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arXiv 2022年

作者： Tay, Fuyang Lin, Xiao Shi, Xihang Chen, Hongsheng Kaminer, Ido Zhang, Baile Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation ZJUHangzhou Global Science and Technology Innovation Center College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley–Curl Institute Rice University HoustonTX77005 United States International Joint Innovation Center The Electromagnetics Academy Zhejiang University Zhejiang University Haining314400 China Department of Electrical Engineering Technion-Israel Institute of Technology Haifa32000 Israel Jinhua Institute of Zhejiang University Zhejiang University Jinhua321099 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 637371 Singapore Centre for Disruptive Photonic Technologies Nanyang Technological University 637371 Singapore

Free-electron radiation is a fundamental photon emission process that is induced by fast-moving electrons interacting with optical media. Historically, it has been understood that, just like any other photon emission process, free-electron radiation must be constrained within a finite time interval known as the "formation time", whose concept is applicable to both Cherenkov radiation and transition radiation, the two basic mechanisms describing radiation from a bulk medium and from an interface, respectively. Here we reveal an alternative mechanism of free-electron radiation far beyond the previously defined formation time. It occurs when a fast electron crosses the interface between vacuum and a plasmonic medium supporting bulk plasmons. While emitted continuously from the crossing point on the interface — thus consistent with the features of transition radiation — the extra radiation beyond the conventional formation time is supported by a long tail of bulk plasmons following the electron’s trajectory deep into the plasmonic medium. Such a plasmonic tail mixes surface and bulk effects, and provides a sustained channel for electron-interface interaction. These results also settle the historical debate in Ferrell radiation, regarding whether it is a surface or bulk effect, from transition radiation or plasmonic oscillation. Copyright © 2022, The Authors. All rights reserved.

关键词： Plasmonics

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Hamiltonian Hopping for Efficient Chiral Mode Switching in Encircling Exceptional Points

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Physical Review Letters 2020年第18期125卷 187403-187403页

作者： Aodong Li Jianji Dong Jian Wang Ziwei Cheng John S. Ho Dawei Zhang Jing Wen Xu-Lin Zhang C. T. Chan Andrea Alù Cheng-Wei Qiu Lin Chen Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan 430074 China Department of Electrical and Computer Engineering National University of Singapore Singapore 117583 Singapore Engineering Research Center of Optical Instrument and Systems Ministry of Education and Shanghai Key Lab of Modern Optical System University of Shanghai for Science and Technology No. 516 Jungong Road Shanghai 200093 China State Key Laboratory of Integrated Optoelectronics College of Electronic Science and Engineering Jilin University Changchun 130012 China Department of Physics The Hong Kong University of Science and Technology Clear Water Bay Hong Kong 999077 China Photonics Initiative Advanced Science Research Center City University of New York New York New York 10031 USA Physics Program Graduate Center City University of New York New York New York 10016 USA

Dynamically encircling exceptional points (EPs) can lead to chiral mode switching as the system parameters are varied along a path that encircles EP. However, conventional encircling protocols result in low transmittance due to path-dependent losses. Here, we present a paradigm to encircle EPs that includes fast Hamiltonian variations on the parameter boundaries, termed Hamiltonian hopping, enabling ultrahigh-efficiency chiral mode switching. This protocol avoids path-dependent loss and allows us to experimentally demonstrate nearly 90% efficiency at 1550 nm in the clockwise direction, overcoming a long-standing challenge of non-Hermitian optical systems and powering up new opportunities for EP physics.

关键词： Open quantum systems & decoherence PT-symmetric quantum mechanics Photonics Waveguides

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Protein and lipid expansion microscopy with trypsin and tyramide signal amplification for 3D imaging

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Scientific reports 2023年第1期13卷 21922页

作者： Ueh-Ting Tim Wang Xuejiao Tian Yae-Huei Liou Sue-Ping Lee Hsiao-Tang Hu Chieh-Han Lu Po-Ting Lin Ya-Jen Cheng Peilin Chen Bi-Chang Chen Affiliated Senior High School of National Taiwan Normal University Taipei 106348 Taiwan. Research Center for Applied Sciences Academia Sinica Taipei 11529 Taiwan. Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica and National Tsing Hua University Taipei 11529 Taiwan. Department of Engineering and System Science National Tsing Hua University Hsinchu 300 Taiwan. Institute of Molecular Biology Academia Sinica Taipei 11529 Taiwan. Institute and Undergraduate Program of Electro-Optical Engineering National Taiwan Normal University Taipei 116 Taiwan. Neuroscience Program NPAS Academia Sinica Taipei 11529 Taiwan ROC. Research Center for Applied Sciences Academia Sinica Taipei 11529 Taiwan. chenb10@gate.sinica.edu.tw.

