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Статті в журналах з теми "Non-Diffractive waves"

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Surma, Mateusz, Mateusz Kaluza, Patrycja Czerwińska, Paweł Komorowski, and Agnieszka Siemion. "Neural-network based approach to optimize THz computer generated holograms." Photonics Letters of Poland 13, no. 4 (December 30, 2021): 88. http://dx.doi.org/10.4302/plp.v13i4.1124.

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Terahertz (THz) optics often encounters the problem of small f number values (elements have relatively small diameters comparing to focal lengths). The need to redirect the THz beam out of the optical axis or form particular intensity distributions resulted in the application of iterative holographic methods to design THz diffractive elements. Elements working on-axis do not encounter significant improvement while using iterative holographic methods, however, for more complicated distributions the difference becomes meaningful. Here, we propose a totally different approach to design THz holograms, utilizing a neural network based algorithm, suitable also for complicated distributions. Full Text: PDF ReferencesY. Tao, A. Fitzgerald and V. Wallace, "Non-Contact, Non-Destructive Testing in Various Industrial Sectors with Terahertz Technology", Sensors, 20(3), 712 (2020). CrossRef J. O'Hara, S. Ekin, W. Choi and I. Song, "A Perspective on Terahertz Next-Generation Wireless Communications", Technologies, 7(2), 43 (2019). CrossRef L. Yu et al., "The medical application of terahertz technology in non-invasive detection of cells and tissues: opportunities and challenges", RSC Advances, 9(17), 9354 (2019). CrossRef A. Siemion, "The Magic of Optics—An Overview of Recent Advanced Terahertz Diffractive Optical Elements", Sensors, 21(1), 100 (2020). CrossRef A. Siemion, "Terahertz Diffractive Optics—Smart Control over Radiation", J. Infrared Millim. Terahertz Waves, 40(5), 477 (2019). CrossRef M. Surma, I. Ducin, P. Zagrajek and A. Siemion, "Sub-Terahertz Computer Generated Hologram with Two Image Planes", Appl. Sci., 9(4), 659 (2019). CrossRef S. Banerji and B.Sensale-Rodriguez, "A Computational Design Framework for Efficient, Fabrication Error-Tolerant, Planar THz Diffractive Optical Elements", Sci. Rep., 9(1), 5801 (2019). CrossRef J. Sun and F. Hu, "Three-dimensional printing technologies for terahertz applications: A review", Int. J. RF. Microw. C. E., 30(1) (2020). CrossRef E. Castro-Camus, M. Koch and A. I. Hernandez-Serrano, "Additive manufacture of photonic components for the terahertz band", J. Appl. Phys., 127(21), 210901 (2020). CrossRef https://community.wolfram.com/groups/-/m/t/2028026?p_%20479%20p_auth=blBtLb5d DirectLink P. Komorowski, et al., "Three-focal-spot terahertz diffractive optical element-iterative design and neural network approach", Opt. Express, 29(7), 11243-11253 (2021) CrossRef M. Sypek, "Light propagation in the Fresnel region. New numerical approach", Opt. Commun., 116(1-3), 43 (1995). CrossRef
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Rozenman, Georgi Gary, Shenhe Fu, Ady Arie, and Lev Shemer. "Quantum Mechanical and Optical Analogies in Surface Gravity Water Waves." Fluids 4, no. 2 (May 27, 2019): 96. http://dx.doi.org/10.3390/fluids4020096.

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We present the theoretical models and review the most recent results of a class of experiments in the field of surface gravity waves. These experiments serve as demonstration of an analogy to a broad variety of phenomena in optics and quantum mechanics. In particular, experiments involving Airy water-wave packets were carried out. The Airy wave packets have attracted tremendous attention in optics and quantum mechanics owing to their unique properties, spanning from an ability to propagate along parabolic trajectories without spreading, and to accumulating a phase that scales with the cubic power of time. Non-dispersive Cosine-Gauss wave packets and self-similar Hermite-Gauss wave packets, also well known in the field of optics and quantum mechanics, were recently studied using surface gravity waves as well. These wave packets demonstrated self-healing properties in water wave pulses as well, preserving their width despite being dispersive. Finally, this new approach also allows to observe diffractive focusing from a temporal slit with finite width.
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Mohammadi Estakhri, Nasim, Christos Argyropoulos, and Andrea Alù. "Graded metascreens to enable a new degree of nanoscale light management." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, no. 2049 (August 28, 2015): 20140351. http://dx.doi.org/10.1098/rsta.2014.0351.

