Fracture-cave reservoirs in carbonate rocks are characterized by a large difference in fracture and cavity size,and a sharp variation in lithology and velocity,thereby resulting in complex diffraction responses.Some s...Fracture-cave reservoirs in carbonate rocks are characterized by a large difference in fracture and cavity size,and a sharp variation in lithology and velocity,thereby resulting in complex diffraction responses.Some small-scale fractures and caves cause weak diffraction energy and would be obscured by the continuous reflection layer in the imaging section,thereby making them difficult to identify.This paper develops a diffraction wave imaging method in the dip domain,which can improve the resolution of small-scale diffractors in the imaging section.Common imaging gathers(CIGs)in the dip domain are extracted by Gaussian beam migration.In accordance with the geometric differences of the diffraction being quasilinear and the reflection being quasiparabolic in the dip-domain CIGs,we use slope analysis technique to filter waves and use Hanning window function to improve the diffraction wave separation level.The diffraction dip-domain CIGs are stacked horizontally to obtain diffraction imaging results.Wavefield separation analysis and numerical modeling results show that the slope analysis method,together with Hanning window filtering,can better suppress noise to obtain the diffraction dip-domain CIGs,thereby improving the clarity of the diffractors in the diffraction imaging section.展开更多
We discuss the nonlinear Schr6dinger equation with variable coefficients in 21） graded-index waveguides with different distributed transverse diffractions and obtain exact bright and dark soliton solutions. Based on ...We discuss the nonlinear Schr6dinger equation with variable coefficients in 21） graded-index waveguides with different distributed transverse diffractions and obtain exact bright and dark soliton solutions. Based on these solutions, we mainly investigate the dynamical behaviors of solitons in three different diffraction decreasing waveguides with the hyperbolic, Gaussian and Logarithmic profiles. Results indicate that for the same parameters, the amplitude of bright solitons in the Logarithmic profile and the amplitude of dark solitons in the Gaussian profile are biggest respectively, and the amplitude in the hyperbolic profile is smallest, while the width of solitons has the opposite case.展开更多
Owing to the formal analogy between their governing equations,concepts from electromagnetic wave physics have been successfully extended to water-wave systems.Here,we propose and experimentally demonstrate the water-w...Owing to the formal analogy between their governing equations,concepts from electromagnetic wave physics have been successfully extended to water-wave systems.Here,we propose and experimentally demonstrate the water-wave metagratings(WMGs)capable of wavefront modulation based on the generalized Snell’s law.These WMGs generate anomalous diffraction,including both retroreflection and negative refraction,by engineering the integer parity of supercells.As a proof of concept,we realize broadband water-wave focusing using WMGs.This work opens new avenues for compact and tunable water-wave devices,with potential applications in wave-energy harvesting and marine engineering.展开更多
Electrically driven structural patterns in liquid crystals(LCs)have attracted considerable attention due to their electrooptical applications.Here,we disclose various appealing reconfigurable LC microstructures in a d...Electrically driven structural patterns in liquid crystals(LCs)have attracted considerable attention due to their electrooptical applications.Here,we disclose various appealing reconfigurable LC microstructures in a dual frequency nematic LC(DFNLC)owing to the electroconvection-induced distortion of the LC director,including one-dimensional rolls,chevron pattern,two-dimensional grids,and unstable chaos.These patterns can be switched among each other,and the lattice constants are modulated by tuning the amplitude and frequency of the applied electric field.The electrically switchable self-assembled microstructures and their beam steering capabilities thus provide a feasible way to tune the functions of DFNLC-based optical devices.展开更多
A set of coupled wave equations of acoustooptic diffraction with multiple acoustic waves along different directions is put forward and its solutions are derived. The characteristics of the diffraction efficiency, com ...A set of coupled wave equations of acoustooptic diffraction with multiple acoustic waves along different directions is put forward and its solutions are derived. The characteristics of the diffraction efficiency, com -pression, cross modulation, and intermodulation intensities are analyzed theoretically. The theoretical results are supported by experimental measurements through our new multiple directional acoustooptic devices.展开更多
The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing t...The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing to this multi-principal element nature,high-entropy alloys exhibit complex deformation behavior dominated by alternating and coupled deformation mechanisms.Therefore,elucidating these intricate deformation mechanisms remains a key challenge in current research.Neutron diffraction(ND)techniques offer distinct advantages over traditional microscopic methods for characterizing such complex deformation behavior.The strong penetration capability of neutrons enables in-situ,real-time,and non-destructive detection of structural evolution in most centimeter-level bulk samples under complex environments,and ND allows precise characterization of lattice site occupations for light elements,such as C and O,and neighboring elements.This review discussed the principles of ND,experiment procedures,and data analysis.Combining with recent advances in the research about face-centered cubic high-entropy alloy,typical examples of using ND to investigate the deformation behavior were summarized,ultimately revealing deformation mechanisms dominated by dislocations,stacking faults,twinning,and phase transformations.展开更多
