检索结果-内蒙古大学图书馆

Structural investigations, enhanced dielectric and electrical characteristics of iron-doped Bi2O3 thin films designed for high-frequency applications

引用

JOURNAL OF THE AUSTRALIAN CERAMIC SOCIETY 2024年第5期60卷 1645-1655页

作者： Qasrawi, A. F. Atari, Samah S. Arab Amer Univ Dept Phys Jenin Palestine Istinye Univ Dept Elect & Elect Engn TR-34010 Istanbul Turkiye

Herein thin films of bismuth oxide are doped with iron by the thermal deposition technique under a vacuum pressure of 10(-5) mbar. The doping content varied in the range of 3.0 wt.% to 13.0 wt.%. It is found that undoped and Fe-doped Bi2O3 films exhibited monoclinic structure with lattice parameters of a=7.9765 angstrom,b=7.1253 angstrom,c=4.5964 angstrom and beta=102.203(degrees) and space group 8/Lc140. Fe-doping below the solubility limit (13.0 wt %) resulted in smaller crystallites, larger strains and larger defect densities. Above the solubility limits orthorhombic Fe2O3 occupied 30.6% of the total phase of Bi2O3 films. Fe-doped Bi2O3 films showed lower dielectric constant value, lower electrical conductivities and larger microwave cutoff frequencies. Analyses of the ac conductivity spectra indicated that the ac conduction is dominated by the correlated barrier hopping. The increased doping level below the solubility limit decreased the density of localized states near Fermi level and increased the correlated barrier height. It is also observed that 3.0 wt% of Fe can improve the cutoff frequency from 133 to 160 GHz. The cutoff frequency spectra of pure and doped samples displayed values that suits 6G waveguides, field effect transistors, and other high-frequency applications.

关键词： Fe doped Bi2O3 Dielectric Ac conduction Gigahertz waveguides 6G technology

来源：评论

学校读者我要写书评

暂无评论

Earthquake Response Spectra for Tall Steel Pylons with Attached Heavy Masses Located in Greece

引用

JOURNAL OF EARTHQUAKE ENGINEERING 2024年第1期28卷 202-218页

作者： Dadoulis, Georgios I. Manolis, George D. Aristotle Univ Thessaloniki Dept Civil Engn Lab Expt Mech Thessaloniki Greece Aristotle Univ Thessaloniki Dept Civil Engn Lab Expt Mech GR-54124 Thessaloniki Greece

In this work, earthquake response spectra are derived for tall, flexible steel pylons with attached heavy masses by using representative far-field records of recent strong motion earthquakes in the Greek domain, as recorded on firm ground. These pylons serve a variety of purposes, such as lighting posts, electric power lines and wind turbines, the latter being a key component in the production of "green" energy. The response spectra are constructed by modelling the combined pylon-mass system as a waveguide, which is the first step for an accurate determination of the displacement functions describing axial and flexural vibrations and for gauging the influence of the attached mass on the solution to the eigenvalue problem. The methodology can be extended to develop response spectra for more categories of structural elements with an attached mass of arbitrary magnitude, for ground motions recorded in other earthquake prone regions, as well as for transient motions at the level of the attached mass.

关键词： Response spectra flexural vibrations axial vibrations pylons waveguides attached mass

来源：评论

学校读者我要写书评

暂无评论

Insensitive edge solitons in a non-Hermitian topological lattice

引用

Physical Review B 2024年第18期110卷 L180302-L180302页

作者： Bertin Many Manda Laboratoire d'Acoustique de l'Université du Mans (LAUM) UMR 6613 Institut d'Acoustique–Graduate School (IA-GS) CNRS Le Mans Université Avenue Olivier Messiaen 72085 Le Mans France

In this Letter, we demonstrate that the synergetic interplay of topology, nonreciprocity, and nonlinearity is capable of unprecedented effects. We focus on a nonreciprocal variant of the Su-Shrieffer-Heeger chain with local Kerr nonlinearity. We find a continuous family of nonreciprocal edge solitons (NESs) emerging from the topological edge mode, with near-zero energy, in great contrast from their reciprocal counterparts. Analytical results show that this energy decays exponentially towards zero when increasing the lattice size. Consequently, despite the absence of chiral and sublattice symmetries within the system, we obtain zero-energy NESs, which are insensitive to growing Kerr nonlinearity. Even more surprising, these zero-energy NESs also persist in the strong nonlinear limit. Our work may enable different avenues for the control of nonlinear topological waves without requiring the addition of complex chiral- or sublattice-preserving nonlinearities.

