study drifting modulation instability(MI)that exhibits asymmetric discrete spectrum recurrences in the nonlinear stage within the framework of the focusing nonlinear Schr¨odinger equation.We demonstrate that such...study drifting modulation instability(MI)that exhibits asymmetric discrete spectrum recurrences in the nonlinear stage within the framework of the focusing nonlinear Schr¨odinger equation.We demonstrate that such drifting MI can arise either from the local periodization of general breathers or from numerical simulations starting with an initial modulation containing asymmetric sidebands.展开更多
In order to improve the detection accuracy of Doppler asymmetric spatial heterodyne(DASH)interferometer in harsh temperatures,an opto-mechanical-thermal integration analysis is carried out.Firstly,the correlation betw...In order to improve the detection accuracy of Doppler asymmetric spatial heterodyne(DASH)interferometer in harsh temperatures,an opto-mechanical-thermal integration analysis is carried out.Firstly,the correlation between the interference phase and temperature is established according to the working principle and the phase algorithm of the interferometer.Secondly,the optical mechanical thermal analysis model and thermal deformation data acquisition model are designed.The deformation data of the interference module and the imaging optical system at different temperatures are given by temperature load simulation analysis,and the phase error caused by thermal deformation is obtained by fitting.Finally,based on the wind speed error caused by thermal deformation of each component,a reasonable temperature control scheme is proposed.The results show that the interference module occupies the main cause,the temperature must be controlled within(20±0.05)℃,and the temperature control should be carried out for the temperature sensitive parts,and the wind speed error caused by the part is 3.8 m/s.The thermal drift between the magnification of the imaging optical system and the thermal drift of the relative position between the imaging optical system and the detector should occupy the secondary cause,which should be controlled within(20±2)℃,and the wind speed error caused by the part is 3.05 m/s.In summary,the wind measurement error caused by interference module,imaging optical system,and the relative position between the imaging optical system and the detector can be controlled within 6.85 m/s.The analysis and temperature control schemes presented in this paper can provide theoretical basis for DASH interferometer engineering applications.展开更多
In this article,a single-board integrated millimeter-wave(mm-Wave)asymmetric full-digital beamforming(AFDBF)array is developed for beyond-fifth-generation(B5G)and sixth-generation(6G)communications.The proposed integr...In this article,a single-board integrated millimeter-wave(mm-Wave)asymmetric full-digital beamforming(AFDBF)array is developed for beyond-fifth-generation(B5G)and sixth-generation(6G)communications.The proposed integrated array effectively addresses the challenge of arranging a large number of ports in a full-digital array by designing vertical connections in a three-dimensional space and successfully integrating full-digital transmitting(Tx)and receiving(Rx)arrays independently in a single board.Unlike the traditional symmetric array,the proposed asymmetric array is composed of an 8×8 Tx array arranged in a square shape and an 8+8 Rx array arranged in an L shape.The center-to-center distance between two adjacent elements is 0.54k0 for both the Tx and Rx arrays,where k0 is the free-space wavelength at 27 GHz.The proposed AFDBF array possesses a more compact structure and lower system hardware cost and power consumption compared with conventional brick-type full-digital arrays.In addition,the energy efficiency of the proposed AFDBF array outperforms that of a hybrid beamforming array.The measurement results indicate that the operating frequency band of the proposed array is 24.25–29.50 GHz.An eight-element linear array within the Tx array can achieve a scanning angle ranging from-47°to+47°in both the azimuth and the elevation planes,and the measured scanning range of each eight-element Rx array is–45°to+45°.The measured maximum effective isotropic radiated power(EIRP)of the eight-element Tx array is 43.2 dBm at 28.0 GHz(considering the saturation point).Furthermore,the measured error vector magnitude(EVM)is less than 3%when 64-quadrature amplitude modulation(QAM)waveforms are used.展开更多
