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Zhang Z, Wang Z, Zhang C, Yao Z, Zhang S, Wang R, Tian Z, Han J, Chang C, Lou J, Yan X, Qiu C. Advanced Terahertz Refractive Sensing And Fingerprint Recognition Through Metasurface-Excited Surface Waves. Adv Mater 2024; 36:e2308453. [PMID: 38180283 DOI: 10.1002/adma.202308453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 12/27/2023] [Indexed: 01/06/2024]
Abstract
High-sensitive metasurface-based sensors are essential for effective substance detection and insightful bio-interaction studies, which compress light in subwavelength volumes to enhance light-matter interactions. However, current methods to improve sensing performance always focus on optimizing near-field response of individual meta-atom, and fingerprint recognition for bio-substances necessitates several pixelated metasurfaces to establish a quasi-continuous spectrum. Here, a novel sensing strategy is proposed to achieve Terahertz (THz) refractive sensing, and fingerprint recognition based on surface waves (SWs). Leveraging the long-range transmission, strong confinement, and interface sensitivity of SWs, a metasurface-supporting SWs excitation and propagation is experimentally verified to achieve sensing integrations. Through wide-band information collection of SWs, the proposed sensor not only facilitates refractive sensing up to 215.5°/RIU, but also enables the simultaneous resolution of multiple fingerprint information within a continuous spectrum. By covering 5 µm thickness of polyimide, quartz and silicon nitride layers, the maximum phase change of 91.1°, 101.8°, and 126.4° is experimentally obtained within THz band, respectively. Thus, this strategy broadens the research scope of metasurface-excited SWs and introduces a novel paradigm for ultrasensitive sensing functions.
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Affiliation(s)
- Zeyan Zhang
- School of Physics, Peking University, Beijing, 100871, China
- Innovation Laboratory of Terahertz Biophysics, National Innovation Institute of Defense Technology, Beijing, 100071, China
| | - Zhuo Wang
- State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Fudan University, Shanghai, 200433, China
| | - Chao Zhang
- Department of Neurosurgery Center, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China
| | - Zhibo Yao
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Key Laboratory of Optoelectronic Information Technology (Ministry of Education of China), Tianjin University, Tianjin, 300072, China
| | - Shoujun Zhang
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Key Laboratory of Optoelectronic Information Technology (Ministry of Education of China), Tianjin University, Tianjin, 300072, China
| | - Ride Wang
- Innovation Laboratory of Terahertz Biophysics, National Innovation Institute of Defense Technology, Beijing, 100071, China
| | - Zhen Tian
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Key Laboratory of Optoelectronic Information Technology (Ministry of Education of China), Tianjin University, Tianjin, 300072, China
| | - Jiaguang Han
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Key Laboratory of Optoelectronic Information Technology (Ministry of Education of China), Tianjin University, Tianjin, 300072, China
| | - Chao Chang
- School of Physics, Peking University, Beijing, 100871, China
- Innovation Laboratory of Terahertz Biophysics, National Innovation Institute of Defense Technology, Beijing, 100071, China
| | - Jing Lou
- Innovation Laboratory of Terahertz Biophysics, National Innovation Institute of Defense Technology, Beijing, 100071, China
| | - Xueqing Yan
- School of Physics, Peking University, Beijing, 100871, China
| | - Chengwei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore
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2
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Shaheen S, Hicke K, Krebber K. Blast-Assisted Subsurface Characterisation Using a Novel Distributed Acoustic Sensing Setup Based on Geometric Phases. Sensors (Basel) 2023; 24:30. [PMID: 38202892 PMCID: PMC10780498 DOI: 10.3390/s24010030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 12/13/2023] [Accepted: 12/18/2023] [Indexed: 01/12/2024]
Abstract
A novel DAS setup based on geometric phases in coherent heterodyne detection is applied for the first time to the characterisation of the Earth's subsurface. In addition, an optimisation of the proposed setup in terms of its spatial resolution is also presented for the first time. The surface waves are generated by strong blasts of 25 kg of explosives at a dedicated test site. A 10 km dark fiber link in the vicinity of the test site connected to the test setup records the resulting strain signals. The spike-free and low-noise strain data thus obtained minimize post-processing requirements, making the setup a candidate for real-time seismic monitoring. An analysis of the dispersion characteristics of the generated surface waves is performed using a recently reported optimised seismic interferometric technique. Based on the dispersion characteristics, the shear wave velocities of the surface waves as a function of the depth profile of the Earth's crust are determined using an optimised evolutionary algorithm.
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Affiliation(s)
- Sabahat Shaheen
- Bundesanstalt für Materialforschung und -Prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany; (K.H.); (K.K.)
