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Conference on Optical Modelling and Design II

作者： Wahl, Pierre Ly-Gagnon, Dany-Sebastien Debaes, Christof Miller, David A. B. Thienpont, Hugo Vrije Univ Brussel Brussels Photon Team B PHOT Pl Laan 2 B-1050 Brussels Belgium Stanford Univ Dept Elect Engn Stanford CA 94030 USA

ISBN: (纸本)9780819491213

Numerical calculations with finite-difference time-domain (FDTD) on metallic nanostructures in a broad optical spectrum require an accurate approximation of the permittivity of dispersive materials. In this paper, we present the algorithms behind B-CALM (Belgium-California Light Machine), an open-source 3D-FDTD solver operating on Graphical Processing Units (GPUs) with multi-pole dispersion models. Our modified architecture shows a reduction in computing times for multi-pole dispersion models. We benchmark B-CALM by computing the absorption efficiency of a metallic nanosphere on a broad spectral range with a six-poles Drude-Lorentz model and compare it with Mie theory.

关键词： finite-difference time-domain method Absorption Computer simulations 3D modeling Mie scattering Optical spheres Performance modeling Dispersion Gold Plasmonics

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New method for numerical approximations of vector derivatives based on digital signal processing techniques

New method for numerical approximations of vector derivative...

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Conference on Wireless Sensing, Localization and Processing VII

作者： Brice, Henry Ahmed, Mohammed Zakia Univ Plymouth Sch Comp & Math Plymouth PL4 8AA Devon England

ISBN: (纸本)9780819490827

Accurate propagation models are required for predicting the propagation of electromagnetic waves within complex environments. This paper proposes the use of a new method to accurately compute the divergence and curl of electromagnetic fields. The computation of the derivatives of vector fields is normally approximated using numerical methods such as the finite-difference time-domain method (FDTD), the finite Integration Technique and the Multi-Resolution time-domain method. These methods are all limited in terms of their accuracy, resolution, computational efficiency and numerical stability. This paper introduces a new method for computing derivatives based on Two-Dimensional (2D) Digital Signal Processing (DSP) techniques. The method involves computing a numerical approximation of the derivative of a function by considering the frequency domain definition of the derivative and designing a 2D finite impulse response (FIR) filter that implements the differentiation. Appropriate windowing functions are used to ensure that the FIR response is as close to the ideal 2D differentiator response as possible. This paper provides an example where the curl of a vector field is determined using this method and accuracy within a few percent is achieved. The proposed innovative method can be extended to three dimensions and used to find numerical solutions of Maxwells Equations, thus allowing it to be applied to the design of accurate propagation models.

关键词： Digital signal processing Radio propagation Numerical analysis 3D modeling Maxwell's equations Systems modeling Wave propagation Dysprosium finite-difference time-domain method Matrices

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Customised birefringence in nanostructured micro-optical devices

Customised birefringence in nanostructured micro-optical dev...

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Conference on Micro-Optics

作者： Waddie, Andrew J. Nowosielski, Jedrzej M. Filipkowski, Adam Stepien, Ryszard Pysz, Dariusz Buczynski, Ryszard Taghizadeh, Mohammad R. Heriot Watt Univ Scottish Univ Phys Alliance Sch Engn & Phys Sci Inst Photon & Quantum Syst Edinburgh EH14 4AS Midlothian Scotland Inst Elect Mat Technol ITME PL-01919 Warsaw Poland Warsaw Univ Fac Phys PL-02093 Warsaw Poland

ISBN: (纸本)9780819491206

We present the design and fabrication details of a customised nanostuctured form birefringent material based upon a second order effective medium theory composite composed of two mechanically and thermally matched soft glasses. The design, which shows uniform birefringence over several hundred nanometres, is fabricated using a modified stack-and-draw method to produce a final element with feature sizes in the 50-100nm range. A method for measuring the effective birefringence of the composite material is presented along with the preliminary results from the fabricated component.

关键词： Nanolithography Nanostructuring Polarization Birefringence Glasses Refractive index Composites Nanostructures Custom fabrication finite-difference time-domain method

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Simplified PIC-FDTD Simulation for the Development of Tunable Table-top Smith-Purcell Terahertz Free Electron Laser

Simplified PIC-FDTD Simulation for the Development of Tunabl...

