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Emerging probing perspective of two-dimensional materials physics:terahertz emission spectroscopy

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Light(science & Applications) 2024年第7期13卷 1278-1298页

作者： Yifei Wu Yuqi Wang Di Bao Xiaonan Deng Simian Zhang Lin Yu-chun Shengxian Ke Jianing Liu Yingjie Liu Zeli Wang Pingren Ham Andrew Hanna Jiaming Pan Xinyue Hu Zhengcao Li Ji Zhou Chen Wang State Key laboratory of New Ceramics and Fine Processing Key Laboratory of Advanced Materials of Ministry of EducationSchool of Materials Science and EngineeringTsinghua University100084 BeijingChina Beijing Advanced Innovation Center for Integrated Circuits 100084 BeijingChina

Terahertz(THz)emission spectroscopy(TES)has emerged as a highly effective and versatile technique for investigating the photoelectric properties of diverse materials and nonlinear physical processes in the past few ***,research on two-dimensional(2D)materials has experienced substantial growth due to their atomically thin structures,exceptional mechanical and optoelectronic properties,and the potential for applications in flexible electronics,sensing,and ***,these materials offer advantages such as tunable bandgap,high carrier mobility,wideband optical absorption,and relatively short carrier *** applying TES to investigate the 2D materials,their interfaces and heterostructures,rich information about the interplay among photons,charges,phonons and spins can be unfolded,which provides fundamental understanding for future *** it is timely to review the nonlinear processes underlying THz emission in 2D materials including optical rectification,photon-drag,high-order harmonic generation and spin-to-charge conversion,showcasing the rich diversity of the TES employed to unravel the complex nature of these *** applications based on THz emissions,such as THz lasers,ultrafast imaging and biosensors,are also *** further,we analyzed the unique advantages of spintronic terahertz emitters and the future technological advancements in the development of new THz generation mechanisms leading to advanced THz sources characterized by wide bandwidth,high power and integration,suitable for industrial and commercial *** continuous advancement and integration of TES with the study of 2D materials and heterostructures promise to revolutionize research in different areas,including basic materials physics,novel optoelectronic devices,and chips for post-Moore’s era.

关键词： optoelectronic versatile exceptional

Retrospective and prospective review of the generalized nonlinear strength theory for geomaterials

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International Journal of Minerals,Metallurgy and Materials 2024年第8期31卷 1767-1787页

作者： Shunchuan Wu Jiaxin Wang Shihuai Zhang Shigui Huang Lei Xia Qianping Zhao Faculty of Land Resource Engineering Kunming University of Science and TechnologyKunming 650093China Key laboratory of Geohazard Forecast and Geoecological Restoration in Plateau Mountainous Area MNRKunming 650093China Yunnan Key laboratory of Geohazard Forecast and Geoecological Restoration in Plateau Mountainous Area Kunming 650093China School of Earth and Space sciences University of Science and Technology of ChinaHefei 230026China School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China

Strength theory is the basic theory for calculating and designing the strength of engineering materials in civil,hydraulic,mechanical,aerospace,military,and other engineering ***,the comprehensive study of the generalized nonlinear strength theory(GNST)of geomaterials has significance for the construction of engineering rock *** paper reviews the GNST of geomaterials to demonstrate the research status of nonlinear strength characteristics of geomaterials under complex stress ***,it systematically summarizes the research progress of GNST(classical and empirical criteria).Then,the latest research the authors conducted over the past five years on the GNST is introduced,and a generalized three-dimensional(3D)nonlinear Hoek‒Brown(HB)criterion(NGHB criterion)is proposed for practical *** criterion can be degenerated into the existing three modified HB criteria and has a better prediction *** strength prediction errors for six rocks and two in-situ rock masses are 2.0724%-3.5091%and 1.0144%-3.2321%,***,the development and outlook of the GNST are expounded,and a new topic about the building strength index of rock mass and determining the strength of in-situ engineering rock mass is *** summarization of the GNST provides theoretical traceability and optimization for constructing in-situ engineering rock mass strength.

