Showing papers on "Transmission coefficient published in 1992"
TL;DR: The maximal fluctuation theorem as discussed by the authors holds for a wide variety of systems, in one, two and three dimensions, and it is shown by numerical simulations that these coefficients are either O 0 or / 1.
Abstract: the medium. We apply this result to trace(T TL)M, where TL is the amplitude transmission matrix. The eigenfunctions of TL T define a set of channels through which the current flows, and the eigenvalues are the corresponding transmission coefficients. We prove that these coefficients are either O 0 or / 1. As L increases more channels are shut down. This is the maximal fluctuation theorem: fluctuations cannot be greater than this. We expect that our classification scheme will prove of further value in proving theorems about limiting distributions. We show by numerical simulations that our theorem holds good for a wide variety of systems, in one, two and three dimensions. Disordered media scatter waves incident upon them, and induce in the scattered wavefield a degree of disorder which is far more extreme than the physical disorder of the medium itself. The fluctuations are brought about by multiple scattering of the wavefield and its ability to interfere constructively or destructively with itself. The most extreme instances are found in the absence of absorption, when multiple scattering can have free rein. As a specific example we consider the system shown in figure 1 in which waves are incident on a slab of disordered material of finite thickness in one direction, but effectively infinite in the other directions. We shall assume that the slab is statistically homogeneous. The waves can be either transmitted through or reflected from the slab. Statistics in the transmission coefficient pose particular challenges: as the thickness, L, of the slab is increased fluctuations in the transmission coefficient, far from settling down to some 'average' value, become more extreme. The question is what can we say about the limiting scattering properties of a thick slab of material ? As far as we are aware this question has only been addressed for special cases. The results we derive here apply in very general circumstances,
106 citations
TL;DR: In this paper, the authors review recent numerical and analytical results related to the coexistence of nonlinear wave propagation and disorder effects, mostly for soliton bearing systems, and demonstrate that nonlinear transmission strongly depends on the soliton type: results are different for dynamical, topological, and envelope solitons.
102 citations
TL;DR: In this paper, an efficient, elegant, and systematic formulation technique which combines Fourier transform with matrix analysis methods is proposed for problems related to radiation by dipole or other sources in the presence of an arbitrarily general stratified anisotropic medium has been recently developed.
Abstract: An efficient, elegant, and systematic formulation technique which, combining Fourier transform with matrix analysis methods, is suitable for problems related to radiation by dipole or other sources in the presence of an arbitrarily general stratified anisotropic medium has been recently developed. This technique is adapted further extended to allow the presence of general bianisotropic media described by four tensors with no limitations on their elements. Two specific applications pertaining to some canonical problems of fundamental importance are included to exemplify the method and demonstrate its usefulness: radiation by an arbitrarily oriented elementary electric dipole source located in the vicinity of a general bianisotropic slab, either grounded or ungrounded, leading to the expressions of the dyadic Green's function of the structure, and reflection and transmission of an arbitrarily polarized plane wave incident upon such a slab, leading to closed-form concise expressions for the reflection and transmission coefficient matrices. >
101 citations
TL;DR: In this article, a wave flume with regular waves of very small amplitude-to-wavelength ratio (less than 0.01) was used to validate the oscillating surface pressure theory applied to wave energy absorption by oscillating water column (OWC) devices.
Abstract: Experiments were performed in a wave flume with regular waves of very small amplitude-to-wavelength ratio (less than 0.01). Their purpose was mainly the validation of the oscillating surface pressure theory of Sarmento and Falcao (1985) applied to wave energy absorption by oscillating water column (OWC) devices. Experimental and theoretical curves for the efficiency and for the reflection and transmission coefficients were obtained and compared. The test also included the validation of the two-wave-gauge experimental procedure used to decouple direct and reflected wave trains, as well as the effects of increasing the depth of immersion of the OWC overhang on the efficiency-wave period curves.
81 citations
TL;DR: In this article, dielectric measurements were made on polyethylene, polypropylene, and a stabilizer, Irganox 1010, down to and below the temperature of liquid helium.
Abstract: Dielectric measurements were made on polyethylene, polypropylene, and a stabilizer, Irganox 1010, down to and below the temperature of liquid helium. All three materials exhibited a relaxation in which the frequency is proportional to the absolute temperature with f/T≃1 kHz/K. This phenomenon is indicative of quantum mechanical tunneling with an activation enthalpy close to zero and a negative activation entropy. Alternatively, the relationship may be expressed in terms of a transmission coefficient of about 3×10 -7
51 citations
01 Jan 1992
TL;DR: In this paper, a theoretical analysis based on application of the continuity, momentum, and energy equations to flow through the slots in the breakwater, accounting for head losses associated with flow constriction and reexpansion is presented.