We propose a novel fast numerical calculation method for the Rayleigh-Sommerfeld diffraction integral,which is developed based on the existing scaled convolution method.This approach enables fast cal-culations for gen...We propose a novel fast numerical calculation method for the Rayleigh-Sommerfeld diffraction integral,which is developed based on the existing scaled convolution method.This approach enables fast cal-culations for general cases of off-axis scenarios where the sampling intervals and numbers of the input and observation planes are unequal.Additionally,it allows for arbitrary adjustment of the sampling interval of the impulse response function,facilitating a manual trade-off between computational load and accuracy.The er-rors associated with this method,which is equivalent to interpolation,primarily arise from the discontinuities of the sampling matrix of the impulse response function on its boundaries of periodic extension.To address this issue,we propose the concept of the padding function and its construction method,and evaluate its ef-fectiveness in enhancing computational accuracy.The feasibility of the proposed method is verified by nu-merical simulation and compared with the direct integration DI-method in a simplified scenario.It shows that the proposed method has good computational accuracy for the general case where the sampling interval of the input and observation plane is not equal under non-near-field diffraction,and when the diffraction distance is large,although the computational accuracy of the proposed method cannot exceed that of the DI-method,the computational amount can be significantly reduced with almost no effect on the computational accuracy.This method provides a general numerical calculation scheme of diffraction in the non-near field case for areas such as computational holography.展开更多
Optical phase-gradient metasurfaces have garnered significant attention for enabling flexible light manipulation,with applications across diverse domains.In this work,we will demonstrate that the metasurfaces with pha...Optical phase-gradient metasurfaces have garnered significant attention for enabling flexible light manipulation,with applications across diverse domains.In this work,we will demonstrate that the metasurfaces with phase gradient modulation can be used to achieve illusion optics,featuring the advantages of simple geometric structure and feasible implementation compared with the well-known transformation optics method.The underlying mechanism is the anomalous diffraction law caused by the phase gradient,which provides a theoretical basis for freely manipulating the propagation path of light.By considering a specific example,we will demonstrate that the phase gradient can transform spatial coordinates in real space into illusion space,thereby converting a plane in real space into a curved surface structure in illusion space to achieve the illusion effect.This approach provides a viable alternative to transformation optics for designing illusion devices.展开更多
Ultra-thin glass(UTG)possesses a broad spectrum of applications in high-end electronic devices,such as foldable smartphones and flexible displays.Laser beam shaping for arc cutting UTG screens helps reduce stress conc...Ultra-thin glass(UTG)possesses a broad spectrum of applications in high-end electronic devices,such as foldable smartphones and flexible displays.Laser beam shaping for arc cutting UTG screens helps reduce stress concentration,thereby effectively enhancing their safety and longevity.However,the existing three-dimensional(3D)holography algorithms in beam shaping often suffer from high computational complexity and limited flexibility.To address these issues,we propose an iterative holographic algorithm combined with 3D chirp-z transform(3D-CZT)that generates 3D designable multi-foci with 90%light field uniformity.It also effectively corrects spherical aberration caused by refractive index mismatches,while maintaining precise beam shaping throughout the material.Moreover,by focusing on a specific region,the 3D-CZT method reduces the single iteration time to 0.5 seconds,achieving a speed one order of magnitude faster than conventional algorithms.On this basis,customizable glass-edge cutting by shaping the 3D-focused beam within the material is achieved.The glass edge demonstrates high geometric fidelity and remains smooth,mitigating the risk of micro-cracks.This work proposes a sophisticated and efficient methodology for the laser cutting of transparent materials.展开更多
Head-up displays(HUDs)are emerging as key components of intelligent vehicles,requiring wide-depth,large-area,and high-efficiency dynamic imaging,which remains difficult to realize with traditional refractive optics.Co...Head-up displays(HUDs)are emerging as key components of intelligent vehicles,requiring wide-depth,large-area,and high-efficiency dynamic imaging,which remains difficult to realize with traditional refractive optics.Computer-generated holography(CGH)with diffraction optics offers a promising solution to these technical demands.However,CGH optimization based on the fast Fourier transform(FFT)faces limitations such as zero-padding redundancy,coupled sampling intervals,and incompatible near-and farfield propagation models.Here,we report a holography-based multiplane HUD using a matrix multiplication(MM)-assisted diffraction algorithm that restructures the Fresnel integral into two sequential matrix operations,thus eliminating zero-padding and enabling fully decoupled sampling between object and image planes.Compared with FFT-based angular spectrum methods,the MM approach significantly improves computational speed and memory efficiency for hologram design,which is validated by demonstrating dual-plane holography with a size ratio exceeding 100:1 and unified reconstruction across Fresnel and Fraunhofer regimes within a single computation.A prototype HUD system is demonstrated successfully to exhibit multiple-plane holographic virtual images that can be mixed with real-world objects at three independent planes.The technique might be one of the potential candidates for next-generation intelligent vehicle displays.展开更多
Speckle-based optical cryptosystems are promising technologies for information security.However,existing techniques mostly rely on digital decryption,resulting in computational delay and undermining the high-speed adv...Speckle-based optical cryptosystems are promising technologies for information security.However,existing techniques mostly rely on digital decryption,resulting in computational delay and undermining the high-speed advantage of optical encryption.Moreover,conventional neural networks are typically effective only on images from the same distribution as the training datasets,limiting their general applicability.In this paper,we propose an all-optical high-speed decryption scheme for real-time recovery of speckle-encoded ciphertexts.By constructing a physics-informed diffractive neural network that approximates the inverse transmission matrix of the scattering medium,secret images can be directly reconstructed from speckle fields without optoelectronic conversion or post-processing.The network is trained with only 2048 samples from the MNIST dataset.Its transfer learning capability is validated across three out-of-distribution datasets,with decrypted images achieving a Pearson correlation coefficient of 0.82 and a structural similarity index measure of 0.75,demonstrating excellent transfer learning capability.For the first time,to our knowledge,this scheme simultaneously overcomes the bottlenecks of decryption delay and limited network generalizability in conventional speckle-based cryptosystems,achieving real-time image decryption with strong transferability.It provides a new pathway for developing low-power,real-time,and broadly applicable optical encryption systems,demonstrating significant potential for applications in high-speed security optical communications.展开更多
