Total Field Distribution Research Articles

Properties of surface plasmon polaritons excited by generalized cylindrical vector beams

Properties of surface plasmon polaritons (SPPs) excited by generalized cylindrical vector (CV) beams in high-numerical-aperture microscopic system are investigated both theoretically and experimentally. The CV beams can be decomposed into radial and azimuthal polarization components with different weights, and only the radial polarization component is able to excite SPPs in our system; thus, the total field on the metal film contributed by both the excited SPPs and directly transmitted fields is completely determined by the ratio between radial and azimuthal components of the incident CV beam. A variety of total field distributions such as virtual probe, flat-topped pattern, and doughnut can dynamically be obtained through simply selecting the desired CV beams.

Photonic density of states of cholesteric liquid crystal cells

Using the exact analytical expressions for the reflection and transmission matrices for the finite thickness cholesteric liquid crystal (CLC) layer, we calculated its photonic density of states (PDS) of the eigen polarizations (EPs). We investigated the influence of absorption and gain, as well as the CLC cell thickness and CLC local dielectric anisotropy on PDS. We presented the full picture of distribution of total field in the CLC layer and outside it for two EPs. The possibility of connections between the PDS and the density of the light energy accumulated in the medium was investigated, and it was shown that these characteristics had analogous spectra and, besides, the influences of the problem parameters on these characteristics were also analogous. We showed that there existed a critical value of the parameter characterizing the gain beyond which the lasing mode was quenched and the feedback vanished. We showed that in the presence of gain there existed a critical value of numbers of pitches in the CLC layer beyond which the lasing mode was again quenched and the feedback vanished, too. It is shown that the subject system can work as a low-threshold laser or a multi-position trigger.

Theory of Cowling channel formation by reflection of shear Alfven waves from the auroral ionosphere

AbstractWe present the first complete formulation of the coupling between the ionospheric horizontal currents (including Hall currents) and the field‐aligned currents (FAC) via shear Alfven waves, which can describe the formation of a Cowling channel without any a priori parameterization of the secondary (Hall polarization) electric field strength. Our theory reorganizes the Cowling channel by “primary” and “secondary” fields. Until now there are no theoretical frameworks, which can derive these separated components from observed or given total conductance, electric field, and FAC distributions alone. But when a given incident where Alfven wave is considered as the driver, the reflected wave can be uniquely decomposed into the primary and secondary components. We show that the reflected wave can, depending on actual conditions, indeed carry FAC that connect to divergent Hall currents. With this new method, we can identify how large the secondary electric field becomes, how efficiently the divergent Hall current is closed within the ionosphere, and how much of the Hall current continues out to the magnetosphere as FAC. In typical ionospheric situations, only a small fraction of FAC is connected to Hall currents at conductance gradients, i.e., the secondary field is relatively strong. But when conductances are relatively low compared with Alfven conductance and/or horizontal scales smaller than ~10 km, the Hall FAC may become significant.

The zonal disintegration mechanism of surrounding rock around deep spherical tunnels under hydrostatic pressure condition: a non-euclidean continuum damage model

A new non-Euclidean continuum damage model is proposed to investigate the zonal disintegration phenomenon of the surrounding rocks around deep spherical tunnels under hydrostatic pressure condition as well as the total elastic stress field distributions. The elastic stress fields of the surrounding rocks around deep spherical tunnels under hydrostatic pressure condition are obtained. If the elastic stresses of the surrounding rocks satisfy the strength criterion of the deep rock masses, the number, size and location of fractured and nonfractured zones are determined. The effect of physico-mechanical parameters of the surrounding rocks on the zonal disintegration phenomenon is studied and numerical computation is carried out. It is found from numerical results that the number, size and location of fractured and non-fractured zones are sensitive to the physico-mechanical parameters of the surrounding rocks.