Abstract: Wave interaction with a vertical slotted wave barrier, also called a wave screen or slit-type breakwater, is considered. A theoretical analysis is presented based on application of the continuity, momentum, and energy equations to flow through the slots in the breakwater, accounting for head losses associated with flow constriction and re-expansion. As a result, relatively simple expressions are found for the wave transmission coefficient and for the wave forces on the wall. These are then verified by laboratory experiments with regular waves.
40 citations
TL;DR: In this paper, the transmission properties of polytype interband tunneling heterostructures are analyzed based on a two-band k⋅P theory formulation, and the expressions for the continuity equation and the conservation of particle in the two-, three-, and four-dimensional image of the tunnel are rigorously derived.
Abstract: In this work, based on a two‐band k⋅P theory formulation, the transmission properties of polytype interband tunneling heterostructures are analyzed. The expressions for the continuity equation and the conservation of particle in the two‐band picture of the interband tunneling are rigorously derived. A general and explicit relation between the quasibound state and the transmission resonance is established. Close‐form analytical expressions for the transmission coefficient and the resonant condition are also derived. Our analysis provides reasonable explanations to all available experimental results in the polytype interband tunnel heterostructures, and insight to the design of the interband tunnel devices. In particular, the double quantum well structure is examined in detail for achieving strong resonances and multiple negative differential resistances.
33 citations
TL;DR: In this article, a complete analytical expression for a fluctuation-dissipation relation which determines the current noise spectrum of a point contact where the transmission coefficient can be large is obtained.
32 citations
TL;DR: In this article, a density functional calculation of the effects due to both electron−electron direct and exchange-correlation interactions on the effective, single-electron potential, the conduction electron density profile, the device transmission coefficient, and the current-voltage characteristics of a GaAs−AlGaAs quantum-well tunnel diode is presented.
Abstract: Results are presented of a density functional calculation of the effects due to both electron‐electron direct and exchange‐correlation interactions on the effective, single‐electron potential, the conduction electron density profile, the device transmission coefficient, and the current‐voltage characteristics of a GaAs‐AlGaAs quantum‐well tunnel diode. The calculation proceeds by self‐consistently solving the Kohn–Sham and Poisson equations, accounting for the strong, electric‐field‐induced nonequilibrium effects by employing a spatially varying chemical potential which is essential for maintaining net charge neutrality. The exchange potential used is the Dirac local‐density approximation and the correlation potential is determined from the Wigner interpolation formula. The results show a number of interesting effects: it is found that the direct, electrostatic repulsion due to the buildup of charge within the spacer layers extends far beyond the device, well into the contact layers. Furthermore, the depression of carrier density within the quantum well leads to a reduction in the exchange‐correlation screening of the direct interaction. Consequently, the total band bending in the vicinity of the device is enhanced by the exchange‐correlation interaction, a result in contradiction with a previous Hartree–Fock calculation [K. Bandara and D. Coon, Appl. Phys. Lett. 53, 1865 (1988)]. In the case of a resonantly biased quantum well, the formation of an exchange‐correlation hole due to the population of the resonant level within the quantum well is also observed. Finally, elastic scattering effects have been modeled by including random noise in the barrier conduction band. This causes a broadening of the resonant level within the quantum well, which in turn leads to an enhanced current flow through the overbiased device, although this enhancement is not as large as that seen experimentally. This suggests that the enhanced current flow in the overbiased device is likely to be due to inelastic scattering processes that are not included in this model.
20 citations
TL;DR: This work analyzes the transmission through a resonant cavity using a simple, yet quite general, scattering model with two pairs of propagating states in each region and finds that when the cavity weakly confines one pair of states and strongly confines the other, the transmission coefficient for the weakly confined state displays sharp antiresonances.
Abstract: We analyze the transmission through a resonant cavity using a simple, yet quite general, scattering model with two pairs of propagating states in each region. We find that when the cavity weakly confines one pair of states and strongly confines the other, the transmission coefficient for the weakly confined state displays sharp antiresonances (without resonances) when the single-pass phase for the strongly confined state is approximately n π with n an integer. This behavior is similar to that observed in multiple-state heterostructure tunneling models
19 citations
TL;DR: In this article, the effects of self-gravity on the over-reflection phenomena of linear non-axisymmetric waves in differentially rotating (Keplerian) discs are examined.
