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Fiber Optic and Atmospheric Optical Communication || Optical Wave Propagation
摘要： Electromagnetic (EM) wave plays a key role in modern communication systems, radio and optical, including optical telecommunication systems. Therefore, fiber optic or laser communications emphasize the EM phenomena described mathematically by Maxwell’s unified theory, which we will consider in detail subsequently. Investigation of optical communications started just after the invention of the laser in 1960. Atmospheric propagation of optical waves was investigated parallelly with improvements in optical lasers and understanding of the problems of optical wave’s generation both in the time and space domains. Thus, problems with weather, line-of-site (LOS) clearance, beam spreading and bending in the real atmosphere consisting of gaseous structures (aerosols, fog, smoke, turbulence, etc.), and hydrometeors (snow, rain, clouds, etc.) eliminated free-space optical communication as a major aspect in wireless communication.
关键词： Optical Wave Propagation,Maxwell’s Equations,Atmospheric Propagation,Electromagnetic Waves,Fiber Optic Communication
更新于2025-09-11 14:15:04
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - The Role of the Magnetic Constant, j.10, in the Redefinition of the SI
摘要： This paper explores the origins of the ‘magnetic constant’, μ0, within the present SI, and its role in the imminent redefinition. An attention to the history and meaning of this constant helps to clarify the structure of our unit system, and reveals the extent to which practical unit choices in electricity influence the way we write the fundamental equations of physics. A concern is raised about the use of the name ‘vacuum magnetic permeability’, as this suggests a physical meaning that is not justified. The potential for misinterpretation will increase when μ0 becomes experimentally determined in the revised SI.
关键词： Revision of the SI,Electrical Units,Maxwell’s Equations,Quantum Standards,Unit Systems
更新于2025-09-10 09:29:36
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Electromagnetic field behavior of 3D Maxwell's equations for chiral media
摘要： This article focuses on numerically studying the eigenstructure behavior of generalized eigenvalue problems (GEPs) arising in three dimensional (3D) source-free Maxwell’s equations with magnetoelectric coupling effects which model 3D reciprocal chiral media. It is challenging to solve such a large-scale GEP efficiently. We combine the null-space free method with the inexact shift-invert residual Arnoldi method and MINRES linear solver to solve the GEP with a matrix dimension as large as 5,308,416. The eigenstructure is heavily determined by the chirality parameter γ. We show that all the eigenvalues are real and finite for a small chirality γ. For a critical value γ = γ?, the GEP has 2 × 2 Jordan blocks at infinity eigenvalues. Numerical results demonstrate that when γ increases from γ?, the 2 × 2 Jordan block will first split into a complex conjugate eigenpair, then rapidly collide with the real axis and bifurcate into positive (resonance) and negative eigenvalues with modulus smaller than the other existing positive eigenvalues. The resonance band also exhibits an anticrossing interaction. Moreover, the electric and magnetic fields of the resonance modes are localized inside the structure, with only a slight amount of field leaking into the background (dielectric) material.
关键词： anticrossing eigencurves,Maxwell’s equations,shift-invert residual Arnoldi method,three-dimensional chiral medium,resonance mode,null-space free eigenvalue problem
更新于2025-09-10 09:29:36
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VALIDATION OF A CONVOLUTION INTEGRAL FOR CONDUCTIVITY IMAGING
摘要： Magnetic induction tomography has been under consideration for imaging electrical conductivity distributions within the human body. Multi-coil systems are most commonly employed for this task, requiring a numerical solution of Maxwell’s equations at each position of the coil array. An alternative uses a single coil placed near the conductive target while measuring coil self-impedance changes at a number of unique locations. Recently, a closed-form solution of Maxwell’s equations, in the form of a 3D convolution integral, was found for a single coil consisting of concentric circular loops that relates impedance change (loss) to an arbitrary conductivity. Its development required spatially uniform permittivity and permeability, yet showed quantitative agreement with experiment. Here, we provide a much more rigorous test of the convolution integral in experiments that allow large permittivity changes across coil dimensions. Loss is measured while the coil is placed at known positions relative to plastic columns of variable diameter which are ?lled with salt solutions of varying conductivity. In all cases, coil loss varies linearly with conductivity and with zero intercept. Quantitative agreement is observed only when column diameter is greater than or equal to coil diameter. Because of linearity, the convolution integral is useful for image reconstruction, though contrast could be either reduced or enhanced in those circumstances when relative permittivity change exceeds ～ 70.
