20 results about "Mode purity" patented technology

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 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 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 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.

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 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 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.

The invention discloses a programmable structured optical fiber laser and a modulation method in the technical field of lasers, the laser is based on the combination of intracavity mode dynamic shaping and time domain optical field regulation, a wavefront shaper is embedded in a resonant cavity, phase distribution of the wavefront shaper is controlled through programming, phase modulation is performed on intracavity laser, and the optical fiber is obtained. Stable output of continuous laser and pulse laser of structured light is achieved. A wavefront phase loaded by the wavefront shaper is regulated and controlled by adopting a phase compensation algorithm, and a Gaussian beam is recovered from a light field of a generated structured light part and returns to a cavity for continuous oscillation. According to the scheme, the inevitable problems of mode degradation, light beam quality reduction and energy loss of traditional out-of-cavity shaping are avoided, and the light beam quality factor and the mode purity of the output structured light are remarkably improved. According to the laser, the two functions of laser generation and structured light modulation are integrated in a compact system, various structured light patterns are dynamically generated, and any device does not need to be replaced.

The invention discloses a distributed feedback type laser chip based on buried heterojunction and a preparation method, and relates to the technical field of semiconductor devices, the chip comprises a substrate and an epitaxial layer arranged on the substrate, the epitaxial layer comprises a buffer layer, a lower waveguide layer, a lower limiting layer, an active region, an upper limiting layer, an upper waveguide layer and a buried layer; the epitaxial layer comprises an MESA high platform so as to realize laser output of the optical waveguide; the chip further comprises an N-face electrode layer, a grating layer and a P-face electrode layer, and a conductive path is formed to screen laser modes. Wherein the buried layer comprises a grating buried layer, a heterojunction buried layer and a top buried layer, the grating buried layer is used for burying the grating into the chip, the heterojunction buried layer is used for burying the MESA high platform into the chip, and the top buried layer is doped with Zn and is in contact with the P-surface electrode layer. According to the invention, the problems of low single-mode purity and large optical signal loss caused by weak constraint of a conventional laser chip on a light field and carriers and light field leakage are solved.

The invention discloses an OAM mode multiplication and division operation method and system based on an optical diffraction neural network, and relates to the field of orbital angular momentum. Digital signals are represented through OAM mode coding, any 2n times of digital multiplication / division operation can be achieved, the operation function has the advantages of being high in expandability, flexible, controllable and the like, and the method and system can be applied to the field of orbital angular momentum. A basic framework is expected to be established for complex arithmetic operation in a high-dimensional optical space, and a potential solution is provided for practical application of optical digital calculation; the OAM mode serves as an operation physical dimension, mode parallel independent transformation is completed through the optical diffraction neural network to achieve OAM mode numerical value shifting, and therefore digital multiplication / division operation is completed, and the obtained output array has high mode purity.

The invention provides a staggered-ring cladding hollow-core anti-resonance optical fiber and a manufacturing method thereof, and belongs to the technical field of optical fibers. The optical fiber comprises a fiber core area formed by air, a plurality of anti-resonance tube units periodically arranged around the fiber core area, and a protective outer cladding covering the outside. Each anti-resonance tube unit comprises an outer cladding tube, a polygonal star-shaped inner supporting structure arranged in the outer cladding tube, and capillary tubes arranged in sub-regions divided by the inner supporting structure. The manufacturing method mainly comprises the following steps: preparing anti-resonance tube unit preforms, assembling and consolidating a plurality of unit preforms into a composite preform, carrying out wire drawing molding on the composite preform, coating the composite preform with a protective outer cladding, and the like. Accurate positioning and spatial arrangement of the capillary tubes are realized through the star-shaped inner support structure, and a strong and uniform anti-resonance interface can be constructed around the fiber core, so that the transmission bandwidth and the mode purity of the optical fiber are remarkably improved.

The application relates to the technical field of electromagnetic ultrasonic nondestructive testing, and discloses a design method of an electromagnetic ultrasonic excitation probe. The method obtains an initial electromagnetic model of the probe and a multi-frequency electromagnetic response spectrum of a material to be detected, constructs a medium coupling function according to the initial model, and performs electromagnetic field remapping on the initial model to form a probe energy distribution image. An energy imbalance area in the image is identified, a structural defect vector is established, and the structural defect vector is decomposed into a spatial position component and an energy intensity component. Magnetic circuit correction instructions are generated according to the spatial position component, and coil excitation compensation instructions are generated according to the energy intensity component. The probe after the instructions are executed is subjected to electromagnetic characteristic iteration simulation until the energy imbalance area is eliminated, and finally, optimized probe design parameters are generated. Through material response and model remapping, decoupling and accurate compensation of the defect vector, the probe energy distribution is optimized, and the mode purity of ultrasonic guided waves and the detection signal-to-noise ratio are improved.

The invention relates to a micro-hemispherical resonator gyroscope driving device based on cavity light force, which is applied to the technical field of micro-optical electro-mechanical systems (MOEMS) and high-precision gyroscopes, and aims to solve the problems that the excitation intensity of a second-order wine-cup-shaped working mode is difficult to further improve due to the limitation of an electrode gap in the conventional electrostatic push-pull driven micro-hemispherical resonator gyroscope; the existing cavity light force driven micro-hemisphere gyroscope has the problems of poor second-order mode excitation symmetry and large amplitude fluctuation. According to the invention, multi-path symmetrical optical push-pull driving is adopted, the second-order working mode of the micro-hemispherical harmonic oscillator can be efficiently and purely excited, and the driving efficiency and the mode purity are increased by magnitude compared with a single-path driving scheme; and a phase-locked loop injection-locking mechanism is used to suppress frequency cracking, and high-precision and high-stability detection of the angular velocity signal is finally realized.

The application relates to the technical field of resonant cavities, in particular to a powder material dielectric property separation type cylindrical resonant cavity based on a quasi-optical 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 in a cylindrical structure, the material of the sample bin is flexible polytetrafluoroethylene, magnetic attraction points are respectively arranged on the top and the bottom of the sample bin, 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 in a cylindrical structure, a heat insulation sleeve is arranged on the surface of the lower cavity, and a wave-absorbing material layer is attached to the inner wall of the lower cavity; the diamond coating has superhard characteristics and extremely low surface roughness, can significantly reduce the scattering loss of electromagnetic waves on the inner wall of the cavity, can quickly dissipate the heat generated by electromagnetic energy in the cavity, and can inhibit the influence of temperature fluctuation on the Q value; the cavity is divided into three parts, i.e. an upper part, a middle part and a lower part, and is connected through the magnetic attraction points to form a modular quasi-optical cavity, and in combination with the wave-absorbing material layer and high-precision processing, single-mode purity can be realized.

One or more aspects of the present disclosure include coating the inside of an overmoded, smooth wall metallic waveguide with a thin dielectric layer. Coating the inside of a waveguide with a dielectric layer, as described in more detail herein, may result in similar boundary conditions to corrugated waveguides and may achieve extremely low transmission loss (e.g., propagating the HE11 mode). Such dielectric lined waveguides are an efficient (e.g., cost-effective) alternative to corrugated waveguides (e.g., for broadband microwave transmission, particularly at frequencies above 300 GHz). The systems and techniques described herein may improve hybrid electric mode purity (e.g., HE11 mode purity of approximately 98%). Dielectric lined waveguides described herein may have applications in many fields demanding low attenuation millimeter and terahertz transmission (e.g., such as radar, high-frequency communication systems, THz dynamic nuclear polarization, electron cyclotron heating in magnetically confined fusion experiments, etc.).