Expansion microscopy, whereby the relative positions of biomolecules are physically increased via hydrogel expansion, can be used to reveal ultrafine structures of cells under a conventional microscope. Despite its utility for achieving super-resolution imaging, expansion microscopy suffers a major drawback, namely reduced fluorescence signals caused by excessive proteolysis and swelling effects. This caveat results in a lower photon budget and disfavors fluorescence imaging over a large field of view that can cover an entire expanded cell, especially in 3D. In addition, the complex procedures and specialized reagents of expansion microscopy hinder its popularization. Here, we modify expansion microscopy by deploying trypsin digestion to reduce protein loss and tyramide signal amplification to enhance fluorescence signal for point-scanning-based imaging. We name our new methodology TT-ExM to indicate dual trypsin and tyramide treatments. TT-ExM may be applied for both antibody and lipid staining. TT-ExM displayed enhanced protein retention for endoplasmic reticulum and mitochondrial markers in COS-7 cell cultures. Importantly, TT-ExM-based lipid staining clearly revealed the complex 3D membrane structures in entire expanded cells. Through combined lipid and DNA staining, our TT-ExM methodology highlighted mitochondria by revealing their DNA and membrane structures in cytoplasm, as well as the lipid-rich structures formed via phase separation in nuclei at interphase. We also observed lipid-rich chromosome matrices in the mitotic cells. These high-quality 3D images demonstrate the practicality of TT-ExM. Thus, readily available reagents can be deployed in TT-ExM to significantly enhance fluorescence signals and generate high-quality and ultrafine-resolution images under confocal microscopy.

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Silica nanocone array as a template for fabricating a plasmon induced hot electron photodetector

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Photonics Research 2019年第3期7卷 294-299页

作者： ZHIQIANG YANG KANG DU FANFAN LU YANG PANG SHIJIA HUA XUETAO GAN WENDING ZHANG SOO JIN CHUA TING MEI Key Laboratory of Space Applied Physics and Chemistry Ministry of Education and Shaanxi Key Laboratory of Optical Information TechnologySchool of Science Northwestern Polytechnical University Department of Electrical and Computer Engineering National University of Singapore LEES Program Singapore-MIT Alliance for Research & Technology (SMART)

Plasmon induced hot electrons have attracted a great deal of interest as a novel route for photodetection and lightenergy harvesting. Herein, we report a hot electron photodetector in which a large array of nanocones deposited sequentially with aluminum, titanium dioxide, and gold films can be integrated functionally with nanophotonics and microelectronics. The device exhibits a strong photoelectric response at around 620 nm with a responsivity of 180 μA/W under short-circuit conditions with a significant increase under 1 V reverse bias to 360 μA/W. The increase in responsivity and a red shift in the peak value with increasing bias voltage indicate that the bias causes an increase in the hot electron tunneling effect. Our approach will be advantageous for the implementation of the proposed architecture on a vast variety of integrated optoelectronic devices.

关键词： Silica nanocone array plasmon induced hot electron photodetector

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Low-frequency conductivity of low wear high-entropy alloys

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Nature communications 2024年第1期15卷 4554页

