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Reciprocity condition in synchronously time-periodic bianisotropic materials

Physical Review B 2022年第21期106卷 214301-214301页

作者： Somayeh Boshgazi Mohammad Memarian Khashayar Mehrany Behzad Rejaei Department of Electrical Engineering Sharif University of Technology Tehran Iran

In this paper, a sufficient reciprocity condition for general time-periodic modulated bianisotropic media is extracted from first principles. Reciprocity of various cases of significant importance, including stationary bianisotropic media, time-varying (TV) isotropic media, TV anisotropic media, and TV bianisotropic media, are investigated using this condition. We prove that synchronous time modulation of stationary bianisotropic yet reciprocal media (chiral, pseudochiral, and achiral) does not lead to nonreciprocity, unless the modulation function breaks time reversal symmetry. This is in contrast to recently published research. The theoretical results are validated using in-house finite difference time domain simulations.

关键词： Magnetoelectric effect Non-reciprocal transmission Metamaterials Bloch wave theory Bloch-Floquet theorem Electromagnetic wave theory finite-difference time-domain method Materials modeling T-symmetry

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Transport through Amorphous Photonic Materials with Localization and Bandgap Regimes

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Physical Review Letters 2022年第15期129卷 157402-157402页

作者： Frank Scheffold Jakub Haberko Sofia Magkiriadou Luis S. Froufe-Pérez Department of Physics University of Fribourg CH-1700 Fribourg Switzerland Faculty of Physics and Applied Computer Science AGH University of Science and Technology Aleja Mickiewicza 30 Krakow 30-059 Poland

We propose a framework that unifies the description of light transmission through three-dimensional amorphous dielectric materials that exhibit both localization and a photonic bandgap. We argue that direct, coherent reflection near and in the bandgap attenuates the generation of diffuse or localized photons. Using the self-consistent theory of localization and considering the density of states of photons, we can quantitatively describe the total transmission of light for all transport regimes: transparency, light diffusion, localization, and bandgap. Comparison with numerical simulations of light transport through hyperuniform networks supports our theoretical approach.

关键词： Anderson localization Photonic crystals Photonics Scattering theory Disordered systems Diffusion & random walks finite-difference time-domain method Light scattering

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Optical sensing in single-mode filters base on surface plasmon H-shaped cavities

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OPTICS COMMUNICATIONS 2022年 505卷 127534-127534页

作者： Khani, Shiva Hayati, Mohsen Razi Univ Fac Engn Elect Engn Dept Kermanshah *** Iran

Three novel refractive index (RI) sensors based on one, two, and three H-shaped cavities (HCs) and metal- insulator-metal (MIM) waveguides are proposed in this paper. By coupling more than one HC (two and three), the Q-factor and then the FOM value of the designed RI sensors increase. A well-known method for increasing the sharpness transition between the passband and stopband of a spectrum is coupling cavities together. Fortunately, the proposed HC has such a property that increases the FOM value. The maximum obtained FOM of the proposed sensors using one, two, and three HCs reached 69.5, 100.19, and 108.36 RIU-1, respectively. Three proposed plasmonic structures which are used to design RI sensors have single-mode spectra in a wide wavelength range of 500 to 2000 nm. A single-mode spectrum is easier to cope with in circuits with higher complexity such as RI sensors. The metal and insulator materials that are used in the designed structures are silver and air, respectively. The finite-difference time-domain (FDTD) method is used for the numerical investigation of the proposed RI sensors. To verify FDTD simulations, the basic rectangular cavity which is used to design HC is analyzed using an analytical method. In summary, the benefits of the proposed RI sensors are having single-mode spectra in a wide wavelength range and also their simple structures. The proposed topology easily be redesigned and adapted with different numbers of HCs without disturbing its single-mode spectrum to achieve various FOM values. Furthermore, considering the fact that the proposed cavity is based on rectangular shapes, it has a simple fabrication process. Taking into account the mentioned advantages of the proposed structures, they can be used in integrated optical circuits for optical communication purposes.