Buried Effects of Surface Plasmon Resonance Modes for Periodic Metal–Dielectric Nanostructures Consisting of Coupled Spherical Metal Nanoparticles with Cylindrical Pore Filled with a Dielectric

We numerically investigate the buried effects of surface plasmon resonance (SPR) modes for the periodic silver-shell nanopearl dimer (PSSND) array and their solid counterparts with different buried depths in a silica substrate by means of finite element method with three-dimensional calculations. The investigated PSSND array is an important novel geometry for plasmonic metal nanoparticles (MNPs), combining the highly attractive nanoscale optical properties of both metallic nanoshell and cylindrical pore filled with a dielectric. Numerical results for SPR modes corresponding to the effects of different illumination wavelengths, absorption spectra, pore–dielectric, electric field components and total field distribution, charge density distribution, and the model of the induced local field or an applied field of the PSSND array are reported as well. It can be found that the buried MNPs with cylindrical pore filled with a dielectric in a substrate exhibit tunable SPR modes corresponding to the bonding and antibonding modes that are not observed for their solid counterparts.

Monte Carlo simulation of positive corona discharge in SF6

Gas-insulated systems are now a major component of power transmission and distribution systems all over the world. There has been considerable interest in non-thermal discharges over the past decade due to the increased number of industrial applications. Diverse applications demand a solid physical and chemical understanding of the operational principals of such discharges. This paper focuses on the most important and widely used variety of non-thermal discharges, the corona discharge. Positive corona in SF6 is studied for a point to plane electrode gap using Monte Carlo simulation technique. The initiation and development of successive avalanches are traced as function of time. The simulation provides a detailed structure of avalanches from which essential properties of corona discharge with regard to total field distribution, propagation of successive avalanches and ion distribution can be discerned.

ANALYSIS OF A WIDE SPECTRAL RANGE PLASMONIC OUTLINE BOWTIE ANTENNA RANGING IN 0.3-5.0 μm

We numerically analyze a broadband plasmonic outline bowtie antenna over a large parameter space by means of finite element method with three-dimensional calculation. The antenna is composed of a pair of triangular gold with outline shape placed in close proximity to each another. We show how the structural parameters affect the antenna resonance conditions, such as peak resonances wavelengths, electric field intensities, propagation properties, component field and total field distributions, charge densities and electrical filed stream lines at spectral points of interest. In addition, the characteristics of transmittance spectral of a periodic antenna array corresponding to the bonding mode and anti-bonding mode are investigated as well. Simulation results show that it is possible to tune an antenna with a constant length over a wide spectral range (ranging in 0.3–5.0μm or more range) while maintaining a constant antenna dimension, reduce the antenna footprint by a factor of 4.98, and increase the gap enhancement by 23%. This article has been removed from the website on January 3, 2013, because it has been found to violate plagiarism rule of our journal. Received 18 October 2012, Accepted 16 November 2012, Scheduled 7 December 2012 * Corresponding author: Yuan-Fong Chau (yfc01@uch.edu.tw).

Zonal disintegration mechanism of cross-anisotropic rock mass around a deep circular tunnel under dynamic unloading

A mechanical model is proposed to investigate zonal disintegration mechanism of cross-anisotropic rock masses around a deep circular tunnel subjected to dynamic unloading under hydrostatic pressure condition as well as the total elastic stress-field distributions. Effects of unloading rate and dynamic mechanical parameters on the zonal disintegration phenomenon of the surrounding rock masses around a deep circular tunnel as well as the total elastic stress field distributions are taken into account. Numerical computation is carried out. The location, number and size of fractured and non-fractured zones are determined using the Hoek–Brown criterion. It is found from numerical results that the location, number and size of fractured and non-fractured zones significantly depend on unloading rate and dynamic mechanical parameters of deep rock masses.

Delay spread of electromagnetic waves along random rough surface

This paper is concerned with a numerical analysis of propagation characteristics of electromagnetic waves traveling along two-dimensional (2D) random rough surface (RRS). Ray searching algorithm is based on 2D discrete ray tracing method, and the field distribution corresponding to each searched ray is computed by using source and image diffraction coefficients. Numerical computations are carried out for total field distributions along RRS as well as delay profiles at an arbitrary observation point which is far from a source antenna. Detailed discussions are made on the effect of directivity of source or receive antenna to the delay spreads of received powers.