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3
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Liu T, Meng Y, Wang J, Ma H, Chen H, Fu X, Zhu R, Liu C, Han Y, Li W, Tang W, Qu S. Dual-Channel Surface Waves Directional Radiation with Customizable Intensity and Switchable Pattern. ACS Appl Mater Interfaces 2023. [PMID: 37465891 DOI: 10.1021/acsami.3c06632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
Achieving the conversion from surface waves (SWs) to propagating waves has captivated long-standing interest, and various ingenious metasurfaces benefiting from the powerful control capability for electromagnetic waves are able to realize efficient SWs directional radiation. Nevertheless, most existing schemes still suffer from the bottlenecks of single radiation channel, uncontrollable radiation intensity, and immutable radiation pattern, which immensely hinder their practical application in high-integration intelligent devices. Herein, a series of appealing strategies are proposed to achieve the dual-channel SWs directional radiation with customizable radiation intensity and switchable radiation pattern. The dual-channel SWs radiation metadevice based on the phase modulation metasurface is designed to directionally radiate SWs in left-handed circular polarized channel and right-handed circular polarized channel and possesses the broadband frequency scanning characteristic. More strikingly, the intensity-customizable dual-channel SWs radiation metadevice loaded with lumped resistors can control the realized gain of two circular polarized radiation beams, and the pattern-switchable dual-channel SWs radiation metadevice loaded with PIN diodes can dynamically adjust the radiation direction of the radiation beams. Numerous simulations and experiments of the proof-of-concept prototypes with modular design corroborate the theoretical predictions. Our methodology shows unprecedented flexibility in regulating SWs directional radiation and has enormous potential in engineering applications.
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Affiliation(s)
- Tonghao Liu
- Shaanxi Key Laboratory of Artificially-Structured Functional Materials and Devices, Air Force Engineering University, Xi'an 710051, China
| | - Yueyu Meng
- Shaanxi Key Laboratory of Artificially-Structured Functional Materials and Devices, Air Force Engineering University, Xi'an 710051, China
| | - Jiafu Wang
- Shaanxi Key Laboratory of Artificially-Structured Functional Materials and Devices, Air Force Engineering University, Xi'an 710051, China
| | - Hua Ma
- Shaanxi Key Laboratory of Artificially-Structured Functional Materials and Devices, Air Force Engineering University, Xi'an 710051, China
| | - Hongya Chen
- Shaanxi Key Laboratory of Artificially-Structured Functional Materials and Devices, Air Force Engineering University, Xi'an 710051, China
| | - Xinmin Fu
- Shaanxi Key Laboratory of Artificially-Structured Functional Materials and Devices, Air Force Engineering University, Xi'an 710051, China
| | - Ruichao Zhu
- Shaanxi Key Laboratory of Artificially-Structured Functional Materials and Devices, Air Force Engineering University, Xi'an 710051, China
| | - Chao Liu
- Shaanxi Key Laboratory of Artificially-Structured Functional Materials and Devices, Air Force Engineering University, Xi'an 710051, China
| | - Yajuan Han
- Shaanxi Key Laboratory of Artificially-Structured Functional Materials and Devices, Air Force Engineering University, Xi'an 710051, China
| | - Weihan Li
- State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China
- Frontiers Science Center for Mobile Information Communication and Security, Southeast University, Nanjing 210096, China
| | - Wenxuan Tang
- State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China
- Frontiers Science Center for Mobile Information Communication and Security, Southeast University, Nanjing 210096, China
| | - Shaobo Qu
- Shaanxi Key Laboratory of Artificially-Structured Functional Materials and Devices, Air Force Engineering University, Xi'an 710051, China
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4
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Adams JW, Chen L, Serano P, Nazarian A, Ludwig R, Makaroff SN. Miniaturized Dual Antiphase Patch Antenna Radiating into the Human Body at 2.4 GHz. IEEE J Electromagn RF Microw Med Biol 2023; 7:182-186. [PMID: 37886656 PMCID: PMC10601022 DOI: 10.1109/jerm.2023.3247959] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
An on-body antenna, comprised of two closely-spaced antiphase patch elements, for microwave imaging may provide enhanced signal penetration into the tissue. By further integrating a 180-degree on-chip power combiner with the dual antiphase patch antenna element, a low-profile miniaturized antenna, integrated into a single 18.5 mm x 10 mm x 1.6 mm circuit board assembly, is designed and evaluated both numerically and experimentally. This is the smallest on-body antenna known to the authors for the given frequency band. This linearly polarized antenna may potentially serve as a building block of a dense antenna array for prospective high-resolution microwave imaging. A 2.4 GHz band was chosen as the design target. The final antenna size was a compromise between the miniaturization, the SNR (Signal-to-Noise Ratio), and the targeted antenna bandwidth (2.3-2.5 GHz). The effect of surface waves (the secondary radiating components) was also factored in the design consideration, while maximizing the detected signals' SNR.
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Affiliation(s)
- Johnathan W Adams
- Electrical and Computer Engineering Department, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - Louis Chen
- Electrical and Computer Engineering Department, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - Peter Serano
- Electrical and Computer Engineering Department, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - Ara Nazarian
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215
| | - Reinhold Ludwig
- Electrical and Computer Engineering Department, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - Sergey N Makaroff
- Electrical and Computer Engineering Department, Worcester Polytechnic Institute, Worcester, MA 01609, USA
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5
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Abstract
Exchange of material across the nearshore region, extending from the shoreline to a few kilometers offshore, determines the concentrations of pathogens and nutrients near the coast and the transport of larvae, whose cross-shore positions influence dispersal and recruitment. Here, we describe a framework for estimating the relative importance of cross-shore exchange mechanisms, including winds, Stokes drift, rip currents, internal waves, and diurnal heating and cooling. For each mechanism, we define an exchange velocity as a function of environmental conditions. The exchange velocity applies for organisms that keep a particular depth due to swimming or buoyancy. A related exchange diffusivity quantifies horizontal spreading of particles without enough vertical swimming speed or buoyancy to counteract turbulent velocities. This framework provides a way to determinewhich processes are important for cross-shore exchange for a particular study site, time period, and particle behavior.
