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Designing multilayered wire-grid polarizers using a monochromatic recursive convolution finite-difference time-domain algorithm

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JOURNAL OF THE SOCIETY FOR INFORMATION DISPLAY 2014年第2期22卷 98-105页

作者： Banerjee, Saswatee Sumitomo Chem Co Ltd Adv Mat Res Lab Tsukuba Ibaraki Japan

Multilayered wire-grid polarizers (WGP) find application as low-reflection polarizers in projection-type liquid crystal display devices. A multilayered WGP is formed by adding thin layers on top of the metal ridges of an ordinary WGP. The ordinary WGP consists of a periodic array of parallel metal ridges, where the period of the array and the width of any individual metal ridge are typically less than the wavelength of the incident light. Such WGPs are often used as efficient polarizers. However, in certain applications, it is important to reduce the reflection from the WGP while preserving the polarization efficiency. One of the ways to achieve this goal is to add thin layers on top of the metal ridges of the ordinary WGP. The reduction in reflection from the multilayered WGP depends on the number and material of these additional layers. In this paper, we describe a design method for multilayered WGPs based on an effective medium theory, thin-film computation method and a monochromatic recursive convolution finite-difference time-domain algorithm. The goal of design process is to identify suitable materials and thicknesses for the additional thin layers needed to lower the reflection appreciably. The design method is explained with the help of bilayered WGPs.

关键词： wire-grid polarizers WGP multilayered subwavelength gratings optical design finite-difference time-domain algorithm FDTD

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A novel contour-path finite-difference time-domain (CPFDTD) algorithm for modeling objects with curved surfaces

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MICROWAVE AND OPTICAL TECHNOLOGY LETTERS 2001年第4期28卷 285-287页

作者： Min, Y Kil, B Lee, S Hanyang Univ Div Elect & Comp Engn Seoul 133791 South Korea

A novel CPFDTD algorithm for modeling smooth curved surfaces is presented. This scheme subdivides electric fields on the distorted grid into the extended contour field, the nondistorted field, and the quasiavailable field to avoid the collinear borrowing approximation. Several earlier methods are applied to the E-plane sectoral horn antenna to obtain far-field patterns. To show the validity and applicability of our method, computed far-field patterns are compared with measured values. (C) 2001 John Wiley & Sons, Inc.

关键词： finite-difference time-domain algorithm curved surfaces E-plane horn antenna far-field patterns

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A novel contour-path finite-difference time-domain (CPFDTD) algorithm for modeling objects with curved surfaces

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Microwave and Optical Technology Letters 2000年第4期28卷

作者： Yikyu Min Byungsoo Kil Sangseol Lee Division of Electronic and Computer Engineering Hanyang University Seoul 133-791 Korea

A novel CPFDTD algorithm for modeling smooth curved surfaces is presented. This scheme subdivides electric fields on the distorted grid into the extended contour field, the nondistorted field, and the quasiavailable field to avoid the collinear borrowing approximation. Several earlier methods are applied to the E -plane sectoral horn antenna to obtain far-field patterns. To show the validity and applicability of our method, computed far-field patterns are compared with measured values. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 28: 285–287, 2001.

关键词： finite-difference time-domain algorithm curved surfaces E-plane horn antenna far-field patterns

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Combining standard with optimised split-step finite-difference time-domain methods for the study of graphene configurations

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IET SCIENCE MEASUREMENT & TECHNOLOGY 2019年第8期13卷 1150-1157页

作者： Amanatiadis, Stamatios A. Zygiridis, Theodoros T. Kantartzis, Nikolaos, V Aristotle Univ Thessaloniki Dept Elect & Comp Engn Thessaloniki 54124 Greece Ormylia Fdn Art Diag Ctr Ormylia 63071 Greece Univ Western Macedonia Dept Elect & Comp Engn Kozani 50131 Greece

In this study, the authors propose a hybrid computational model for the reliable simulation of electromagnetic-wave phenomena emerging in graphene structures, which incorporates two variations of an unconditionally-stable finite-difference time-domain algorithm. The new approach features: (a) a dispersive model that relies on the auxiliary differential equation technique and takes into consideration the graphene's surface conductivity, and (b) a modified discretisation algorithm implementing error-optimised spatial approximations, which is appropriate for graphene-free mesh nodes. The resulting update equations are devoid of time-step restrictions, thus formulating a suitable and useful computational framework for the investigation of contemporary graphene-based problems, which commonly call for densely-sampled grids and/or prolonged simulations. After theoretically assessing the fundamental features of the proposed algorithm, the propagation properties of surface waves on graphene are extracted numerically and compared with analytical estimations, so that computational validation is provided. In addition, a realistic surface-wave coupler configuration is simulated and its main characteristics are extracted accurately, exemplifying the method's robustness on more complex setups.

