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Development and analysis of Crank-Nicolson scheme for metamaterial Maxwell's equations on nonuniform rectangular grids

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NUMERICAL methodS FOR PARTIAL DIFFERENTIAL EQUATIONS 2018年第6期34卷 2040-2059页

作者： Wang, Xiang Li, Jichun Fang, Zhiwei Nanchang Univ Dept Math Sci Nanchang Jiangxi Peoples R China Univ Nevada Dept Math Sci Las Vegas NV 89154 USA

In this paper, we develop a fully implicit scheme on staggered grids to solve the Maxwell's equations when Drude metamaterial is involved. Unconditional stability and optimal error estimate of the scheme are proved. Numerical results are provided to support the theoretical analysis, and used to demonstrate the applicability of the scheme to simulate the complicated backward wave propagation phenomenon occurring in metamaterials.

关键词： backward wave propagation finite-difference time-domain method Maxwell's equations metamaterial nonuniform rectangular mesh

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Stochastic LOD-FDTD method for two-dimensional electromagnetic uncertainty problems

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COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 2017年第5期36卷 1442-1456页

作者： Salis, Christos Kantartzis, Nikolaos Zygiridis, Theodoros Univ Western Macedonia Dept Informat & Telecommun Engn Kozani Greece Aristotle Univ Thessaloniki Dept Elect & Comp Engn Thessaloniki Greece

Purpose - Random media uncertainties exhibit a significant impact on the properties of electromagnetic fields that usually deterministic models tend to neglect. As a result, these models fail to quantify the variation in the calculated electromagnetic fields, leading to inaccurate outcomes. This paper aims to introduce an unconditionally stable finite-difference time-domain (FDTD) method for assessing two-dimensional random media uncertainties in one simulation. Design/methodology/approach - The proposed technique is an extension of the stochastic FDTD (S-FDTD) scheme, which approximates the variance of a given field component using the Delta method. Specifically in this paper, the Delta method is applied to the locally one-dimensional (LOD) FDTD scheme (hence named S-LOD-FDTD), to achieve unconditional stability. The validity of this algorithm is tested by solving two-dimensional random media problems and comparing the results with other methods, such as the Monte-Carlo (MC) and the S-FDTD techniques. Findings - This paper provides numerical results that prove the unconditional stability of the S-LOD-FDTD technique. Also, the comparison with the MC and the S-FDTD methods shows that reliable outcomes can be extracted even with larger time steps, thus making this technique more efficient than the other two aforementioned schemes. Research limitations/implications - The S-LOD-FDTD method requires the proper quantification of various correlation coefficients between the calculated fields and the electrical parameters, to achieve reliable results. This cannot be known beforehand and the only known way to calculate them is to run a fraction of MC simulations. Originality/value - This paper introduces a new unconditional stable technique for measuring material uncertainties in one realization.

关键词： finite-difference time-domain method Locally one-dimensional method Random media Stochastic methods

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Energy-absorption-based explanation of the TiO₂/C photocatalytic activity enhancement mechanism

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JOURNAL OF CATALYSIS 2017年 348卷 246-255页

作者： Yuan, Yuan Ruan, Zhao-Hui Huang, Xing Jiang, Yan-Qiu Tan, He-Ping Harbin Inst Technol Sch Energy Sci & Engn 92 West Dazhi St Harbin 150001 Peoples R China Harbin Inst Technol Sch Chem & Chem Engn MILT Key Lab Crit Mat Technol New Energy Convers 92 West Dazhi St Harbin 150001 Peoples R China

The reason for the significant photocatalytic activity improvement exhibited by TiO2/C is currently a topic of great research interest, and many different explanations of this phenomenon have been proposed. In this paper, we provide a new explanation of this enhancement mechanism that takes into consideration the energy absorption characteristics of TiO2/C. First, we determined the relationship among the wavelength of the incident light, the TiO2 particle radius, and the energy of the scattered light based on the results of Mie analysis. Then the energy absorption characteristics inside TiO2/C were observed using the finite-difference time-domain method. The calculated results revealed that light can be scattered by TiO2 particles during the light transfer process, causing the amorphous C near the TiO2 particles to absorb more energy than the C in other regions. This phenomenon can enable the amorphous C near the TiO2 particles to produce photoelectrons, which can subsequently migrate to the conduction band of TiO2, resulting in enhanced photocatalytic activity. (C) 2017 Elsevier Inc. All rights reserved.