Abstract: The effects of self-gravity on the over-reflection phenomena of linear non-axisymmetric waves in differentially rotating (Keplerian) discs are examined. Coordinates comoving with the unperturbed differential rotation are used. In the comoving coordinates, Poisson's equation for the perturbed gravitational potential can be readily solved and the perturbation equations reduce to a single second-order ordinary differential equation with respect to time t. Also an exact expression for the conserved wave action density can be found. Connecting the WKBJ solutions for t → -∞ and t → ∞ numerically, the transmission coefficient T and the reflection coefficient R of waves are obtained as functions of the normalized azimuthal wavenumber K y for various values of the self-gravity parameter 1/Q (the inverse of Toomre's parameter)
TL;DR: The reflectance measurement system is considered in a specific case where the incident beam overfills the back side port of the sphere, and the correction functions for measured spectra are derived for this case.
Abstract: A method of measuring the total reflection and transmission spectra of scattering materials with an integrating sphere and a Fourier-transform infrared spectrometer is studied. The reflectance measurement system is considered in a specific case where the incident beam overfills the back side port of the sphere, and the correction functions for measured spectra are derived for this case. Correction formulas are based on the energy balance between incident radiation and absorbed or escaped radiation in the system. The absorption spectrum of the material is calculated from the corrected spectra. The optical properties of paper samples and radiating surfaces of infrared dryers in the 0.4–20-μm wavelength range are determined. The correction formulas are compared with previous work presented in the literature.
TL;DR: In this article, a detailed analysis of microwave transmission through high-Tc superconducting thin films in a waveguide has been presented, and a method to calculate the complex conductivity and hence the surface resistance and the penetration depth from the transmission coefficient S21 for films of thickness smaller than the penetration depths has been given.
Abstract: A detailed analysis of microwave transmission through high-Tc superconducting thin films in a waveguide has been presented. A method to calculate the complex conductivity and hence the surface resistance and the penetration depth from the transmission coefficient S21 for films of thickness smaller than the penetration depth has been given. Verification of the method has been performed for 12 GHz transmission through YBa2Cu3O7 thin films prepared on LaAlO3 substrate in the K-band waveguide.
TL;DR: In this article, a scattering framework was developed to account for truncations of refractive-index profiles, the effects of a finite core width on the propagation constants for sech2x potentials were illustrated, and the behavior of the bound modes in response to variations in the width of the waveguide core was described.
Abstract: Gradient-index planar optical waveguides with exponential and sech2x refractive-index profiles are analyzed. By using a scattering framework, reflection and transmission coefficients for the infinite exponential profile are derived, and these scattering data are analyzed to obtain mode propagation constants and describe the effects of varying the height of the refractive-index profile. The theory is then developed to account for truncations of refractive-index profiles, the effects of a finite core width on the propagation constants for sech2x potentials are illustrated, the behavior of the bound modes in response to variations in the width of the waveguide core is described, and the appearance of leaky modes for the truncated structure is discussed.
TL;DR: In this paper, the propagation of Langmuir waves loaded with trapped particles in a weakly inhomogeneous plasma with a density hump is considered and it is shown that the reversibility of energy exchange between these particles and the wave entails the possibility of wave penetration through an opacity region with transmission coefficient D = 1.
TL;DR: In this paper, a tunneling current across a thin wall of a narrow-wide-narrow (NWN) cavity region in an electron waveguide is calculated, where a lead is attached to the cavity region at right angle through a thin tunneling barrier to drain the current.
Abstract: A tunneling current across a thin wall of a narrow‐wide‐narrow (NWN) cavity region in an electron waveguide is calculated. A lead is attached to the cavity region at right angle through a thin tunneling barrier to drain the current. The transmission coefficient through the NWN waveguide shows successive dips due to resonances through quasibound states in the cavity region as the length of the cavity region or the Fermi energy of an incident electron is varied. The transmission coefficient leaking out the tunneling barrier shows peaks that line up with the dips in the forward transmission probability, demonstrating that a tunneling spectroscopy of the quasibound state levels is provided through sweeping the Fermi energy.
TL;DR: A theoretical study of bistability in a two-coupler optical fiber ring resonator is presented, caused mainly by the degenerate two-wave mixing in which the circulating intensity of the fiber ring depends on the intensity ratio of the signal to the pump beams.