作者： Cheng-Hsien Yeh Wen-Dung Hsu Bernard Haochih Liu Chan-Shan Yang Chen-Yun Kuan Yuan-Chun Chang Kai-Sheng Huang Song-Syun Jhang Chia-Yen Lu Peter K Liaw Chuan-Feng Shih Department of Electrical Engineering National Cheng Kung University Tainan 70101 Taiwan. Department of Materials Science and Engineering National Cheng Kung University Tainan 70101 Taiwan. wendung@mail.ncku.edu.tw. Applied High Entropy Technology (AHET) Center National Cheng Kung University Tainan 70101 Taiwan. wendung@mail.ncku.edu.tw. Program on Semiconductor Packaging and Testing Academy of Innovative Semiconductor and Sustainable Manufacture National Cheng Kung University Tainan 70101 Taiwan. wendung@mail.ncku.edu.tw. Department of Materials Science and Engineering National Cheng Kung University Tainan 70101 Taiwan. hcliu@mail.ncku.edu.tw. Applied High Entropy Technology (AHET) Center National Cheng Kung University Tainan 70101 Taiwan. hcliu@mail.ncku.edu.tw. Applied High Entropy Technology (AHET) Center National Cheng Kung University Tainan 70101 Taiwan. csyang@ntnu.edu.tw. Institute and Undergraduate Program of Electro-Optical Engineering National Taiwan Normal University Taipei 11677 Taiwan. csyang@ntnu.edu.tw. Department of Materials Science and Engineering National Cheng Kung University Tainan 70101 Taiwan. Institute and Undergraduate Program of Electro-Optical Engineering National Taiwan Normal University Taipei 11677 Taiwan. Department of Materials Science and Engineering The University of Tennessee Knoxville TN 37996 USA. Department of Electrical Engineering National Cheng Kung University Tainan 70101 Taiwan. cfshih@mail.ncku.edu.tw. Applied High Entropy Technology (AHET) Center National Cheng Kung University Tainan 70101 Taiwan. cfshih@mail.ncku.edu.tw. Program on Semiconductor Packaging and Testing Academy of Innovative Semiconductor and Sustainable Manufacture National Cheng Kung University Tainan 70101 Taiwan. cfshih@mail.ncku.edu.tw.

High-entropy alloys (HEAs) provide new research avenues for alloy combinations in the periodic table, opening numerous possibilities in novel-alloy applications. However, their electrical characteristics have been relatively underexplored. The challenge in establishing an HEA electrical conductivity model lies in the changes in electronic characteristics caused by lattice distortion and complexity of nanostructures. Here we show a low-frequency electrical conductivity model for the Nb-Mo-Ta-W HEA system. The cocktail effect is found to explain trends in electrical-conductivity changes in HEAs, while the magnitude of the reduction is understood by the calculated plasma frequency, free electron density, and measured relaxation time by terahertz spectroscopy. As a result, the refractory HEA NbMoTaW thin film exhibits both high hardness and excellent conductivity. This combination of NbMoTaW makes it suitable for applications in atomic force microscopy probe coating, significantly improving their wear resistance and atomic-scale image resolution.

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Marangoni convection-driven laser fountains and waves on free surfaces of liquids

arXiv

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arXiv 2021年

作者： Lin, Feng Quraishy, Aamir Nasir Tong, Tian Li, Runjia Yang, Guang Mohebinia, Mohammadjavad Qiu, Yi Vishal, Talari Zhao, Junyi Zhang, Wei Zhong, Hong Zhang, Hang Zhou, Chaofu Tong, Xin Yu, Peng Hu, Jonathan Dong, Suchuan Liu, Dong Wang, Zhiming Schaibley, John R. Bao, Jiming Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China ChengduSichuan610054 China Department of Electrical and Computer Engineering University of Houston HoustonTX77204 United States Department of Physics University of Arizona TucsonAZ85721 United States James C. Wyant College of Optical Sciences University of Arizona TucsonAZ85721 United States Department of Mechanical Engineering University of Houston HoustonTX77204 United States Materials Science and Engineering Program University of Houston HoustonTX77204 United States School of Science Southwest Petroleum University ChengduSichuan610500 China Department of Electrical and Systems Engineering Washington University in St. Louis St. LouisMO63130 United States Department of Electrical & Computer Engineering Baylor University WacoTX76798 United States Department of Mathematics Purdue University West LafayetteIN47907 United States Department of Physics Texas Center for Superconductivity University of Houston HoustonTX77204 United States

It is well accepted that an outward Marangoni convection from a low surface tension region will make the surface depressed. Here, we report that this established perception is only valid for thin liquid films. Using surface laser heating, we show that in deep liquids a laser beam actually pulls up the fluid above the free surface generating fountains with different shapes. Whereas with decreasing liquid depth a transition from fountain to indentation with fountain-in-indentation is observed. Further, high-speed imaging reveals a transient surface process before steady elevation is formed, and this dynamic deformation is subsequently utilized to resonantly excite giant surface waves by a modulated laser beam. Computational fluid dynamics models reveal the underlying flow patterns and quantify the depth-dependent and time-resolved surface deformations. Our discoveries and techniques have upended the century-old perception and opened up a new regime of interdisciplinary research and applications of Marangoni-induced interface phenomena and optocapillary fluidic surfaces - the control of fluids with light. © 2021, CC BY.

