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On the representation of reinforced concrete structures in FDTD-based simulations to compute lightning-induced magnetic fields

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ELECTRIC POWER SYSTEMS RESEARCH 2024年 230卷

作者： Naranjo-Villamil, Susana Guiffaut, Christophe Gazave, Julien Piedallu, Eric Reineix, Alain Marquois, Boris EDF Grp EDF Power Networks Lab Ave Renardieres F-77250 Moret Loing Et Orvanne Ile De France France XLIM Res Inst CEM & Diffract 123 Ave Albert Thomas F-87000 Limoges Haute Vienne France EDF Grp EDF DIPNN DITEGG 905 Ave Camp Menthe F-13090 Aix En Provence Provence Alpes France

Reinforced concrete structures are generally well protected against the adverse effects of a direct lightning strike. Nevertheless, when it occurs, the electromagnetic field generated by the lighting current flowing through their reinforcement can cause a malfunction of sensitive electronic devices. The electromagnetic field can be estimated using full-wave methods, although the accuracy of the estimation depends on the representatives of the model, which is why experimental validation is essential. This paper presents the numerical model of a reinforced concrete structure where a transient current was injected to emulate a direct lightning strike. Full-wave simulations are conducted using TEMSI-FD and the results are compared to the measurements made at the testing facility of EDF TEGG. The simulation results were in good agreement with the measurements, especially when the soil was used as the return path for the current.

关键词： Lightning Magnetic field Reinforced concrete Measurements finite-difference time-domain method

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Numerical investigation of plasmon-enhanced emission from a nanofiber coupled single photon emitter

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APPLIED PHYSICS EXPRESS 2024年第1期17卷 012003-012003页

作者： Xuan, Yining Sun, Rui Baek, Soyoung Sadgrove, Mark Edamatsu, Keiichi Tohoku Univ Res Inst Elect Commun Sendai 9808577 Japan Tohoku Univ Grad Sch Engn Dept Elect Engn Sendai 9808579 Japan Tokyo Univ Sci Dept Phys Tokyo 1628601 Japan

This study explores the enhancement of emission from a single photon emitter in a quantum communication network by coupling the source with an optical nanofiber and leveraging gold nanoparticles for Purcell enhancement. Large Purcell enhancements of more than 50 times were recently reported experimentally, but the understanding of important issues, including the maximum Purcell factor and limits to quantum efficiency due to ohmic losses, is still lacking. Our findings reveal that the reported experimental results are reasonable, and confirm that such composite devices provide a promising route for high-efficiency single photon sources coupled to an optical fiber-based quantum communication network.

关键词： Quantum information and communication technologies Single photon emitter Optical nanofiber Purcell effect finite-difference time-domain method

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Tunable narrowband perfect absorption and active phase transition driven by gain-coupled bound states in the continuum: A basis for sensing

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Physical Review Applied 2024年第5期22卷 054002页

作者： Xiao Wang Huachun Zhu Te Ji Weiwei Peng Hongwei Zhao Maoxiong Zhao Lei Shi Min Chen Jie Wang Shanghai 201800 China Shanghai Synchrotron Radiation Facility Beijing 100049 China State Key Laboratory of Surface Physics and Department of Physics

Plasmonic nanostructures provide an excellent platform for tailoring the light-matter interaction, and have found applications ranging from perfect absorption to phase modulation. However, realizing narrowband perfect plasmonic absorbers and dynamical control of light response remains challenging, primarily due to the high intrinsic losses and the limited tunability of metallic components. Here, a gain-coupled-bound state in the continuum (BIC) strategy is proposed to achieve a narrowband perfect plasmonic absorber with tailored functionality. The bandwidth can be dramatically reduced, with quadratic scalability dependence on the perturbation parameters of the quasi-BIC, essentially arising from the powerful physics of BIC in radiation engineering. Moreover, this strategy can make the reflection phase of the plasmonic absorber undergo across a full phase diagram. In particular, it displays functional phase transitions upon crossing the critical coupling or lasing during tailoring loss by gain. This phase transition is further utilized to realize a highly sensitive phase interrogation refractometric sensor. This work provides a profound physical insight into the tailoring functionalities of absorption and phase response, and may open up possibilities for trace detection in biochemical and chemical analysis.