关键词： Edge states Kerr effect Skin effect Topological insulators Topological phases of matter Non-Hermitian systems Solitons waveguides

来源：评论

学校读者我要写书评

暂无评论

Acoustic black hole with functionally graded perforated rings

引用

JOURNAL OF APPLIED PHYSICS 2024年第23期135卷

作者： Petrover, Kayla Baz, A. Naval Surface Warfare Ctr Carderock Signature Div Bethesda MD 20817 USA Univ Maryland Dept Mech Engn Baltimore MD 21250 USA

A new class of acoustic black hole (ABH) waveguides is presented, which relies in its operation on an array of optimally designed functionally graded perforated rings (FGPRs). In this manner, the developed ABH is provided with built-in energy dissipation characteristics generated by virtue of the flow through perforations, which enhances its acoustic absorption behavior and makes the speed of the propagating waves vanish faster when reaching the end of the waveguide. Furthermore, the particular design of the rings enables sandwiching of additional porous absorbing layers between the rings to further boost the absorption characteristics of the proposed ABH. Accordingly, the operating principle of the new class of ABH is radically different from that of the conventional ABH that employs sequential solid-flat rings of decreasing inner radii to create a virtual power law taper necessary for generating the black hole effect, but through reactive means rather than the effective dissipative means of the proposed ABH. Therefore, this paper develops a transfer matrix modeling (TMM) approach to model the absorption and reflection characteristics of the new class of ABH, in an attempt to predict its behavior, optimize the selection of its design parameters, and more importantly, demonstrate its merits as effective means for controlling sound propagation. Numerical examples are presented to highlight the merits and behavior of the proposed ABH. Predictions of the TMM are validated against experimental results that are available in the literature for one and two micro-perforated plates. Comparisons are also established between the ABH with FGPR and the conventional ABH in order to distinguish the behavior and underlying principles of their operations. (c) 2024 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license(https://***/licenses/by/4.0/)

关键词： waveguides

来源：评论

学校读者我要写书评

暂无评论

Tunable perfect absorption of microwave radiation via dielectric slabs in irregular arrangements

引用

Physical Review Applied 2024年第6期22卷 L061001-L061001页

作者： A.A. Fernández-Marín C.A. Flores-Castro E. Ramírez-Hintze V. Domínguez-Rocha J.A. Franco-Villafañe Instituto de Física Universidad Autónoma de San Luis Potosí 78290 San Luis Potosí San Luis Potosí Mexico Departamento de Ciencias Básicas Tecnológico Nacional de México—Campus Tehuacán 75770 Tehuacán Puebla Mexico Facultad de Ciencias Universidad Autónoma de San Luis Potosí 78290 San Luis Potosí San Luis Potosí Mexico Departamento de Ciencias Básicas Universidad Autónoma Metropolitana-Azcapotzalco 02128 Mexico City Mexico CONAHCYT—Instituto de Física Universidad Autónoma de San Luis Potosí 78290 San Luis Potosí San Luis Potosí Mexico

This study introduces a passive approach for achieving tunable perfect absorption of microwave radiation, using non-Hermitian physics to manipulate electromagnetic waves without conductive elements. By using common dielectric slabs in irregular configurations within a rectangular waveguide, we can completely absorb electromagnetic energy, efficiently converting it into heat, while minimizing conductive losses. This method contrasts with the use of traditional metamaterials that rely on conductive components to absorb energy. Using the transfer-matrix method and sequential quadratic programming for optimization, our research identifies specific nonuniform placements of FR4 slabs that maximize absorption within targeted microwave bands. Experimental validation, executed in a standard WR90 waveguide connected to a vector network analyzer, confirms the theoretical and finite-element-simulation results, underscoring the effectiveness of our passive strategy. This work advances our understanding of non-Hermitian systems in electromagnetic wave control and offers significant potential for applications in reducing electromagnetic pollution and enhancing secure communications.