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Affiliation(s)
- Melissa Moulton
- Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, Colorado, USA;
- Applied Physics Laboratory, University of Washington, Seattle, Washington, USA
| | - Sutara H Suanda
- Department of Physics and Physical Oceanography, University of North Carolina Wilmington, Wilmington, North Carolina, USA;
| | - Jessica C Garwood
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon, USA; ,
| | - Nirnimesh Kumar
- Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA
| | - Melanie R Fewings
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon, USA; ,
| | - James M Pringle
- Department of Earth Sciences and Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, New Hampshire, USA;
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Alharbi O, Kane T, Henderson D. Impact of a Turbulent Ocean Surface on Laser Beam Propagation. Sensors (Basel) 2022; 22:7676. [PMID: 36236776 PMCID: PMC9570779 DOI: 10.3390/s22197676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 09/25/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
The roughness of the ocean surface significantly impacts air-to-sea imaging, oceanographic monitoring, and optical communication. Most current and previous methods for addressing this roughness and its impact on optical propagation are either entirely statistical or theoretical, or are 'mixed methods' based on a combination of statistical models and parametric-based physical models. In this paper, we performed experiments in a 50-foot-wave tank on wind-generated waves, in which we varied the wind speed to measure how the surface waves affect the laser beam propagation and develop a geometrical optical model to measure and analyze the refraction angle and slope angle of the laser beam under various environmental conditions. The study results show that the laser beam deviations/distortions and laser beam footprint size are strongly related to wind speed and laser beam incidence angle.
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Affiliation(s)
- Omar Alharbi
- Department of Electrical Engineering, The Pennsylvania State University, University Park, State College, PA 16802, USA or
- Department of Electrical Engineering, College of Engineering, Majmaah University, Majmaah 11952, Saudi Arabia
| | - Tim Kane
- Department of Electrical Engineering, The Pennsylvania State University, University Park, State College, PA 16802, USA or
| | - Diane Henderson
- Department of Mathematics, The Pennsylvania State University, University Park, State College, PA 16802, USA
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7
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Schnitzer O, Brandão R. Absorption characteristics of large acoustic metasurfaces. Philos Trans A Math Phys Eng Sci 2022; 380:20210399. [PMID: 35858090 PMCID: PMC9653220 DOI: 10.1098/rsta.2021.0399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 04/08/2022] [Indexed: 06/15/2023]
Abstract
Metasurfaces formed of arrays of subwavelength resonators are often tuned to 'critically couple' with incident radiation, so that at resonance dissipative and radiative damping are balanced and absorption is maximized. Such design criteria are typically derived assuming an infinite metasurface, whereas the absorption characteristics of finite metasurfaces, even very large ones, can be markedly different in certain frequency intervals. This is due to the excitation of surface waves, intrinsic to resonant metasurfaces and especially meta-resonances, namely collective resonances where the surface waves form standing-wave patterns over the planar metasurface domain. We illustrate this issue using a detailed model of a Helmholtz-type acoustic metasurface formed of cavity-neck pairs embedded into a rigid substrate, with geometric and dissipation effects included from first principles (R. Brandão and O. Schnitzer, Wave Motion, 97, 102583, 2020). This article is part of the theme issue 'Wave generation and transmission in multi-scale complex media and structured metamaterials (part 1)'.
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Affiliation(s)
- O. Schnitzer
- Department of Mathematics, Imperial College London, 180 Queen’s Gate, London SW7 2AZ, UK
| | - R. Brandão
- Department of Mathematics, Imperial College London, 180 Queen’s Gate, London SW7 2AZ, UK
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8
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Benech N, Camargo A, Negreira C. Simplified Green's function for surface waves in quasi-incompressible elastic plates with application to elastography. J Phys Condens Matter 2022; 34:214004. [PMID: 35234669 DOI: 10.1088/1361-648x/ac5993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 03/01/2022] [Indexed: 06/14/2023]
Abstract
Surface wave elastography is a growing method to estimate the elasticity in soft solids. It is particularly useful in the case of agrifoods like meat, cheese, or fruits because it does not require major infrastructure or large equipment and could be developed in portable devices. However, estimating the shear elastic properties from surface wave measurements is not straightforward. The shear wavelength in those materials is cm sized for the excitation frequencies usually employed in elastography (∼102 Hz), and the size of samples is comparable to it. Thus, the surface wave speed is frequency dependent with no direct relation to the shear wave speed. In this work we propose a simplified Green's function for soft solid elastic plates which allows to retrieve the shear elasticity from near field measurements. The model is compared with experimental results obtained in agar-gelatin phantoms and food samples (cheese and bovine liver). The results show a good overall agreement although improvements can be achieved by incorporating diffraction and viscosity to the model.