关键词： Analytical chemistry Bound states in the continuum Light propagation, transmission & absorption Photonics Plasmonics Metasurfaces Coupled mode theory finite-difference time-domain method

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Theory of nonlinear terahertz susceptibility in ferroelectrics

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Physical Review B 2024年第5期110卷 054311-054311页

作者： Yujie Zhu Taorui Chen Aiden Ross Bo Wang Xiangwei Guo Venkatraman Gopalan Long-Qing Chen Jia-Mian Hu Department of Materials Science and Engineering Materials Science Division

An analytical theory is developed for predicting the nonlinear susceptibility of ionic polarization to continuous electromagnetic waves in both bulk and strained thin film ferroelectrics. Using a perturbation method for solving the nonlinear equation of motion for ionic polarization within the framework of Landau-Ginzburg-Devonshire theory, the full second-order nonlinear susceptibility tensor is derived as a function of frequency, temperature, and strain. The theory predicts the coexistence of a significantly enhanced second-order dielectric susceptibility and a relatively low dielectric loss in BaTiO3 films with a strain-stabilized monoclinic ferroelectric phase and in a strained SrTiO3 film near its temperature-driven second-order ferroelectric-to-paraelectric phase transition. In this paper, we establish a theoretical framework for predicting and exploiting nonlinear interactions between terahertz waves and ferroelectric materials and, more generally, suggest exciting opportunities to strain-engineer nonlinear dynamical properties of ferroelectrics beyond the static and quasistatic limits.

关键词： Ferroelectricity Ferroelectrics Classical electromagnetism Electromagnetic wave theory finite-difference time-domain method Landau-Ginzburg-Devonshire theory Phase-field modeling

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Phase-change nonlocal metasurfaces for dynamic wave-front manipulation

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Physical Review Applied 2024年第4期21卷 044004-044004页

作者： Tingting Liu Dandan Zhang Wenxing Liu Tianbao Yu Feng Wu Shuyuan Xiao Lujun Huang Andrey E. Miroshnichenko Institute for Advanced Study Nanchang University Nanchang 330031 China School of Physics and Materials Science Nanchang University Nanchang 330031 China School of Optoelectronic Engineering Guangdong Polytechnic Normal University Guangzhou 510665 China School of Physics and Electronic Sciences East China Normal University Shanghai 200241 China School of Engineering and Technology University of New South Wales Canberra ACT 2612 Australia

Recent advances in nonlocal metasurfaces have enabled unprecedented success in shaping the wave front of light with spectral selectivity, offering alternative solutions for many emerging nanophotonics applications. The ability to tune both the spectral and spatial properties of such a class of metasurfaces is highly desirable, but the dynamic nonvolatile control remains elusive. Here, we demonstrate active narrowband wave-front manipulation by harnessing quasi-bound states in the continuum (quasi-BICs) in phase-change nonlocal metasurfaces. The proof-of-principle metasurfaces made of Sb2S3 allow for nonvolatile, reversible, and tunable spectral control over wave front and switchable spatial response at a given wavelength in the near-infrared regime. The design principle mainly builds upon the combination of the geometry phase of quasi-BICs and the dynamic tunability of phase-change meta-atoms to tailor the spatial response of light at tunable resonant wavelengths. By tuning the crystallization level of Sb2S3 meta-atoms through controlling the external stimuli, the dynamic nonlocal wave-front-shaping functionalities of beam steering, one-dimensional, and two-dimensional focusing, and holographic imaging are achieved exclusively at resonant wavelengths, with functionally transparent off resonance. This work represents a critical advance towards developing an integrated dynamic nonlocal metasurface for future augmented and virtual reality wearables.

关键词： Bound states in the continuum Nanophotonics Nonlocality Phase-change materials Chalcogenides Metasurfaces Optical materials & elements finite-difference time-domain method

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Single-photon generation through cavity-STIRAP in a neutral QD embedded in a micropillar cavity: an FDTD model study

Single-photon generation through cavity-STIRAP in a neutral ...