关键词： Surface plasmon polaritons Refractive index sensor H-shaped cavity Metal-insulator-metal waveguide finite-difference time-domain method

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Quantum-Coherent Light-Electron Interaction in a Scanning Electron Microscope

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Physical Review Letters 2022年第23期128卷 235301-235301页

作者： R. Shiloh T. Chlouba P. Hommelhoff Physics Department Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Staudtstraße 1 91058 Erlangen Germany.

The last two decades experimentally affirmed the quantum nature of free electron wave packets by the rapid development of transmission electron microscopes into ultrafast, quantum-coherent systems. So far, all experiments were restricted to the bounds of transmission electron microscopes enabling one or two photon-electron interaction sites. We show the quantum coherent coupling between electrons and light in a scanning electron microscope, at unprecedentedly low, subrelativistic energies down to 10.4 keV. These microscopes not only afford the yet-unexplored energies from ∼0.5 to 30 keV providing the optimum electron-light coupling efficiency, but also offer spacious and easily configurable experimental chambers for extended, cascaded optical set ups, potentially boasting thousands of photon-electron interaction sites. Our results make possible experiments in electron wave packet shaping, quantum computing, and spectral imaging with low-energy electrons.

关键词： Electron beams & optics Near-field optics Quantum computation Quantum measurements Semiclassical physics Ultrafast optics Electron techniques finite-difference time-domain method Scanning electron microscopy

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Study on Bifurcating Light Trajectory in a Distorted Photonic Crystal with Multiple Slip Dislocations

Study on Bifurcating Light Trajectory in a Distorted Photoni...

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Conference on Lasers and Electro-Optics Europe (CLEO EUROPE)

作者： Yuki Kawamoto Jinpei Hashizume Hitoshi Kitagawa Kyoko Kitamura Kyoto Institute of Technology/ Matsugasaki Kyoto Japan Japan Science and Technology Agency PREST Kawaguchi Saitama Japan

ISBN: (纸本)9798350345995

A distorted photonic crystal (DPC) is a photonic crystal (PC) that exhibits adiabatic change (lattice distortion) in its lattice properties. We have previously reported that light (electromagnetic wave) propagations in DPCs are curved even when maintaining effective refractive index (averaged in each lattice point) by using the two-dimensional finite-difference time-domain (2D-FDTD) analysis, and have experimentally demonstrated the trajectory by using THz region [1]. Not only to distortions to lattice constant, but we also have shown the DPC based on the lattice points shape that can bend and meander the light propagation [2]. These phenomena can be explained by adiabatic variations of group velocity vectors along the direction of distortion as results of the anisotropic refractive indices induced by lattice distortion. Since no spatial varies of refractive index, these light propagation controls using lattice distortion will be new approach in the fields of transformation optics. So far, we have studied the lattice distortions in which the direction of distortion and dependence of lattice distortion are the identical (e.g., the distortion in the $y$ -direction varies in proportion to $y^domain$ ). In this study, we analyze light propagation in a DPC in which the direction of distortion and dependence of lattice distortion are different.

关键词： Effective refractive index finite-difference time-domain method Light propagation Photonic crystals Refractive index Transformation optics

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Ultrafast Nanoplasmonic Photoelectron Dynamics Between the Multiphoton and Strong-Field Regimes with Tunable IR Excitation

Ultrafast Nanoplasmonic Photoelectron Dynamics Between the M...

