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Finite-time Mittag-Leffler synchronization of fractional-order delayed memristive neural networks with parameters uncertainty and discontinuous activation functions

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Chinese Physics B 2020年第4期29卷 127-138页

作者： Chong Chen Zhixia Ding Sai Li Liheng Wang Hubei Key Laboratory of Optical Information and Pattern Recognition School of Electrical and Information EngineeringWuhan Institute of TechnologyWuhan 430205China

The finite-time Mittag-Leffler synchronization is investigated for fractional-order delayed memristive neural networks(FDMNN)with parameters uncertainty and discontinuous activation *** relevant results are obtained under the framework of Filippov for such ***,the novel feedback controller,which includes the discontinuous functions and time delays,is proposed to investigate such ***,the conditions on finite-time Mittag-Leffler synchronization of FDMNN are established according to the properties of fractional-order calculus and inequality analysis *** the same time,the upper bound of the settling time for Mittag-Leffler synchronization is accurately *** addition,by selecting the appropriate parameters of the designed controller and utilizing the comparison theorem for fractional-order systems,the global asymptotic synchronization is achieved as a ***,a numerical example is given to indicate the correctness of the obtained conclusions.

关键词： fractional-order delayed memristive neural networks(FDMNN) parameters uncertainty discontinuous activation functions finite-time Mittag-Leffler synchronization

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Finite-time Mittag-Leffler synchronization of fractional-order complex-valued memristive neural networks with time delay

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Chinese Physics B 2022年第10期31卷 297-306页

作者： Guan Wang Zhixia Ding Sai Li Le Yang Rui Jiao Hubei Key Laboratory of Optical Information and Pattern Recognition School of Electrical and Information EngineeringWuhan Institute of TechnologyWuhan 430205China

Without dividing the complex-valued systems into two real-valued ones, a class of fractional-order complex-valued memristive neural networks(FCVMNNs) with time delay is investigated. Firstly, based on the complex-valued sign function, a novel complex-valued feedback controller is devised to research such systems. Under the framework of Filippov solution, differential inclusion theory and Lyapunov stability theorem, the finite-time Mittag-Leffler synchronization(FTMLS) of FCVMNNs with time delay can be realized. Meanwhile, the upper bound of the synchronization settling time(SST) is less conservative than previous results. In addition, by adjusting controller parameters, the global asymptotic synchronization of FCVMNNs with time delay can also be realized, which improves and enrich some existing results. Lastly,some simulation examples are designed to verify the validity of conclusions.

关键词： finite-time Mittag-Leffler synchronization fractional-order complex-valued memristive neural networks time delay

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Non-uniform Strong Noise Removal Method of Non-cooperative Mine Target Image 7

Non-uniform Strong Noise Removal Method of Non-cooperative M...

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7th International Conference on information Science and Control Engineering, ICISCE 2020

作者： Wu, Shikang Shi, Yu Wu, Jinmeng Hubei Key Laboratory of Optical Information and Pattern Recognition

ISBN: (纸本)9781728164069

The detection of mine targets will be interfered by the underwater non-uniform strong noise (organic matter, suspended particles, etc). To solve this problem, the paper proposes a novel denoising method. Firstly, a new optimization filtering algorithm LEP-EPC is proposed based on the local edge-preserving (LEP) filtering algorithm. A spatially adaptive edge perception constraint regularization term is introduced into the model to better represent the edges and details of the image, so that the edge-preserving and smoothing property of the algorithm is better. Secondly, the paper uses multi-scale strategy to solve the non-uniformity of strong noise, iteratively applies the LEP-EPC algorithm to the noise removal results of each scale to generate multi-scale decomposition, and gradually increases the denoising scale in the process of multi-scale decomposition. The strong noise of different scales is gradually separated from the mine targets image. The experimental results show that the proposed algorithm can remove the underwater non-uniform strong noise while retaining the mine target information, which also has a certain guiding significance for mine operation. © 2020 IEEE.

关键词： Iterative methods

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Optimized Spectral Purity of Heralded Single Photons at the Telecom O-Band

arXiv

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arXiv 2025年

作者： Cai, Wu-Hao Baek, Soyoung Jin, Rui-Bo Kaneda, Fumihiro Graduate School of Science Tohoku University 6-3 Aramaki Aza-Aoba Sendai980-8578 Japan Research Institute of Electrical Communication Tohoku University 2-1-1 Katahira Sendai980-8577 Japan Hubei Key Laboratory of Optical Information and Pattern Recognition Wuhan Institute of Technology Wuhan430205 China PRESTO Japan Science and Technology Agency Kawaguchi332-0012 Japan

We report on optimizing the spectral purity of heralded single photons in the telecom O-band, where single photons can be propagated with low loss and low dispersion in a standard telecom optical fiber. We numerically searched for various group-velocity-matching conditions and corresponding optimal poling structures of a potassium titanyl phosphate crystal for spontaneous parametric downconversion. Our poling optimization results using phase-matching coherence-length and sub-coherence-length modulation schemes show > 99.4% spectral purity with pump wavelengths ranging from 603.8 nm to 887.3 nm. Some optimized configurations are feasible with off-the-shelf lasers and single-photon detectors. Moreover, by investigating noise photon spectra for different poling optimization methods, we show that, in practice, appropriate, gentle spectral filtering helps achieve high purity. This study will pave the way for developing practical quantum sources for quantum information applications at the telecom O-band. © 2025, CC BY.