关键词： differential equations graphene finite difference time-domain analysis surface conductivity electromagnetic wave propagation graphene structures finite-difference time-domain algorithm dispersive model auxiliary differential equation technique modified discretisation algorithm error-optimised spatial approximations graphene-free mesh nodes resulting update equations time-step restrictions useful computational framework contemporary graphene-based problems computational validation optimised split-step finite-difference time-domain graphene configurations hybrid computational model reliable simulation electromagnetic wave phenomena surface wave propagation properties surface conductivity realistic surface wave coupler configuration C

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Electromagnetic coupling between arbitrarily bent wires and scatterers analysed by a hybrid MoMTD/FDTD approach

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IEE PROCEEDINGS-MICROWAVES ANTENNAS AND PROPAGATION 2000年第4期147卷 261-266页

作者： Cerri, G Chiarandini, S Russo, P Schiavoni, A Univ Ancona Dipartimento Elettron & Automat I-60131 Ancona Italy Ctr Studi & Lab Telecomun SpA CSELT I-10140 Turin Italy

The payer presents a new hybrid method for efficiently studying the coupling between an antenna and an inhomogeneous penetrable object, lying in the near field region of the source. It is based on the combination of the marching on in time version of the method of moment (MoMTD), and the finite-difference in time-domain (FDTD) algorithm. The use of the equivalence principle leads to the treatment of the original complex problem as the interaction of two simpler subproblems, each of them approached differently. The hybrid method is validated by comparing our results obtained for significant strong coupling cases with data computed by other numerical techniques and with experimental values.

关键词： Antenna theory finite difference time-domain analysis method of moments near field region electromagnetic coupling Electromagnetic wave propagation FDTD algorithm inhomogeneous penetrable object hybrid MoMTD/FDTD approach bent wires marching on in time version antenna electromagnetic wave scattering finite-difference time-domain algorithm antenna theory subproblems Other numerical methods scatterers equivalence principle

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Transient electromagnetic sounding using a 5 m square loop

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EXPLORATION GEOPHYSICS 2009年第2期40卷 193-196页

作者： Yan, Shu Chen, Ming Sheng Shi, Xian Xin Jiangsu Univ Sch Comp Sci & Telecommun Engn Zhengzhou 212013 Jiangsu Peoples R China China Coal Res Inst Xian Branch Xian 710054 Shaanxi Peoples R China Xi An Jiao Tong Univ Sch Elect & Informat Engn Xian 710049 Shaanxi Peoples R China

Our study of the diffusion of transient electromagnetic (TEM) fields into a two-dimensional (2D) earth, simulated by a finite-difference time-domain (FDTD) algorithm, proves that the depth of investigation depends primarily on the measurement time and the ground resistivity. Sufficient signal strength can be gained by a small central-loop configuration equipped with a high-power transmitter and a large equivalent area receiver coil. When receiver sensitivity is 1 mV, average resistivity of the overlying section is around 50 Omega.m, and the noise level is 3 to 20 nV/m(2), a depth of exploration of 150 m can be achieved with a 5 m x 5 m loop with 100 A of transmitter current;for a noise level of 0.1 nV/m(2), the depth of exploration is up to 800 m with 1200 A of transmitter current. The results have been compared with results from the electrical resistivity method and from large loop techniques, and verified by drilling. We show that using a small loop can attain not only a greater depth of investigation but also higher resolution. The small loop configuration with a high-power transmitter is a convenient combination, and useful for exploration in mountainous terrains and restricted sites.

关键词： central loop finite-difference time-domain algorithm high-power transmitter small loop transient electromagnetic method

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Simple pictograph for displaying complex field data in TEM cell tissue sample

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ELECTRONICS LETTERS 2002年第8期38卷 359-360页

作者： Lim, HB Cook, GG Barker, AT Coulton, LA Univ Sheffield Dept Elect & Elect Engn Radar & Commun Grp Sheffield S1 3JD S Yorkshire England Royal Hallamshire Hosp Dept Med Phys & Clin Engn Sheffield S10 2JF S Yorkshire England Univ Sheffield No Gen Hosp Div Clin Sci Sheffield S5 7AU S Yorkshire England

A simple diagram is described Cor displaying complex field data calculated using an original finite-difference time-domain algorithm. This polar plot is used to display field properties within a culture medium placed in a transverse electro-magnetic (TEM) cell, and shows the presence of an elliptically polarised exposure field with reactive phasing, arising from a plane wave incident field. The pictograph aids in comprehending this field behaviour, which may be relevant to any biological effects.

