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Secondary electron emission and photoemission from a negative electron affinity semiconductor with large mean escape depth of excited electrons

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Chinese Physics B 2023年第4期32卷 677-690页

作者：谢爱根董红杰刘亦凡 School of Physics and Optoelectronic Engineering Nanjing University of Information Science and TechnologyNanjing 210044China Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean Nanjing University of Information Science&TechnologyNanjing 210044China Jiangsu international Joint Laboratory on Meteorological Photonics and Optoelectronic Detection Nanjing University of Information Science&TechnologyNanjing 210044China

The formulae for parameters of a negative electron affinity semiconductor(NEAS)with large mean escape depth of secondary electrons A(NEASLD)are *** methods for obtaining parameters such asλ,B,E_(pom)and the maximumδandδat 100.0 keV≥E_(po)≥1.0 keV of a NEASLD with the deduced formulae are presented(B is the probability that an internal secondary electron escapes into the vacuum upon reaching the emission surface of the emitter,δis the secondary electron yield,E_(po)is the incident energy of primary electrons and E_(pom)is the E_(po)corresponding to the maximumδ).The parameters obtained here are analyzed,and it can be concluded that several parameters of NEASLDs obtained by the methods presented here agree with those obtained by other *** relation between the secondary electron emission and photoemission from a NEAS with large mean escape depth of excited electrons is investigated,and it is concluded that the presented method of obtaining A is more accurate than that of obtaining the corresponding parameter for a NEAS with largeλ_(ph)(λ_(ph)being the mean escape depth of photoelectrons),and that the presented method of calculating B at E_(po)>10.0 keV is more widely applicable for obtaining the corresponding parameters for a NEAS with largeλ_(ph).

关键词： negative electron affinity semiconductor secondary electron emission photoemission the probability secondary electron yield large mean escape depth of excited electrons

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Performance of a four deep neural network structure in moiré fringe intelligent analysis

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Applied Optics 2025年第9期64卷 2208-2216页

作者： Zeng, Xinyu Chen, Yunyun Cheng, Weihao Xie, Wenzhuo Yang, Cuihong State Key Laboratory Cultivation Base of Atmospheric Optoelectronic Detection and Information Fusion Nanjing University of Information Science & Technology Nanjing210044 China Jiangsu Engineering Research Center for Intelligent Optoelectronic Sensing Technology of Atmosphere Nanjing University of Information Science & Technology Nanjing210044 China Jiangsu International Joint Laboratory on Meteorological Photonics and Optoelectronic Detection Nanjing University of Information Science & Technology Nanjing210044 China Nanjing University of Information Science & Technology Nanjing210044 China

Moiré fringe analysis holds significant importance in the assessment of flow fields, while deep learning is advancing rapidly and is frequently employed to handle complex computational challenges. In this paper, the performance of U-net, Unet++, Unet 3+, and ResUnet in moiré fringe analysis is compared and analyzed. The results indicate significant differences among the four neural networks in terms of the training time, prediction speed, prediction accuracy, and generalization capability regarding positional variations. Among the four neural networks, ResUnet exhibits the shortest training times, highest accuracy, and fastest prediction speeds while also exhibiting good generalization capability. Consequently, in practical applications, using ResUnet for moiré fringe analysis is an excellent choice. © 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.

关键词： Deep neural networks

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Tunable polarimetric sensitive terahertz absorber 6

Tunable polarimetric sensitive terahertz absorber

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6th Conference on Frontiers in Optical Imaging and Technology: Novel Technologies in Optical Systems

作者： Zhu, Haixia Ni, Bo Feng, Zhenjie Qian, Yitong Zhou, Xiaoyan Ni, Haibin Yang, Lingsheng Chang, Jianhua Jiangsu Key Laboratory of Meteorological Observation and Information Processing School of Electronic and Information Engineering Nanjing University of Information Science and Technology Nanjing210044 China

ISBN: (数字)9781510679672

ISBN: (纸本)9781510679665

In this paper, an absorber based on split square graphene is designed, which produces double absorption peaks at different polarization incidence. The absorption rates of x-polarized waves at 7.86 THz and 12.63THz are 97.9% and 91.2% respectively. The absorption rates of y-polarized waves at 6.30 THz and 10.52 THz are 94.1% and 93.2%. In this paper, an absorber based on split square graphene is designed, which produces double absorption peaks at different polarization incidence. The absorption rates of x-polarized waves at 7.86 THz and 12.63THz are 97.9% and 91.2% respectively. The absorption rates of y-polarized waves at 6.30 THz and 10.52 THz are 94.1% and 93.2%. The effect of Fermi level on the dual polarization absorptivity of graphene is discussed. Therefore, this work may have great reference value for terahertz sensing, selective spectral detection and other fields. The effect of Fermi level on the dual polarization absorptivity of graphene is discussed. Therefore, this work may have great reference value for terahertz sensing, selective spectral detection and other fields. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