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Optical metasurfaces, typically referred to as two-dimensional metamaterials, are arrays of engineered subwavelength inclusions suitably designed to tailor the light properties, including amplitude, phase and polarization state, over deeply subwavelength scales. By exploiting anomalous localized interactions of surface elements with optical waves, metasurfaces can go beyond the functionalities offered by conventional diffractive optical gratings. The innate simplicity of implementation and the distinct underlying physics of their wave–matter interaction distinguish metasurfaces from three-dimensional metamaterials and provide a valuable means of moulding optical waves in the desired manner. Here, we introduce a general approach based on the electromagnetic equivalence principle to develop and synthesize graded, non-periodic metasurfaces to generate arbitrarily prescribed distributions of electromagnetic waves. Graded metasurfaces are realized with a single layer of spatially modulated, electrically polarizable nanoparticles, tailoring the scattering response of the surface with nanoscale resolutions. We discuss promising applications based on the proposed local wave management technique, including the design of ultrathin optical carpet cloaks, alignment-free polarization beam splitters and a novel approach to enable broadband light absorption enhancement in thin-film solar cells. This concept opens up a practical route towards efficient planarized optical structures with potential impact on the integrated nanophotonic technology.
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Yaxin, Zhang, Zeng Hongxin, Kou Wei, Wang Lan, Daniel M. Mittleman, and Yang Ziqiang. "Terahertz smart dynamic and active functional electromagnetic metasurfaces and their applications." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2182 (September 14, 2020): 20190609. http://dx.doi.org/10.1098/rsta.2019.0609.

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The demand for smart and multi-functional applications in the terahertz (THz) frequency band, such as for communication, imaging, spectroscopy, sensing and THz integrated circuits, motivates the development of novel active, controllable and informational devices for manipulating and controlling THz waves. Metasurfaces are planar artificial structures composed of thousands of unit cells or metallic structures, whose size is either comparable to or smaller than the wavelength of the illuminated wave, which can efficiently interact with the THz wave and exhibit additional degrees of freedom to modulate the THz wave. In the past decades, active metasurfaces have been developed by combining diode arrays, two-dimensional active materials, two-dimensional electron gases, phase transition material films and other such elements, which can overcome the limitations of conventional bulk materials and structures for applications in compact THz multi-functional antennas, diffractive devices, high-speed data transmission and high-resolution imaging. In this paper, we provide a brief overview of the development of dynamic and active functional electromagnetic metasurfaces and their applications in the THz band in recent years. Different kinds of active metasurfaces are cited and introduced. We believe that, in the future, active metasurfaces will be combined with digitalization and coding to yield more intelligent metasurfaces, which can be used to realize smart THz wave beam scanning, automatic target recognition imaging, self-adaptive directional high-speed data transmission network, biological intelligent detection and other such applications. This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring’.
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DE MICHELI, E., G. MONTI BRAGADIN, and G. A. VIANO. "RIEMANNIAN GEOMETRICAL OPTICS: SURFACE WAVES IN DIFFRACTIVE SCATTERING." Reviews in Mathematical Physics 12, no. 06 (June 2000): 849–72. http://dx.doi.org/10.1142/s0129055x00000332.