关键词： Light propagation, transmission & absorption Optimization problems Optoelectronics RF energy harvesting devices Metamaterials Non-Hermitian systems waveguides Microwave techniques

来源：评论

学校读者我要写书评

暂无评论

Tutorial 2.0: computing topological invariants in 3D photonic crystals

引用

OPTICAL MATERIALS EXPRESS 2024年第9期14卷 2161-2177页

作者： Devescovi, Chiara Morales-perez, Antonio De Paz, Maria blanco Manes, Juan luis Bradlyn, Barry Vergniory, Maia g. Garcia-etxarri, Aitzol Swiss Fed Inst Technol Inst Theoret Phys CH-8093 Zurich Switzerland Donostia Int Phys Ctr Paseo Manuel Lardizabal 4 Donostia San Sebastian 20018 Spain Univ Basque Country UPV EHU Mat & Appl Phys Dept Donostia San Sebastian Spain Univ Autonoma Madrid Dept Fis Teor Mat Condensada E-28049 Madrid Spain Univ Autonoma Madrid Condensed Matter Phys Ctr IFIMAC E-28049 Madrid Spain Univ Basque Country UPV EHU Phys Dept Bilbao Spain Univ Illinois Dept Phys Urbana IL USA Max Planck Inst Chem Phys Solids D-01187 Dresden Germany Basque Fdn Sci IKERBASQUE Maria Diaz Haro 3 Bilbao 48013 Spain

The field of topological photonics has been on the rise due to its versatility in manufacturing and its applications as topological lasers or unidirectional waveguides. Contrary to 1D or 2D photonic crystals, the transversal and vectorial nature of light in 3D precludes using standard methods for diagnosing topology. This tutorial describes the problems that emerge in computing topological invariants in 3D photonic crystals and the diverse strategies for overcoming them. Firstly, we introduce the fundamentals of light propagation in 3D periodic media and expose the complications of directly implementing the usual topological diagnosis tools. Secondly, we describe the properties of electromagnetic Wilson loops and how they can be used to diagnose topology and compute topological invariants in 3D photonic crystals. Finally, we apply the previously described methods to several examples of 3D photonic crystals showing different topological phases, such as Weyl nodes and walls, 3D photonic Chern insulators, and photonic axion insulators.

关键词： Laser applications Light propagation Optical materials Photonic crystals Refractive index waveguides

来源：评论

学校读者我要写书评

暂无评论

Diffusive metasurfaces based on transverse magnetized ferrite for reduction of radar cross section

引用

OPTICS EXPRESS 2024年第11期32卷 18972-18983页

作者： Liang, Chengpeng Wu, Minghui Li, Feifei Li, Shiyin Poo, Yin Nanjing Univ Sch Elect Sci & Engn Nanjing 210093 Peoples R China China Univ Min & Technol Sch Informat & Control Engn Xuzhou 210019 Peoples R China

Diffusive metasurfaces have attracted a great deal of interest in recent years for their promising radar cross section reduction ability. In this work, we proposed a methodology for designing non-tunable and tunable diffusive metasurfaces with transverse magnetized ferrite (TMF). The metasurfaces are two-dimensional arrays configured by metal plates and TMFs backed by metal plates, where the TMFs are functioned as perfect magnetic conductor and magnetic absorbers in lossless and lossy cases, respectively. The designed tunable metasurface allows for control of the operating frequency by adjusting the biased magnetic field, while the non-tunable version provides a wider operation band. This paper demonstrates that the ferrite-based metasurface have exotic stealth performance at microwave frequencies and offers a new approach to design stealth structures.

关键词： Absorbers Metasurfaces Phase plates Radar Reflection coefficient waveguides

来源：评论

学校读者我要写书评

暂无评论

A guiding light: spectroscopy on digital microfluidic devices using in-plane optical fibre waveguides

引用

ANALYTICAL AND BIOANALYTICAL CHEMISTRY 2015年第24期407卷 7467-7475页

作者： Choi, Kihwan Mudrik, Jared M. Wheeler, Aaron R. Univ Toronto Dept Chem Toronto ON M5S 3H6 Canada Univ Toronto Inst Biomat & Biomed Engn Toronto ON M5S 3G9 Canada Donnelly Ctr Cellular & Biomol Res Toronto ON M5S 3E1 Canada

We present a novel method for in-plane digital microfluidic spectroscopy. In this technique, a custom manifold (.stl file available online as ESM) aligns optical fibres with a digital microfluidic device, allowing optical measurements to be made in the plane of the device. Because of the greater width vs thickness of a droplet on-device, the in-plane alignment of this technique allows it to outperform the sensitivity of vertical absorbance measurements on digital microfluidic (DMF) devices by similar to 14x. The new system also has greater calibration sensitivity for thymol blue measurements than the popular NanoDrop system by similar to 2.5x. The improvements in absorbance sensitivity result from increased path length, as well as from additional effects likely caused by liquid lensing, in which the presence of a water droplet between optical fibres increases fibre-to-fibre transmission of light by similar to 2x through refraction and internal reflection. For interrogation of dilute samples, stretching of droplets using digital microfluidic electrodes and adjustment of fibre-to-fibre gap width allows absorbance path length to be changed on-demand. We anticipate this new digital microfluidic optical fibre absorbance and fluorescence measurement system will be useful for a wide variety of analytical applications involving microvolume samples with digital microfluidics.