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Conference on Lasers and Electro-Optics Europe (CLEO EUROPE)

作者： Balázs Bánhegyi Gábor Ligeti Zsolt G. Kiss Zsuzsanna Pápa Péter Rácz Péter Dombi Wigner Research Centre for Physics Budapest Hungary Budapest University of Technology and Economics Budapest Hungary ELI-ALPS Research Institute Szeged Hungary

ISBN: (纸本)9798350345995

We examined transitions between multiphoton-induced photoemission and strong-field tunnelling of electrons at the surface of gold nanoparticles using infrared femtosecond pulses between 800 nm and 2.4 µm with our newest experiments. In addition to the observation of non-adiabatic tunneling [1], we establish the theoretical background of plasmonic excitation in the infrared range, calculate spectra by solving the time-dependent Schrödinger equation (TDSE), and then verify the predictions with experimental results.

关键词： Femtosecond pulses Field enhancement finite-difference time-domain method Gold Nanoparticles Tunneling

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Three-Temperature Modeling of Laser Excitation in Silicon and Parametric Dependence of Damage Threshold

Three-Temperature Modeling of Laser Excitation in Silicon an...

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Conference on Lasers and Electro-Optics Europe (CLEO EUROPE)

作者： Prachi Venkat Tomohito Otobe Kansai Photon Science Institute National Institutes for Quantum Science and Technology Kyoto Japan Photon Science Center The University of Tokyo Tokyo Japan

ISBN: (纸本)9798350345995

Laser processing of semi-conductors such as silicon has numerous applications in nano-structuring and fabrication industry, and requires a detailed understanding of the dynamics. The interaction involves complex processes such as photo-absorption, recombination, impact ionization and re-distribution of the energy due to carrier-phonon dynamics. Numerical modeling proves to be useful in understanding the physics of the interaction. Based on the density-dependent Two-Temperature model (nTTM) [1], we have developed a one-dimensional Three-Temperature model (1D-3TM) and studied the laser-excitation process and damage in silicon [2]. In 1D-3TM, three sub-systems for electrons, holes and the lattice are considered and their evolution dynamics are calculated separately. This approach gives a more clear picture of the electron dynamics and the evolution of quasi-temperatures in the system. We also take into account the evolution of optical properties of silicon during the interaction and the effect of band-gap re-normalization on them. The laser field is modeled using finite difference time domain (FDTD) method [2].

关键词： finite-difference time-domain method Ionization Lasers Optical properties Silicon Thin films

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Hybrid FDTD-PE method for Loran-C ASF prediction with near-source complex topography

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IET MICROWAVES ANTENNAS & PROPAGATION 2020年第2期14卷 171-176页

作者： Wang, Dan-Dan Pu, Yu-Rong Xi, Xiao-Li Zhou, Li-Li Xian Univ Technol Fac Automat & Informat Engn Xian Peoples R China Shaanxi Univ Sci & Technol Coll Elect & Informat Engn Xian Peoples R China

The parabolic equation (PE) method and finite-difference time-domain (FDTD) method are combined to predict long-range Loran-C additional secondary factors (ASFs) in situations with near-source complex topography. The non-uniform FDTD method is employed in the complex source region, while the PE method is used for propagation over smooth terrain to a long distance. By using the advantages of each algorithm, the hybrid FDTD-PE approach is capable of modelling the near-source topographic details, while saving much computational resources as compared to a full FDTD solution. Numerical results along several paths are used to validate the hybrid algorithm. Furthermore, the hybrid method is applied to analyse the effect of near-source topographic complexities, including non-flat land, land-sea transition, and island (cliff)-sea transition, on the navigational coverage for the planning of the Loran-C systems.

关键词： approximation theory finite difference time-domain analysis topography (Earth) parabolic equations near-source topographic details FDTD solution hybrid algorithm hybrid method near-source topographic complexities Loran-C systems hybrid FDTD-PE method Loran-C ASF prediction near-source complex topography parabolic equation method finite-difference time-domain method long-range Loran-C additional secondary factors ASFs nonuniform FDTD method complex source region hybrid FDTD-PE approach

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A Novel All-Optical Sensor Design Based on a Tunable Resonant Nanocavity in Photonic Crystal Microstructure Applicable in MEMS Accelerometers