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25th International Vacuum Nanoelectronics Conference (IVNC)

作者： Okajima, A. Matsui, T. Hata, K. Mie Univ Grad Sch Engn Dept Elect & Elect Engn Tsu Mie 514 Japan

ISBN: (纸本)9781467319836

The compact terahertz (THz) radiation source based on Smith-Purcell (SP) effect has been expected to be the next-generation table-top THz free electron laser (THz-FEL). We have performed a numerical simulation of the generation of SP radiation at THz frequency under the condition of using the electron beam (e-beam) with high repetition THz frequency by simplified particle-in-cell finite difference-time domain (PIC-FDTD) method, and clarified that frequency of SP radiation can be tuned with pre-bunch frequency of e-beam. Our results can lead to the development of more tunable table-top THz-SP-FEL.

关键词： Smith-Purcell radiation Terahertz free electron laser Particle-in-cell code finite-difference time-domain method

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Analysis of pinhole vector diffraction in visible-light

Analysis of pinhole vector diffraction in visible-light

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6th International Symposium on Advanced Optical Manufacturing and Testing Technologies (AOMATT)

作者： Wang Li Rao ChangHui Rao XueJun Yang JinSheng Chinese Acad Sci Inst Opt & Elect Chengdu 610209 Peoples R China

ISBN: (纸本)9780819491008

Using Hartmann-Shack (H-S) wave-front sensor to test lenses with high numerical aperture, the reference spherical wave-front from pinhole is used to calibrate the Hartmann sensor to improve the precision of calibration, but intensity uniformity of the reference spherical wave-front affects the precision of Hartmann sensor's calibration. Based on the vector diffraction theory, intensity uniformity is calculated with finite-difference time-domain method in case of a converging Gaussian incident visible light on pinhole. In order to proof the correctness of the intensity model of pinhole vector diffraction, experimentation of intensity is performed in visible-light. When the pinhole is the material aluminum with thickness 200nm and pinhole diameter 500nm, the absolute error of intensity uniformity is about 2.57% and 2.31% within 0.75 NA and 0.5 NA of diffracted wave-front by comparing experiment result with simulation result, so the intensity model is accurate.

关键词： Vector diffraction of pinhole intensity uniformity numerical aperture finite-difference time-domain method wave front error Hartmann-Shack sensor

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finite-difference time-domain analysis on leak transmission characteristics of narrow gaps

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ACOUSTICAL SCIENCE AND TECHNOLOGY 2011年第5期32卷 182-193页

作者： Asakura, Takumi Sakamoto, Shinichi Shimizu Corp Inst Technol Koto Ku 3-4-17 Etchujima Tokyo 1358530 Japan Univ Tokyo Inst Ind Sci Meguro Ku Tokyo 1538505 Japan

The sound insulation performance of such wall systems as window sashes, doors, and movable partition walls is often affected by sound waves propagating through narrow gaps that exist at their peripheral parts. In this paper, the leak transmission characteristics through narrow gaps existing in the window sash was investigated through numerical and experimental studies. First, the validity of the finite-difference time-domain (FDTD) method with nonuniform-mesh system was confirmed through 1-dimensional and 2-dimensional numerical studies. Second, narrow gaps at the peripheral parts of a window sash were numerically modeled and their leak transmission characteristics were calculated by the 3-dimensional FDTD method. To evaluate the calculation results, they were compared with measurement results of leak transmission characteristics of a real window sash. As a result, numerical results showed good agreement with the experimental results.

关键词： Leak transmission Gap finite-difference time-domain method Nonuniform-mesh

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Analysis of photonic crystal on LED extraction efficiency

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Journal of Measurement Science and Instrumentation 2012年第2期3卷 191-195页

作者：丁庆安郭晓涵郭银景孙红雨 Dept. of Communication Engineering Shandong University of Science and Technology Qingdao 266510 China School of Electronic Engineering University of Electronic Science and Technology of China Chengdu 611731 China

Because of its very low light extraction efficiency(LEE),LED is limited to be widely used under the condition of the internal quantum efficiency which up to 90%.In order to fullfill the design of a more efficient GaN-based blue light LED,the model including deeply etched surface photonic crystals(PhCs)LED is discussed using mode analysis method from light waveguide *** distributions of all order modes in GaN layer are obtained by the effective index *** light extraction efficiencies are also calculated by finite-difference time-domain method(FDTD).The emulated results fully coincide with the former *** the manufacture of the surface photonic crystal is feasible,the work can be very meaningful to design and manufacture the high efficiency GaN-based blue light LED in factory for a large amount.