Owing to their intricate molecular frameworks and copious chiral centers,the structural identification and configurational assignment of natural products are challenging tasks.Comprehensive spectral data analysis is c...Owing to their intricate molecular frameworks and copious chiral centers,the structural identification and configurational assignment of natural products are challenging tasks.Comprehensive spectral data analysis is crucial for the confirmation of absolute configurations.Ignoring critical parameters will lead to false structure,which may confuse the total synthesis and drug development.Herein,the configurations of seven heterogeneous Pallavicinia diterpenoids(PDs) isolated from Pallavicinia liverworts are revised using a combination of single-crystal X-ray diffraction and electronic circular dichroism(ECD) calculations.Meanwhile,identification of five unprecedented PD heterodimers PD-dimers A-E(18-22) along with eleven previously undescribed PDs(5-9,13-17,23) obtained by the reinvestigation of the Chinese liverwort Pallavicinia subciliata have resulted in corrections and support the revised conclusions.展开更多
Accurate temperature control and effective oxide removal are essential for achieving high-quality epitaxial growth in molecular beam epitaxy(MBE).However,traditional methods often rely on manual identification of refl...Accurate temperature control and effective oxide removal are essential for achieving high-quality epitaxial growth in molecular beam epitaxy(MBE).However,traditional methods often rely on manual identification of reflection high-energy electron diffraction(RHEED)patterns.This process is heavily influenced by the grower’s experience,leading to issues with reproducibility and limiting the potential for automation.In this report,we propose an unsupervised learning framework for realtime RHEED analysis during the deoxidation process.By incorporating temporal similarity constraints into contrastive learning,our model generates smooth and interpretable feature trajectories that illustrate transitions in the deoxidation state,thus eliminating the need for manual labeling.The model,pre-trained using grouped contrastive loss,shows significant improvement in RHEED feature boundary discrimination and localization of critical regions.We evaluated its generalizability through two transfer learning strategies:calibration-free clustering and few-shot fine-tuning.The pre-trained model achieved a clustering accuracy of 88.1%for GaAs deoxidation samples without additional labels and reached an accuracy of 94.3%to 95.5%after fine-tuning with just five sample pairs across GaAs,Ge,and InAs substrates.This framework is optimized for resource-constrained edge devices,allowing for real-time,plug-and-play integration with existing MBE systems and swift adaptation across various materials and equipment.This work paves the way for greater automation and improved reproducibility in semiconductor manufacturing.展开更多
High-precision optical frequency measurement serves as a cornerstone of modern science and technology,enabling advancements in fields ranging from fundamental physics to quantum information technologies.Obtaining prec...High-precision optical frequency measurement serves as a cornerstone of modern science and technology,enabling advancements in fields ranging from fundamental physics to quantum information technologies.Obtaining precise photon frequencies,especially in the ultraviolet or even extreme ultraviolet regimes,is a key goal in both light–matter interaction experiments and engineering applications.High-order harmonic generation(HHG)is an ideal light source for producing such photons.In this work,we propose an optical temporal interference model(OTIM)that establishes an analogy with multi-slit Fraunhofer diffraction(MSFD)to manipulate fine-frequency photon generation by exploiting the temporal coherence of HHG processes.Our model provides a unified physical framework for three distinct non-integer HHG generation schemes:single-pulse,shaped-pulse,and laser pulse train approaches,which correspond to single-MSFD-like,double-MSFD-like,and multi-MSFD-like processes,respectively.Arbitrary non-integer HHG photons can be obtained using our scheme.Our approach provides a new perspective for accurately measuring and controlling photon frequencies in fields such as frequency comb technology,interferometry,and atomic clocks.展开更多
Achieving extreme fast charging(XFC,-6 C)capability remains a challenge for Li ion batteries in electric vehicle applications.This work employs time-resolved X-ray diffraction(XRD)to investigate the structural evoluti...Achieving extreme fast charging(XFC,-6 C)capability remains a challenge for Li ion batteries in electric vehicle applications.This work employs time-resolved X-ray diffraction(XRD)to investigate the structural evolution and capacity contributions of a series of LiNi_(x)Co_(y)Mn_(z)O_(2)(x+y+z=1,NCM)cathodes under XFC conditions.All NCM cathodes(NCM-92,NCM-83,and NCM-622)deliver -60%of their capacities with less than 2%unit cell volume expansion during the H1-H2 phase transition,but the subsequent H2-H3 phase transition exhibits significant compositional and rate dependence.The NCM-92 cathode shows a maximum d-spacing shrinkage of-5.3%at 6 C,which is larger than that of NCM-83(-4.1%)and NCM-622(-0.05%).Furthermore,NCM-92 follows a“phase heterogeneity”pathway for its structural evolution above 4.2 V,distinct from the“solid-solution”pathway observed in NCM-83 and NCM-622.This phase heterogeneity is evidenced by the splitting of the(003)diffraction peak and a decrease in intensity during the H2-H3 phase transition,indicating the formation of lithium-rich/depleted domains.These findings establish a direct correlation between cathode composition,structural dynamics,and XFC performance,highlighting a critical trade-off between structural stability and fast-charging capability in nickel-rich layered oxides.展开更多
To overcome the limitations of traditional single-crystal X-ray diffraction(SCXRD)for microcrystalline materials and the peak-overlapping issue of powder X-ray diffraction(PXRD),this study employed cryogenic continuou...To overcome the limitations of traditional single-crystal X-ray diffraction(SCXRD)for microcrystalline materials and the peak-overlapping issue of powder X-ray diffraction(PXRD),this study employed cryogenic continuous rotation electron diffraction(cryo-cRED)with a low-dose strategy to determine the crystal structure of CL30,a novel silicogermanate framework.It is confirmed that CL30 crystallizes in the C2/m space group and has layered topology composed of discontinuous zigzag chains connected by double four-membered ring(d4r)units,with fluoride anions(F^(-))occluded in the d4r units.In CL30,charge balance involves organic structure-directing agent(OSDA)cations,occluded F^(-),and terminal oxygen sites whose protonation state cannot be established from the present three dimensional(3D)ED data.F^(-)encapsulated in the d4r units contributes to charge compensation as the counter-anion to OSDA cations,rather than only balancing the framework charge.Although the refinement indices(R_(1)=0.29,wR_(2)=0.71)exceeded typical small-molecule crystallography standards,the structural model remained highly reliable,as supported by geometric restraints and validation.In electron diffraction,elevated R_(1) values are commonly attributed to the intrinsic factors of the technique,such as dynamic scattering,detector noise from scintillator-based detectors,and TEM stage instability(large spheres of confusion).This study introduces a new structural prototype to the silicogermanate family and establishes a feasible workflow for determining the structures of radiation-sensitive microcrystalline porous materials.展开更多