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Photonic Sensors 2021年第4期11卷 457-471页

作者： Mojtaba HOSSEINZADEH SANI Hamed SAGHAEI Mohammad Amin MEHRANPOUR Afsaneh ASGARIYAN TABRIZI Department of Electrical Engineering Imam Reza International UniversityMashhad ***Iran Department of Electrical Engineering Shahrekord BranchIslamic Azaci UniversityShahrekord ***Iran Department of Electrical Engineering Sari BranchIslamic Azad UniversitySari ***Iran Academic Center for Education Cultureand Research(ACECR)Tabriz ***Iran

In view of the large scientific and technical interest in the microelectromechanical system(MEMS)accelerometer sensor and the limitations of capacitive,resistive piezo,and piezoelectric methods,we focus on the measurement of the seismic mass displacement using a novel design of the all-optical sensor(AOS).The proposed AOS consists of two waveguides and a ring resonator in a two-dimensional rod-based photonic crystal(PhC)microstructure,and a holder which connects the central rod of a nanocavity to a proof *** photonic band structure of the AOS is calculated with the plane-wave expansion approach for TE and TM polarization modes,and the light wave propagation inside the sensor is analyzed by solving MaxwelFs equations using the finite-difference time-domain *** results of our simulations demonstrate that the fundamental PhC has a free spectral range of about 730 nm covering the optical communication *** also show that the AOS has the resonant peak of 0.8 at 1.644μm,quality factor of 3288,full width at half maximum of 0.5nm,and figure of merit of ***,for the maximum 200nm nanocavity displacements in the x-or y-direction,the resonant wavelengths shift to 1.618μm and 1.547μm,*** also calculate all characteristics of the nanocavity displacement in positive and negative directions of the jc-axis and *** small area of 104.35μm^(2)and short propagation time of the AOS make it an interesting sensor for various applications,especially in the vehicle navigation systems and aviation safety tools.

关键词： Photonic crystal MEMS accelerometer sensor tunable resonator finite-difference time-domain method

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Hybrid method for transient responses of transmission line in an apertured enclosure based on FETD method and transmission line equations

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IET SCIENCE MEASUREMENT & TECHNOLOGY 2020年第9期14卷 685-695页

作者： Gong, Yanfei Jiang, Luhang Beijing Informat Sci & Technol Univ Minist Educ Optoelect Measurement Technol & Instr Key Lab 35 Beisihuan Middle Rd Beijing Peoples R China North China Elect Power Univ Sch Elect & Elect Engn 2 Beinong Rd Beijing Peoples R China

A hybrid method combining the finite-element time-domain (FETD) method and transmission line (TL) equations (FETD-TL) is presented for evaluating the transient responses of a lossy TL in an apertured rectangular enclosure excited by electromagnetic pulses. First, the electric fields in the enclosure without the TL are calculated based on the Bethe's small holes theory and the mirror procedure. Then, the enclosure's electric fields are introduced into the second-order TL equation for current as the equivalent distributed sources. The transient currents induced on the TL are obtained by solving the second-order TL equation for current based on the FETD method with a single iteration variable. Finally, the transient voltages induced on the TL are computed by discretising the first-order TL equation. Compared with the method based on finite-difference time-domain (FDTD) method and TL (FDTD-TL) via several examples, the proposed hybrid method is proved to be correct and effective, which possesses much higher convenience and efficiency than FDTD-TL method in dealing with TL model terminated by complex lumped parametric networks.

关键词： transmission line theory lumped parameter networks transient response electromagnetic pulse finite element analysis finite difference time-domain analysis iterative methods complex lumped parametric networks single iteration variable equivalent distributed sources Bethe small holes theory finite-element time-domain method apertured enclosure FDTD-TL method hybrid method finite-difference time-domain method first-order TL equation transient voltages FETD method transient currents second-order TL equation apertured rectangular enclosure transient responses transmission line equations

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