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Optomechanically Induced Birefringence and Optomechanically Induced Faraday Effect

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Physical Review Letters 2019年第2期123卷 023602-023602页

作者： Robert Duggan Javier del Pino Ewold Verhagen Andrea Alù Department of Electrical and Computer Engineering The University of Texas at Austin Austin Texas 78712 USA Center for Nanophotonics AMOLF Science Park 104 1098 XG Amsterdam The Netherlands Photonics Initiative Advanced Science Research Center City University of New York New York 10031 USA Physics Program Graduate Center City University of New York New York 10016 USA Department of Electrical Engineering City College of The City University of New York New York 10031 USA

We demonstrate an optomechanical platform where optical mode conversion mediated by mechanical motion enables the arbitrary tailoring of polarization states of propagating light fields. Optomechanical interactions are realized in a Fabry-Pérot resonator, which naturally supports two polarization-degenerate states while an optical control field induces rotational symmetry breaking. Applying such principles, the entire Poincaré sphere is spanned by just optical control of the driving field, realizing reciprocal and nonreciprocal optomechanically induced birefringence for linearly polarized and circularly polarized control driving. A straightforward extension of this setup also enables all-optical tunable isolation and circulation. Our findings open new avenues to exploit optomechanics for the arbitrary manipulation of light polarization.

关键词： Nonlinear optics Optomechanics

PixelSteganalysis: Pixel-wise Hidden Information Removal with Low Visual Degradation

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arXiv 2019年

作者： Jung, Dahuin Bae, Ho Choi, Hyun-Soo Yoon, Sungroh The Dept. of Electrical and Computer Engineering Seoul National University Seoul08826 Korea Republic of Dept. of Cyber Security Ewha Womans University Seoul03760 Korea Republic of Dept. of Computer Science & Engineering Interdisciplinary Graduate Program in Medical Bigdata Convergence Kangwon National University Chuncheon 24341 Korea Republic of Ziovision Chuncheon24341 Korea Republic of Interdisciplinary Program in Artificial Intelligence Seoul National University Seoul08826 Korea Republic of

Recently, the field of steganography has experienced rapid developments based on deep learning (DL). DL based steganography distributes secret information over all the available bits of the cover image, thereby posing difficulties in using conventional steganalysis methods to detect, extract or remove hidden secret images. However, our proposed framework is the first to effectively disable covert communications and transactions that use DL based steganography. We propose a DL based steganalysis technique that effectively removes secret images by restoring the distribution of the original images. We formulate a problem and address it by exploiting sophisticated pixel distributions and an edge distribution of images by using a deep neural network. Based on the given information, we remove the hidden secret information at the pixel level. We evaluate our technique by comparing it with conventional steganalysis methods using three public benchmarks. As the decoding method of DL based steganography is approximate (lossy) and is different from the decoding method of conventional steganography, we also introduce a new quantitative metric called the destruction rate (DT). The experimental results demonstrate performance improvements of 10-20% in both the decoded rate and the DT. Copyright © 2019, The Authors. All rights reserved.

关键词： Steganography

A smartphone application to detection and classification of coffee leaf miner and coffee leaf rust

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arXiv 2019年

作者： Manso, Giuliano L. Knidel, Helder Krohling, Renato A. Ventura, José A. Labcin-Laboratory of Computing and Engineering Inspired by Nature UFES-Federal University of Espirito Santo Vitória Brazil PPGI-Graduate Program in Computer Science UFES Vitória Brazil Production Engineering Department UFES Vitória Brazil Incaper Rua Afonso Sarlo Vitória ES29052-010 Brazil