This paper examines the effect of Fe addition on the microstructure characterized by scanning electron microscopy/electron backscattered diffraction,neutron diffraction,and synchrotron X-ray tomography and the mechani...This paper examines the effect of Fe addition on the microstructure characterized by scanning electron microscopy/electron backscattered diffraction,neutron diffraction,and synchrotron X-ray tomography and the mechanical properties of Al-Mg-Mn-Fe-Cu alloys.The findings reveal that the microstructures of the alloys consisted of an Al matrix,Al_(6)(FeMn),and Al_(2)CuMg phase particles.The addition of Fe significantly increased the yield strength(YS),and ultimate tensile strength(UTS)of the alloys,while reducing elongation.The transformation of the 3D morphology of the Al_(6)(FeMn)phase from separated and fine particles with Chinese-script morphology to interconnected rod-like structure as Fe content increased from 0.1%to 0.8%.This strengthening effect was attributed to the slip lines being blocked at the vicinity of the inter-connected Fe-rich phase,leading to grain rotation and dislocation density increment around the Fe-rich phase,ultimately improving the strength of the alloys.However,the Fe-rich phases and Al_(2)CuMg phases were found to be prone to cracking under tensile stress,resulting in decreased elongation of the alloys.This study provides a potential application in the design and manufacturing of new non-heat-treatable Al alloys for the automotive industry.展开更多
Chemical investigation of the marine-derived fungus Chaetomium globosum HBU-45 led to the discovery of chaeglobol A(1).Its structure was determined by spectroscopic analysis,computational electronic circular dichroism...Chemical investigation of the marine-derived fungus Chaetomium globosum HBU-45 led to the discovery of chaeglobol A(1).Its structure was determined by spectroscopic analysis,computational electronic circular dichroism(ECD)/optical rotatory dispersion(ORD)methods,and X-ray crystallography.Compound 1 represents a new skeleton with an uncommon 6/6/6/5/6/5/6/5 octacyclic system,which is presumably biosynthesized via a[4+2]cycloaddition and an enzymatic cyclization.Chaeglobol A(1)exhibited inhibitory activity against B.dothidea by destroying cell membrane integrity and causing oxidative damage within the cells.展开更多
We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW...We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW structure interacts with a weak probe laser field,a spatially independent 2D standing-wave(SW)field,and a Laguerre–Gaussian(LG)vortex field,respectively.The results indicate that the diffraction patterns are highly sensitive to amplitude modulation and phase modulation.Because of the existence of vortex light,it is possible to realize asymmetric high-order diffraction in the SQW structure,and then a 2D asymmetric grating is established.By adjusting the detunings of the probe field,vortex field,and SW field,as well as the interaction length,diffraction intensity,and direction of the 2D asymmetric electromagnetically induced grating(EIG)can be controlled effectively.In addition,the number of orbital angular momenta(OAM)and beam waist parameter can be used to modulate the diffraction intensity and energy transfer of the probe light in different regions.High-order diffraction intensity is enhanced and high-efficiency 2D asymmetric diffraction grating with different diffraction patterns is obtained in the scheme.Such 2D asymmetric diffraction grating may be beneficial to the research of optical communication and innovative semiconductor quantum devices.展开更多
Two novel out-of-plane ordered quaternary borides M'_(4)VSiB_(2) (M'=Nb and Mo) have been synthesized. The out-of-plane ordered characteristic has been confirmed by the X-ray diffraction, the neutron powder di...Two novel out-of-plane ordered quaternary borides M'_(4)VSiB_(2) (M'=Nb and Mo) have been synthesized. The out-of-plane ordered characteristic has been confirmed by the X-ray diffraction, the neutron powder diffraction and the scanning transmission electron microscopy with high-angle angular dark field images. By adjusting the stoichiometric ratio of Mo and V, the 16l site preferentially occupied by relatively larger atom and 4c site by relatively smaller atom have been confirmed. The further first-principle calculation demonstrates the dynamical and thermodynamical stability of Mo_(4)VSiB_(2) o-T2 phase. This work confirms the transition metal occupation strategy of o-T2 phase and enriches the out-of-plane ordered laminated borides family.展开更多
基金funded jointly by the National Natural Science Foundation of China(No.41104069)Shandong Province Higher Educational Science and Technology Program(No.J17KA197)+1 种基金Open Foundation of Shandong Provincial Key Laboratory of Depositional Mineralization&Sedimentary Minerals of Shandong University of Science and Technology(No.DMSM2018018)Chunhui Research Foundation of Shengli College,China University of Petroleum(No.KY2017007)。
文摘Fracture-cave reservoirs in carbonate rocks are characterized by a large difference in fracture and cavity size,and a sharp variation in lithology and velocity,thereby resulting in complex diffraction responses.Some small-scale fractures and caves cause weak diffraction energy and would be obscured by the continuous reflection layer in the imaging section,thereby making them difficult to identify.This paper develops a diffraction wave imaging method in the dip domain,which can improve the resolution of small-scale diffractors in the imaging section.Common imaging gathers(CIGs)in the dip domain are extracted by Gaussian beam migration.In accordance with the geometric differences of the diffraction being quasilinear and the reflection being quasiparabolic in the dip-domain CIGs,we use slope analysis technique to filter waves and use Hanning window function to improve the diffraction wave separation level.The diffraction dip-domain CIGs are stacked horizontally to obtain diffraction imaging results.Wavefield separation analysis and numerical modeling results show that the slope analysis method,together with Hanning window filtering,can better suppress noise to obtain the diffraction dip-domain CIGs,thereby improving the clarity of the diffractors in the diffraction imaging section.
