- 标题
- 摘要
- 关键词
- 实验方案
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Implementation of General Dispersive Anisotropic Materials in Lebedev FDTD
摘要： A finite-difference time-domain (FDTD) algorithm—the Lebedev FDTD method—is augmented to allow for the simulation of electromagnetic waves in general dispersive anisotropic materials. Distinct dispersions may be applied to each of the principal axes of the anisotropic medium. The method is based on the auxiliary differential equation and is simple to implement. Because of the collocated nature of the algorithm, multiterm dispersions necessary in previous implementations are avoided. Lebedev grid has previously been studied in detail by different research groups for the simulation of anisotropy. In this paper, we specifically focus on extending frequency-dispersive materials to this method and provide multiple examples to demonstrate the accuracy, validity, and stability of the method.
关键词： dispersive,Anisotropic,invisibility cloak,finite-difference time-domain (FDTD),transformation optics
更新于2025-09-04 15:30:14
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Stability-Improved ADE-FDTD Method for Wideband Modeling of Graphene Structures
摘要： A stability-improved auxiliary differential equation (ADE) finite-difference time-domain (FDTD) method is developed for broadband modelling graphene-based devices in this paper. By introducing an electric polarization term characterized with an auxiliary equation, the graphene sheet is incorporated into the FDTD method without decreasing the Courant–Friedrich–Levy (CFL) number. The stability condition is analyzed and numerical experiments are carried out to validate the proposed method with analytical results. It is further applied to investigate some properties of metal-graphene Split-Ring Resonator (SRR).
关键词： Auxiliary differential equation (ADE),split-ring resonator (SRR),wideband,graphene,finite-difference time-domain (FDTD)
更新于2025-09-04 15:30:14
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Asymmetric light transmission effect based on an evolutionary optimized semi-Dirac cone dispersion photonic structure
摘要： In this paper, we present the numerical and experimental demonstration of asymmetric light transmission by a compact photonic crystal (PC) structure, which sustains semi-Dirac cone dispersion. The semi-Dirac point is obtained by exploiting plane-wave expansion method in a rectangular unit cell of a cylindrical dielectric rod, forming a PC structure. The preselected part of the corresponding PC structure is optimized via differential evolution to maximize the transmission efficiency in one direction, and to minimize in the opposite direction. In this regard, finite-difference time-domain method is integrated with the optimization algorithm to numerically design a compact PC structure with asymmetric light transmission effect. The detailed numerical investigation of the optimized PC structure is represented, and the experiments in the microwave regime are performed to verify the numerical results. The experimentally measured transmission efficiency reaches 78% for one direction, whereas in the opposite direction it reduces to 11%. The physical mechanism of asymmetric light transmission is related to differences of the projection of the wave incident from both directions into the eigenmodes of the photonic structure.
关键词： asymmetric light transmission,semi-Dirac cone dispersion,photonic crystal,differential evolution,finite-difference time-domain method
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Resonance Frequency Inversion of Cold Unmagnetized Plasma Based on CDLT-FDTD and PSO Methods
摘要： Current density Laplace finite-difference time-domain (CDLT-FDTD) method conjunction with particle swarm optimization (PSO) method is introduced to reconstruct the resonance frequency of cold unmagnetized plasma medium. During the inversion, the resonance frequency of the plasma is reconstructed by Fourier series expansion method and the traditional direct method, respectively. The simulation results show that the Fourier series expansion method has better reconstruction accuracy than the traditional direct method, and the number of unknowns is only 1/3 of that of the traditional direct method.
关键词： finite-difference time-domain method,Fourier series expansion,particle swarm optimization,Current density Laplace transform
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Graphene Based Absorber Using LTJEC FDTD
摘要： A terahertz absorber using graphene is simulated using Laplace transform current density convolution finite difference time domain method. An absorber with approximately unity absorption is designed with a graphene ribbon array and a graphene sheet. The numerical results are presented to validate the proposed structure and demonstrate that the graphene sheet is an appropriate material to develop a broadband absorber.