关键词： rock mechanics rock mass strength strength theory failure criterion Hoek-Brown criterion intermediate principal stress deviatoric plane smoothness and convexity

Application of the Conditional nonlinear Local Lyapunov Exponent to Second-Kind Predictability

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Advances in Atmospheric sciences 2024年第9期41卷 1769-1786页

作者： Ming ZHANG Ruiqiang DING Quanjia ZHONG Jianping LI Deyu LU State Key laboratory of Earth Surface Processes and Resource Ecology(ESPRE)/Key laboratory of Environmental Change and Natural Disasters of Chinese Ministry of EducationBeijing Normal UniversityBeijing 100875China Department of Ocean science Hong Kong University of Science and TechnologyHong KongChina College of Oceanic and Atmospheric sciences/Frontiers science Center for Deep Ocean Multispheres and Earth System(DOMES)/Key laboratory of Physical Oceanography Ministry of Education/Academy of the Future Ocean/Center for Ocean Carbon NeutralityOcean University of ChinaQingdao 266100China Laoshan laboratory Qingdao 266237China State Key laboratory of Numerical Modeling for Atmospheric sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth science University of Chinese Academy of SciencesBeijing 100049China

In order to quantify the influence of external forcings on the predictability limit using observational data,the author introduced an algorithm of the conditional nonlinear local Lyapunov exponent(CNLLE)*** effectiveness of this algorithm is validated and compared with the nonlinear local Lyapunov exponent(NLLE)and signal-to-noise ratio methods using a coupled Lorenz *** results show that the CNLLE method is able to capture the slow error growth constrained by external forcings,therefore,it can quantify the predictability limit induced by the external *** this basis,a preliminary attempt was made to apply this method to measure the influence of ENSO on the predictability limit for both atmospheric and oceanic variable *** spatial distribution of the predictability limit induced by ENSO is similar to that arising from the initial conditions calculated by the NLLE *** similarity supports ENSO as the major predictable signal for weather and climate *** addition,a ratio of predictability limit(RPL)calculated by the CNLLE method to that calculated by the NLLE method was *** RPL larger than 1 indicates that the external forcings can significantly benefit the long-term predictability *** instance,ENSO can effectively extend the predictability limit arising from the initial conditions of sea surface temperature over the tropical Indian Ocean by approximately four months,as well as the predictability limit of sea level pressure over the eastern and western Pacific ***,the impact of ENSO on the geopotential height predictability limit is primarily confined to the troposphere.

关键词： conditional nonlinear local Lyapunov exponent second-kind predictability coupled Lorenz model ENSO

Absence of metallicity and bias-dependent resistivity in low-carrier-density EuCd_(2)As_(2)

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science China(Physics,Mechanics & Astronomy) 2024年第4期67卷 119-125页

作者： Yuxiang Wang Jianwen Ma Jian Yuan Wenbin Wu Yong Zhang Yicheng Mou Jiaming Gu Peihong Cheng Wu Shi Xiang Yuan Jinglei Zhang Yanfeng Guo Cheng Zhang State Key laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing Fudan UniversityShanghai 200433China School of Physical science and Technology ShanghaiTech UniversityShanghai 201210China State Key laboratory of Precision Spectroscopy East China Normal UniversityShanghai 200241China Anhui Province Key laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field Laboratory of the Chinese Academy of SciencesHefei 230031China School of Physics and Electronic science East China Normal UniversityShanghai 200241China Zhangjiang Fudan International Innovation Center Fudan UniversityShanghai 201210China ShanghaiTech laboratory for Topological Physics Shanghai 201210China

EuCd_(2)As_(2)was theoretically predicted to be a minimal model of Weyl semimetals with a single pair of Weyl points in the ferromagnet ***,the heavily p-doped Eu Cd_(2)As_(2)crystals in previous experiments prevent direct identification of the semimetal ***,we present a comprehensive magneto-transport study of high-quality Eu Cd_(2)As_(2)crystals with ultralow bulk carrier density(10^(13)cm^(-3)).In contrast to the general expectation of a Weyl semimetal phase,Eu Cd_(2)As_(2)shows insulating behavior in both antiferromagnetic and ferromagnetic states as well as surface-dominated conduction from band ***,the application of a dc bias current can dramatically modulate the resistance by over one order of magnitude,and induce a periodic resistance oscillation due to the geometric *** nonlinear transport results from the high nonequilibrium state induced by an electrical field near the band *** results suggest an insulating phase in Eu Cd_(2)As_(2)and put a strong constraint on the underlying mechanism of anomalous transport properties in this system.