基金Supported by the Higher School Visiting Scholar Development Project under Grant No.FX2013103the Research Fund under Grant No.ZCI2XJY003+2 种基金 Research Fund for the Doctoral Program under Grant No.Z301B13519 of the Zhejiang University of Media and CommunicationsZhejiang Province Science Foundation for Youths under Grant No.LQ12F05005National Natural Science Foundation of China under Grant No.11374254
文摘We discuss the nonlinear Schr6dinger equation with variable coefficients in 21） graded-index waveguides with different distributed transverse diffractions and obtain exact bright and dark soliton solutions. Based on these solutions, we mainly investigate the dynamical behaviors of solitons in three different diffraction decreasing waveguides with the hyperbolic, Gaussian and Logarithmic profiles. Results indicate that for the same parameters, the amplitude of bright solitons in the Logarithmic profile and the amplitude of dark solitons in the Gaussian profile are biggest respectively, and the amplitude in the hyperbolic profile is smallest, while the width of solitons has the opposite case.
基金supported by the National Key Research and Development Program of China(No.2023YFA1407104)Shenzhen Science and Technology Program(No.JCYJ20240813145614019)+1 种基金the National Natural Science Foundation of China(Nos.12274357 and 124B2086)Fujian Provincial Natural Science Foundation of China(No.2023J06011).
文摘Owing to the formal analogy between their governing equations,concepts from electromagnetic wave physics have been successfully extended to water-wave systems.Here,we propose and experimentally demonstrate the water-wave metagratings(WMGs)capable of wavefront modulation based on the generalized Snell’s law.These WMGs generate anomalous diffraction,including both retroreflection and negative refraction,by engineering the integer parity of supercells.As a proof of concept,we realize broadband water-wave focusing using WMGs.This work opens new avenues for compact and tunable water-wave devices,with potential applications in wave-energy harvesting and marine engineering.
基金supported by the National Key Research and Development Program of China(No.2021YFA1202000)National Natural Science Foundation of China(Nos.52003115 and RK106LH21001)Natural Science Foundation of Jiangsu Province(Nos.BK20212004 and BK20200320).
文摘Electrically driven structural patterns in liquid crystals(LCs)have attracted considerable attention due to their electrooptical applications.Here,we disclose various appealing reconfigurable LC microstructures in a dual frequency nematic LC(DFNLC)owing to the electroconvection-induced distortion of the LC director,including one-dimensional rolls,chevron pattern,two-dimensional grids,and unstable chaos.These patterns can be switched among each other,and the lattice constants are modulated by tuning the amplitude and frequency of the applied electric field.The electrically switchable self-assembled microstructures and their beam steering capabilities thus provide a feasible way to tune the functions of DFNLC-based optical devices.
基金The project is supported by National Natural Science Foundation of China.
文摘A set of coupled wave equations of acoustooptic diffraction with multiple acoustic waves along different directions is put forward and its solutions are derived. The characteristics of the diffraction efficiency, com -pression, cross modulation, and intermodulation intensities are analyzed theoretically. The theoretical results are supported by experimental measurements through our new multiple directional acoustooptic devices.
基金National Key R&D Program of China(2023YFB3711904,2022YFA1603801)National Natural Science Foundation of China(12404230,52471181,52301213,52130108,52471005)+2 种基金National Nature Science Foundation of Zhejiang Province(LY23E010002)Open Fund of the China Spallation Neutron Source,Songshan Lake Science City(KFKT2023B11)Guangdong Basic and Applied Basic Research Foundation(2022A1515110805,2024A1515010878)。
文摘The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing to this multi-principal element nature,high-entropy alloys exhibit complex deformation behavior dominated by alternating and coupled deformation mechanisms.Therefore,elucidating these intricate deformation mechanisms remains a key challenge in current research.Neutron diffraction(ND)techniques offer distinct advantages over traditional microscopic methods for characterizing such complex deformation behavior.The strong penetration capability of neutrons enables in-situ,real-time,and non-destructive detection of structural evolution in most centimeter-level bulk samples under complex environments,and ND allows precise characterization of lattice site occupations for light elements,such as C and O,and neighboring elements.This review discussed the principles of ND,experiment procedures,and data analysis.Combining with recent advances in the research about face-centered cubic high-entropy alloy,typical examples of using ND to investigate the deformation behavior were summarized,ultimately revealing deformation mechanisms dominated by dislocations,stacking faults,twinning,and phase transformations.
文摘We propose a novel fast numerical calculation method for the Rayleigh-Sommerfeld diffraction integral,which is developed based on the existing scaled convolution method.This approach enables fast cal-culations for general cases of off-axis scenarios where the sampling intervals and numbers of the input and observation planes are unequal.Additionally,it allows for arbitrary adjustment of the sampling interval of the impulse response function,facilitating a manual trade-off between computational load and accuracy.The er-rors associated with this method,which is equivalent to interpolation,primarily arise from the discontinuities of the sampling matrix of the impulse response function on its boundaries of periodic extension.To address this issue,we propose the concept of the padding function and its construction method,and evaluate its ef-fectiveness in enhancing computational accuracy.The feasibility of the proposed method is verified by nu-merical simulation and compared with the direct integration DI-method in a simplified scenario.It shows that the proposed method has good computational accuracy for the general case where the sampling interval of the input and observation plane is not equal under non-near-field diffraction,and when the diffraction distance is large,although the computational accuracy of the proposed method cannot exceed that of the DI-method,the computational amount can be significantly reduced with almost no effect on the computational accuracy.This method provides a general numerical calculation scheme of diffraction in the non-near field case for areas such as computational holography.