关键词： Deformation

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Configurable antiferromagnetic domains and lateral exchange bias in atomically thin CrPS4

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Nature Materials 2025年 1-10页

作者： Yu-Xuan Wang Thomas K. M. Graham Xin-Yue Zhang Brian B. Zhou Ricardo Rama-Eiroa Elton J. G. Santos Mohammad H. Badarneh Md Ariful Islam Rafael Nunes Gontijo Ganesh Prasad Tiwari Tibendra Adhikari Zhong Lin Kenji Watanabe Takashi Taniguchi Claire Besson Department of Physics Boston College Chestnut Hill MA USA Donostia International Physics Center (DIPC) Donostia-San Sebastián Spain Institute for Condensed Matter and Complex Systems School of Physics and Astronomy University of Edinburgh Edinburgh UK Higgs Centre for Theoretical Physics University of Edinburgh Edinburgh UK Department of Physics Applied Physics and Astronomy Binghamton University Binghamton NY USA Materials Science and Engineering Program Binghamton University Binghamton NY USA Research Center for Electronic and Optical Materials National Institute for Materials Science Tsukuba Japan Research Center for Materials Nanoarchitectonics National Institute for Materials Science Tsukuba Japan Department of Chemistry Binghamton University Binghamton NY USA

Interfacial exchange coupling between antiferromagnets (AFMs) and ferromagnets (FMs) crucially makes it possible to shift the FM hysteresis, known as exchange bias, and to switch AFM states. Two-dimensional magnets unlock opportunities to combine AFM and FM materials; however, the buried AFM–FM interfaces obtained by stacking remains challenging to understand. Here we demonstrate interfacial control via intralayer exchange coupling in the layered AFM CrPS4, where connected even and odd layers realize pristine lateral interfaces between AFM-like and FM-like regions. We distinguish antiphase even-layer states by scanning nitrogen-vacancy centre magnetometry due to a weak surface magnetization. This surface magnetization enables control over the even-layer state, with different regions switching at distinct fields due to their own lateral couplings. We toggle three AFM domains adjacent to a FM-like region and demonstrate a tunable multilevel exchange bias. Our nanoscale visualization unveils the microscopic origins of exchange bias and advances single two-dimensional crystals for hybrid AFM–FM technologies.

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Highly accelerated EPI with wave encoding and multi-shot simultaneous multi-slice imaging

arXiv

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arXiv 2021年

作者： Cho, Jaejin Liao, Congyu Tian, Qiyuan Zhang, Zijing Xu, Jinmin Lo, Wei-Ching Poser, Benedikt A. Stenger, V. Andrew Stockmann, Jason Setsompop, Kawin Bilgic, Berkin Athinoula A. Martinos Center for Biomedical Imaging Massachusetts General Hospital BostonMA United States Harvard Medical School BostonMA United States Radiological Sciences Laboratory Stanford University Palo AltoCA United States State Key Laboratory of Modern Optical Instrumentation College of Optical Science and Engineering Zhejiang University Hangzhou China Siemens Medical Solutions BostonMA United States Maastricht Brain Imaging Centre Maastricht University Maastricht Netherlands MR Research Program Department of Medicine John A. Burns School of Medicine University of Hawai'i HI United States Harvard-MIT Health Sciences and Technology Massachusetts Institute of Technology CambridgeMA United States