Generally, the identification and classification of plant diseases and/or pests are performed by an expert . One of the problems facing coffee farmers in Brazil is crop infestation, particularly by leaf rust Hemileia vastatrix and leaf miner Leucoptera coffeella. The progression of the diseases and or pests occurs spatially and temporarily. So, it is very important to automatically identify the degree of severity. The main goal of this article consists on the development of a method and its i implementation as an App that allow the detection of the foliar damages from images of coffee leaf that are captured using a smartphone, and identify whether it is rust or leaf miner, and in turn the calculation of its severity degree. The method consists of identifying a leaf from the image and separates it from the background with the use of a segmentation algorithm. In the segmentation process, various types of backgrounds for the image using the HSV and YCbCr color spaces are tested. In the segmentation of foliar damages, the Otsu algorithm and the iterative threshold algorithm, in the YCgCr color space, have been used and compared to k-means. Next, features of the segmented foliar damages are calculated. For the classification, artificial neural network trained with extreme learning machine have been used. The results obtained shows the feasibility and effectiveness of the approach to identify and classify foliar damages, and the automatic calculation of the severity. The results obtained are very promising according to experts. Copyright © 2019, The Authors. All rights reserved.

关键词： Neural networks

Development of a smartphone-based app for determination of formaldehyde concentration indoors 15

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Development of a smartphone-based app for determination of f...

15th Conference of the International Society of Indoor Air Quality and Climate, INDOOR AIR 2018

作者： Zhang, Siyang Shapiro, Nicholas Gehrke, Gretchen Castner, Jessica Liu, Zhenlei Guo, Beverly Zhang, Jianshun Haines, Sarah Kormos, David Frey, Paige Qin, Rongjun Dannemiller, Karen C. Department of Computer Science and Engineering Ohio State University United States Public Laboratory for Open Technology and Science Department of Mechanical and Aerospace Engineering Syracuse University Environmental Science Graduate Program Ohio State University United States Department of Civil Environmental and Geodetic Engineering College of Engineering Ohio State University United States Strand Associates Incorporated Department of Electrical and Computer Engineering Ohio State University United States Department of Environmental Health Sciences College of Public Health Ohio State University United States

ISBN: (纸本)9781713826514

Formaldehyde is a ubiquitous contaminant in the indoor environment that is both a carcinogen and irritant. The goal of this project is to develop a smartphone-based app for use by citizen scientists or researchers that can be paired with low-cost colorimetric badges for detection of indoor formaldehyde. We conducted both national and geographically-targeted surveys prior to app design. We have subsequently developed the app and conducted a beta test. Surveys of 147 individuals indicated broad public interest in formaldehyde testing using smartphone technology. Testing of the badges indicated consistent change in illumination with increasing formaldehyde exposure. Beta testing indicated users were able to navigate the existing app, and highlighted areas for improvement including incorporation of public surveys. Planned future analysis includes extensive calibration testing and a community-based field test. © 2018 15th Conference of the International Society of Indoor Air Quality and Climate, INDOOR AIR 2018. All rights reserved.

关键词： Formaldehyde

Galaxy clusters at z∼1 imaged by ALMA with the Sunyaev-Zel’dovich effect

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arXiv 2022年

作者： Kitayama, Tetsu Ueda, Shutaro Okabe, Nobuhiro Akahori, Takuya Hilton, Matt Hughes, John P. Ichinohe, Yuto Kohno, Kotaro Komatsu, Eiichiro Lin, Yen-Ting Miyatake, Hironao Oguri, Masamune Sifón, Cristóbal Takakuwa, Shigehisa Takizawa, Motokazu Tsutsumi, Takahiro van Marrewijk, Joshiwa Wollack, Edward J. Department of Physics Toho University Chiba Funabashi274-8510 Japan No. 1 Section 4 Roosevelt Road Taipei10617 Taiwan Institute of Astronomy National Tsing Hua University Hsinchu30013 Taiwan Department of Physics Hiroshima University 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima739-8526 Japan Astrophysical Science Center Hiroshima University 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima739-8526 Japan Core Research for Energetic Universe Hiroshima University Department of Physics Hiroshima University 1-3-1 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima739-8526 Japan Physics Program Graduate School of Advanced Science and Engineering Hiroshima University 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima739-8526 Japan Mizusawa VLBI observatory National Astronomical Observatory of Japan 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Operation Division SKA Observatory Jodrell Bank Lower Withington MacclesfieldSK11 9DL United Kingdom Astrophysics Research Centre University of KwaZulu-Natal Westville Campus Durban4041 South Africa School of Mathematics Statistics & Computer Science University of KwaZulu-Natal Westville Campus Durban4041 South Africa Wits Centre for Astrophysics School of Physics University of the Witwatersrand Private Bag 3 Johannesburg2050 South Africa Department of Physics and Astronomy Rutgers The State University of New Jersey PiscatawayNJ08854-8019 United States Department of Physics Rikkyo University 3-34-1 Nishi-Ikebukuro Toshima-ku Tokyo171-8501 Japan Institute of Astronomy School of Science The University of Tokyo 2-21-1 Osawa Mitaka Tokyo181-0015 Japan Research Center for the Early Universe School of Science The University of Tokyo 7-3-1 Hongo Bunkyo Tokyo113-0033 Japan Max-Planck-Institut für Astrophysik Karl-Schwarzschild Str. 1 GarchingD-85741 Germany The University of Tokyo Institutes for Advanced Study The University of Tokyo 5-1-5 Kashiwanoha Chiba277-8583 Japan Nagoya University Nagoya464-8