基金supported by the National Natural Science Foundation of China (Grant Nos.12274313 and 62375234)the Gusu Leading Talent Plan for Scientific and Technological Innovation and Entrepreneurship (Grant No.ZXL2024400)。
文摘Optical phase-gradient metasurfaces have garnered significant attention for enabling flexible light manipulation,with applications across diverse domains.In this work,we will demonstrate that the metasurfaces with phase gradient modulation can be used to achieve illusion optics,featuring the advantages of simple geometric structure and feasible implementation compared with the well-known transformation optics method.The underlying mechanism is the anomalous diffraction law caused by the phase gradient,which provides a theoretical basis for freely manipulating the propagation path of light.By considering a specific example,we will demonstrate that the phase gradient can transform spatial coordinates in real space into illusion space,thereby converting a plane in real space into a curved surface structure in illusion space to achieve the illusion effect.This approach provides a viable alternative to transformation optics for designing illusion devices.
基金supported by the National Key Research and Development Program of China(Nos.2021YFF0502700、2024YFB4610700)the National Natural Science Foundation of China(Nos.62325507、62375253、52375582、62475252)+3 种基金Major Scientific and Technological Projects in Anhui Province(202203a05020014)the CAS Project for Young Scientists in Basic Research(No.YSBR-049)Joint Research and Development Projects(2024CSJGG0500)the Fundamental Research Funds for the Central Universities(WK2090050048)。
文摘Ultra-thin glass(UTG)possesses a broad spectrum of applications in high-end electronic devices,such as foldable smartphones and flexible displays.Laser beam shaping for arc cutting UTG screens helps reduce stress concentration,thereby effectively enhancing their safety and longevity.However,the existing three-dimensional(3D)holography algorithms in beam shaping often suffer from high computational complexity and limited flexibility.To address these issues,we propose an iterative holographic algorithm combined with 3D chirp-z transform(3D-CZT)that generates 3D designable multi-foci with 90%light field uniformity.It also effectively corrects spherical aberration caused by refractive index mismatches,while maintaining precise beam shaping throughout the material.Moreover,by focusing on a specific region,the 3D-CZT method reduces the single iteration time to 0.5 seconds,achieving a speed one order of magnitude faster than conventional algorithms.On this basis,customizable glass-edge cutting by shaping the 3D-focused beam within the material is achieved.The glass edge demonstrates high geometric fidelity and remains smooth,mitigating the risk of micro-cracks.This work proposes a sophisticated and efficient methodology for the laser cutting of transparent materials.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB3607300)the National Natural Science Foundation of China(Grant Nos.62322512,62225506,and 12134013)+7 种基金the Fundamental Research Funds for the Central Universities(Grant Nos.WK2030000108 and WK2030000090)the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-049)supported by the National Natural Science Foundation of China(Grant Nos.12174260 and 12574326)the Shanghai Rising-Star Program(Grant No.21QA1406400)the Shanghai Science and Technology Development Fund(Grant Nos.21ZR1443500 and 21ZR1443600)the support from the China Postdoctoral Science Foundation(Grant No.2023M743364)support from the Center for Micro and Nanoscale Research and Fabrication,University of Science and Technology of Chinasupported by the UPOLabs,which provided the experimental and technical support。
文摘Head-up displays(HUDs)are emerging as key components of intelligent vehicles,requiring wide-depth,large-area,and high-efficiency dynamic imaging,which remains difficult to realize with traditional refractive optics.Computer-generated holography(CGH)with diffraction optics offers a promising solution to these technical demands.However,CGH optimization based on the fast Fourier transform(FFT)faces limitations such as zero-padding redundancy,coupled sampling intervals,and incompatible near-and farfield propagation models.Here,we report a holography-based multiplane HUD using a matrix multiplication(MM)-assisted diffraction algorithm that restructures the Fresnel integral into two sequential matrix operations,thus eliminating zero-padding and enabling fully decoupled sampling between object and image planes.Compared with FFT-based angular spectrum methods,the MM approach significantly improves computational speed and memory efficiency for hologram design,which is validated by demonstrating dual-plane holography with a size ratio exceeding 100:1 and unified reconstruction across Fresnel and Fraunhofer regimes within a single computation.A prototype HUD system is demonstrated successfully to exhibit multiple-plane holographic virtual images that can be mixed with real-world objects at three independent planes.The technique might be one of the potential candidates for next-generation intelligent vehicle displays.
基金supported by the Guangdong Major Project of Basic Research(Grant No.2020B0301030009)the National Natural Science Foundation of China(Grant Nos.12174204,12174203,12074203,62335012,and 62435010)+5 种基金the Natural Science Foundation of Guangdong Province(Grant No.2023A1515012888)the Science and Technology Innovation Commission of Shenzhen(Grant Nos.JCYJ20220818101417039 and JCYJ20241202124428038)the Medical-Engineering Interdisciplinary Research Foundation of Shenzhen University(Grant No.86901/00000311)the Scientific Instrument Developing Project of Shenzhen University(Grant No.2023YQ001)the Shenzhen University 2035 Initiative(Grant No.2023B004)the Key R&D Program of Zhejiang(Grant No.30003AA240100)。
文摘Speckle-based optical cryptosystems are promising technologies for information security.However,existing techniques mostly rely on digital decryption,resulting in computational delay and undermining the high-speed advantage of optical encryption.Moreover,conventional neural networks are typically effective only on images from the same distribution as the training datasets,limiting their general applicability.In this paper,we propose an all-optical high-speed decryption scheme for real-time recovery of speckle-encoded ciphertexts.By constructing a physics-informed diffractive neural network that approximates the inverse transmission matrix of the scattering medium,secret images can be directly reconstructed from speckle fields without optoelectronic conversion or post-processing.The network is trained with only 2048 samples from the MNIST dataset.Its transfer learning capability is validated across three out-of-distribution datasets,with decrypted images achieving a Pearson correlation coefficient of 0.82 and a structural similarity index measure of 0.75,demonstrating excellent transfer learning capability.For the first time,to our knowledge,this scheme simultaneously overcomes the bottlenecks of decryption delay and limited network generalizability in conventional speckle-based cryptosystems,achieving real-time image decryption with strong transferability.It provides a new pathway for developing low-power,real-time,and broadly applicable optical encryption systems,demonstrating significant potential for applications in high-speed security optical communications.