A semiconductor optical amplifier and electroabsorption modulator monolithically integrated with a spotsize converter input and output is fabricated by means of selective area growth,quantum well intermixing,and asymm...A semiconductor optical amplifier and electroabsorption modulator monolithically integrated with a spotsize converter input and output is fabricated by means of selective area growth,quantum well intermixing,and asymmetric twin waveguide technology. A 1550-1600nm lossless operation with a high DC extinction ratio of 25dB and more than 10GHz 3dB bandwidth are successfully achieved. The output beam divergence angles of the device in the horizontal and vertical directions are as small as 7.3°× 18.0°, respectively, resulting in a 3.0dB coupling loss with a cleaved single-mode optical fiber.展开更多
高光谱图像分类是遥感领域的核心难题,其挑战主要源于高光谱图像的光谱维度高、空间分辨率低,导致分类任务中难以充分提取高光谱图像的空谱特征。针对现有的卷积神经网络(CNN)高光谱图像分类模型参数量大、计算资源消耗高、分类精度不...高光谱图像分类是遥感领域的核心难题,其挑战主要源于高光谱图像的光谱维度高、空间分辨率低,导致分类任务中难以充分提取高光谱图像的空谱特征。针对现有的卷积神经网络(CNN)高光谱图像分类模型参数量大、计算资源消耗高、分类精度不足的问题,提出了一种基于注意力机制的轻量化网络高光谱图像分类模型(AMLW-CNN)。为了增强网络的特征提取能力,将空谱特征提取模块设计为2个多尺度提取模块,并将空间特征提取模块的各卷积层通过残差结构连接,同时引入注意力机制来强化网络对有效特征的提取。另外,为了减少模型参数量,采用非对称卷积来替代三维卷积核、深度可分离卷积来替换二维卷积核。实验结果表明:AMLW-CNN的分类精度优于对比算法,计算复杂度更低,鲁棒性更强。在Indian Pines、Salinas和Pavia U 3个数据集上的总体分类精度分别达到了98.5%、99.8%、99.9%。展开更多
Despite utilization of state-of-the-art Cu-based catalysts,achieving high selectivity and stability in multicarbon(C^(2+))compounds production through electrocatalytic CO_(2)reduction reaction(CO_(2)RR)remains a criti...Despite utilization of state-of-the-art Cu-based catalysts,achieving high selectivity and stability in multicarbon(C^(2+))compounds production through electrocatalytic CO_(2)reduction reaction(CO_(2)RR)remains a critical and challenging objective.Here we employ lattice chlorine-doped Cu_(2)O nanocubes(Cl_(d)-Cu_(2)O NCs)with well-defined{100}facets as a model catalyst to demonstrate that halogen doping can serve as a versatile and effective strategy for modulating surface charge distribution,thereby enhancing asymmetric C-C coupling toward high-selectivity C^(2+)products in CO_(2)RR.Compared to Cl-free Cu_(2)O NCs,Cl_(d)-Cu_(2)O NCs exhibit a greatly enhanced C^(2+)Faraday efficiency,i.e.,~85%at-1.1 V(versus the reversible hydrogen electrode).Additionally,the Cl_(d)-Cu_(2)O NCs demonstrate significantly enhanced long-term durability,attributed to better preservation of the cubic morphology and more stable Cu^(δ+)states.In-situ electrochemical studies reveal that Cl_(d)-Cu_(2)O NCs facilitate the formation of the key asymmetric*COH and*OCCOH intermediates,ultimately leading to higher C^(2+)products.Density functional theory(DFT)calculations confirm that the introduced Cl-dopants disrupt the charge balance of the Cu_(2)O(100)surface,enriching the Cl-adjacent Cu atoms with more electrons compared to those near O atoms.This unbalanced charge distribution significantly reduces the free energy of the rate-determining step for asymmetric C-C coupling from the*CO to*OCCOH on Cl-doped Cu_(2)O(100)surface,requiring only 1.04 e V,in contrast to 1.50 e V on pristine Cu_(2)O(100)surface.This study provides valuable insights into the surface charge modulation of Cu_(2)O catalysts via halogen doping for enhancing asymmetric C-C coupling and C^(2+)production in CO_(2)RR.展开更多
Resonances are usually associated with finite systems—the vibrations of clamped strings in a guitar or the optical modes in a cavity defined by mirrors.In optics,resonances may be induced in infinite continuous media...Resonances are usually associated with finite systems—the vibrations of clamped strings in a guitar or the optical modes in a cavity defined by mirrors.In optics,resonances may be induced in infinite continuous media via periodic modulations of their optical properties.Here we demonstrate that periodic modulations of the permittivity of a featureless thin film can also act as a symmetry-breaking mechanism,allowing the excitation of photonic quasi-bound states in the continuum(qBICs).By interfering two ultrashort laser pulses in the unbounded film,transient resonances can be tailored through different parameters of the pump beams.We show that the system offers resonances tunable in wavelength and quality-factor,and spectrally selective enhancement of third-harmonic generation.Due to a fast decay of the permittivity asymmetry,we observe ultrafast dynamics,enabling time-selective near-field enhancement with picosecond precision.Optically induced permittivity asymmetries may be exploited in on-demand weak to ultrastrong light-matter interaction regimes and light manipulation at dynamically chosen wavelengths in lithography-free metasurfaces.展开更多
基金work was supported by the NSFC(Grant Nos.12522501 and 12247103)the Sci-entific Research Innovation Capability Support Project for Young Faculty(Grant No.SRICSPYF-BS2025131).