Monte Carlo simulation of corona discharge in SF 6

Sulphur hexafluoride (SF 6) is one of the most widely used gaseous dielectrics for electric power systems and a number of high-voltage applications. There are many industrial applications where the electric corona discharge is used. In most cases the corona discharge is an inherently dynamic process; all parameters vary in time. Monte Carlo simulation of corona discharges in gas offers several advantages to study fundamental processes. Furthermore, it gives a fair qualitative description of the corona discharge itself as a function of space and time. This paper describes the development of negative coronas in SF 6 in a point–plane gap. Detailed structure of avalanches is presented, the total field distribution, propagation of successive avalanches and ion distribution are studied.

Modeling of Local Magnetic Field Enhancements within Solar Flux Ropes

To model and study local magnetic-field enhancements in a solar flux rope we consider the magnetic field in its interior as a superposition of two linear (constant α) force-free magnetic-field distributions, viz. a global one, which is locally similar to a part of the cylinder, and a local torus-shaped magnetic distribution. The newly derived solution for a toroid with an aspect ratio close to unity is applied. The symmetry axis of the toroid and that of the cylinder may or may not coincide. Both the large and small radii of the toroid are set equal to the cylinder’s radius. The total magnetic field distribution yields a flux tube which has a variable diameter with local minima and maxima. In principle, this approach can be used for the interpretation and analysis of solar-limb observations of coronal loops.

Theoretical Estimation of Scattering Waves in Transverse Section of Upper Body for On-Body Wireless Communications

This paper attempts to analyze theoretically the propagation characteristics in the transverse section of upper body to support on-body wireless communications. The analytical estimation assumes that the human body is structured as a lossy-dielectric circular cylinder with infinite length that consists of the 2/3-muscle equivalent uniform tissue. Each scattering electric field formulation inside and outside of the cylinder is derived for scattering characteristics in the propagation environment including the human body when the source current has the vertical direction to the cylinder surface or the horizontal direction to the cylinder axis. In order to confirm the reliability of the formulation, total electric field distributions at 2.45GHz are compared with the results by the finite-difference time-domain (FDTD) method. In each current direction, general scattering characteristics and the influence on the total propagation are estimated. Furthermore, from scattering and total electric field intensities evaluated with the variations of operating frequency, radius of the human body, and distance between a source and the human body, propagation characteristics are investigated to assist in the design of a device for on-body propagation channel with the upper body.

Design of a wavelength independent grating in the resonance domain

We propose using blazed gratings in the resonance domain with period larger than the wavelength for anti-reflection and polarization selection. The inherent problem in this region is wavelength dispersion, which is solved by analyzing the total reflectivity and electric field distribution. The positional relationship between the area of strong electric field, and the side and tip of the grating is crucial to the wavelength dispersion of total reflectivity.

Comparisons of Simulated and Measured Electric Field Distributions in a Cabin of a Simplified Scale Car Model

The electric fields inside and outside a car must be carefully determined when designing a wireless communication system to be employed in the car. This paper introduces an effective simulation method and a precise measurement method of electric field distributions in a cabin of a simplified scale car model. A 1/3 car model is employed for ease of measurement. The scaled frequency of 2859MHz, 3 times 953MHz, is employed. The use of a moment method simulator utilizing the multilevel fast multipole method allows calculations to be performed on a personal computer. In order to judge the accuracy of simulation results, convergence of simulation output in accordance with segment size (triangle edge length) changes is ensured. Simulation loads in the case of metallic body only and a metallic body with window glass are also shown. In the measurements, an optical electric field probe is employed so as to minimize the disturbances that would otherwise be caused by metallic feed cable; precise measurement results are obtained. Comparisons of measured and simulated results demonstrate very good agreement which confirms the accuracy of the calculated results. 3-dimensional electric field distributions in the car model are shown and 3-dimensional standing wave shapes are clarified. Moreover, calculated and measured radiation patterns of the car model are shown so the total electric field distributions around a car are clarified.