基金supported by the National Natural Science Foundation of China (Nos.82293682,82293684,and 82173703)。
文摘Owing to their intricate molecular frameworks and copious chiral centers,the structural identification and configurational assignment of natural products are challenging tasks.Comprehensive spectral data analysis is crucial for the confirmation of absolute configurations.Ignoring critical parameters will lead to false structure,which may confuse the total synthesis and drug development.Herein,the configurations of seven heterogeneous Pallavicinia diterpenoids(PDs) isolated from Pallavicinia liverworts are revised using a combination of single-crystal X-ray diffraction and electronic circular dichroism(ECD) calculations.Meanwhile,identification of five unprecedented PD heterodimers PD-dimers A-E(18-22) along with eleven previously undescribed PDs(5-9,13-17,23) obtained by the reinvestigation of the Chinese liverwort Pallavicinia subciliata have resulted in corrections and support the revised conclusions.
基金supported by the Beijing Natural Science Foundation(Grant Nos.F251036 and L248103)CAS Project for Young Scientists in Basic Research(Grant Nos.YSBR-090 and YSBR-05)National Natural Science Foundation of China(Grant No.62274159).
文摘Accurate temperature control and effective oxide removal are essential for achieving high-quality epitaxial growth in molecular beam epitaxy(MBE).However,traditional methods often rely on manual identification of reflection high-energy electron diffraction(RHEED)patterns.This process is heavily influenced by the grower’s experience,leading to issues with reproducibility and limiting the potential for automation.In this report,we propose an unsupervised learning framework for realtime RHEED analysis during the deoxidation process.By incorporating temporal similarity constraints into contrastive learning,our model generates smooth and interpretable feature trajectories that illustrate transitions in the deoxidation state,thus eliminating the need for manual labeling.The model,pre-trained using grouped contrastive loss,shows significant improvement in RHEED feature boundary discrimination and localization of critical regions.We evaluated its generalizability through two transfer learning strategies:calibration-free clustering and few-shot fine-tuning.The pre-trained model achieved a clustering accuracy of 88.1%for GaAs deoxidation samples without additional labels and reached an accuracy of 94.3%to 95.5%after fine-tuning with just five sample pairs across GaAs,Ge,and InAs substrates.This framework is optimized for resource-constrained edge devices,allowing for real-time,plug-and-play integration with existing MBE systems and swift adaptation across various materials and equipment.This work paves the way for greater automation and improved reproducibility in semiconductor manufacturing.
基金supported by the National Natural Science Foundation of China(Grant No.12304379)the Natural Science Foundation of Liaoning Province(Grant No.2024BS-269)the Guangdong Basic and Applied Basic Research Foundation(Grant No.025A1515011117)。
文摘High-precision optical frequency measurement serves as a cornerstone of modern science and technology,enabling advancements in fields ranging from fundamental physics to quantum information technologies.Obtaining precise photon frequencies,especially in the ultraviolet or even extreme ultraviolet regimes,is a key goal in both light–matter interaction experiments and engineering applications.High-order harmonic generation(HHG)is an ideal light source for producing such photons.In this work,we propose an optical temporal interference model(OTIM)that establishes an analogy with multi-slit Fraunhofer diffraction(MSFD)to manipulate fine-frequency photon generation by exploiting the temporal coherence of HHG processes.Our model provides a unified physical framework for three distinct non-integer HHG generation schemes:single-pulse,shaped-pulse,and laser pulse train approaches,which correspond to single-MSFD-like,double-MSFD-like,and multi-MSFD-like processes,respectively.Arbitrary non-integer HHG photons can be obtained using our scheme.Our approach provides a new perspective for accurately measuring and controlling photon frequencies in fields such as frequency comb technology,interferometry,and atomic clocks.
基金financially supported by Fujian Science&Technology Innovation Laboratory for Energy Devices of China(21C LAB)。
文摘Achieving extreme fast charging(XFC,-6 C)capability remains a challenge for Li ion batteries in electric vehicle applications.This work employs time-resolved X-ray diffraction(XRD)to investigate the structural evolution and capacity contributions of a series of LiNi_(x)Co_(y)Mn_(z)O_(2)(x+y+z=1,NCM)cathodes under XFC conditions.All NCM cathodes(NCM-92,NCM-83,and NCM-622)deliver -60%of their capacities with less than 2%unit cell volume expansion during the H1-H2 phase transition,but the subsequent H2-H3 phase transition exhibits significant compositional and rate dependence.The NCM-92 cathode shows a maximum d-spacing shrinkage of-5.3%at 6 C,which is larger than that of NCM-83(-4.1%)and NCM-622(-0.05%).Furthermore,NCM-92 follows a“phase heterogeneity”pathway for its structural evolution above 4.2 V,distinct from the“solid-solution”pathway observed in NCM-83 and NCM-622.This phase heterogeneity is evidenced by the splitting of the(003)diffraction peak and a decrease in intensity during the H2-H3 phase transition,indicating the formation of lithium-rich/depleted domains.These findings establish a direct correlation between cathode composition,structural dynamics,and XFC performance,highlighting a critical trade-off between structural stability and fast-charging capability in nickel-rich layered oxides.