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Affiliation(s)
- Nicolás Benech
- Laboratorio de Acústica Ultrasonora, Facultad de Ciencias, Universidad de la República, Igua 4225, 11400, Montevideo, Uruguay
| | - Andrés Camargo
- Laboratorio de Acústica Ultrasonora, Facultad de Ciencias, Universidad de la República, Igua 4225, 11400, Montevideo, Uruguay
| | - Carlos Negreira
- Laboratorio de Acústica Ultrasonora, Facultad de Ciencias, Universidad de la República, Igua 4225, 11400, Montevideo, Uruguay
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9
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Villas Bôas AB, Lenain L, Cornuelle BD, Gille ST, Mazloff MR. A Broadband View of the Sea Surface Height Wavenumber Spectrum. Geophys Res Lett 2022; 49:e2021GL096699. [PMID: 35865998 PMCID: PMC9285931 DOI: 10.1029/2021gl096699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 01/25/2022] [Accepted: 01/31/2022] [Indexed: 06/15/2023]
Abstract
Airborne lidar altimetry can measure the sea surface height (SSH) over scales ranging from hundreds of kilometers to a few meters. Here, we analyze the spectrum of SSH observations collected during an airborne lidar campaign conducted off the California coast. We show that the variance in the surface wave band can be over 20 times larger than the variance at submesoscales and that the observed SSH variability is sensitive to the directionality of surface waves. Our results support the hypothesis that there is a spectral gap between meso-to-submesoscale motions and small-scale surface waves and also indicate that aliasing of surface waves into lower wavenumbers may complicate the interpretation of SSH spectra. These results highlight the importance of better understanding the contributions of different physics to the SSH variability and considering the SSH spectrum as a continuum in the context of future satellite altimetry missions.
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Affiliation(s)
- Ana B. Villas Bôas
- California Institute of TechnologyLa JollaCAUSA
- Colorado School of MinesGoldenCOUSA
- Scripps Institution of OceanographyUniversity of California San DiegoLa JollaCAUSA
| | - Luc Lenain
- Scripps Institution of OceanographyUniversity of California San DiegoLa JollaCAUSA
| | - Bruce D. Cornuelle
- Scripps Institution of OceanographyUniversity of California San DiegoLa JollaCAUSA
| | - Sarah T. Gille
- Scripps Institution of OceanographyUniversity of California San DiegoLa JollaCAUSA
| | - Matthew R. Mazloff
- Scripps Institution of OceanographyUniversity of California San DiegoLa JollaCAUSA
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10
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Lan J, Zhang J, Jia X, Gao R. Optimization Design of Surface Wave Electromagnetic Acoustic Transducers Based on Simulation Analysis and Orthogonal Test Method. Sensors (Basel) 2022; 22:s22020524. [PMID: 35062485 PMCID: PMC8777999 DOI: 10.3390/s22020524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/30/2021] [Accepted: 01/05/2022] [Indexed: 11/29/2022]
Abstract
The energy conversion of electromagnetic acoustic transducers (EMATs) is typically lower, which seriously restricts the application of EMATs in the field of non-destructive testing and evaluation. In this work, parameters of surface wave EMATs, including structural parameters and electrical parameters, are investigated using the orthogonal test method to improve the transducer’s energy conversion efficiency. Based on the established finite element 2-D model of EMATs, the amplitude of the displacement components at the observation point of a plate is the optimization objective to be maximized with five parameters pertaining to the magnets, meander-line coils, and excitation signal as design variables. Results show that the signal amplitude of EMATs is 3.48 times on in-plane and 3.49 times on out-of-plane, respectively, compared with the original model. Furthermore, a new material (amorphous nanocrystalline material of type 1K107) is applied to optimize the magnetic circuit of EMATs and enhance the eddy current in an aluminum plate to increase the signal amplitude. Finally, the signal amplitudes obtained from the three types of models, that is, the original one, the optimization one after an orthogonal test, and the optimization one with the addition of magnetic concentrators, are analyzed and compared, indicating that the signal amplitude, compared with the original one, is 6.02 times on in-plane and 6.20 times on out-of-plane, respectively.
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11
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Horstmann J, Bödewadt J, Carrasco R, Cysewski M, Seemann J, Streβer M. A Coherent on Receive X-Band Marine Radar for Ocean Observations. Sensors (Basel) 2021; 21:s21237828. [PMID: 34883833 PMCID: PMC8659718 DOI: 10.3390/s21237828] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 10/21/2021] [Accepted: 10/29/2021] [Indexed: 11/16/2022]
Abstract
Marine radars are increasingly popular for monitoring meteorological and oceanographic parameters such as ocean surface wind, waves and currents as well as bathymetry and shorelines. Within this paper a coherent on receive marine radar is introduced, which is based on an incoherent off the shelf pulsed X-band radar. The main concept of the coherentization is based on the coherent on receive principle, where the coherence is achieved by measuring the phase of the transmitted pulse from a leak in the radar circulator, which then serves as a reference phase for the transmitted pulse. The Doppler shift frequency can be computed from two consecutive pulse-pairs in the time domain or from the first moment of the Doppler spectrum inferred by means of a short time Fast Fourier Transform. From the Doppler shift frequencies, radial speed maps of the backscatter of the ocean surface are retrieved. The resulting backscatter intensity and Doppler speed maps are presented for horizontal as well as vertical polarization, and discussed with respect to meteorological and oceanographic applications.
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12
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Kolínský P, Schneider FM, Bokelmann G. Surface Wave Diffraction Pattern Recorded on AlpArray: Cameroon Volcanic Line Case Study. J Geophys Res Solid Earth 2020; 125:e2019JB019102. [PMID: 32999803 PMCID: PMC7507139 DOI: 10.1029/2019jb019102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 05/07/2020] [Accepted: 05/19/2020] [Indexed: 06/11/2023]
Abstract
Stripe-like patterns of surface wave arrival angle deviations have been observed by several seismological studies around the world, but this phenomenon has not been explained so far. Here we test the hypothesis that systematic arrival angle deviations observed at the AlpArray broadband seismic network in Europe are interference patterns caused by diffraction of surface waves at single small-scaled velocity anomalies. We use the observed pattern of Rayleigh waves from two earthquakes under the Southern Atlantic Ocean, and we fit this pattern with theoretical arrival angles derived by a simple modeling approach describing the interaction of a seismic wavefield with small anomalies. A grid search inversion scheme is implemented, which indicates that the anomaly is located in Central Africa, with its head under Cameroon. Moreover, the inversion enables the characterization of the anomaly: The anomaly is inferred to be between 320 and 420 km wide, matching in length the 2,500 km long upper mantle low-velocity region under the volcano-capped swells of the Cameroon volcanic line. We show that this approach can be generally used for studying the upper mantle anomalies worldwide.