Abstract: A theoretical study of bistability in a two-coupler optical fiber ring resonator is presented The bistability is caused mainly by the degenerate two-wave mixing in which the circulating intensity of the fiber ring depends on the intensity ratio of the signal to the pump beams The dependence of the bistability on various parameters of the fibers and the couplers is investigated
TL;DR: In this article, the modulation of the output signal from a thin-film transformer was studied and the effect from the control pinhole adjacent to the input strip line was larger than the effects observed from other control pinholes.
Abstract: The modulation of the output signal from a thin-film transformer was studied. This type of thin-film transformer uses a strip line and an amorphous CoNbZr magnetic film. The changes in reflection and transmission coefficients for the transformer were observed by the application of a local magnetic field using a control current. The reflection coefficient changed drastically; however, the change of the transmission coefficient was small. The effect from the control pinhole adjacent to the input strip line was larger than the effects observed from other control pinholes. Two types of thin-film transformer with two control pinholes were prepared. The local magnetic field near the input and output pinholes can be adjusted by the polarity and intensity of the control current. It was demonstrated that the characteristics of the thin-film transformer were controllable by a local magnetic field. >
TL;DR: In this article, a theoretical study of the light propagation in multilayered insulating structures as a function of the angle of incidence is performed, and results for the electromagnetic energy density inside the sample are presented.
01 Apr 1992-Compel-the International Journal for Computation and Mathematics in Electrical and Electronic Engineering
TL;DR: In this article, fast, accurate, and efficient numerical algorithms for each are presented and compared to each other and to traditional WKB and Fowler Nordheim approaches for silicon field emission, as each approach admits a trajectory interpretation, the methods for incorporating each into a larger ensemble particle Monte Carlo (EPMC) simulation of quantum transport are briefly discussed.
Abstract: Standard treatments of the field emission problem typically rely on approximations to the evaluation of the Transmission Coefficient (TC). Recently, the Wigner Distribution Function (WDF) has been applied to this problem. In this paper, fast, accurate, and efficient numerical algorithms for each are presented and compared to each other and to traditional WKB and Fowler Nordheim approaches for silicon field emission. As each approach admits a trajectory interpretation, the methods for incorporating each into a larger Ensemble Particle Monte Carlo (EPMC) simulation of quantum transport are briefly discussed.
TL;DR: In this paper, an optical property of a quasi-periodic multilayer constructed of two types of layer, A and B, is discussed, and it is shown that the transmission coefficient has, for the wavelength of light, many barriers where the transmission coefficients vanishes.
Abstract: An optical property of a quasi-periodic multilayer constructed of two types of layer, A and B, is discussed. For light propagation through a quasi-periodic medium, we find that the transmission coefficient has, for the wavelength of light, many barriers where the transmission coefficient vanishes.
TL;DR: In this article, the authors reported the contactless determination of the conductivity, the mobility and the carrier concentration of II-VI semiconductors by means of the technique of the partially filled waveguide at a microwave frequency of 9 GHz.
Abstract: We report the contactless determination of the conductivity, the mobility and the carrier concentration of II–VI semiconductors by means of the technique of the partially filled waveguide at a microwave frequency of 9 GHz. The samples are CdHgTe epitaxial layers, grown on CdZnTe substrates by molecular beam epitaxy. The conductivity is determined from the transmission coefficient of the sample in the partially filled waveguide. For the analysis of the experimental data, the complex transmission coefficient is calculated by a rigorous multi-mode matching procedure. By varying the conductivity of the sample, we obtain an optimum fit of the calculated data to the experimental results. Comparison with conductivity data determined by the van der Pauw method shows that our method allows to measure the conductivity with good accuracy. The behaviour of the transmission coefficient of the sample is discussed in dependence on the layer conductivity, the layer thickness and the dielectric constant of the substrate. The calculations require to consider in detail the distribution of the electromagnetic fields in the sample region. The usual assumption of a hardly disturbed TE10 mode cannot be used in our case. By applying a magnetic field in extraordinary Voigt configuration, galvanomagnetic measurements have been carried out which yield the mobility and thus the carrier concentration. These results are also in good agreement with van der Pauw transport measurements.
TL;DR: In this paper, the transmission coefficient of compositionally nonabrupt GaAs/Al x Ga 1−x As heterojunctions is calculated for electrons and holes, corresponding to observed transmission resonant peaks for l as short as two GaAs lattice parameters.