关键词： Digital microfluidics Microfluidics Fluorescence Absorbance Spectrophotometry UV/Vis Fibre optics Optical fibres waveguides

来源：评论

学校读者我要写书评

暂无评论

Comprehensive system engineering approach for the design and analysis of the polymer-based high-speed optical interconnects for electro-optical printed circuit board applications

引用

OPTICAL ENGINEERING 2024年第12期63卷 125103-125103页

作者： Mitra, Srimanta Patel, Hriday Sharma, B. N. Sarkar, Arti Sarkar, Somya S. ISRO Space Applicat Ctr Sensors Dev Area Ahmadabad Gujarat India

A comprehensive approach is proposed for system design and analysis of polymer-based optical interconnects (OIs) on FR4 substrate for electro-optical printed circuit boards (EOPCB) to enable high-speed data transfer exceeding 10 Gbps. The design approach is based on achieving vertical coupling of light from the external light source into the waveguides in the optical layer. Prior component-level design and analysis are accomplished, followed by system-level study and further sensitivity analysis. The main building block of the optical layer for light transmission is the optical waveguides, which are designed and optimized in terms of core and cladding dimensions, core-cladding polymer materials, sidewall roughness, bend radius, and the transmitting source's divergence and misalignment. Based on the simulation studies, various design rules are defined. The designed optical interconnect meets the system-level bit error rate (BER) requirement of 10(-12). System-level Monte Carlo analysis shows that the achieved BER performance is optimum within the statistical Gaussian variation of the input design parameters. Finally, the sensitivity of the BER performance is studied against a 10% variation in the input design parameters. The proposed approach can significantly help in the system design and analysis of OIs for EOPCBs.

关键词： bit error rate electro-optical printed circuit board optical interconnect waveguides Monte Carlo analysis

来源：评论

学校读者我要写书评

暂无评论

Precise Characterization of a Waveguide Fiber Interface in Silicon Carbide

引用

ACS PHOTONICS 2024年第6期11卷 2160-2170页

作者： Krumrein, Marcel Nold, Raphael Davidson-Marquis, Flavie Bouamra, Arthur Niechziol, Lukas Steidl, Timo Peng, Ruoming Koerber, Jonathan Stoehr, Rainer Gross, Nils Smet, Jurgen H. Ul-Hassan, Jawad Udvarhelyi, Peter Gali, Adam Kaiser, Florian Wrachtrup, Joerg Univ Stuttgart Inst Phys 3 IQST D-70569 Stuttgart Germany Univ Stuttgart Res Ctr Scope D-70569 Stuttgart Germany Luxembourg Inst Sci & Technol Mat Res & Technol MRT Dept L-4422 Belvaux Luxembourg Univ Luxembourg Dept Phys & Mat Sci L-4362 Belvaux Luxembourg Max Planck Inst Solid State Res Solid State Nanophys D-70569 Stuttgart Germany Linkoping Univ Dept Phys Chem & Biol S-58183 Linkoping Sweden Wigner Res Ctr Phys H-1121 Budapest Hungary Budapest Univ Technol & Econ Inst Phys Dept Atom Phys H-1117 Budapest Hungary MTA WFK Lendulet Momentum Semicond Nanostruct Res H-1525 Budapest Hungary Max Planck Inst Solid State Res D-70569 Stuttgart Germany

Spin-active optical emitters in silicon carbide are excellent candidates toward the development of scalable quantum technologies. However, efficient photon collection is challenged by undirected emission patterns from optical dipoles, as well as low total internal reflection angles due to the high refractive index of silicon carbide. Based on recent advances with emitters in silicon carbide waveguides, we now demonstrate a comprehensive study of nanophotonic waveguide-to-fiber interfaces in silicon carbide. We find that across a large range of fabrication parameters, our experimental collection efficiencies remain above 90%. Further, by integrating silicon vacancy color centers into these waveguides, we demonstrate an overall photon count rate of 181 kilo-counts per second, which is an order of magnitude higher compared to standard setups. We also quantify the shift of the ground state spin states due to strain fields, which can be introduced by waveguide fabrication techniques. Finally, we show coherent electron spin manipulation with waveguide-integrated emitters with state-of-the-art coherence times of T-2 similar to 42 mu s. The robustness of our methods is very promising for quantum networks based on multiple orchestrated emitters.

关键词： Silicon carbide Color centers waveguides Fiber collection Strain

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：