文摘study drifting modulation instability(MI)that exhibits asymmetric discrete spectrum recurrences in the nonlinear stage within the framework of the focusing nonlinear Schr¨odinger equation.We demonstrate that such drifting MI can arise either from the local periodization of general breathers or from numerical simulations starting with an initial modulation containing asymmetric sidebands.
文摘In order to improve the detection accuracy of Doppler asymmetric spatial heterodyne(DASH)interferometer in harsh temperatures,an opto-mechanical-thermal integration analysis is carried out.Firstly,the correlation between the interference phase and temperature is established according to the working principle and the phase algorithm of the interferometer.Secondly,the optical mechanical thermal analysis model and thermal deformation data acquisition model are designed.The deformation data of the interference module and the imaging optical system at different temperatures are given by temperature load simulation analysis,and the phase error caused by thermal deformation is obtained by fitting.Finally,based on the wind speed error caused by thermal deformation of each component,a reasonable temperature control scheme is proposed.The results show that the interference module occupies the main cause,the temperature must be controlled within(20±0.05)℃,and the temperature control should be carried out for the temperature sensitive parts,and the wind speed error caused by the part is 3.8 m/s.The thermal drift between the magnification of the imaging optical system and the thermal drift of the relative position between the imaging optical system and the detector should occupy the secondary cause,which should be controlled within(20±2)℃,and the wind speed error caused by the part is 3.05 m/s.In summary,the wind measurement error caused by interference module,imaging optical system,and the relative position between the imaging optical system and the detector can be controlled within 6.85 m/s.The analysis and temperature control schemes presented in this paper can provide theoretical basis for DASH interferometer engineering applications.
基金supported by the National Key Research and Development Program of China(2020YFB1804900 and 2022YFE0210900)the Fundamental Research Funds for the Central Universities(2242022k60008 and 2242022k30003)+2 种基金the National Natural Science Foundation of China(62301152 and 61627801)the Youth Talent Promotion Foundation of Jiangsu Science and Technology Association(TJ-2023-074)the Startup Research Fund of Southeast University(RF1028623286).
文摘In this article,a single-board integrated millimeter-wave(mm-Wave)asymmetric full-digital beamforming(AFDBF)array is developed for beyond-fifth-generation(B5G)and sixth-generation(6G)communications.The proposed integrated array effectively addresses the challenge of arranging a large number of ports in a full-digital array by designing vertical connections in a three-dimensional space and successfully integrating full-digital transmitting(Tx)and receiving(Rx)arrays independently in a single board.Unlike the traditional symmetric array,the proposed asymmetric array is composed of an 8×8 Tx array arranged in a square shape and an 8+8 Rx array arranged in an L shape.The center-to-center distance between two adjacent elements is 0.54k0 for both the Tx and Rx arrays,where k0 is the free-space wavelength at 27 GHz.The proposed AFDBF array possesses a more compact structure and lower system hardware cost and power consumption compared with conventional brick-type full-digital arrays.In addition,the energy efficiency of the proposed AFDBF array outperforms that of a hybrid beamforming array.The measurement results indicate that the operating frequency band of the proposed array is 24.25–29.50 GHz.An eight-element linear array within the Tx array can achieve a scanning angle ranging from-47°to+47°in both the azimuth and the elevation planes,and the measured scanning range of each eight-element Rx array is–45°to+45°.The measured maximum effective isotropic radiated power(EIRP)of the eight-element Tx array is 43.2 dBm at 28.0 GHz(considering the saturation point).Furthermore,the measured error vector magnitude(EVM)is less than 3%when 64-quadrature amplitude modulation(QAM)waveforms are used.
文摘A semiconductor optical amplifier and electroabsorption modulator monolithically integrated with a spotsize converter input and output is fabricated by means of selective area growth,quantum well intermixing,and asymmetric twin waveguide technology. A 1550-1600nm lossless operation with a high DC extinction ratio of 25dB and more than 10GHz 3dB bandwidth are successfully achieved. The output beam divergence angles of the device in the horizontal and vertical directions are as small as 7.3°× 18.0°, respectively, resulting in a 3.0dB coupling loss with a cleaved single-mode optical fiber.