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The geometrical diffraction theory, in the sense of Keller, is here reconsidered as an obstacle problem in the Riemannian geometry. The first result is the proof of the existence and the analysis of the main properties of the "diffracted rays", which follow from the non-uniqueness of the Cauchy problem for geodesics in a Riemannian manifold with boundary. Then, the axial caustic is here regarded as a conjugate locus, in the sense of the Riemannian geometry, and the results of the Morse theory can be applied. The methods of the algebraic topology allow us to introduce the homotopy classes of diffracted rays. These geometrical results are related to the asymptotic approximations of a solution of a boundary value problem for the reduced wave equation. In particular, we connect the results of the Morse theory to the Maslov construction, which is used to obtain the uniformization of the asymptotic approximations. Then, the border of the diffracting body is the envelope of the diffracted rays and, instead of the standard saddle point method, use is made of the procedure of Chester, Friedman and Ursell to derive the damping factors associated with the rays which propagate along the boundary. Finally, the amplitude of the diffracted rays when the diffracting body is an opaque sphere is explicitly calculated.
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Дисертації з теми "Non-Diffractive waves"

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Paković‎, Srdan. "Contributions to the theory of non diffractive waves and synthesis of metallic Bessel beam/X-wave launchers." Thesis, Rennes 1, 2021. http://www.theses.fr/2021REN1S128.

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Cette thèse présente les contributions de l'auteur au domaine des ondes non-diffractives. Essentiellement, les ondes non diffractives sont des faisceaux électromagnétiques qui rayonnent une énergie localisée avec une variété d'applications pratiques potentielles. Le travail présenté dans cette thèse peut être divisé en deux parties. Dans la première partie, un nouveau concept de synthèse de lanceurs de faisceaux de Bessel/ondes X à profil spline a été proposé. Tout d'abord, un outil basé sur l'adaptation de mode est présenté. L'outil est capable d'évaluer les paramètres S, les diagrammes de rayonnement en champ proche et lointain de structures métalliques à symétrie azimutale. Ensuite, des lanceurs métalliques à faisceau de Bessel/ à impulsion sont synthétisés à l'aide de cet outil ad hoc. Le concept a été validé expérimentalement en fabriquant et en mesurant un lanceur pour fonctionner dans une gamme de fréquences de 75 à 105 GHz. Le lanceur est la première démonstration d'un lanceur d'ondes X à de telles fréquences. Dans la deuxième partie, nous avons étudié l'utilisation d'ondes non diffractives pour le transfert d'énergie sans fil. Tout d'abord, l'utilisation de faisceaux de Bessel-Gauss pour le WPT est étudiée. Les performances supérieures des faisceaux de Bessel-Gauss par rapport aux faisceaux de Bessel sont démontrées. Un lanceur Bessel-Gauss a été conçu pour valider cette affirmation. Le coefficient de transfert de puissance du lanceur dépasse 50 % pour les distances dépassant sa portée de non diffraction
This thesis present the author’s contributions to the field of non-diffractive waves. Essentially, non-diffractive waves are electromagnetic beams that radiate localized energy with a variety of potential practical applications. The work presented in this thesis can be divided into two parts. In the first part, a novel concept of synthesizing metallic spline profiled Bessel beam/X-wave launchers has been proposed. First, an ad-hoc tool based on mode matching is presented. The tool is capable of evaluating the S parameters, near-, and far-field radiation patterns of metallic structures with azimuthal symmetry. Then, metallic Bessel beam/X-wave launchers are synthesized using the ad-hoc tool. The concept has been experimentally validated by manufacturing and measuring an X-wave launcher operating in a 75-105 GHz frequency range. The fabricated launcher is the first experimental demonstration of an X-wave launcher at such frequencies. In the second part, we have investigated the use of non-diffractive waves for wireless power transfer. First, the use of Bessel-Gauss beams for WPT is investigated. The superior performance of Bessel-Gauss beams compared to Bessel beams is demonstrated. A Bessel-Gauss launcher has been designed for validating this claim. The power transfer coefficient of the launcher exceeds 50% for distances exceeding its non-diffractive range
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Storeck, Gero [Verfasser], Claus [Akademischer Betreuer] Ropers, Claus [Gutachter] Ropers, and Stefan [Gutachter] Mathias. "Non-equilibrium structural Dynamics of incommensurate Charge-Density Waves : Diffractive Probing with a micron-scale ultrafast Electron Gun / Gero Storeck ; Gutachter: Claus Ropers, Stefan Mathias ; Betreuer: Claus Ropers." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://d-nb.info/1213096286/34.