关键词： light-emitting diode(LED) photonic crystal(PhC) light extraction efficiency(LEE) mode analysis finite-difference time-domain method

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Calculation and research of electromagnetic fields in space around lightning path with finite difference time domain method

Calculation and research of electromagnetic fields in space ...

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4th International Symposium on Electromagnetic Compatibility

作者： Li Qian Zhao Zhibin Cui Xiang N China Elect Power Univ Baoding 071003 Peoples R China

ISBN: (纸本)9781424410224

In this paper, numerical calculation method based on analytical formulas and FDTD are studied. A physical model for nature lightning is built in this paper, the lightning channel as a long ling wire, lightning current's double exponential pulse time domain waveform. The numerical method from dipole formula is obtained by scattering lightning current at time and space, With finite difference time domain(FDTD) method, lightning space is dispersed and electromagnetic fields for whole free space are solved, with the computer program, the results are consistent with results of references and simulating test.

关键词： finite-difference time-domain method lightning lightning current FDTD mesh generation

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Numerical Analysis of Curved Frequency Selective Surface by finite-difference time-domain

Numerical Analysis of Curved Frequency Selective Surface by ...

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International Symposium on Photoelectronic Detection and Imaging 2011 - Terahertz Wave Technologies and Applications

作者： Chen Xin-yi Wang Jian-bo Chen Gui-bo Sun Guan-cheng Lu Jun Changchun Univ Sci & technol Sch Sci Changchun 130022 Peoples R China

ISBN: (纸本)9780819488367

Frequency selective surface is a monolayer or multilayer 2D periodic structure which is composed of multiple resonance units scattering by a two-dimensional periodic array on dielectric layer. FSS can't absorb radio frequency energy, but can filter the frequency which is therefore applied in microwave technique or stealth technology. The relative research on curved FSS is relatively scarce since the curved FSS structure can be obtained only when FSS is attached on the materials surfaces of curved structures in engineering application. However, curved FSS is widely applied in practical engineering;therefore, the research on curved FSS structure has important significance. In this paper, a curved FSS structure model of Y-pore unit is established and numerical simulated by means of FDTD. The influence of curvature on FSS transmission characteristics is studied according to the analysis on the changing of radar cross section (RCS). The results show: the center frequency point of the plane band pass FSS structure drifts after the curve surface deformation of the structure;the center frequency point of the curved band pass FSS structure drifts with the changing of the curvature radius, i. e. with the decreasing of curvature radius, the frequency point drifts towards high points and the transmittance decreases. The design of FSS radome demands of accurate and stable center resonance frequency;therefore, the actual situation of curved surface should be considered in practical engineering application when band pass FSS is made into frequency selection filtering radome. The curvature radius should be long enough to avoid center frequency drifting and transmittance deceasing.

关键词： Curved Frequency Selective Surface finite-difference time-domain method Radar Cross-Section Curvature

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Bandgap characteristics of 2D plasma photonic crystal with oblique incidence:TM case

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Chinese Physics B 2011年第6期20卷 1-6页

作者：谢应涛杨利霞 Department of Communication Engnerring Jiangsu University State Key Laboratory of Millimeter Waves Southeast University

A novel periodic boundary condition （PBC）, that is the constant transverse wavenumber （CTW） method, is introduced to solve the time delay in the transverse plane with oblique incidence. Based on the novel PBC, the FDTD/PBC algorithm is proposed to study periodic structure consisting of plasma and vacuum. Then the reflection coefficient for the plasma slab from the FDTD/PBC algorithm is compared with the analytic results to show the validity of our technique. Finally, the reflection coefficients for the plasma photonic crystals are calculated using the FDTD/PBC algorithm to study the variation of bandgap characteristics with the incident angle and the plasma parameters. Thus it has provided the guiding sense for the actual manufacturing plasma photonic crystal.

关键词： finite-difference time-domain method photonic crystal plasma periodic boundary condition

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