关键词： Polarization

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MSF-Net: A Multilevel Spatiotemporal Feature Fusion Network Combines Attention for Action Recognition

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Computer Systems Science & Engineering 2023年第11期47卷 1433-1449页

作者： Mengmeng Yan Chuang Zhang Jinqi Chu Haichao Zhang Tao Ge Suting Chen School of Electronic and Information Engineering Nanjing University of Information Science and TechnologyNanjing210044China Jiangsu Key Laboratory of Meteorological Observation and Information Processing Nanjing210044China

An action recognition network that combines multi-level spatiotemporal feature fusion with an attention mechanism is proposed as a solution to the issues of single spatiotemporal feature scale extraction,information redundancy,and insufficient extraction of frequency domain information in channels in 3D convolutional neural ***,based on 3D CNN,this paper designs a new multilevel spatiotemporal feature fusion(MSF)structure,which is embedded in the network model,mainly through multilevel spatiotemporal feature separation,splicing and fusion,to achieve the fusion of spatial perceptual fields and short-medium-long time series information at different scales with reduced network parameters;In the second step,a multi-frequency channel and spatiotemporal attention module(FSAM)is introduced to assign different frequency features and spatiotemporal features in the channels are assigned corresponding weights to reduce the information redundancy of the feature ***,we embed the proposed method into the R3D model,which replaced the 2D convolutional filters in the 2D Resnet with 3D convolutional filters and conduct extensive experimental validation on the small and medium-sized dataset UCF101 and the largesized dataset *** findings revealed that our model increased the recognition accuracy on both *** on the UCF101 dataset,in particular,demonstrate that our model outperforms R3D in terms of a maximum recognition accuracy improvement of 7.2%while using 34.2%fewer *** MSF and FSAM are migrated to another traditional 3D action recognition model named C3D for application *** test results based on UCF101 show that the recognition accuracy is improved by 8.9%,proving the strong generalization ability and universality of the method in this paper.

关键词： 3D convolutional neural network action recognition MSF FSAM

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Secondary electron emission model for photo-emission from metals in the vacuum ultraviolet

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Nuclear Science and Techniques 2022年第8期33卷 89-105页

作者： Ai-Gen Xie Yi-Fan Liu Hong-Jie Dong School of Physics and Optoelectronic Engineering Nanjing University of Information Science&TechnologyNanjing 210044China Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean Nanjing University of Information Science&TechnologyNanjing 210044China Jiangsu International Joint Laboratory on Meteorological Photonics and Optoelectronic Detection Nanjing University of Information Science&TechnologyNanjing 210044China

This study investigates two secondary electron emission(SEE)models for photoelectric energy distribution curves f(E_(ph),hγ),B,E_(mean),absolute quantum efficiency(AQE),and the mean escape depth of photo-emitted electronsλof *** proposed models are developed from the density of states and the theories of photo-emission in the vacuum ultraviolet and SEE,where B is the mean probability that an internal photo-emitted electron escapes into vacuum upon reaching the emission surface of the metal,and E_(mean)is the mean energy of photo-emitted electrons measured from *** formulas for f(E_(ph),hγ),B,λ,E_(mean),and AQE that were obtained were shown to be correct for the cases of Au at hγ=8.1–11.6 eV,Ni at hγ=9.2–11.6 eV,and Cu at hγ=7.7–11.6 *** photoelectric cross sections(PCS)calculated here are analyzed,and it was confirmed that the calculated PCS of the electrons in the conduction band of Au at hγ=8.1–11.6eV,Ni at hγ=9.2–11.6 eV,and Cu at hγ=7.7–11.6 eV are correct.

关键词： Absolute quantum efficiency Photoelectric cross section Mean escape depth of photo-emitted electrons Probability Photo-emission from metals Secondary electron emission Vacuum ultraviolet Mean energy of photo-emitted electrons

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Design of Flexible Wearable Antenna Based on Artificial Magnetic Conductor Structure

Design of Flexible Wearable Antenna Based on Artificial Magn...