We present high angular-resolution measurements of the thermal Sunyaev-Zel’dovich effect (SZE) toward two galaxy clusters, RCS J2319+0038 at z = 0.9 and HSC J0947−0119 at z = 1.1, by the Atacama Large Millimeter/submillimeter Array (ALMA) in Band 3. They are supplemented with available Chandra X-ray data, optical data taken by Hyper Suprime-Cam on Subaru, and millimeter-wave SZE data from the Atacama Cosmology Telescope. Taking into account departures from spherical symmetry, we have reconstructed non-parametrically the inner pressure profile of two clusters as well as electron temperature and density profiles for RCS J2319+0038. This is one of the first such measurements for an individual cluster at z >∼ 0.9. We find that the inner pressure profile of both clusters is much shallower than that of local cool-core clusters. Our results consistently suggest that RCS J2319+0038 hosts a weak cool core, where radiative cooling is less significant than in local cool cores. On the other hand, HSC J0947−0119 exhibits an even shallower pressure profile than RCS J2319+0038 and is more likely a non-cool-core cluster. The SZE centroid position is offset by more than 140 h−170kpc from the peaks of galaxy distribution in HSC J0947−0119, suggesting a stronger influence of mergers in this cluster. We conclude that these distant clusters are at a very early stage of developing the cool cores typically found in clusters at lower redshifts. Copyright © 2022, The Authors. All rights reserved.

关键词： Millimeter waves

The limits of near Field Immersion Microwave Microscopy evaluated by imaging bilayer graphene Moiré patterns

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arXiv 2020年

作者： Ohlberg, Douglas A.A. Tami, Diego Gadelha, Andreij C. Neto, Eliel G.S. Santana, Fabiano C. Miranda, Daniel Avelino, Wellington Watanabe, Kenji Taniguchi, Takashi Campos, Leonardo C. Ramirez, Jhonattan C. do Rego, Cássio Gonçalves Jorio, Ado Medeiros-Ribeiro, Gilberto Microscopy Center Universidade Federal de Minas Gerais Belo HorizonteMG31270-901 Brazil Electrical Engineering Graduate Program Universidade Federal de Minas Gerais Belo HorizonteMG31270-901 Brazil Physics Department Universidade Federal de Minas Gerais Belo HorizonteMG31270-901 Brazil Instituto de Física Universidade Federal da Bahia Campus Universitário de Ondina Salvador - BA40170-115 Brazil 1-2-1 Sengen Tsukuba-cityIbaraki305-0047 Japan Department of Electronic Engineering School of Engineering Universidade Federal de Minas Gerais Belo HorizonteMG31270-901 Brazil Technology Innovation Graduate Program Universidade Federal de Minas Gerais Belo HorizonteMG31270-901 Brazil Computer Science Department Universidade Federal de Minas Gerais Belo HorizonteMG31270-901 Brazil