关键词： complex field data display finite-difference time-domain algorithm FDTD algorithm biological effects of fields diagrams culture medium elliptically polarised exposure field reactive phasing electromagnetic fields biological tissue samples finite difference time-domain analysis biological effects Numerical approximation and analysis dosimetry experiments field properties polar plot Radiation protection and dosimetry Radiation dosimetry in medical physics Biological effects of radiations transverse electromagnetic cell Other numerical methods plane wave incident field biological techniques dosimetry pictograph Biophysical instrumentation and techniques

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Analysis of finite periodic structure by FDTD and SOC technique

Analysis of finite periodic structure by FDTD and SOC techni...

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Asia-Pacific Microwave Conference

作者： Ye, Z. B. Chen, R. S. Yang, Y. Nanjing Univ Sci & Technol Dept Commun Engn Nanjing 210094 Peoples R China

ISBN: (纸本)078039433X

In this paper, the application of the finite-difference time-domain (FDTD) algorithm combined with the short-open calibration SOC technique to three-dimensional finite periodic structure is presented. We can get the scattering parameters of the whole periodic structure through analyzing only one cell of it. So the combination of the SOC technique and FDTD for finite periodic structures makes the calculation much faster and much more accurate. Results for finite periodic structure are well compared with the conventional FDTD method.

关键词： S-parameters calibration finite difference time-domain analysis microstrip discontinuities periodic structures 3D finite periodic structure finite-difference time-domain algorithm scattering parameters short-open calibration technique

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GPR antenna simulations and optimizations in time domain 4

GPR antenna simulations and optimizations in time domain

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4th International Conference on Antenna Theory and Techniques

作者： Ligthart, LP Yarovoy, AG Kirana, AY Delft Univ Technol Int Res Ctr Telecommun Transmiss NL-2628 CD Delft Netherlands

ISBN: (纸本)0780378814

The development and optimization of transient antennas for Ground Penetrating Radar would be difficult without numerical simulations of their performance. To this end the FDTD algorithm should be considered as a useful and powerful tool for transient antenna analysis. As an example of such analysis we describe simulations of the dielectric wedge antenna. Good agreement between theoretical predictions and experimental results was observed. Some of the antenna characteristics (like the radial component of the electric field in the near zone, the radiated waveform and the antenna footprint in different grounds) cannot be measured easily, so the correct theoretical (numerical) model is essential for their determination. The numerical model of the antenna can also be used for optimization of the antenna. As an example of such optimization we present a design of the shield for the dielectrically embedded dipole antenna.

关键词： transient antennas finite-difference time-domain algorithm Ground Penetrating Radar

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Fabrication of gold nanorod arrays on a cylindrical surface of optical fibers by using in-situ electrodeposition

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OPTICAL MATERIALS 2019年 98卷 109424-000页

作者： Dang, Jie Li, Wei Zhang, Jue Peking Univ Acad Adv Interdisciplinary Studies Beijing 100871 Peoples R China Peking Univ Coll Engn Beijing 100871 Peoples R China

Optical fiber is an excellent light-coupled substrate, which has the characteristics of large a length-diameter ratio with a cylindrical surface. Recently, various methods have been reported in order to improve the ability of local optical fields. In particular, methods aimed to address the efficient coupling and optical resonances by modifying metal nanostructures on the light-coupled substrate have been developed. However, existing methods are largely applicable to planar or tip substrates, and it remains a significant challenge to prepare metal nanostructures on a cylindrical substrate. In this study, we proposed a novel strategy to fabricate gold nanorods arrays (AuNRs) by electrodepositing them in anodized aluminum oxide (AAO) templates on the cylindrical surface of optical fibers. Briefly, AAO templates were prepared in-situ by using a constant current density secondary oxidation method on the cylindrical surface of optical fibers, and then the AuNRs were in-situ deposited in the AAO templates by electrodeposition. The features of the AuNRs such as diameter, nanorod pitch, and height could be easily regulated by adjusting the parameters of electrodeposition and the anode oxidation. The SEM images demonstrates that AuNRs exhibit a satisfactory consistency with a uniform diameter and favorable self-supporting properties. The relationships between the current density, pore diameter and pore distribution were explored, combined with the voltage-time curve during anodic oxidation. Furthermore, the surface plasmon resonance (SPR) optical properties of the AuNRs on the cylindrical surface were analyzed using the finite-difference time-domain algorithm (FDTD) method. Results suggest that this alternative in-situ electrodeposition strategy has the potentials to be applied to SPR optical fiber sensing.

关键词： Cylindrical surface of optical fibers Anodized aluminum oxide templates Gold nanorods arrays In-situ electrodeposition finite-difference time-domain algorithm

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