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Affiliation(s)
- Petr Kolínský
- Department of Meteorology and GeophysicsUniversity of ViennaViennaAustria
| | - Felix M. Schneider
- Department of Meteorology and GeophysicsUniversity of ViennaViennaAustria
- Section “Seismology”Helmholtz Centre Potsdam—German Research Centre for Geosciences (GFZ)PotsdamGermany
| | - Götz Bokelmann
- Department of Meteorology and GeophysicsUniversity of ViennaViennaAustria
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13
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Abstract
We investigate a model which shows how the introduction of a perturbing dielectric close to an electromagnetic surface wave leads to radiation away from the surface through the dielectric. This resembles a surface waveguide passing through a wall or being deployed underground. Our theory, which is based on the mode-matching technique, allows quantitative determination of losses from a bound surface wave mode up to the point of its complete extinction. For a surface wave supported by a coated, conducting sheet the attenuation due to the perturbing dielectric is calculated for a number of frequencies, permittivities of the perturbation and separations between the sheet and the perturbing dielectric. The accuracy of our results is verified by simulation of the system with a full-wave numerical solution. Finally, we report experimental data of perturbed surface waves on a cable, which are in qualitative agreement with our model.
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Affiliation(s)
- Tobias Schaich
- Department of Physics - Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK.,BT Labs, Adastral Park, Orion Building, Martlesham Heath, Ipswich IP5 3RE, UK
| | - Anas Al Rawi
- Department of Physics - Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK.,BT Labs, Adastral Park, Orion Building, Martlesham Heath, Ipswich IP5 3RE, UK
| | - Trevor Morsman
- BT Labs, Adastral Park, Orion Building, Martlesham Heath, Ipswich IP5 3RE, UK
| | - Mike Payne
- Department of Physics - Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
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14
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Poulin M, Giannacopoulos S, Skorobogatiy M. Surface Wave Enhanced Sensing in the Terahertz Spectral Range: Modalities, Materials, and Perspectives. Sensors (Basel) 2019; 19:s19245505. [PMID: 31847130 PMCID: PMC6960725 DOI: 10.3390/s19245505] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Revised: 12/08/2019] [Accepted: 12/10/2019] [Indexed: 11/30/2022]
Abstract
The terahertz spectral range (frequencies of 0.1–10 THz) has recently emerged as the next frontier in non-destructive imaging and sensing. Here, we review amplitude-based and phase-based sensing modalities in the context of the surface wave enhanced sensing in the terahertz frequency band. A variety of surface waves are considered including surface plasmon polaritons on metals, semiconductors, and zero gap materials, surface phonon polaritons on polaritonic materials, Zenneck waves on high-k dielectrics, as well as spoof surface plasmons and spoof Zenneck waves on structured interfaces. Special attention is paid to the trade-off between surface wave localization and sensor sensitivity. Furthermore, a detailed theoretical analysis of the surface wave optical properties as well as the sensitivity of sensors based on such waves is supplemented with many examples related to naturally occurring and artificial materials. We believe our review can be of interest to scientists pursuing research in novel high-performance sensor designs operating at frequencies beyond the visible/IR band.
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Cherednichenko K, Graham W. Frequency-dependent impedance and surface waves on the boundary of a stratified dielectric medium. Philos Trans A Math Phys Eng Sci 2019; 377:20190218. [PMID: 31474199 PMCID: PMC6732373 DOI: 10.1098/rsta.2019.0218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/25/2019] [Indexed: 05/30/2023]
Abstract
We analyse waves propagating along the interface between half-spaces filled with a perfect dielectric and a Lorentz material. We show that the corresponding interface condition leads to a generalization of the classical Leontovich condition on the boundary of a dielectric half-space. We study when this condition supports propagation of (dispersive) surface waves. We derive the related dispersion relation for waves along the boundary of a stratified half-space and determine the relationship between the loss parameter, frequency and wavenumber for which interfacial waves exist. This article is part of the theme issue 'Modelling of dynamic phenomena and localization in structured media (part 1)'.
