The Surface Wave on the Boundary between a Hyperbolic Magnetooptical Single-Axis Metamaterial and an Isotropic Dielectric

Journal of Communications Technology and Electronics - The propagation of the surface wave along the boundary between a hyperbolic magnetooptical single-axis metamaterial and an isotropic...     

Propagation of electromagnetic waves in a nonlinear metamaterial layer

Propagation of electromagnetic TE waves in a nonlinear dielectric layer with generalized Kerr’s nonlinearity is considered. The layer is located between two isotropic nonmagnetic semi-infinite media with constant electrodynamic parameters. The dispersion equation for the eigenvalues of the problem (propagation constants) is derived. The behavior of dispersion curves is qualitatively analyzed. Propagation of waves in a nonlinear metamaterial is studied.     

Investigation of the Interfaces in Ni-FUSI/Hf-Based/Si and Ni-FUSI/SiO<Subscript>2</Subscript>/Si Stacks by Physical and Electrical Characterization Techniques

The combination of full Ni silicidation (Ni-FUSI) gate electrodes and hafnium-based high-k gate dielectrics is one of the most promising replacements for poly-Si/SiO₂/Si gate stacks for the future complementary metal–oxide–semiconductor (CMOS) sub-45-nm technology node. The key challenges to successfully adopting the Ni-FUSI/high-k dielectric/Si gate stack for advanced CMOS technology are mostly due to the interfacial properties. The origins of the electrical and physical characteristics of the Ni-FUSI/dielectric oxide interface and dielectric oxide/bulk interface were studied in detail. We found that Ni-FUSI undergoes a phase transformation during silicide formation, which depends more on annealing temperature than on the underlying gate dielectric material. The correlations of Ni–Si phase transformations with their electrical and physical changes were established by sheet resistance measurements, x-ray diffraction (XRD), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS) analyses. The leakage current density–voltage (J–V) and capacitance–voltage (C–V) measurement techniques were employed to study the dielectric oxide/Si interface. The effects of the postdeposition annealing (PDA) treatment on the interface charges of dielectric oxides were studied. We found that the PDA can effectively reduce the trapping density and leakage current and eliminate hysteresis in the C–V curves. In addition, the changes in chemical bonding features at HfO₂/Si and HfSiO/Si interfaces due to PDA treatment were evaluated by XPS measurements. XPS analysis provides a better interpretation of the electrical outcomes. As a result, HfSiO films exhibited superior performance in terms of thermal stability and electrical characteristics.     

波导参数和传播常数对光折变表面波的影响

基于质点振荡的模型和数值模拟的方法,研究了波导参数和传播常数对光折变晶体与线性电介质界面光折变表面波类型和局域表面波模的影响。当波导参数大于传播常数时,在光折变晶体与线性电介质界面可以产生非局域表面波。当波导参数小于传播常数时,在光折变晶体与线性电介质界面可以产生振荡表面波和局域表面波。在局域表面波形成的系统内,正波导参数的光波能量比负波导参数的光波能量在光折变晶体内聚集得多。在给定一个局域表面波形成的物理系统,传播常数越大,表面波在线性电介质和光折变晶体中衰减就越快,对应表面波模的波峰离界面就越近。     

Modes of a planar nonlinear-metamaterial waveguide

Modes of a planar dielectric waveguide are investigated. The waveguide is made from a nonlinear metamaterial with a negative permittivity and a negative permeability. The mode wavenumbers and field distributions are calculated for structures with parabolic permittivity and permeability profiles. It is shown that anomalously high field intensities can be observed in such a structure. The dependences of the mode propagation coefficients on the electric field are analyzed for the case of nonlinear media. The effect of nonlinearity saturation is considered.     

Surface waves on the interface between a left-handed and a right-handed medium

The frequency regions where a surface wave (SW) exists on a dielectric/metamaterial interface are determined for the case when the metamaterial??s refractive index is negative. With allowance for the conditions of TE and TM SW existence in the structure, the characteristic frequencies that can be controlled with the help of the external magnetic field are calculated. On the basis of dispersion dependences for SWs, it is shown that the TM (TE) wave is forward (backward), and the backward wave is substantially slowed in the structure.     

Diffuse like and cross-polarized fields scattered from irregularlayered structures-full-wave analysis

The full-wave solution for scattering from two-dimensional (2-D) irregular layered structures is expressed as a sum of radiation fields, the lateral waves and the surface waves. Only the radiation far fields are considered in this work. The lateral waves and surface waves are ignored since excitations of plane waves are considered and the observation points are in the far fields. The scattering coefficients appearing in the full-wave generalized telegraphists' equations for irregular layered structures are proportional to the derivatives of the surface heights at each interface. Using a first-order iterative procedure to solve the generalized telegraphists' equations, the diffusely scattered fields from irregular layered structures are expressed as a sum of first-order fields scattered at each rough interface. In this paper, the like and cross-polarized diffuse scattered fields are derived for three medium irregular structures with 2-D rough interfaces. The thickness of the coating material or thin film between the two interfaces is arbitrary, however, in this work it is assumed to be constant. Thus, in this case, both interfaces are rough and there are five different scattering processes identified in the full-wave results. A physical interpretation is given to the five different scattering mechanisms that contribute to the diffusely scattered fields. This work can be used to provide realistic analytical models of propagation across irregular stratified media such as ice or snow covered terrain, remote sensing of coated rough surfaces, or the detection of buried objects in the presence of signal clutter from the rough interfaces     