关键词： Graphene,Broadband absorber,Finite difference time domain method,Laplace transform
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO) - Hangzhou, China (2018.8.13-2018.8.17)] 2018 IEEE International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO) - Sensing Characteristics of Fano Resonance in Y-shaped Gold Nanorods Array
摘要： Fano resonance of metallic nanostructure is good for reducing the irradiation loss. Fano resonance of metallic nanostructure is also could improve the spectral resolution. Due to its unique sensitivity, Fano resonance is widely used in physics and engineering fields such as optical sensors, optical switches transparent resonators. In this paper, time-domain finite difference method is used to design a kind of Y-type gold periodic nanorods array, which has obvious Fano resonance phenomenon at 1.12-(cid:541)m wavelength. When the array structural parameters change, the Fano resonance valley has a dramatic movement. The Y-type gold nanoarray structures have better sensing characteristics, and its figure of merit is 10.68. It shows the special nanoarray can be used for infrared sensors.
关键词： finite difference time domain,Fano resonance,localized surface plasmon resonance
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Low-pass Frequency Selective Surface for a Dual-band Gyro-multiplier Characterized by THz-TDS
摘要： This work investigates the performance of a low-pass frequency selective surface (FSS) fabricated from perforated hole array on a copper plate for the use in a dual-band high power gyro-multiplier. The output beam from the high power gyro-multiplier contains signals at two separating bands carrying peak power up to 2 kW. The frequency separating components therefore are required to stand high power and produce low insertion loss. Metallic perforated array is an ideal option to meet these requirements. Considering the fabrication accuracy, low-pass FSS is selected. The fabrication of the low-pass FSS is based on precision milling technology. The performance of the FSS is evaluated using a terahertz time domain spectroscopy.
关键词： gyro-multiplier,terahertz time domain spectroscopy,quasi-optics,frequency selective surface
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Stable TD-EFIE Discretized with Implicit Runge-Kutta Methods
摘要： The convolution quadrature discretized Time Domain-Electric Field Integral Equation (TD-EFIE) suffers from: (i) an ill-conditioning of the system matrix at large time steps (low frequency) and (ii) spurious static currents that slowly grow or remain constant at late times (DC instability). A stabilization procedure that solves these two problems is presented here for discretizations based on Implicit Runge Kutta methods. It leverages quasi-Helmholtz projectors in order to separate the loop and star components, and rescale them independently to remove the instabilities.
关键词： Time Domain,Preconditioning,Low Frequency,Electric Field Integral Equation,DC Instability
更新于2025-09-04 15:30:14
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2018) - Nagoya (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Experimental Characterization of Artificial Human Skin with Melanomas for Accurate Modelling and Detection in Healthcare Application
摘要： A preliminary investigation is carried out on the artificial human skin tissues with and without metastatic melanomas using Terahertz Time Domain Spectroscopy (THz-TDS). Both the refractive indexes and absorption coefficients of artificial skin with melanomas are higher than the normal artificial skin samples over the entire frequency range between 0.2 THz to 1.6 THz. The reason is that tumour cells degrade the in contraction of fibroblasts causing more water content malignant tissues. This study quantifies the impact of melanomas on the optical parameters of artificial skin tissue and can help in techniques that will diagnose and prevent tumours at the early stage.
关键词： artificial human skin,absorption coefficient,Terahertz Time Domain Spectroscopy,refractive index,melanomas
更新于2025-09-04 15:30:14
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Handbook of Advanced Non-Destructive Evaluation || Terahertz Techniques in NDE
摘要： So far, terahertz measurement technology has rarely been used in industry. This book chapter presents therefore the underlying technologies, the resulting possibilities and exemplary applications. The introduction describes the basic properties of terahertz systems and the advantages of terahertz technology over established techniques such as infrared, X-rays and ultrasound. The two industrially relevant terahertz techniques, time domain spectrometer and FMCW system, are described in detail. In addition, the metrological basics for their main applications are introduced. Imaging is required in many applications. Different approaches are presented. Before the chapter concludes with an outlook on future applications, current application examples are discussed. This concerns applications in the fields of coating thickness measurement, safety, materials research, testing of lightweight materials and inline testing. An extensive reference list provides a deeper insight into the topics addressed.
关键词： lightweight materials,materials research,coating thickness measurement,terahertz,NDE,FMCW,imaging,inline testing,time-domain spectroscopy
更新于2025-09-04 15:30:14