基金supported by the National Natural Science Foundation of China (Grant No.12374021)Beijing Natural Science Foundation (Grant No.1252031)。
文摘To overcome the limitations of traditional single-crystal X-ray diffraction(SCXRD)for microcrystalline materials and the peak-overlapping issue of powder X-ray diffraction(PXRD),this study employed cryogenic continuous rotation electron diffraction(cryo-cRED)with a low-dose strategy to determine the crystal structure of CL30,a novel silicogermanate framework.It is confirmed that CL30 crystallizes in the C2/m space group and has layered topology composed of discontinuous zigzag chains connected by double four-membered ring(d4r)units,with fluoride anions(F^(-))occluded in the d4r units.In CL30,charge balance involves organic structure-directing agent(OSDA)cations,occluded F^(-),and terminal oxygen sites whose protonation state cannot be established from the present three dimensional(3D)ED data.F^(-)encapsulated in the d4r units contributes to charge compensation as the counter-anion to OSDA cations,rather than only balancing the framework charge.Although the refinement indices(R_(1)=0.29,wR_(2)=0.71)exceeded typical small-molecule crystallography standards,the structural model remained highly reliable,as supported by geometric restraints and validation.In electron diffraction,elevated R_(1) values are commonly attributed to the intrinsic factors of the technique,such as dynamic scattering,detector noise from scintillator-based detectors,and TEM stage instability(large spheres of confusion).This study introduces a new structural prototype to the silicogermanate family and establishes a feasible workflow for determining the structures of radiation-sensitive microcrystalline porous materials.
基金support from the Natural Science Foundation of China(Nos.52104373,52074131,and 51974092)the Basic and Applied Basic Foundation of Guangdong Province(No.2020B1515120065)。
文摘This paper examines the effect of Fe addition on the microstructure characterized by scanning electron microscopy/electron backscattered diffraction,neutron diffraction,and synchrotron X-ray tomography and the mechanical properties of Al-Mg-Mn-Fe-Cu alloys.The findings reveal that the microstructures of the alloys consisted of an Al matrix,Al_(6)(FeMn),and Al_(2)CuMg phase particles.The addition of Fe significantly increased the yield strength(YS),and ultimate tensile strength(UTS)of the alloys,while reducing elongation.The transformation of the 3D morphology of the Al_(6)(FeMn)phase from separated and fine particles with Chinese-script morphology to interconnected rod-like structure as Fe content increased from 0.1%to 0.8%.This strengthening effect was attributed to the slip lines being blocked at the vicinity of the inter-connected Fe-rich phase,leading to grain rotation and dislocation density increment around the Fe-rich phase,ultimately improving the strength of the alloys.However,the Fe-rich phases and Al_(2)CuMg phases were found to be prone to cracking under tensile stress,resulting in decreased elongation of the alloys.This study provides a potential application in the design and manufacturing of new non-heat-treatable Al alloys for the automotive industry.
基金funded by the S&T Program of Hebei(No.21323202D)the Natural Science Interdisciplinary Research Program of Hebei University(No.DXK201913)+4 种基金the Natural Sci-ence Foundation of Hebei Province of China(Nos.H2024201028,H2020201029)the Excellent Youth Research Innovation Team of Hebei University(No.QNTD202406)the Hebei University Research and Innovation Team(No.IT2023C1)the Innovation Capacity Improvement Plan of Hebei Province(No.20567605H)the National Training Program of Innovation and Entrepreneurship for Undergraduates(No.DC2024177)。
文摘Chemical investigation of the marine-derived fungus Chaetomium globosum HBU-45 led to the discovery of chaeglobol A(1).Its structure was determined by spectroscopic analysis,computational electronic circular dichroism(ECD)/optical rotatory dispersion(ORD)methods,and X-ray crystallography.Compound 1 represents a new skeleton with an uncommon 6/6/6/5/6/5/6/5 octacyclic system,which is presumably biosynthesized via a[4+2]cycloaddition and an enzymatic cyclization.Chaeglobol A(1)exhibited inhibitory activity against B.dothidea by destroying cell membrane integrity and causing oxidative damage within the cells.
基金supported by the National Natural Science Foundation of China(Grant No.12105210)the Knowledge Innovation Program of Wuhan-Basi Research(Grant No.2023010201010149)。
文摘We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW structure interacts with a weak probe laser field,a spatially independent 2D standing-wave(SW)field,and a Laguerre–Gaussian(LG)vortex field,respectively.The results indicate that the diffraction patterns are highly sensitive to amplitude modulation and phase modulation.Because of the existence of vortex light,it is possible to realize asymmetric high-order diffraction in the SQW structure,and then a 2D asymmetric grating is established.By adjusting the detunings of the probe field,vortex field,and SW field,as well as the interaction length,diffraction intensity,and direction of the 2D asymmetric electromagnetically induced grating(EIG)can be controlled effectively.In addition,the number of orbital angular momenta(OAM)and beam waist parameter can be used to modulate the diffraction intensity and energy transfer of the probe light in different regions.High-order diffraction intensity is enhanced and high-efficiency 2D asymmetric diffraction grating with different diffraction patterns is obtained in the scheme.Such 2D asymmetric diffraction grating may be beneficial to the research of optical communication and innovative semiconductor quantum devices.
基金supported by the National Youth Talent Support Program(No.QNBJ-2022-03)the National Natu-ral Science Foundation of China(No.52371180)the Fundamental Research Funds for the Central Universities(Nos.N2209005 and N2309001).
文摘Two novel out-of-plane ordered quaternary borides M'_(4)VSiB_(2) (M'=Nb and Mo) have been synthesized. The out-of-plane ordered characteristic has been confirmed by the X-ray diffraction, the neutron powder diffraction and the scanning transmission electron microscopy with high-angle angular dark field images. By adjusting the stoichiometric ratio of Mo and V, the 16l site preferentially occupied by relatively larger atom and 4c site by relatively smaller atom have been confirmed. The further first-principle calculation demonstrates the dynamical and thermodynamical stability of Mo_(4)VSiB_(2) o-T2 phase. This work confirms the transition metal occupation strategy of o-T2 phase and enriches the out-of-plane ordered laminated borides family.