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Photonics for Quantum Conference

作者： Slavcheva, Gaby M. Koleva, Mirella Mueller, Kai Taylor, Robert Quantopticon Ltd 13 Broomfield Guildford GU2 8LQ Surrey England Tech Univ Munich Walter Schottky Inst Coulombwall 4 D-85748 Garching Germany Tech Univ Munich Phys Dept Coulombwall 4 D-85748 Garching Germany Univ Oxford Dept Phys Clarendon Lab Oxford OX1 3PU England

ISBN: (纸本)9781510654761;9781510654754

We investigate cavity-assisted Stimulated Raman Adiabatic passage (STIRAP) schemes in semiconductor quantum dots (QDs) embedded in an optical cavity as a route for generation of high-quality single photons with programmable waveform. This work addresses the need for high-purity, indistinguishable photons in linear quantum computing, boson sampling, and quantum communications. We develop a time-dependent Maxwell-pseudospin model of single-photon generation through cavity-assisted adiabatic passage in a.-system isolated in a neutral InAs QD in a realistic GaAs/AlGaAs micropillar cavity. As a model.-system, we consider QD biexciton triplet states coupled to dark-exciton states by a circularly polarised pulse and a cavity field. Our simulations demonstrate control of the emitted single-photon pulse waveform by the driving pulse characteristics: shape, duration, intensity and detuning.

关键词： cavity-QED single photons STIRAP semiconductor quantum dots micropillar cavities Maxwellpseudospin equations finite-difference time-domain method

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Layer Number-Dependent Enhanced Photoluminescence from a Quantum Dot Metamaterial Optical Resonator

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ACS APPLIED ELECTRONIC MATERIALS 2021年第1期3卷 468-475页

作者： Takekuma, Haruka Leng, Junfu Tateishi, Kazutaka Xu, Yang Chan, Yinthai Ryuzaki, Sou Wang, Pangpang Okamoto, Koichi Tamada, Kaoru Kyushu Univ Inst Mat Chem & Engn IMCE Fukuoka 8190395 Japan ASTAR Inst Mat Res & Engn IMRE Singapore 138634 Singapore Natl Univ Singapore NUS Dept Chem Singapore 117543 Singapore Fukuoka Ind Acad Symphonic FiaS Inst Syst Informat Technol & Nanotechnol ISIT Nanomat Grp Fukuoka 8190388 Japan Osaka Prefecture Univ Dept Phys & Elect Sakai Osaka 5998531 Japan Tohoku Univ Adv Inst Mat Res AIMR Sendai Miyagi 9808577 Japan

High-density colloidal quantum dot (QD) thin films are promising materials for optoelectronic devices. Our experimental data revealed a unique layer number-dependent photo- luminescence (PL) from multilayered QDs on a gold substrate. Compared with the PL intensity of QDs on glass substrates, the PL intensity of CdSe/ZnS QD multilayers on the gold substrate was enhanced approximately 10-fold with 6 layers (film thickness: 42 nm). This phenomenon was simply and reasonably explained by an optical simulation using the finite-difference time-domain method with the effective medium approximation, where the light confinement effect of the high-refractive index QD film acting as a "metamaterial optical resonator" was considered together with a long-range exciton-surface plasmon coupling and mirror effects. This result explains the QD film properties from both quantum physics and optical metamaterial viewpoints. This finding is important for the design of high-luminescence thin-film displays composed of condensed QD films.

关键词： quantum dots self-assembly exciton-surface plasmon coupling photoluminescence metamaterial finite-difference time-domain method

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Sub-50-pm displacement sensing via phase-matched metasurface-prism configuration

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Optics Letters 2025年第12期50卷 3919-3922页

作者： Zhouxin LiangXin GuJiaqi LiLixun WuZhaoxiang ZhuShuqing LinYuhang LinYujie Chen Siyuan Yu State Key Laboratory of Optoelectronic Materials and Technologies Guangdong Provincial Key Laboratory of Optoelectronic Information Processing Chips and Systems School of Electronics and Information Technology Sun Yat-sen University Guangzhou 510275 China