TL;DR: In this article, the effects of the random fluctuations on the ultrasound propagation were investigated in a laminated solid layer with alternating plies of two different materials, and it was shown that there is an exponential decay in the amplitude of the transmission coefficient at all frequencies, which increases with increasing frequency.
TL;DR: In this article, the authors extended the gyrokinetic theory of ion cyclotron resonance to include propagation at arbitrary angles to a straight equilibrium magnetic field with a linear perpendicular gradient in strength.
Abstract: The gyrokinetic theory of ion cyclotron resonance is extended to include propagation at arbitrary angles to a straight equilibrium magnetic field with a linear perpendicular gradient in strength. The case of the compressional Alfven wave propagating in a D(3He) plasma is analyzed in detail. A self‐consistent local dispersion relation is obtained using a single mode description; this approach enables three‐dimensional effects to be included and permits efficient calculation of the transmission coefficient. The dependence of this quantity on the species density ratio, minority temperature, plasma density, magnetic field, and equilibrium scale length is obtained. A self‐consistent treatment of the variation of the field polarization across the resonant region is included. Families of transmission curves are given as a function of the normalized parallel wave number for parameters relevant to JET [see, for example, J. Jacquinot et al., Plasma Phys. 30, 1467 (1988)]. Perpendicular absorption by the minority io...
TL;DR: In this paper, the propagation of torsional waves in a prestressed elastic tube filled with a viscous fluid is studied and the dispersion relation is obtained, and the speed of the propagation and the transmission coefficient are numerically analyzed as a function of inner pressure, stretch ratio, frequency and thickness.
TL;DR: In this article, a two dimensional rectangular beam with one reinforcement layer located at middepth is simulated by numerical calculation on a supercomputer and the effect of gradient distribution of the stiffness in the interphase layer on the wave energy transmission from matrix to fiber is analyzed as an amplitude transmission coefficient.
Abstract: In order to obtain a physical interpretation of experimental data obtained in ultrasonic-acoustic measurements, we simulate the experiment by numerical calculation on a supercomputer. The composite we discuss here is a two dimensional rectangular beam which has one reinforcement layer located at middepth. The Finite Strip Method (FSM) is used to formulate the composite and modal analysis and Duhatnel integral equation are also used to obtain its dynamic response for the impulsive incident wave. Making use of the Visualization Technique of Stress Wave Propagation (VTSWP) we obtain the animated simulation of stress wave propagation in a composite. The effect of gradient distribution of the stiffness in the interphase layer on the wave energy transmission from matrix to fiber is also analyzed as an amplitude transmission coefficient (ATC).
TL;DR: The condition for resonant tunnelling in a system of two rectangular barriers can be interpreted in terms of the band structure and phase change of Bloch electrons in an infinite periodic system having a part of the two-barrier system as the periodicity as mentioned in this paper.
TL;DR: In this paper, the modulation of the output signal from a thin film transformer was studied and the changes in reflection and transmission coefficients were observed by the application of the local magnetic field using a control current.
Abstract: The modulation of the output signal from a thin film transformer was studied. The changes in reflection and transmission coefficients for the thin film transformer were observed by the application of the local magnetic field using a control current. The reflection coefficient changed drastically. However, the change of the transmission coefficient was small. The effect from the control pinhole adjacent to the input strip line were larger than those observed from other control pinholes. Two types of the thin film transformer with two control pinholes were prepared. The local magnetic field near the input and output pinholes can be adjusted by the polarity and intensity of the control current. It was certified that the characteristics of the thin film transformer were controllable by a local magnetic field.
TL;DR: In this paper, the effect of inelastic scattering on resonant tunnelling through a double-barrier semiconductor heterostructure is studied using the transfer matrix method incorporating a phenomenological damping of the wavefunction propagation in the quantum well.
Abstract: The effect of inelastic scattering on resonant tunnelling through a double-barrier semiconductor heterostructure is studied using the transfer matrix method incorporating a phenomenological damping of the wavefunction propagation in the quantum well The coherent and sequential contributions to the transmission coefficient are evaluated analytically in a Lorentzian lineshape approximation close to resonance In contrast to previous results it is found that the integrated total transmission coefficient is in general dependent on the inelastic scattering rate Numerical calculations show that realistic values of current peak to valley ratios at 77 K are obtained assuming a mean inelastic scattering time approximately 10-12 s The tunnelling is then almost totally sequential