Analysis of step discontinuities on planar dielectric waveguidecontaining a gyrotropic layer

Nonreciprocal wave propagation characteristics through step discontinuities on planar dielectric waveguides with a gyrotropic layer such as ferrite are presented. In the proposed nonreciprocal structures, the wave propagates from a dielectric waveguide to a ferrite and dielectric waveguide or vice versa, where two structures are connected to create abrupt discontinuities. Nonreciprocal scattering coefficients for TE excitation are calculated at 35 GHz using the well-known mode-matching method     

Electromagnetic waves and oscillations in the layered semiconductor-dielectric-semiconductor structure

Theoretical and numerical studies of the electromagnetic properties of the layered semiconductor — dielectric — semiconductor (SDS) structure was carried out. It was shown that the weak damping guide and surface waves may exist in this structure and retardation of surface waves may be several times more than for the semiconductor — dielectric (SD) interface. If this structure contains reflections it leads to the formation of high Q-factor resonance oscillations. It was found that at the beginning of intermode coupling of two surface oscillations in the studied resonance structure, hybrid surface oscillations with near resonance frequencies are formed. Their electromagnetic field components along the wave propagation direction are orthogonal to each other and modulated along the SD interface by orthogonal envelopes.     

TM Nonlinear electromagnetic waves guided by an inhomogeneous medium

Analytical dispersion relations and the power flow expression for TM (polarized) nonlinear electromagnetic surface waves propagating along the interface of an inhomogeneous and dielectric nonlinear media have been investigated theoretically. An inhomogeneous dielectric cover has the dielectric permittivityε=a+bz, which is contacted with a strongly nonlinear Kerr like layer. The existence conditions for these waves to be propagated are studied. These waves have no counterpart in the linear isotropic regime. The power flow versus the wave index, and the consequence interface nonlinearity might be evaluated for a variety of inhomogeneity parameters, which are found to be inhomogeneity dependent, and could lead to optical hysterisis and bistability.     

Electromagnetic THz Radiation Modeling by DPSM

THz or T-ray imaging and spectroscopy are becoming increasingly popular nondestructive evaluation techniques for damage detection and characterization of materials. In order to understand the interaction between the T-ray electromagnetic waves and dielectric media a reliable model of electromagnetic wave propagation through dielectric materials must be developed. A recently developed semi-analytical method called the distributed point source method (DPSM) is extended to model electromagnetic wave propagation in THz range. Since T-ray signals generated by emitters or sources are close to Gaussian beams, the DPSM modeling is carried out for Gaussian beams generated by finite sized emitters. The DPSM generated results are compared with the analytical and experimental results. T-ray propagation in layered structures in absence of any anomaly and the interaction between the Gaussian beam and the spherical scatterer are also investigated.     

Quasi-ray Gaussian beam algorithm for time-harmonic two-dimensionalscattering by moderately rough interfaces

Gabor-based Gaussian beam (GB) algorithms, in conjunction with the complex source point (CSP) method for generating beam-like wave objects, have found application in a variety of high-frequency wave propagation and diffraction scenarios. Of special interest for efficient numerical implementation is the noncollimated narrow-waisted species of GB, which reduces the computationally intensive complex ray tracing for collimated GB propagation and scattering to quasi-real ray tracing, without the failure of strictly real ray field algorithms in caustic and other transition regions. The Gabor-based narrow-waisted CSP-GB method has been applied previously to two-dimensional (2-D) propagation from extended nonfocused and focused aperture distributions through arbitrarily curved 2-D layered environments. In this 2-D study the method is applied to aperture-excited field scattering from, and transmission through, a moderately rough interface between two dielectric media. It is shown that the algorithm produces accurate and computationally efficient solutions for this complex propagation environment, over a range of calibrated combinations of the problem parameters. One of the potential uses of the algorithm is as an efficient forward solver for inverse problems concerned with profile and object reconstruction     

Propagation of a surface acoustic wave in a layered system containing a two-dimensional conducting layer

A surface acoustic wave can propagate in a piezoelectric crystal above which lies a two-dimensional conducting layer. The electric fields excited by the wave in the crystal penetrate into the two-dimensional layer and excite dissipative currents in it, which results in absorption of the wave and change of its velocity. These characteristics are calculated for different configurations of the layered system taking into account not only the surface conductivity but also surface diffusion. When the layer has an elastic contact with the crystal, for the configuration allowance is made not only for the piezoelectric but also the deformation interaction of the sound wave with the electrons. Fiz. Tekh. Poluprovodn. 31, 478–482 (April 1997)     

Ray Methods for Trapped and Slightly Leaky Modes in Multilayered or Multiwave Regions

Ray-optical techniques presented previously by the authors for study of mode propagation in homogeneously filled waveguides are extended to accommodate multilayered regions and regions capable of supporting multiple wave species. Emphasis is placed on a self-consistent ray treatment which illustrates alternative methods for dealing with ray coupling at boundaries and with the presence of multiple wave types, either in a single layer or in adjacent regions. Both closed and open structures are analyzed, with discussion of the latter limited to modes with small leakage due either to duct inhomogeneities or to curvature. Examples include layered dielectric waveguides with a straight or circular axis, and compressible plasma waveguides which are illustrative of media wherein two wave species (electromagnetic and electroacoustic) can propagate.     