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16
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Xu B, Luan L, Chen H, Wang J, Zheng W. Experimental Study on Active Interface Debonding Detection for Rectangular Concrete-Filled Steel Tubes with Surface Wave Measurement. Sensors (Basel) 2019; 19:s19153248. [PMID: 31344793 PMCID: PMC6695857 DOI: 10.3390/s19153248] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 07/04/2019] [Accepted: 07/14/2019] [Indexed: 02/01/2023]
Abstract
Concrete-filled steel tube (CFST) members have been widely employed as major structural members carrying axial or vertical loads and the interface bond condition between steel tube and concrete core plays key roles in ensuring the confinement effect of steel tube on concrete core. An effective interface debonding defect detection approach for CFSTs is critical. In this paper, an active interface debonding detection approach using surface wave measurement with a piezoelectric lead zirconate titanate (PZT) patch as sensor mounted on the outer surface of the CFST member excited with a PZT actuator mounted on the identical surface is proposed in order to avoid embedding PZT-based smart aggregates (SAs) in concrete core. In order to validate the feasibility of the proposed approach and to investigate the effect of interface debonding defect on the surface wave measurement, two rectangular CFST specimens with different degrees of interface debonding defects on three internal surfaces are designed and experimentally studied. Surface stress waves excited by the PZT actuator and propagating along the steel tube of the specimens are measured by the PZT sensors with a pitch and catch pattern. Results show that the surface-mounted PZT sensor measurement is sensitive to the existence of interface debonding defect and the interface debonding defect leads to the increase in the voltage amplitude of surface wave measurement. A damage index defined with the surface wave measurement has a linear relationship with the heights of the interface debonding defects.
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Affiliation(s)
- Bin Xu
- College of Civil Engineering, Huaqiao University, Xiamen 361021, China
- Key Laboratory for Intelligent Infrastructure and Monitoring of Fujian Province (Huaqiao University), Xiamen 361021, China
| | - Lele Luan
- Department of Civil and Environmental Engineering, Northeastern University, Boston, MA 02115, USA
| | - Hongbing Chen
- Department of Civil Engineering, Tsinghua University, Beijing 100084, China.
| | - Jiang Wang
- College of Civil Engineering, Huaqiao University, Xiamen 361021, China.
| | - Wenting Zheng
- College of Civil Engineering, Huaqiao University, Xiamen 361021, China
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17
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Wootton PT, Kaplunov J, Colquitt DJ. An asymptotic hyperbolic-elliptic model for flexural-seismic metasurfaces. Proc Math Phys Eng Sci 2019; 475:20190079. [PMID: 31423092 DOI: 10.1098/rspa.2019.0079] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 06/17/2019] [Indexed: 11/12/2022] Open
Abstract
We consider a periodic array of resonators, formed from Euler-Bernoulli beams, attached to the surface of an elastic half-space. Earlier studies of such systems have concentrated on compressional resonators. In this paper, we consider the effect of the flexural motion of the resonators, adapting a recently established asymptotic methodology that leads to an explicit scalar hyperbolic equation governing the propagation of Rayleigh-like waves. Compared with classical approaches, the asymptotic model yields a significantly simpler dispersion relation, with closed-form solutions, shown to be accurate for surface wave-speeds close to that of the Rayleigh wave. Special attention is devoted to the effect of various junction conditions joining the beams to the elastic half-space which arise from considering flexural motion and are not present for the case of purely compressional resonators. Such effects are shown to provide significant and interesting features and, in particular, the choice of junction conditions dramatically changes the distribution and sizes of stop bands. Given that flexural vibrations in thin beams are excited more readily than compressional modes and the ability to model elastic surface waves using the scalar wave equation (i.e. waves on a membrane), the paper provides new pathways towards novel experimental set-ups for elastic metasurfaces.
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Affiliation(s)
- P T Wootton
- School of Computing and Mathematics, Keele University, Keele ST5 5BG, UK
| | - J Kaplunov
- School of Computing and Mathematics, Keele University, Keele ST5 5BG, UK
| | - D J Colquitt
- Department of Mathematical Sciences, University of Liverpool, Liverpool L69 7ZL, UK
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18
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Wan Y, Cheng M, Zheng Z, Liu K. Polarization-Modulated, Goos⁻Hanchen Shift Sensing for Common Mode Drift Suppression. Sensors (Basel) 2019; 19:s19092088. [PMID: 31060331 PMCID: PMC6539583 DOI: 10.3390/s19092088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/01/2019] [Accepted: 05/03/2019] [Indexed: 12/29/2022]
Abstract
A polarization-modulation-based Goos–Hanchen (GH) sensing scheme leveraging the polarization-dependence of the Bloch surface wave enhanced GH shift is proposed and experimentally demonstrated. Based on a simple setup utilizing a liquid crystal modulator to switch the polarization state of the input beam periodically, the alternating positions of the reflected beam for both polarizations are monitored by a lock-in amplifier to handily retrieve the GH shift signal. The conventional direct measurement of the beam position for the target state of polarization is vulnerable to instabilities in the optomechanical setup and alignment. Our proposed scheme provides a sensitive yet robust GH shift-sensing setup where the common mode drift and noise could be suppressed to ensure better system stability.
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Affiliation(s)
- Yuhang Wan
- School of Electronics and Information Engineering, Beihang University, 37 Xueyuan Rd., Beijing 100083, China.
| | - Mengxuan Cheng
- School of Electronics and Information Engineering, Beihang University, 37 Xueyuan Rd., Beijing 100083, China.
| | - Zheng Zheng
- School of Electronics and Information Engineering, Beihang University, 37 Xueyuan Rd., Beijing 100083, China.
- Collaborative Innovation Center of Geospatial Technology, 129 Luoyu Rd., Wuhan 430079, China.
- Beijing Advanced Innovation Center for Big Date-based Precision Medicine, Beihang University, 37 Xueyuan Rd., Beijing 100083, China.
| | - Kai Liu
- School of Electronics and Information Engineering, Beihang University, 37 Xueyuan Rd., Beijing 100083, China.
- Collaborative Innovation Center of Geospatial Technology, 129 Luoyu Rd., Wuhan 430079, China.