文摘高光谱图像分类是遥感领域的核心难题,其挑战主要源于高光谱图像的光谱维度高、空间分辨率低,导致分类任务中难以充分提取高光谱图像的空谱特征。针对现有的卷积神经网络(CNN)高光谱图像分类模型参数量大、计算资源消耗高、分类精度不足的问题,提出了一种基于注意力机制的轻量化网络高光谱图像分类模型(AMLW-CNN)。为了增强网络的特征提取能力,将空谱特征提取模块设计为2个多尺度提取模块,并将空间特征提取模块的各卷积层通过残差结构连接,同时引入注意力机制来强化网络对有效特征的提取。另外,为了减少模型参数量,采用非对称卷积来替代三维卷积核、深度可分离卷积来替换二维卷积核。实验结果表明:AMLW-CNN的分类精度优于对比算法,计算复杂度更低,鲁棒性更强。在Indian Pines、Salinas和Pavia U 3个数据集上的总体分类精度分别达到了98.5%、99.8%、99.9%。
基金supported by the National Natural Science Foundation of China(U24A20563,22171093)the Natural Science Foundation of Fujian Province(2022J02008)+5 种基金the Fujian Provincial Chemistry Discipline Alliance Foundationthe Scientific Research Funds of Huaqiao Universitythe support from the Early Career Scheme grant(21300323)the General Research Fund(11309025)from the Research Grants Council of the Hong Kong Special Administrative Regionthe Guang Dong Basic and Applied Basic Research Foundation(2025A1515010008)the CityU funds(9610600,9610663,7020103)。
文摘Despite utilization of state-of-the-art Cu-based catalysts,achieving high selectivity and stability in multicarbon(C^(2+))compounds production through electrocatalytic CO_(2)reduction reaction(CO_(2)RR)remains a critical and challenging objective.Here we employ lattice chlorine-doped Cu_(2)O nanocubes(Cl_(d)-Cu_(2)O NCs)with well-defined{100}facets as a model catalyst to demonstrate that halogen doping can serve as a versatile and effective strategy for modulating surface charge distribution,thereby enhancing asymmetric C-C coupling toward high-selectivity C^(2+)products in CO_(2)RR.Compared to Cl-free Cu_(2)O NCs,Cl_(d)-Cu_(2)O NCs exhibit a greatly enhanced C^(2+)Faraday efficiency,i.e.,~85%at-1.1 V(versus the reversible hydrogen electrode).Additionally,the Cl_(d)-Cu_(2)O NCs demonstrate significantly enhanced long-term durability,attributed to better preservation of the cubic morphology and more stable Cu^(δ+)states.In-situ electrochemical studies reveal that Cl_(d)-Cu_(2)O NCs facilitate the formation of the key asymmetric*COH and*OCCOH intermediates,ultimately leading to higher C^(2+)products.Density functional theory(DFT)calculations confirm that the introduced Cl-dopants disrupt the charge balance of the Cu_(2)O(100)surface,enriching the Cl-adjacent Cu atoms with more electrons compared to those near O atoms.This unbalanced charge distribution significantly reduces the free energy of the rate-determining step for asymmetric C-C coupling from the*CO to*OCCOH on Cl-doped Cu_(2)O(100)surface,requiring only 1.04 e V,in contrast to 1.50 e V on pristine Cu_(2)O(100)surface.This study provides valuable insights into the surface charge modulation of Cu_(2)O catalysts via halogen doping for enhancing asymmetric C-C coupling and C^(2+)production in CO_(2)RR.
文摘Resonances are usually associated with finite systems—the vibrations of clamped strings in a guitar or the optical modes in a cavity defined by mirrors.In optics,resonances may be induced in infinite continuous media via periodic modulations of their optical properties.Here we demonstrate that periodic modulations of the permittivity of a featureless thin film can also act as a symmetry-breaking mechanism,allowing the excitation of photonic quasi-bound states in the continuum(qBICs).By interfering two ultrashort laser pulses in the unbounded film,transient resonances can be tailored through different parameters of the pump beams.We show that the system offers resonances tunable in wavelength and quality-factor,and spectrally selective enhancement of third-harmonic generation.Due to a fast decay of the permittivity asymmetry,we observe ultrafast dynamics,enabling time-selective near-field enhancement with picosecond precision.Optically induced permittivity asymmetries may be exploited in on-demand weak to ultrastrong light-matter interaction regimes and light manipulation at dynamically chosen wavelengths in lithography-free metasurfaces.