电波在有耗分层媒质中传播的频域特性研究

本文在频率域上研究了电波在分层媒质中的传播特性，提出了一种新的电波在有耗分层媒质中的传播的频域模型，利用计算机仿真分析了电波在层状媒质中的传播的频率特性，得出了各介质参数及电波频率与传播持性的关系。     

Solution to the diffraction problem for the periodically corrugated boundary of the chiral half-space

The 2D problem of the diffraction of plane wave at a periodically corrugated interface of the chiral and magnetodielectric media is solved using the modified zero-field method. The system of integral equations is derived for unknown currents on the contour of the cross section of corrugated surface. The method is tested in the problem of diffraction at a perfectly conducting sinusoidally corrugated surface. The numerical results for the diffraction at the sinusoidal and cycloidal corrugated boundaries of the chiral medium and dielectric medium are presented.     

Dyadic eigenfunctions and natural modes for hybrid waves in planar media

A new formulation for studying electromagnetic wave propagation in an open, planarly layered medium is presented based on eigenfunctions of the Hertzian potential dyadic Green's function operator. Due to the complicated coupling of scalar components of potential at material interfaces, elevation of the usual vector eigenfunction problem to dyadic level is found to lead to a convenient, compact representation of wave propagation phenomena. Although we study the source-free problem here, the three columns of the eigenfunction dyadics represent (up to an excitation-dependent amplitude) the vector fields excited by a given three-dimensional source. The general theory of dyadic eigenfunctions is presented, including orthogonality and the possibility of associated functions (root functions) at modal degeneracies, and an example of propagation in a grounded dielectric slab environment is provided.     

Design feasibility of a single-mode optical isolator

Isolator conditions are derived by a perturbation method for optical slab isolators in which magnetooptical crystal and anisotropic dielectric crystal films are integrated for reciprocal and non-reciprocal TE-TM mode conversion functions. The general expressions show that isolator conditions can be satisfied for any combination of wavelength, normalized frequency, waveguide thickness, and gyrotropic constant of the magnetooptical crystal by appropriate choice of the magnitude of the birefringence of the top layer film and its crystal orientation angle. Design examples of single-mode isolators with waveguide thicknesses of 4, 4.5, and 5 μm are given at 1.55 μm wavelength. It is also pointed out that isolators of the above design can be fabricated with Y3Fe5O12, Y1.5Gd1.5Fe3O12, and Tm3Fe5O12crystal films as magnetooptical materials and a solid solution of LiNbO3and LiTaO3as an anisotropic film. Tolerance in the required film thickness becomes less stringent with this design. Isolation of more than 20 dB with an insertion loss of less than 0.12 dB is feasible without any parameter adjustment, even when there is as much as a ten percent deviation in the film thickness.     

Visualization of Negative Refraction in Chiral Nihility Media

Chiral nihility media are known to produce a backward wave as one of their two polarizations, yielding negative refraction at the interface of the chiral nihility medium and free space. In this paper, the analysis of chiral nihility effects is illustrated by showing the propagation of a Gaussian beam, both reflected and refracted from an air-chiral interface, and through layered chiral nihility media that are matched to free space. The critical angle for total reflection, and the index-matched total transmission in a matched chiral half-space, are demonstrated. Also demonstrated are the wave splitting, wave widening, and a wave of “standing phase” in matched chiral nihility slabs.     

Stress wave propagation when the elastic coefficients vary with depth

Of concern is the propagation of distortionless surface waves in a medium that may be nonuniform relative to depth. Distortionless wave propagation in inhomogeneous media was discussed by V. Burke, R. J. Duffin and D. Hazony, inQuart. Appl. Math., 183–194 (1976). Accordingly, the media could be modeled by a distributed electrical ladder network, nonuniform along the axis. We give a two-dimensional development based on Hooke's law and Newton's law which leads to the well-known case of Rayleigh waves in homogeneous media. It will be seen that the available pool of propagation modes greatly increases when high-pass propagation is included. The emphasis is on media where the elastic coefficients track one another as a function of depth. Special cases are studied in detail showing that as a disturbance travels along the surface, it may assume a broadband phase change, which translates into a shape distortion in the time domain, which is periodic with distance. Applications may be found in acousto-optics, in situ monitoring of elongated bodies, high-frequency SAW filters, microstrips, and any situations where surface waves are used in an environment of high precision or relatively large distances. Work supported, in part, by the ONR, C. K. Vasudevan contract monitor.