关键词： Photocatalysis degradation Energy absorption finite-difference time-domain method Optical simulations Photocatalytic activity enhancement mechanism

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Comparison of III-V/Si on-chip lasers with etched facet reflectors

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APPLIED OPTICS 2017年第17期56卷 5086-5091页

作者： Lee, Chee-Wei Ng, Doris Keh-Ting Ren, Min Fu, Yuan-Hsing Kay, Anthony Yew Seng Krishnamurthy, Vivek Pu, Jing Tan, Ai Ling Bin Choo, Soo Wang, Qian ASTAR 2 Fusionopolis Way08-01 Innovis Singapore 138634 Singapore

Electrically pumped heterogeneously integrated III-V/SiO2 semiconductor on-chip lasers with different types of etched facet reflectors are designed and fabricated and their lasing performances are characterized and compared. The III-V quantum-well-based epitaxial layers are bonded on silica-on-silicon substrates and fabricated to form Fabry-Perot lasers with dry-etched rear facets. Three types of reflectors are demonstrated, which are etched facets terminated by air, benzocyclobutene, and metal with a thin layer of SiO2 insulator in-between. The laser devices are characterized and compared, including lasing threshold, external quantum efficiency, and output power, and show the impact of different types of etched facet reflectors on lasing performance. (C) 2017 Optical Society of America

关键词： Chemical vapor deposition finite-difference time-domain method High power lasers Quantum efficiency Reflector design Semiconductor lasers

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Numerical studies on a plasmonic temperature nanosensor based on a metal-insulator-metal ring resonator structure for optical integrated circuit applications

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PHOTONICS AND NANOSTRUCTURES-FUNDAMENTALS AND APPLICATIONS 2017年 25卷 52-57页

作者： Al-mahmod, Md Jubayer Hyder, Rakib Islam, Md Zahurul Bangladesh Univ Engn & Technol Dept Elect & Elect Engn Dhaka 1205 Bangladesh

A nanosensor, based on a metalinsulatormetal (MIM) plasmonic ring resonator, is proposed for potential on-chip temperature sensing and its performance is evaluated numerically. The sensor components can be fabricated by using planar processes on a silicon substrate, making its manufacturing compatible to planar electronic fabrication technology. The sensor, constructed using silver as the metal rings and a thermo-optic liquid ethanol film between the metal layers, is capable of sensing temperature with outstanding optical sensitivity, as high as -0.53 nm/degrees C. The resonance wavelength is found to be highly sensitive to the refractive index of the liquid dielectric film. The resonance peak can be tuned according to the requirement of intended application by changing the radii of the ring resonator geometries in the design phase. The compact size, planar and siliconbased design, and very high resolutions- these characteristics are expected to make this sensor technology a preferred choice for labonachip applications, as compared to other contemporary sensors. (C) 2017 Elsevier B.V. All rights reserved.

关键词： Surface plasmon resonance sensor Metal-insulator-metal waveguide Plasmonic temperaturesensor finite-difference time-domain method Optical integrated circuit

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Effect of absorption treatment with band-shaped absorber inside closed narrow rooms

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ACOUSTICAL SCIENCE AND TECHNOLOGY 2018年第6期39卷 440-443页

作者： Asakura, Takumi Yashima, Wataru Satoh, Fumiaki Tokyo Univ Sci 2641 Yamazaki Noda Chiba 2780022 Japan Chiba Inst Technol 2-17-1 Tsudanma Narashino Chiba 2750016 Japan

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All-optical control of surface plasmons by second-harmonic generation

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Physical Review B 2018年第4期98卷 041407(R)-041407(R)页

作者： Sergio G. Rodrigo Instituto de Ciencia de Materiales de Aragón Departamento de Física de la Materia Condensada CSIC Universidad de Zaragoza Zaragoza E-50009 Spain Centro Universitario de la Defensa Carretera de Huesca s/n Zaragoza E-50090 Spain

All-optical control of surface plasmon polaritons (SPPs) is theoretically demonstrated in arrays of metallic slits. It is shown how the mixing of electromagnetic fields scattered by the slits from a weak beam at λ wavelength, with second-harmonic fields generated by a high-intensity 2λ beam, creates a destructive interference of surface plasmons in one of the two possible directions of emission from the slits, while these are enhanced along the opposite direction. Our method enables spectrally broadband excitation and thus unidirectional launching of SPP pulses as short as ∼20 fs, all-optically controlled. Based on these findings, an ultranarrow bandwidth surface plasmon frequency comb is designed.