Purpose: To introduce wave encoded acquisition and reconstruction techniques for highly accelerated echo planar imaging (EPI) with reduced g-factor penalty and image artifacts. Method: Wave-EPI involves playing sinusoidal gradients during the EPI readout while employing interslice shifts as in blipped-CAIPI acquisitions. This spreads the aliasing in all spatial directions, thereby taking better advantage of 3D coil sensitivity profiles. The amount of voxel spreading that can be achieved by the wave gradients during the short EPI readout period is constrained by the slew rate of the gradient coils and peripheral nerve stimulation (PNS) monitor. We propose to use a "half-cycle" sinusoidal gradient to increase the amount of voxel spreading that can be achieved while respecting the slew and stimulation constraints. Extending wave-EPI to multi-shot acquisition minimizes geometric distortion and voxel blurring at high in-plane resolution, while structured low-rank regularization mitigates shot-to-shot phase variations without additional navigators. We propose to use different point spread functions (PSFs) for the k-space lines with positive and negative polarities, which are calibrated with a FLEET-based reference scan and allow for addressing gradient imperfections. Results: Wave-EPI provided whole-brain single-shot gradient echo (GE) and multi-shot spin echo (SE) EPI acquisitions at high acceleration factors and was combined with g-Slider slab encoding to boost the SNR level in 1mm isotropic diffusion imaging. Relative to blipped-CAIPI, wave-EPI reduced average and maximum g-factors by up to 1.21- and 1.37-fold, respectively. Conclusion: Wave-EPI allows highly accelerated single- and multi-shot EPI with reduced g-factor and artifacts and may facilitate clinical and neuroscientific applications of EPI by improving the spatial and temporal resolution in functional and diffusion imaging. Copyright © 2021, The Authors. All rights reserved.

关键词： Signal encoding

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Terahertz time-domain polarimetry for generalized anistropic and chiral materials 12

Terahertz time-domain polarimetry for generalized anistropic...

引用

Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XII 2019

作者： Cheng, Gong Choi, Won Jin Jang, Hee-Jeong Kotov, Nicholas A. Norris, Theodore B. Department of Physics University of Michigan Ann ArborMI48109 United States Center for Ultrafast Optical Science University of Michigan Ann ArborMI48109 United States Department of Materials Science and Engineering University of Michigan Ann ArborMI48109 United States Department of Chemical Engineering University of Michigan Ann ArborMI48109 United States Biointerfaces Institute University of Michigan Ann ArborMI48109 United States Program in Macromolecular Science and Engineering University of MI Ann ArborMI48109 United States Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109 United States

ISBN: (纸本)9781510624764

We have developed two terahertz (THz) polarimetric methodologies based on terahertz time-domain spectroscopy (THz-TDS) incorporating three wire-grid polarizers. They require no change to existing THz-TDS setups and are free of any complicated electronic controls and synchronizations. In addition to the standard quantities measured by THz-TDS such as transmission and optical constants, they provide complete information on the anisotropy and chirality for a generalized material through measurements of the full electric field vector and hence the Jones matrix, and calculating specific quantities. Thus terahertz time-domain polarimetry (THz-TDP) can be considered as an upgrade of the conventional THz-TDS, needed for full characterization of anisotropic and chiral materials. In this paper, we describe the details of the experimental settings, mathematical procedures and property quantifications in these methodologies. We present experimental results on an anisotropic polymer sheet showing the effectiveness of the methods, and preliminary data for chiral DNA molecules for the first time in the THz frequency range. © 2019 SPIE.

关键词： Polarimeters

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Germanium polishing via femtosecond laser radiation

Germanium polishing via femtosecond laser radiation

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optical Fabrication and Testing, OFT 2019 - Part of optical Design and Fabrication 2019

作者： Taylor, L.L. Xu, J. Smith, T.R. Pomerantz, M. Lambropoulos, J.C. Qiao, J. Rochester Institute of Technology Chester F. Carlson Center for Imaging Science RochesterNY United States University of Rochester Department of Mechanical Engineering RochesterNY United States University of Rochester Materials Science Program RochesterNY United States University of Rochester Laboratory for Laser Energetics RochesterNY United States Aperture Optical Sciences MeridenCT United States

Femtosecond laser polishing of germanium was demonstrated by controlling laser parameters to realize smooth processing. Scalable material removal with optical quality was achieved, showing the capability of femtosecon... 详细信息

ISBN: (纸本)9781943580606

关键词： Germanium

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