the sample bin is magnetically connected with the upper cavity, and the bottom of the sample bin is magnetically connected with the lower cavity; the lower cavity is of a cylindrical structure, the surface of the lower cavity is sleeved with a heat insulation sleeve, and a wave-absorbing material layer is attached to the inner wall of the lower cavity. The diamond coating has a superhard characteristic and extremely low surface roughness, so that the scattering loss of electromagnetic waves on the inner wall of the cavity is remarkably reduced, heat generated by electromagnetic energy in the cavity can be quickly dissipated, and the influence of temperature fluctuation on a Q value is inhibited; the cavity is divided into an upper part, a middle part and a lower part which are connected through magnetic attraction points to form a modular quasi-optical cavity, and the single-mode purity can be achieved by combining the wave-absorbing material layer and high-precision machining.

The present invention relates to a device and method for directly generating a vortex laser in a cavity based on a spiral phase plate, belonging to the field of lasers. The device comprises a sequentially arranged pump source, a pump light coupling mirror, and a laser resonant cavity. The pump light coupling mirror comprises a first convex lens and a second convex lens, and the laser resonant cavity comprises an input coupling mirror, a gain medium, a third convex lens, and an output coupling mirror, which are sequentially arranged. The output coupling mirror directly utilizes a spiral phase plate, whose optical thickness is proportional to the azimuthal rotation and whose surface exhibits a spiral staircase structure. By adjusting the laser, the device can output a high-purity LG mode vortex laser. The device has a simpler and more direct structure and offers higher output power and improved mode purity.

The invention provides a self-adaptive separation and enhancement method for ultrasonic guided wave multi-mode signals, and relates to the technical field of nondestructive detection.The method comprises the steps that a baseline state voucher is established and verified, comprehensive baseline reliability is obtained by calculating voucher validity, maturity and stability, and the quality of reference data is ensured; thirdly, calculating mode purity, an energy attenuation mismatch coefficient and a signal structure complexity entropy based on the physical relevance of the real-time signal so as to quantify the intrinsic conformity of the real-time signal; then, constructing a dynamic working condition base line matched with the current working condition, and calculating an environment working condition deviation degree representing a real-time signal deviation degree by applying a mahalanobis distance; and finally, taking the environment working condition deviation degree, the baseline reliability and the like as state input, and outputting an optimal self-adaptive enhancement strategy and a pipe section integrity evaluation result by the reinforcement learning model. Through step-by-step quantitative evaluation and intelligent decision making, dynamic adaptive adjustment of a signal processing strategy is realized.

The invention discloses a pre-correction network-based coherent synthesis vortex beam wavefront aberration prediction method, and relates to the technical field of vortex beam waves. According to the method, light spot data of a laser phased array system under different turbulence conditions are collected, a deep neural network model is trained through the data to extract features from input historical wavefront data, the future wavefront distortion condition is predicted, and the accuracy and robustness of the model are verified through a large amount of simulation and experimental data; real-time phase modulation is implemented on the basis of the predicted wavefront distortion condition, the lag problem of an existing phase control system is solved, it is ensured that the generated vortex light beam keeps high-quality mode purity in the transmission process, and finally, required experimental data are generated based on an SLM system for testing so as to verify the accuracy of a model.

The present application relates to a kind of super large mode field area multicore optical fiber, and the fiber core is made of multiple doped silica high refractive index round core.By changing the number of the multicore optical fiber core, core refractive index, core radius and core to cladding center distance, the mode field area of optical fiber, dispersion, OAM mode purity, nonlinear coefficient and other optical properties can be adjusted.Under the parameter structure proposed in the present application, in 1500-1600nm waveband, the optical fiber can support 10 OAM mode transmission, and the effective refractive index difference of different order OAM mode is all in 10 ‑4 Above, meet OAM mode stable transmission condition, and the mode field area of each OAM mode is all in 3160 μm 2 Above.At 1550nm, the purity of each OAM mode that the optical fiber can support transmission is all above 99.9%, and the nonlinear coefficient is less than 0.032 W ‑1 / km, and dispersion is between 22-24ps / nm / km.The multicore optical fiber proposed in the present application has super large mode field area, high purity, low dispersion and other characteristics, and has potential application value in OAM optical fiber communication system and high-power OAM optical fiber laser.

The invention discloses an on-chip orbital angular momentum mode generation method based on a sub-wavelength structure. The method comprises the following steps: step 1, designing an in-plane waveguide OAM mode generator; 2, generating and designing an OAM + / -1 mode in the waveguide; and step 3, generating and designing an OAM + / -2 mode in the waveguide. Based on superposition of several basic modes supported in the waveguide and independent of resonance of a specific wavelength, a calculation result shows that the transmission efficiency of the OAM + / -1 mode is always kept at 92% or above and the mode purity is always kept at a high level of 90% or above in an ultra-wide spectrum range from 1335 nm to 1800 nm, which means that the device can cover a plurality of communication wavebands to work and has a wide application prospect. And the information transmission capacity and the spectrum utilization rate of the system-on-chip can be improved. By designing a subwavelength space refractive index modulation light field structure which is finely optimized in the waveguide, high-quality generation of an OAM mode in an on-chip waveguide plane is realized.

This application provides a single-mode vertical-cavity surface-emitting laser (VCSEL) with dual-gradient photonic crystal synergistic modulation, relating to the field of laser technology. The laser, from bottom to top, comprises an n-type substrate, a bottom monolayer graded photonic crystal layer, an n-type DBR layer, an active region, a p-type DBR layer, an interlayer isolation layer, a top bilayer heterogeneous graded photonic crystal layer, and an electrode structure. Through radial synergistic modulation of the bottom aperture, lattice constant, and aperture depth, and the top heterogeneous bilayer photonic crystal, it achieves high-order mode suppression and fundamental mode stabilization enhancement, balancing high power output and single-mode stability under a large aperture structure. This improves the mode purity and manufacturing compatibility of the single-mode VCSEL over a wide temperature and current range, and also exhibits excellent environmental adaptability and batch process consistency.