关键词： optical fibers

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"Molecular waveplate" for the control of ultrashort pulses carrying orbital angular momentum

arXiv

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arXiv 2025年

作者： Xu, Chengqing He, Lixin Tao, Wanchen Zhu, Xiaosong Wang, Feng Xu, Long Xu, Lu Lan, Pengfei Averbukh, Ilya Prior, Yehiam Lu, Peixiang Wuhan National Laboratory for Optoelectronics School of Physics Huazhong University of Science and Technology Wuhan430074 China Hubei Key Laboratory of Optical Information and Pattern Recognition Wuhan Institute of Technology Wuhan430205 China Department of Physics Xiamen University Xiamen361005 China AMOS Department of Chemical and Biological Physics The Weizmann Institute of Science Rehovot7610001 Israel Department of Chemistry University of British Columbia VancouverBCV6T 1Z1 Canada

Ultrashort laser pulses carrying orbital angular momentum (OAM) have become essential tools in Atomic, Molecular, and optical (AMO) studies, particularly for investigating strong-field light-matter interactions. However, controlling and generating ultrashort vortex pulses presents significant challenges, since their broad spectral content complicates manipulation with conventional optical elements, while the high peak power inherent in short-duration pulses risks damaging optical components. Here, we introduce a novel method for generating and controlling broadband ultrashort vortex beams by exploiting the non-adiabatic alignment of linear gas-phase molecules induced by vector beams. The interaction between the vector beam and the gas-phase molecules results in spatially varying polarizability, imparting a phase modulation to a probe laser. This process effectively creates a tunable "molecular waveplate" that adapts naturally to a broad spectral range. By leveraging this approach, we can generate ultrashort vortex pulses across a wide range of wavelengths. Under optimized gas pressure and interaction length conditions, this method allows for highly efficient conversion of circularly polarized light into the desired OAM pulse, thus enabling the generation of few-cycle, high-intensity vortex beams. This molecular waveplate, which overcomes the limitations imposed by conventional optical elements, opens up new possibilities for exploring strong-field physics, ultrafast science, and other applications that require high-intensity vortex beams. Copyright © 2025, The Authors. All rights reserved.

关键词： Molecules

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Fixed-time synchronization of fractional-order complex-valued delayed neural networks with discontinuous activation functions

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Neural Computing and Applications 2024年第26期36卷 15947-15959页

作者： Ding, Zhixia Wang, Jianhao Li, Sai Yang, Le Wang, Liheng School of Electrical and Information Engineering Wuhan Institute of Technology Wuhan430205 China Hubei Key Laboratory of Optical Information and Pattern Recognition Wuhan430205 China

This article concentrates on the fixed-time synchronization (FXTS) of fractional-order complex-valued delayed neural networks with discontinuous activation functions. On the basis of the nonsmooth analysis, differential inclusion theory, Lyapunov stability theorem and complex function theory, some sufficient conditions are developed to guarantee the FXTS of such system by designing a novel fractional-order complex-valued controller. The fixed-time synchronization can make up the limitation of the previous finite-time synchronization results, that is, fixed-time synchronization time relies on the parameters of controller, which is independent of initial values. Additionally, the upper limit of synchronization time is estimated accurately. Furthermore, our results improve some finite-time synchronization and fixed-time synchronization ones. Finally, the effectiveness of theoretical results is demonstrated by some numerical simulations. © The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature 2024.

关键词： Chemical activation

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Yield enhancement of elliptical high harmonics driven by bicircular laser pulses

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Chinese Physics B 2022年第11期31卷 358-363页

作者： Xiaofan Zhang Xiaosong Zhu Hubei Key Laboratory of Optical Information and Pattern Recognition Wuhan Institute of TechnologyWuhan 430205China Wuhan National Laboratory for Optoelectronics and School of Physics Huazhong University of Science and TechnologyWuhan 430074China

We theoretically investigate the yield enhancement of elliptical high harmonics in the interaction of molecules with bicircular laser pulses by solving the time-dependent Schrodinger *** is shown that by adjusting the relative intensity ratio of the two bicircular field components in specific ranges the yield of the molecular high harmonics for the plateau and cutoff regions can be respectively *** analyze this enhancement phenomenon,we calculate the weights of the electron classical ***,we also study the ellipticity distribution of harmonics for different intensity *** find that these enhanced harmonics are elliptically polarized,which we mainly attribute to the recombination dipole moment of the major weighted *** enhanced elliptical extreme ultraviolet and soft x-ray radiations may serve as essential tools for exploring the ultrafast dynamics in magnetic materials and chiral media.