关键词： Nanophotonics Surface plasmon polariton finite-difference time-domain method Optical second-harmonic generation

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Compact polarization rotator for silicon-based cross-slot waveguides using subwavelength gratings

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APPLIED OPTICS 2017年第17期56卷 4892-4899页

作者： Wu, Shengbao Xiao, Jinbiao Southeast Univ Sch Elect Sci & Engn Natl Res Ctr Opt Sensing Commun Integrated Networ Nanjing 210096 Jiangsu Peoples R China

A compact and broadband polarization rotator (PR) for silicon- based cross-slot waveguides using subwavelength gratings (SWGs) is proposed and analyzed. To significantly break the symmetry of the waveguide structure, the diagonal regular Si wires of the cross-slot waveguides are replaced with the full etching SWGs. Moreover, the special properties of the SWGs- whose effective index is adjustable-can effectively enhance the modal birefringence between the two lowest-order hybrid modes, resulting in a more compact device. By utilizing interference effect of the hybrid modes, both transverse electric to transverse magnetic (TE-to-TM) and TM-to-TE conversion can be efficiently realized. Numerical results show that a PR of 12.6 mu m in length at a wavelength of 1.55 mu m is achieved, where the polarization conversion efficiency (PCE) and insertion loss (IL) are, respectively, 97.2% and 0.71 dB, and the reflection loss is below - 20.5 dB for both cases. Moreover, a wide bandwidth of similar to 260 nm for both polarizations is obtained for keeping the PCE over 90% and IL below 1 dB. In addition, fabrication tolerances to the structural parameters are analyzed in detail, and field evolution along the propagation distance is also presented. (C) 2017 Optical Society of America

关键词： finite-difference time-domain method Grating coupler Multimode interference Optical directional couplers Slot waveguides Waveguide cores

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Quantifying Subgridding Errors when Modeling Multiscale Structures with FDTD

Quantifying Subgridding Errors when Modeling Multiscale Stru...

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International Applied Computational Electromagnetics Society Symposium

作者： Madison Le Mohammed Hadi Atef Elsherbeni Electrical Engineering Department Colorado School of Mines Golden USA

ISBN: (纸本)9781728115184;9780996007887

This paper discusses the growing subgridding errors in finite-difference time-domain (FDTD) analysis when applied on electrically large subgrids. FDTD simulations in 1D and 2D spaces are used with a 1:3 contrast ratio. Error levels are found to be linearly proportional to the subgrid's electrical dimension along the wave's propagation path. This linear growth suggests numerical phase error mismatch between coarse and fine grids as the subgridding error source.

关键词： finite-difference time-domain method Numerical error analysis Subgridding Multi-scale problems

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Tunable nonreciprocal transmission system based on MIM waveguide with Kerr nonlinear material

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OPTICS COMMUNICATIONS 2017年 403卷 262-265页

作者： Xiao, Wenfeng Luo, Xin Zhai, Xiang Wang, Lingling Hunan Univ Key Lab Micronano Optoelect Devices Minist Educ Sch Phys & Elect Changsha 410082 Hunan Peoples R China

A novel nonreciprocal MIM waveguide with Kerr nonlinear material in near-infrared region is proposed and the corresponding transmission characteristics are investigated. In the proposed MIM waveguide, a transmission contrast ratio up to 49.2 dB can be achieved between forward and backward transmission by using the finite-difference time-domain (FDTD) method, revealing an excellent nonreciprocal effect. Moreover, the proposed nonreciprocal MIM waveguide can also be flexibly controlled as forward transmission or backward transmission at different wavelengths. Therefore, our results can offer a new possibility and important application in highly integrated optical circuits. (C) 2017 Published by Elsevier B.V.

关键词： Nonreciprocal transmission Metal-insulator-metal waveguide Kerr nonlinear material finite-difference time-domain method

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