关键词： magnetic Weyl semimetal quantum transport Hall effect nonlinear resistivity

Extremum seeking control for UAV close formation flight via improved pigeon-inspired optimization

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science China(Technological sciences) 2024年第2期67卷 435-448页

作者： YUAN GuangSong DUAN HaiBin State Key laboratory of Virtual Reality Technology and Systems School of Automation Science and Electrical EngineeringBeihang University(BUAA)Beijing 100083China

This paper proposes a comprehensive design scheme for the extremum seeking control(ESC)of the unmanned aerial vehicle(UAV)close formation *** proposed design scheme combines a Newton-Raphson method with an extended Kalman filter(EKF)to dynamically estimate the optimal position of the following UAV relative to the leading *** reflect the wake vortex effects reliably,the drag coefficient induced by the wake vortex is considered as a performance ***,the performance function is parameterized by the first-order and second-order terms of its Taylor series *** the excellent performance of nonlinear estimation,the EKF is used to estimate the gradient and the Hessian matrix of the parameterized performance *** output feedback of the proposed scheme is determined by iterative calculation of the Newton-Raphson *** with the traditional ESC and the classic ESC,the proposed design scheme avoids the slow continuous time integration of the *** allows a faster convergence of relative position ***,the proposed method can provide a smoother command during the seeking process as the second-order term of the performance function is taken into *** convergence analysis of the proposed design scheme is accomplished by showing that the output feedback is a supermartingale *** improve estimation performance of the EKF,a improved pigeon-inspired optimization(IPIO)is proposed to automatically tune the noise covariance *** Carlo simulations for a three-UAV close formation show that the proposed design scheme is robust to the initial position of the following UAV.

关键词： unmanned aerial vehicle close formation extremum seeking control Newton-Raphson method improved pigeon-inspired optimization

Breaking the efficiency limitations of dissipative Kerr solitons using nonlinear couplers

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science China(Physics,Mechanics & Astronomy) 2024年第3期67卷 88-94页

作者： Ming Li Xiao-Xiao Xue Yan-Lei Zhang Xin-Biao Xu Chun-Hua Dong Guang-Can Guo Chang-Ling Zou CAS Key laboratory of Quantum Information University of Science and Technology of ChinaHefei 230026China CAS Centerfor Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China Department of Electronic Engineering Beijing National Research Center for Information Science and TechnologyTsinghua University Beijing 100084China

Dissipative Kerr solitons(DKS) have long been suffering from poor power conversion efficiency when driven by continuous-wave lasers. By deriving the critical coupling condition of a multimode nonlinear optics system in a generalized theoretical framework,two efficiency limitations of the conventional pump method of DKS are revealed: the effective coupling rate is too small and is also power-dependent. A general approach is provided to resolve this challenge by introducing two types of nonlinear couplers to couple the soliton cavity and CW input through nonlinear processes. The collective coupler opens multiple coupling channels and the self-adaptive coupler builds a power-independent effective external coupling rate to the DKS for approaching the generalized critical coupling condition, which promises near-unity power conversion efficiencies. For instance, a conversion efficiency exceeding 90% is predicted for aluminum nitride microrings with a nonlinear coupler utilizing second-harmonic generation. The mechanism applies to various nonlinear processes, including Raman and Brillouin scattering, and thus paves the way for micro-solitons toward practical applications.