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2024 Photonics and Electromagnetics Research Symposium, PIERS 2024

作者： Zhou, Yong Zhuang, Jiajie Zhou, Jiahao Nuist Jiangsu Key Laboratory of Meteorological Observation and Information Processing Nanjing210044 China Nuist Collaborative Innovation Center for Atmospheric Environment and Equipment Technology Nanjing210044 China

ISBN: (纸本)9798350375909

This paper designs a dual-band wearable antenna based on a 2×2 artificial magnetic conductor (AMC) array, which is suitable for wireless body area network (WBAN) applications. It works in the ISM bands of 2.45 GHz and 5.8 GHz. The antenna has the characteristics of high gain, low profile, good flexibility and body adaptability. The antenna consists of three layers. The top layer is a T-shaped metal strip-loaded tuning branch antenna fed by coplanar waveguide printed on a PI material substrate, which has dual-band resonance frequency. The middle layer is the dielectric material, which is air in the study. The bottom layer is an AMC reflector composed of a 2 × 2 double circular strip array structure printed on a PDMS material substrate. The simulation results show that S11 = -18.2 dB and -25.5 dB in 2.45 GHz and 5.8 GHz, with the frequency range of 2.3 GHz-2.5 GHz and 5.6 GHz-5.9 GHz. The bandwidth is 200 MHz and 300 MHz for the two resonance frequencies. Also, the gain of the antenna reaches 1.1 dBi and 5.3 dBi in 2.45 GHz and 5.8 GHz respectively. As a comparison, the gain of the single antenna without AMC structure is -1.3 dBi at 2.45 GHz and 3.14 dBi at 5.8 GHz. Thus, the gain of the antenna increases 2.4 dB and 2.16 dB respectively after applied with AMC structure. The antenna with AMC structure is manufactured and measured in microwave anechoic chamber. The test results show that S11 = -22.8 dB and -19.7 dB at frequency 2.55 GHz and 5.65 GHz, with frequency band of 2.2 GHz to 2.7 GHz and 5.6 GHz to 6.0 GHz. The gain is 0.92 dBi and 4.59 dBi at 2.45 GHz and 5.8 GHz respectively. Three bending radii were chosen for bending experiments to investigate the effect of bending on the antenna radiation performance. Experimental results demonstrate that S11 and radiation pattern remain stable, with minimal impact. The test results show good agreement with simulation, and the gain is a little lower than simulation because of the manufacture error. The research demonstrates

关键词： Coplanar waveguides

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Noise Mitigation Based on Geometric Shaping of 32QAM for Discrete Spectrum Nonlinear Frequency Division Multiplexing Systems

Noise Mitigation Based on Geometric Shaping of 32QAM for Dis...

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2024 Asia Communications and Photonics Conference, ACP 2024 and International Conference on information Photonics and Optical Communications, IPOC 2024

作者： Tang, Xue Liu, Bo Ren, Jianxin Mao, Yaya Wu, Xiangyu Song, Xiumin Chen, Shuaidong Ullah, Rahat Institute of Optics and Electronics Nanjing University of Information Science & Technology China Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean China Jiangsu International Joint Laboratory on Meteorological Photonics and Optoelectronic Detection Nanjing China Beijing University of Posts and Telecommunications Beijing China School of communication and information engineering Nanjing University of Posts and Telecommunications Nanjing China

A noise mitigation scheme is proposed for nonlinear frequency division multiplexing systems. This scheme utilizes channel characteristics to design an olive shape geometry with greater ASE noise and phase noise tolera... 详细信息

ISBN: (纸本)9798350379266

关键词： Geometry

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Highly Reliable Multilayer Encryption Scheme With Constellation Shaping Based on Joint Index Modulation

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Journal of Lightwave Technology 2025年第12期43卷 5689-5698页

作者： Zhu, Dongxu Liu, Bo Ren, Jianxin Mao, Yaya Song, Xiumin Chen, Shuaidong Zhao, Lilong Yin, Mengtong Dai, Wei Chen, Guoqing Cai, Junjie Institute of Optics and Electronics Nanjing University of Information Science & Technology Nanjing210044 China State Key Laboratory Cultivation Base of Atmospheric Optoelectronic Detection and Information Fusion Nanjing University of Information Science & Technology Nanjing210044 China Jiangsu International Joint Laboratory for Meteorological Photonics and Optoelectronic Detection Nanjing University of Information Science & Technology Nanjing210044 China Jiangsu Engineering Research Center for Intelligent Optoelectronic Sensing Technology of Atmosphere Nanjing University of Information Science & Technology Nanjing210044 China Beijing University of Posts and Telecommunications Beijing100876 China Department of Electronic Engineering Tsinghua University Beijing100084 China