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19
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Wan Y, Zheng Z, Cheng M, Kong W, Liu K. Polarimetric-Phase-Enhanced Intensity Interrogation Scheme for Surface Wave Optical Sensors with Low Optical Loss. Sensors (Basel) 2018; 18:s18103262. [PMID: 30274165 PMCID: PMC6210300 DOI: 10.3390/s18103262] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 09/19/2018] [Accepted: 09/19/2018] [Indexed: 11/16/2022]
Abstract
A polarimetric-phase-enhanced intensity interrogation scheme leveraging the polarization-dependent sharp phase change induced by the surface wave excitation at a low-optical-loss sensor's surface is proposed and experimentally demonstrated. Based on a simple setup with no moving parts during interrogation, a polarimetric-phase-enhanced intensity can be obtained by subtracting the reflected intensities of two beam polarization states. Our results show a ~4-fold sensitivity increase compared to traditional intensity detection schemes for similar sensors. As novel surface wave optical sensors are designed and engineered with optimized phase responses, this scheme offers a low-complexity solution for such devices instead of traditional phase interrogation schemes.
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Affiliation(s)
- Yuhang Wan
- School of Electronic and Information Engineering, Beihang University, 37 Xueyuan Road, Beijing 100083, China.
| | - Zheng Zheng
- School of Electronic and Information Engineering, Beihang University, 37 Xueyuan Road, Beijing 100083, China.
- Collaborative Innovation Center of Geospatial Technology, 129 Luoyu Road, Wuhan 430079, China.
- Beijing Advanced Innovation Center for Big Date-based Precision Medicine, Beihang University, 37 Xueyuan Road, Beijing 100083, China.
| | - Mengxuan Cheng
- School of Electronic and Information Engineering, Beihang University, 37 Xueyuan Road, Beijing 100083, China.
| | - Weijing Kong
- School of Electronic Engineering, Tianjin University of Technology and Education, 1310 Dagu South Road, Tianjin 300222, China.
| | - Kai Liu
- School of Electronic and Information Engineering, Beihang University, 37 Xueyuan Road, Beijing 100083, China.
- Collaborative Innovation Center of Geospatial Technology, 129 Luoyu Road, Wuhan 430079, China.
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20
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Rychert CA, Harmon N. Constraints on the anisotropic contributions to velocity discontinuities at ∼60 km depth beneath the Pacific. Geochem Geophys Geosyst 2017; 18:2855-2871. [PMID: 29097907 PMCID: PMC5652234 DOI: 10.1002/2017gc006850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 06/27/2017] [Indexed: 06/07/2023]
Abstract
Strong, sharp, negative seismic discontinuities, velocity decreases with depth, are observed beneath the Pacific seafloor at ∼60 km depth. It has been suggested that these are caused by an increase in radial anisotropy with depth, which occurs in global surface wave models. Here we test this hypothesis in two ways. We evaluate whether an increase in surface wave radial anisotropy with depth is robust with synthetic resolution tests. We do this by fitting an example surface wave data set near the East Pacific Rise. We also estimate the apparent isotropic seismic velocity discontinuities that could be caused by changes in radial anisotropy in S-to-P and P-to-S receiver functions and SS precursors using synthetic seismograms. We test one model where radial anisotropy is caused by olivine alignment and one model where it is caused by compositional layering. The result of our surface wave inversion suggests strong shallow azimuthal anisotropy beneath 0-10 Ma seafloor, which would also have a radial anisotropy signature. An increase in radial anisotropy with depth at 60 km depth is not well-resolved in surface wave models, and could be artificially observed. Shallow isotropy underlain by strong radial anisotropy could explain moderate apparent velocity drops (<6%) in SS precursor imaging, but not receiver functions. The effect is diminished if strong anisotropy also exists at 0-60 km depth as suggested by surface waves. Overall, an increase in radial anisotropy with depth may not exist at 60 km beneath the oceans and does not explain the scattered wave observations.
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Lerario G, Ballarini D, Fieramosca A, Cannavale A, Genco A, Mangione F, Gambino S, Dominici L, De Giorgi M, Gigli G, Sanvitto D. High-speed flow of interacting organic polaritons. Light Sci Appl 2017; 6:e16212. [PMID: 30167229 PMCID: PMC6062184 DOI: 10.1038/lsa.2016.212] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 08/18/2016] [Accepted: 08/31/2016] [Indexed: 05/10/2023]
Abstract
The strong coupling of an excitonic transition with an electromagnetic mode results in composite quasi-particles called exciton polaritons, which have been shown to combine the best properties of their individual components in semiconductor microcavities. However, the physics and applications of polariton flows in organic materials and at room temperature are still unexplored because of the poor photon confinement in such structures. Here, we demonstrate that polaritons formed by the hybridization of organic excitons with a Bloch surface wave are able to propagate for hundreds of microns showing remarkable third-order nonlinear interactions upon high injection density. These findings pave the way for the study of organic nonlinear light-matter fluxes and for a technologically promising route of the realization of dissipation-less on-chip polariton devices operating at room temperature.