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Pile, David Fujio Pelleas. "Extremely asymmetrical scattering of waves in periodic Bragg arrays." Queensland University of Technology, 2003. http://eprints.qut.edu.au/15794/.

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This thesis fills in the gaps in the existing theory of wave phenomena in thick diffraction gratings at extreme angles of scattering, i.e. when the scattered wave propagates parallel or almost parallel to the grating boundaries. A consistent theory of a new type of Bragg scattering of bulk and guided optical modes in thick uniform and non-uniform, dissipative and non-dissipative, slanted periodic gratings has been developed. This type of scattering is called extremely asymmetrical scattering (EAS). One of the main distinctive features of EAS is the strong resonant increase of the scattered wave amplitude compared to the amplitude of the incident wave. Several unique combinations of strong resonances shaping a complex multi-resonant pattern of EAS in different types of gratings have been predicted and investigated theoretically and numerically. This includes the prediction of a new resonant wave effect in non-uniform gratings with varying phase – double-resonant EAS, the discovery of several sharp and strong resonances with respect to scattering angle in gratings with the scattered wave propagating almost parallel to the grating boundaries (grazing-angle scattering (GAS)) for the case of second-order scattering, and the prediction of a new type of eigenmode in gratings with second-order scattering (especially in gratings with large amplitude). In addition, several other important practical problems that may be crucial for the experimental observation and application of EAS and GAS have been solved. These are the determination of the tolerance of EAS to small grating imperfections, e.g., fluctuations of the grating amplitude, prediction of unusually high sensitivity of second-order EAS to small variations of mean structural parameters, determination of the effect of weak dissipation on EAS, etc. Physical reasons for the predicted resonances and effects are explained. In particular, the crucial role of the diffractional divergence for EAS and GAS has been revealed, especially for non-uniform gratings. Methods of analysis involve the approximate and rigorous approaches. The approximate method is based on understanding the role of the diffractional divergence in the geometry of EAS and the two-wave approximation (valid for any types of waves). The rigorous approach is based on the rigorous coupled-wave analysis (RCWA) and, in particular, the known enhanced T-matrix algorithm (by Moharam, et al.) that is numerically stable for narrow and wide gratings with arbitrary amplitude (valid only for bulk electromagnetic waves).
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Тези доповідей конференцій з теми "Non-Diffractive waves"

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Zhong, Y. C., and Y. J. Cheng. "Generating and Steering Quasi-Non-Diffractive Beam by Integrated Coding-Metasurface-Based Reflectarray." In 2020 13th UK-Europe-China Workshop on Millimetre-Waves and Terahertz Technologies (UCMMT). IEEE, 2020. http://dx.doi.org/10.1109/ucmmt49983.2020.9295976.

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Knyazev, Boris A., Yulia Yu Choporova, Vladimir S. Pavelyev, Boris O. Volodkin, and Mikhail S. Mitkov. "High-power terahertz non-diffractive bessel beams with angular orbital momentum: Generation and application." In 2015 40th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz). IEEE, 2015. http://dx.doi.org/10.1109/irmmw-thz.2015.7327684.

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He, Xiaoyuan, Li Deng, and Yang Yang. "3D-Printed Sub-Terahertz Lens for Manipulation of Deflective Quasi-Non-Diffractive OAM Waves." In 2021 IEEE Asia-Pacific Microwave Conference (APMC). IEEE, 2021. http://dx.doi.org/10.1109/apmc52720.2021.9661824.

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Ettorre, Mauro, Guido Valerio, Ronan Sauleau, Walter Fuscaldo, Alessandro Galli, and Anthony Grbic. "Generation of non-diffractive bessel beams using leaky-wave modes." In 2014 44th European Microwave Conference (EuMC). IEEE, 2014. http://dx.doi.org/10.1109/eumc.2014.6986466.

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Khan, Siladitya, Soumya Goswami, Fan Feng, and Stephen A. McAleavey. "Non-diffractive Acoustic Radiation Force Push Sequence for Shear Wave Viscoelastography." In 2021 IEEE International Ultrasonics Symposium (IUS). IEEE, 2021. http://dx.doi.org/10.1109/ius52206.2021.9593580.

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