This paper proposes a highly reliable multilayer encryption scheme with constellation shaping based on joint index modulation. Multilayer encryption is used to ensure the security of the scheme. We utilize the 3D-Zhang chaotic system to realize the multidimensional perturbation of bits, subcarriers, and symbols of the original signal. The key information is masked with the signal using joint index modulation (JIM). The cooperative transmission of the initial value of the chaotic system is realized through the position information of the silent subcarriers and the constellation modes of the corresponding subcarriers. The scheme interleaves the initial values of the two chaotic systems to encode them as index bits, realizing the first layer of masked keys. Additional constellation shaping is achieved by optimizing the index mapping rules and changing the distribution of constellation points in the center and in the dual mode. The rotational encryption of the constellation is realized using a one-dimensional sinusoidal chaotic system after the completion of JIM, and the second layer of spherical shell masking of the key information is completed. The experimental implementation demonstrates the successful transmission of a 14 Gb/s 3D-JIM -8QAM signal over a 2 km weakly coupled seven-core fiber. Results confirm that the multi-layer encryption approach ensures secure signal transmission even under partial key leakage, without introducing degradation to the system's transmission performance. Compared to a random constellation distribution, the optimized index mapping scheme provides a coding gain of 0.75 dB at an FEC (Forward Error Correction) threshold of 3.8×10-3. The proposed scheme achieves error-free key transmission, with a bit error rate (BER) consistently maintained at 0. Notably, even minor key misalignments result in a BER of 0.5, facilitating timely key updates. The scheme boasts a vast key space of 10150, effectively resisting brute-force attacks. Due to its hi

关键词： Forward error correction

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A data complementary method for thunderstorm point charge localization based on atmospheric electric field apparatus array group

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Digital Communications and Networks 2021年第2期7卷 170-177页

作者： Xu Yang Hongyan Xing Collaborative Innovation Center for Meteorological Disaster Prediction and Evaluation Nanjing University of Information Science and TechnologyNanjing210044China Jiangsu Key Laboratory of Meteorological Detection and Information Processing Nanjing University of Information Science and TechnologyNanjing210044China

Data loss or distortion causes adverse effects on the accuracy and stability of the thunderstorm point charge *** solve this problem,we propose a data complementary method based on the atmospheric electric field apparatus array *** electric field component measurement model of the atmospheric electric field apparatus is established,and the orientation parameters of the thunderstorm point charge are *** on the mirror method,the thunderstorm point charge coordinates are obtained by using the potential distribution *** test the validity of the basic algorithm,the electric field component measurement error and the localization accuracy are *** the azimuth angle and the elevation angle,the localization parameters also include the distance from the apparatus to the thunderstorm *** on a primary electric field apparatus,we establish the array group of *** on this,the data measured by each apparatus is complementarily processed to regain the thunderstorm point charge *** results show that,compared with the radar map data,this method can accurately reflect the location of the thunderstorm point charge,and has a better localization ***,several observation results during thunderstorm weather have been presented.

关键词： Atmospheric electric field apparatus Array Thunderstorm point charge Data complementary

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MZI/FPI Fiber Optic Dual-parameter Sensor Based on a Double Cone and Air Cavity Structure(Invited)

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光子学报 2024年第10期53卷 64-72页

作者： YUAN Tingxuan ZHAO Lilong REN Jianxin MAO Yaya ULLAH Rahat WU Xiangyu MAO Beibei XIA Wenchao Institute of Optics and Electronics Nanjing University of Information Science&TechnologyNanjing 210044China Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean Nanjing University of Information Science&TechnologyNanjing 210044China Jiangsu International Joint Laboratory on Meteorological Photonics and Optoelectronic Detection Nanjing University of Information Science&TechnologyNanjing 210044China

This paper proposes a Mach Zehnder/Fabry Perot Interferometer(MZI/FPI)fiber sensor based on Single-mode Fiber(SMF)and Hollow-core Fiber(HCF),which has high sensitivity to temperature and lateral *** proposed device consists of two single-mode fiber cones formed by manually controlling the fusion splicer and an air cavity formed by fusing a section of hollow-core *** structure of the sensor is a double cone cascaded air *** the beginning of the design,we compared the basic transmission spectra of single cone structure and double cone structure experimentally,and therefore chose to use double cone structure and air cavity *** undergoes its first reflection at the first interface between the single-mode fiber and the air cavity structure,and its second reflection at the second interface between the air cavity structure and the single-mode *** two reflected light waves produced by the two reflections form FP interference,which can be used to measure lateral *** transmitted light is excited through the first cone,and a portion of the core mode light is excited to the cladding,while another portion of the core mode light continues to propagate in the *** light couples at the second cone,and the cladding mode light couples back into the core,forming MZ interference with the core mode light,which can be used to measure *** use of hollow-core fiber to form an air cavity has little effect on transmitted light,while avoiding the problem of crosstalk in dual parameter *** designing temperature and lateral load experiments,this article verifies the sensitivity characteristics of this sensor to temperature and lateral loads.A significant redshift phenomenon was observed in the temperature experiment.A significant redshift phenomenon also occurred in the lateral load *** wavelength demodulation,the experimental results show that the wavelength sensitivity of the sensor to temperature is 56.29 pm/℃i

关键词： Temperature Lateral load Fiber sensor Mach-Zehnder interferometer Fabry-Pérot interferometer

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