Accurate transverse displacement measurement at the picometer scale is essential for advancing ultraprecision metrology and probing microscopic physical interactions. Here, we demonstrate a high-precision transverse displacement sensor leveraging a phase-matched Pancharatnam–Berry (PB) metasurface and trapezoidal prism configuration, which simplifies optical alignment by eliminating stringent Talbot self-imaging requirements. By synergistically matching the phase gradient of the PB metasurface with the prism geometry, we enable robust signal extraction through the photonic spin Hall effect, while a near-infrared source ( λ = 1550 nm) suppresses environmental interference. Differential amplification further rejects common-mode noise from laser fluctuations and electronic drift. The system achieves a displacement resolution of 46.18 pm under quasi-static conditions (0.2–100 Hz) and 124.86 pm across the full operational bandwidth (0.2–1.25 MHz), surpassing conventional polarization-encoded schemes in both sensitivity and practicality. This work thus presents a strategy for metasurface-enhanced metrology via geometric-phase-engineered photonic architectures, with transformative potential across applications from semiconductor lithography to quantum optomechanics.

关键词： Chemical vapor deposition finite-difference time-domain method Lithography Near infrared Optical testing Phase matching

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Broadband type-I hyperbolicity independent of carrier density in RuOCl2 crystals

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Physical Review B 2024年第11期109卷 115432-115432页

作者： Han Gao Xuejin Zhang Mingzheng Wang Chao Ding Ning Qu Bo Yang Mingwen Zhao School of Science Shandong Jianzhu University Jinan 250100 China School of Physics Shandong University Jinan 250100 Shandong China

The design and fabrication of hyperbolic metamaterials require precise control over the arrangement and dimensions of constituent components, such as nanosheets or nanowires, to achieve the desired hyperbolic dispersion. However, the ongoing challenge lies in further downsizing these components to broaden the hyperbolic regime and enhance the maximal wave vector. In this study, we propose a linear quasi-one-dimensional electron gas array model as a promising category of type-I natural hyperbolic materials (NHMs). The hyperbolic properties in these NHMs remain insensitive to the position of the Fermi level, owing to the linear dispersion relation near the Fermi level. Through first-principles calculations, we have identified a highly promising candidate material, the RuOCl2 crystal, for this model. Our research demonstrates that the RuOCl2 crystal exhibits a broad type-I hyperbolic region that spans from the infrared to the entire visible spectrum, and this property is nearly independent of the Fermi level's position, or equivalently, the carrier density. We also investigate the exceptional negative refraction effects and directional-propagating surface plasmon polaritons that arises from the hyperbolic equifrequency contour. These findings offer a universal approach to designing type-I NHMs, as well as a compelling foundation for development of cutting-edge optoelectronic devices.

关键词： Electronic structure Plasmons Layered crystals Density functional theory finite-difference time-domain method

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Space-time metallic metasurfaces for frequency conversion and beamforming

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Physical Review Applied 2024年第6期21卷 064018-064018页

作者： Salvador Moreno-Rodríguez Antonio Alex-Amor Pablo Padilla Juan F. Valenzuela-Valdés Carlos Molero Department of Signal Theory Telematics and Communications Research Centre for Information and Communication Technologies (CITIC-UGR) Department of Electrical and Systems Engineering

This paper details a class of metal-based space-time metasurfaces for application in wireless communications scenarios. Concretely, we describe space-time metasurfaces that periodically alternate their properties in time between three spatial states: “air,” “conductor,” and “grating.” We analyze the physics of these metastructures via a computationally efficient analytical technique based on the use of Floquet-Bloch series, integral equations, and circuit models. By doing so, we reveal features of these spatiotemporal metasurfaces: scattering parameters, field profiles, diffraction angles, and the nature of the space-time harmonics. The results, corroborated with a self-implemented numerical finite-difference time-domain approach, show the potential application of these space-time metasurfaces as beamformers acting in reflection, in transmission or both. The amplitude and direction of the diffracted orders can be electronically controlled with the parameters of the metasurface. Moreover, the intrinsic ability of time-modulated diffractive metasurfaces to mix and multiply frequencies is tested. We show how two different modulations can lead to the same diffraction angle but with different mixed output frequencies.

关键词： Beam control Frequency conversion Optoelectronics Wave scattering Metagratings Metasurfaces Wireless communication networks finite-difference time-domain method

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