Extended scattering-matrix method for efficient full parallel implementation of rigorous coupled-wave analysis

An extended and refined scattering-matrix method is proposed for the efficient full parallel implementation of rigorous coupled-wave analysis of multilayer structures. The total electromagnetic field distribution in the rigorous coupled-wave analysis is represented by the linear combination of the eigenmodes with their own coupling coefficients. In the proposed scheme, a refined recursion relation of the coupling coefficients of the eigenmodes is defined for complete parallel computation of the electromagnetic field distributions within multilayer structures.

Pseudo-Fourier modal analysis on dielectric slabs with arbitrary longitudinal permittivity and permeability profiles

A pseudo-Fourier modal analysis method for analyzing finite-sized dielectric slabs with arbitrary longitudinal permittivity and permeability profiles is proposed. In the proposed method, the permittivity and permeability profiles are represented by the Fourier expansion without using the conventional staircase approximation. The total electromagnetic field distribution inside a dielectric slab is a linear superposition of extracted pseudo-Fourier eigenmodes with specific coupling coefficients selected to satisfy given boundary conditions. The proposed pseudo-Fourier modal analysis method shows excellent agreement with the conventional rigorous coupled-wave analysis with the S-matrix method.

Theoretical characterization of multilayer photonic crystals having a 2D periodicity

We present a new, very accurate and fast model of photonic bandgap (PBG) structure characterized by a two-dimensional (2D) periodic change of the refractive index and finite height, therefore named quasi 3D PBG. The new model is based on the Floquet–Bloch formalism and allows to find all the propagation characteristics including the space harmonics and the total field distribution, the propagation constants, the guided and radiated power and modal loss induced by the 2D grating. A clear explanation of the physical phenomena occurring when a wave propagates inside the 2D periodic structure is presented, including the photonic bandgap formation and the radiation effects. The approach does not require any theoretical approximation, and can be applied to study rigorously any PBG-based multilayer structures. We have applied the model to investigate several structures for both optical and microwave applications. Copyright © 2005 John Wiley & Sons, Ltd.

Modeling of light propagation through step‐like discontinuities in slab dielectric waveguides

AbstractOne‐way light propagation through a steplike discontinuity of dielectric‐slab waveguide is simulated by using the finite‐difference beam‐propagation method (FD‐BPM) and the Green's function method. The validity of the slowly varying envelope approximation in modeling of the total field distribution and the radiation‐field distribution is analyzed. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 108–114, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20063

Design and Modelling of Photonic Band-Gap Resonance Cavity

An optimal design of Photonic Band-Gap (PBG) based resonance cavities has been carried out and optimal design rules have been drawn by a very fast and accurate computer code, developed by the authors, implementing a new model of one-dimensional finite-size PBG materials. The model also takes into account the presence of defects; it allows to accurately determine the mode propagation constants, electromagnetic harmonics and total field distribution, transmission and reflection coefficients, forward and backward power flow, guided and radiated power and total losses due to radiation, Bragg scattering and out of plane scattering. The design of resonance cavities advancing the state of the art of commercial Dense Wavelength Division Multiplexing (DWDM) filters is performed. A great number of optical cavities have been designed and quickly simulated thanks to the fastness of the code, allowing optimal design rules to be drawn.

Design of guided-wave photonic bandgap devices by using the Bloch-Floquet theory

The design of some 1-D waveguiding photonic bandgap (PBG) devices has been carried out by utilizing a model based on the Bloch-Floquet theorem. A complete analysis of the propagation characteristics, including the modal propagation constants, electromagnetic field harmonics and total field distribution, transmission and reflection coefficients, total forward and backward power flow in the structure, guided and radiated power, and total losses, enable the optimization of the design in very short CPU time.