关键词： single-coil system,conductivity imaging,convolution integral,Maxwell’s equations,Magnetic induction tomography
更新于2025-09-04 15:30:14
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[IEEE 2018 19th International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM) - Erlagol (Altai Republic), Russia (2018.6.29-2018.7.3)] 2018 19th International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM) - Examination of Physical Phenomena and Processes in the Magnetophotonic Composite Media. Magnetophotonics Material Medium
摘要： The development of radioelectronics and informative–and–communicative technologies of the XXI century is associated with the transmission of ever increasing volume of data and is oriented to use of subTHz and THz bands – SHF, EHF, and HHF (0.1 – 10 THz). Elements and devices of these bands can be conditionally divided into 2 levels: up to 1THz electronic equipments are effectively uses, over 1 THz –are photonic devices. The development of photonic technologies is of increasing importance both in the telecommunicative and in the space communication systems. In this report the physical phenomena and processes occurring in magnetooptical (magnetophotonic) composite material media capable of optimally ensuring their efficiency have been investigated to create new element baseline for domestic radioelectronics. The creation of new–generation functional devices capable of operating in subTHz and THz frequency bands will entail the rapid development of telecommunications.
关键词： Kerr effect,laser radiation,magnetophotonics,Maxwell's equations,self–focusing of light,nonlinear photonic media,Green's functions,Nanophotonics,current harmonics
更新于2025-09-04 15:30:14
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LATTICE MAXWELL'S EQUATIONS (Invited Paper)
摘要： We discuss the ab initio rendering of four-dimensional (4-d) spacetime of Maxwell’s equations on random (irregular) lattices. This rendering is based on casting Maxwell’s equations in the framework of the exterior calculus of di?erential forms, and a translation thereof to a simplicial complex whereby ?elds and causative sources are represented as di?erential p-forms and paired with the oriented p-dimensional geometrical objects that comprise the set of spacetime lattice cells (simplices). We pay particular attention to the case of simplicial spacetime lattices because these can serve as building blocks of lattices made of more generic cells (polygons). The generalized Stokes’ theorem is used to construct discrete calculus operations on the lattice based upon combinatorial relations depending solely on the connectivity and relative orientation among simplices. This rendering provides a natural factorization of (lattice) 4-d spacetime Maxwell’s equations into a metric-free part and a metric-dependent part. The latter is encoded by discrete Hodge star operators which are built using Whitney forms, i.e., canonical interpolants for discrete di?erential forms. The derivation of Whitney forms is illustrated here using a geometrical construction based on the concept of barycentric coordinates to represent a point on a simplex, and the generalization thereof to represent higher-dimensional objects (lines, areas, volumes, and hypervolumes) in 4-d. We stress the role of the primal lattice, the barycentric dual lattice, and the barycentric decomposition lattice in achieving a complete description of the lattice theory. Lattice Maxwell’s equations based on the exterior calculus of di?erential forms and on the use of Whitney forms as ?eld interpolants inherits the symplectic structure and discrete analogues of conservation laws present in the continuum theory, such as energy and charge conservation. It also provides precise localization rules for the degrees of freedom associated with the di?erent ?elds and sources on the lattice, and design principles for constructing consistent numerical solution methods that are free from spurious modes, spectral pollution, and (unconditional) numerical instabilities. We also brie?y consider the relationship between lattice 4-d Maxwell’s equations and some incarnations of discretization schemes for Maxwell’s equations in (3 + 1)-d, such as ?nite-di?erences and ?nite-elements.
关键词： exterior calculus,Maxwell’s equations,lattice theory,differential forms,Hodge star operators,Whitney forms
更新于2025-09-04 15:30:14