关键词： high harmonics extreme ultraviolet and soft x-ray bicircular laser pulses

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Probing the launching position of the electron wave packet in molecule strong-field tunneling ionization

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Science China(Physics,Mechanics & Astronomy) 2021年第7期64卷 82-90页

作者： Yueming Zhou Jia Tan Min Li Peixiang Lu School of Physics and Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan430074China Hubei Key Laboratory of Optical Information and Pattern Recognition Wuhan Institute of TechnologyWuhan430205China

Strong-field tunneling ionization is the first step for a broad class of phenomena in intense laser-atom/molecule interactions. Accurate information about the electron wave packet from strong-field tunneling ionization of atoms and molecules is of essential importance for understanding various tunneling ionization triggered processes. Here, we survey the property of the electron wave packet in tunneling ionization of molecules with a method based on strong-field photoelectron holography. By solving the time-dependent Schr ¨odinger equation, it is shown that the holographic interference in the photoelectron momentum distribution exhibits the asymmetric behavior with respect to the laser polarization direction, when the molecule is aligned with a nonzero angle to the linearly polarized laser field. We demonstrate that this asymmetry is due to the nonzero initial transverse displacement of the electron wave packet at tunneling. By analyzing the holographic interference, this transverse displacement for the launching of electron wave packet tunneling from the molecules is accurately retrieved. This displacement is directly related to the electron density distribution in molecules, and thus our work developed a novel concept for probing electronic structure in molecules.

关键词： strong-field tunneling ionization photoelectron holography attosecond dynamics

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Probing time delay of strong-field resonant above-threshold ionization

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Chinese Physics B 2021年第1期30卷 215-220页

作者： Shengliang Xu Qingbin Zhang Cheng Ran Xiang Huang Wei Cao Peixiang Lu School of Physics and Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory of Optical Information and Pattern Recognition Wuhan Institute of TechnologyWuhan 430205China

The high-resolution three-dimensional photoelectron momentum distributions via above-threshold ionization(ATI)of Xe atoms are measured in an intense near circularly polarized laser field using velocity map imaging and tomography reconstruction. Compared to the linearly polarized laser field, the employed near circularly polarized laser field imposes a more strict selection rule for the transition via resonant excitation, and therefore we can selectively enhance the resonant ATI through certain atomic Rydberg states. Our results show the self-reference ionization delay, which is determined from the difference between the measured streaking angles for nonadiabatic ATI via the 4 f and 5 f Rydberg states, is 45.6 as. Our method provides an accessible route to highlight the role of resonant transition between selected states, which will pave the way for fully understanding the ionization dynamics toward manipulating electron motion as well as reaction in an ultrafast time scale.

关键词： above threshold ionization resonant ionization delay transition selection rule

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Study of the 6.x nm short wavelength radiation spectra of laser-produced erbium plasmas for BEUV lithography

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Plasma Science and Technology 2023年第6期25卷 41-51页

作者：吴涛王倩陈柳安陆培祥 Hubei Key Laboratory of Optical Information and Pattern Recognition School of Optical Information and Energy EngineeringWuhan Institute of TechnologyWuhan 430205People's Republic of China Guangdong Intelligent Robotics Institute Dongguan 523808People's Republic of China

Beyond extreme ultraviolet(BEUV)radiation with a wavelength of 6.x nm for lithography is responsible for reducing the source wavelength to enable continued miniaturization of semiconductor *** this work,the Required BEUV light at 6.x nm wavelength was generated in dense and hot Nd:YAG laser-produced Er *** spectral contributions from the 4p–4d and 4d–4f transitions of singly,doubly and triply excited states of Er XXIV–Er XXXII in the BEUV band were calculated using Cowan and the Flexible Atomic *** was also found that the radiative transitions between multiply excited states dominate the narrow wavelength window around 6.x *** the assumption of collisional radiative equilibrium of the laser-produced Er plasmas,the relative ion abundance in the experiment was *** the Boltzmann quantum state energy level distribution and Gram–Charlier fitting function of unresolved transition arrays(UTAs),the synthetic spectrum around 6.x nm was finally obtained and compared with the experimental *** spatio-temporal distributions of electron density and electron temperature were calculated based on radiation hydrodynamic simulation in order to identify the contributions of various ionic states to the UTAs arising from the Er plasmas near 6.x nm.

关键词： laser-produced plasmas unresolved transition array collisional radiative equilibrium

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