关键词： Kerr frequency comb conversion efficiency nonlinear coupler

nonlinear optics of two-dimensional heterostructures

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Frontiers of physics 2024年第3期19卷 19-27页

作者： Xiangkun Zeng Chenyu Wan Zhichen Zhao Di Huang Zhanshan Wang Xinbin Cheng Tao Jiang MOE Key laboratory of Advanced Micro-Structured Materials Shanghai Frontiers Science Center of Digital OpticsInstitute of Precision Optical Engineeringand School of Physics Science and EngineeringTongji UniversityShanghai 200092China Shanghai Institute of Intelligent science and Technology Tongji UniversityShanghai 200092China

Two-dimensional (2D) materials exhibit exceptionally strong nonlinear optical responses, benefiting from their reduced dimensionality, relaxed phase-matching requirements, and enhanced light-matter interaction. With additional degrees of freedom in the modulation of the physical properties by stacking 2D layers together, nonlinear optics of 2D heterostructures becomes increasingly fascinating. In this perspective, we provide a brief overview of recent advances in the field of nonlinear optics of 2D heterostructures, with a particular focus on their remarkable capabilities in characterization and modulation. Given the recent advances and the emergence of novel heterostructures, combined with innovative tuning knobs and advanced nonlinear optical techniques, we anticipate deeper insights into the underlying mechanisms and more associated applications in this rapidly evolving field.

关键词： nonlinear optics 2D heterostructures

Large and nonlinear electric field response in a two-dimensional ferroelectric Rashba material

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中国科学技术大学学报 2024年第6期54卷 8-11,21,I0009页

作者： Li Sheng Xiaomin Fu Chao Jia Xingxing Li Qunxiang Li Key laboratory of Precision and Intelligent Chemistry University of Science and Technology of ChinaHefei 230026China Department of Chemical Physics University of Science and Technology of ChinaHefei 230026China Hefei National Research Center for Physical sciences at the Microscale University of Science and Technology of ChinaHefei 230026China Hefei National laboratory University of Science and Technology of ChinaHefei 230088China

The achievement of electrical spin control is highly *** promising strategy involves electrically mod-ulating the Rashba spin orbital coupling effect in materials.A semiconductor with high sensitivity in its Rashba constant to external electric fields holds great potential for short channel lengths in spin field-effect transistors,which is crucial for preserving spin coherence and enhancing integration ***,two-dimensional(2D)Rashba semiconductors with large Rashba constants and significant electric field responses are highly ***,by employing first-principles calculations,we design a thermodynamically stable 2D Rashba semiconductor,YSbTe_(3),which possesses an indirect band gap of 1.04 eV,a large Rashba constant of 1.54 eV·Åand a strong electric field response of up to 4.80 e·Å^(2).In particular,the Rashba constant dependence on the electric field shows an unusual nonlinear *** the same time,YSbTe_(3)has been identified as a 2D ferroelectric material with a moderate polarization switching energy barrier(~0.33 eV per formula).By changing the electric polarization direction,the Rashba spin texture of YSbTe_(3)can be *** out-standing properties make the ferroelectric Rashba semiconductor YSbTe_(3)quite promising for spintronic applications.

关键词： computational chemistry Rashba effect ferroelectrics spintronics

nonlinear Multimodal Interference as Ultrafast Photonic Device for Dual-Wavelength Domain-Wall Dark Pulse Generation

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Chinese Physics Letters 2024年第7期41卷 47-52页

作者：王珊宋博乐窦鑫河乔飞鸿李响王锦波吕志国 School of Physical science and Technology Key Laboratory of Semiconductor Photovoltaic Technology of Inner Mongolia Autonomous RegionInner Mongolia UniversityHohhot 010021China

In comparison to bright pulses, better stability that is not susceptible to loss makes dark pulses accessible for applications in such fields as signal processing, optics sensing, and quantum communication. Here we investigate the dual-wavelength domain-wall dark pulse generation in a graded-index multimode fiber(GIMF) based anomalous dispersion single-mode fiber(SMF) laser. By optimizing intra-cavity nonlinearity and pulse polarization, the mode-locked states can evolve each other between bright pulses, dark pulses, and bright-dark pulse pairs. The evolution mechanism among them may be relevant to the coherent mode superposition, spectral filtering, and mode selection in SMF-GIMF-SMF hybrid-fiber modulation devices that affect the pulse formation and evolution in temporal, frequency, and space domains. These results provide a valuable reference for promoting further development of nonlinear optics and ultrafast optics, in which ultrafast photonic devices, with low cost, simple manufacture as well as wide adaptability, as novel pulsed generation technique, play a vital role.

关键词： fiber polarization optics