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Affiliation(s)
- Giovanni Lerario
- CNR NANOTEC –Istituto di Nanotecnologia, Via Monteroni, 73100 Lecce, Italy
| | - Dario Ballarini
- CNR NANOTEC –Istituto di Nanotecnologia, Via Monteroni, 73100 Lecce, Italy
| | - Antonio Fieramosca
- CNR NANOTEC –Istituto di Nanotecnologia, Via Monteroni, 73100 Lecce, Italy
| | - Alessandro Cannavale
- CNR NANOTEC –Istituto di Nanotecnologia, Via Monteroni, 73100 Lecce, Italy
- Dipartimento di matematica e fisica ‘Ennio De Giorgi’, Università del Salento, 73100 Lecce, Italy
| | - Armando Genco
- Dipartimento di matematica e fisica ‘Ennio De Giorgi’, Università del Salento, 73100 Lecce, Italy
| | - Federica Mangione
- CNR NANOTEC –Istituto di Nanotecnologia, Via Monteroni, 73100 Lecce, Italy
| | - Salvatore Gambino
- CNR NANOTEC –Istituto di Nanotecnologia, Via Monteroni, 73100 Lecce, Italy
- Dipartimento di matematica e fisica ‘Ennio De Giorgi’, Università del Salento, 73100 Lecce, Italy
| | - Lorenzo Dominici
- CNR NANOTEC –Istituto di Nanotecnologia, Via Monteroni, 73100 Lecce, Italy
| | - Milena De Giorgi
- CNR NANOTEC –Istituto di Nanotecnologia, Via Monteroni, 73100 Lecce, Italy
| | - Giuseppe Gigli
- CNR NANOTEC –Istituto di Nanotecnologia, Via Monteroni, 73100 Lecce, Italy
- Dipartimento di matematica e fisica ‘Ennio De Giorgi’, Università del Salento, 73100 Lecce, Italy
| | - Daniele Sanvitto
- CNR NANOTEC –Istituto di Nanotecnologia, Via Monteroni, 73100 Lecce, Italy
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Zhang X, Xu Y, Yue W, Tian Z, Gu J, Li Y, Singh R, Zhang S, Han J, Zhang W. Anomalous Surface Wave Launching by Handedness Phase Control. Adv Mater 2015; 27:7123-9. [PMID: 26449732 DOI: 10.1002/adma.201502008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 08/19/2015] [Indexed: 05/17/2023]
Abstract
Anomalous launch of a surface wave with different handedness phase control is achieved in a terahertz metasurface based on phase discontinuities. The polarity of the phase profile of the surface waves is found to be strongly correlated to the polarization handedness, promising polarization-controllable wavefront shaping, polarization sensing, and environmental refractive-index sensing.
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Affiliation(s)
- Xueqian Zhang
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072, P. R. China
- The Key Laboratory of Optoelectronics Information and Technology (Ministry of Education), Tianjin University, Tianjin, 300072, P. R. China
| | - Yuehong Xu
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072, P. R. China
- The Key Laboratory of Optoelectronics Information and Technology (Ministry of Education), Tianjin University, Tianjin, 300072, P. R. China
| | - Weisheng Yue
- Advanced Nanofabrication and Imaging Core Lab, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Zhen Tian
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072, P. R. China
- The Key Laboratory of Optoelectronics Information and Technology (Ministry of Education), Tianjin University, Tianjin, 300072, P. R. China
| | - Jianqiang Gu
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072, P. R. China
- The Key Laboratory of Optoelectronics Information and Technology (Ministry of Education), Tianjin University, Tianjin, 300072, P. R. China
| | - Yanfeng Li
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072, P. R. China
- The Key Laboratory of Optoelectronics Information and Technology (Ministry of Education), Tianjin University, Tianjin, 300072, P. R. China
| | - Ranjan Singh
- Centre for Disruptive Photonic Technologies, Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Shuang Zhang
- School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT, UK
| | - Jiaguang Han
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072, P. R. China
- The Key Laboratory of Optoelectronics Information and Technology (Ministry of Education), Tianjin University, Tianjin, 300072, P. R. China
| | - Weili Zhang
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072, P. R. China
- The Key Laboratory of Optoelectronics Information and Technology (Ministry of Education), Tianjin University, Tianjin, 300072, P. R. China
- School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, OK, 74078, USA
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Veres IA, Berer T, Burgholzer P. Numerical modeling of thermoelastic generation of ultrasound by laser irradiation in the coupled thermoelasticity. Ultrasonics 2013; 53:141-9. [PMID: 22658861 PMCID: PMC4067043 DOI: 10.1016/j.ultras.2012.05.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Revised: 05/04/2012] [Accepted: 05/06/2012] [Indexed: 05/20/2023]
Abstract
Laser-generation of ultrasound is investigated in the coupled dynamical thermoelasticity in the presented paper. The coupled heat conduction and wave equations are solved using finite differences. It is shown that the application of staggered grids in combination with explicit integration of the wave equation facilitates the decoupling of the solution and enables the application of a combination of implicit and explicit numerical integration techniques. The presented solution is applied to model the generation of ultrasound by a laser source in isotropic and transversely isotropic materials. The influence of the coupling of the generalized thermoelasticity is investigated and it will be shown, that for ultra high frequency waves (i.e. 100GHz) generated by laser pulses with duration in the picosecond range, the thermal feedback becomes considerable leading to a strong attenuation of the longitudinal bulk wave. Moreover, the coupling leads to dispersion influencing the wave velocities at low frequencies. The numerical simulations are compared to theoretical results available in the literature. Wave fields generated by a line focused laser source are presented by the numerical model for isotropic and for transversely isotropic materials.
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Affiliation(s)
- István A Veres
- Research Center for Non-Destructive Testing GmbH (RECENDT), Altenberger Str. 69, 4040 Linz, Austria.
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