Molecular and atomic imaging required the development of electron and scanning probe microscopies to surpass the physical limits dictated by diffraction [1]. Nano-infrared experiments [2] and pico-cavity tip-enhanced Raman spectroscopy imaging later demonstrated that radiation in the visible range [3] can surpass this limit by using scanning probe tips to access the near-field regime [4]. Here we show that ultimate resolution can be obtained by using scanning microwave imaging microscopy to reveal structures with feature sizes down to 1 nm using a radiation of 0.1 m in wavelength. As a test material we use twisted bilayer graphene, which is not only a very important recent topic due to the discovery of correlated electron effects such as superconductivity [5], but also because it provides a sample where we can systematically tune a superstructure Moiré patterńs modulation from below one up to tens of nanometers. By analyzing the tip-sample distance dynamics, we demonstrate that this ultimate 108 probe-to-pattern resolution can be achieved by using liquid immersion microscopy concepts and exquisite force control exerted on nanoscale water menisci. Copyright © 2020, The Authors. All rights reserved.

关键词： Moire fringes

Nonreciprocal hyperbolic propagation over moving metasurfaces

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Physical Review B 2019年第4期99卷 045407-045407页

作者： Yarden Mazor Andrea Alù Department of Electrical and Computer Engineering The University of Texas at Austin Austin Texas 78712 USA 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 10026 USA Department of Electrical Engineering City College of New York New York New York 10031 USA

Hyperbolic propagation offers exciting opportunities in nanophotonics, from subdiffraction imaging to enhanced local density of states. This transport regime is typically induced by strong modulation of conductivity, i.e., with alternating metallic and dielectric material properties. Here, we analyze a moving impedance surface, showing that suitably tailored homogeneous metasurfaces can support one-way hyperbolic propagation when in motion, adding nonreciprocity to hyperbolic propagation phenomena, and without suffering from nonlocal effects stemming from discretization or finite granularity of the surface.

关键词： Electromagnetism Metamaterials Photonics

Angular-momentum selectivity and asymmetry in highly confined wave propagation along sheath-helical metasurface tubes

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Physical Review B 2019年第15期99卷 155425-155425页

Highly confined surface waves present unique opportunities to enhance light interactions with localized emitters or molecules. Hyperbolic dispersion in metasurfaces allows us to tailor and manipulate surface waves, enhancing the local density of states over broad bandwidths. So far, propagation on this platform was mainly studied in planar geometries, which facilitates the analysis but somehow limits the realm of possibilities. Here we show that “wrapping” hyperbolic metasurfaces into tubes may greatly enrich the wave propagation dynamics along their axis. This system shows strong interaction with fields and sources carrying optical angular momentum and pronounced field asymmetries, and opens pathways to valley-specific excitation and routing. In addition, we demonstrate that various parameter regimes enable strong spin/helicity momentum locking.

关键词： Angular momentum of light Hyperbolic metamaterials Light-matter interaction Surface plasmons Surfaces

Hyperbolic Sound Propagation over Nonlocal Acoustic Metasurfaces

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Physical Review Letters 2019年第24期123卷 244303-244303页

作者： Li Quan Andrea Alù Department of Electrical and Computer Engineering The University of Texas at Austin Austin Texas 78712 USA 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 Department of Electrical Engineering City College of The City University of New York New York 10031 USA

Hyperbolic metasurfaces, supporting extreme anisotropy of the surface impedance tensor, have recently been explored in nanophotonic systems for robust diffractionless propagation over a surface, offering interesting opportunities for subdiffraction imaging and enhanced Purcell emission. In acoustics, due to the longitudinal nature of sound transport in fluids, these phenomena are forbidden by symmetry, requiring the acoustic surface impedance to be inherently isotropic. Here we show that nonlocalities produced by strong coupling between neighboring impedance elements enable extreme anisotropic responses for sound traveling over a surface, supporting negative phase and energy velocities, as well as hyperbolic propagation for acoustic surface waves.

关键词： Acoustics Hyperbolic metamaterials Metamaterials