Left-handed Components Research Articles

Omni-reflectance and enhanced resonant tunneling from multilayers containing left-handed materials

We study the oblique transmission through a one-dimensional photonic crystal consisting of alternating slabs made of ordinary and negative refractive index materials, the latter being dispersive. We investigate the angular dependence of the band gap for this multilayer medium. Our results suggest, unlike a conventional Bragg gap, this type of gap exhibits a rather versatile behavior with varying angle of incidence. We find the angle-dependent characteristics for this type of gap can be quite different for different structural parameters of the constituents. Thus, multilayer structures involving left-handed components are very good candidates for band gap engineering. Specifically, we demonstrate for a certain experimentally realizable structure, the existence of a gap region for each individual polarization which survives for incident angles as high as 85 ° . Moreover, we show how this structure can also function as a highly efficient polarization splitter. Finally, we investigate the multilayer medium when acting as single or double electromagnetic barrier. We study the tunneling properties of such systems for both types of individual barrier layers—right- and left-handed, respectively. We observe the double barrier exhibits resonant tunneling that depends on the “rightness” of the individual barrier layers.

Nanofabricated media with negative permeability at visible frequencies

A great deal of attention has recently been focused on a new class of smart materials--so-called left-handed media--that exhibit highly unusual electromagnetic properties and promise new device applications. Left-handed materials require negative permeability micro, an extreme condition that has so far been achieved only for frequencies in the microwave to terahertz range. Extension of the approach described in ref. 7 to achieve the necessary high-frequency magnetic response in visible optics presents a formidable challenge, as no material--natural or artificial--is known to exhibit any magnetism at these frequencies. Here we report a nanofabricated medium consisting of electromagnetically coupled pairs of gold dots with geometry carefully designed at a 10-nm level. The medium exhibits a strong magnetic response at visible-light frequencies, including a band with negative micro. The magnetism arises owing to the excitation of an antisymmetric plasmon resonance. The high-frequency permeability qualitatively reveals itself via optical impedance matching. Our results demonstrate the feasibility of engineering magnetism at visible frequencies and pave the way towards magnetic and left-handed components for visible optics.

Majorana neutrinos with split fermions in extra dimensions

We propose new solutions to the neutrino mass problem in theories with large extra dimensions in a thick wall scenario. It has recently been argued that our 3-brane could be a thick wall at the boundary of the bulk. The gauge bosons and the Higgs scalars have an almost flat profile on this wall, while fermions could have localized profile with left-handed and right-handed components displaced with respect to each other. We point out that with split fermions it is possible to generate Majorana neutrino masses contributing to the neutrinoless double beta decay. The almost degenerate neutrinos can also come out naturally in this case. Unlike other models of neutrino masses in extra dimensions there are no bulk fields in this scenario.

Classical Euclidean general relativity from `left-handed area = right-handed area'

A classical continuum theory corresponding to Barrett and Crane's model of Euclidean simplicial quantum gravity is presented. The fields in this classical theory are those of SO(4) BF theory, a simple topological theory of an so(4)-algebra-valued 2-form field, , and an SO(4) connection. The left-handed (self-dual) and right-handed (anti-self-dual) components of B define a left-handed and a, generally distinct, right-handed area for each spacetime 2-surface. The theory presented is obtained by adding to the BF action a Lagrange multiplier term which enforces the constraint that the left- and the right-handed areas should be be equal. The solution space of the theory has six branches, two of which reproduce Euclidean general relativity (GR). The other four branches are also characterized and it is shown that the GR branches are stable in the sense that non-degenerate initial data of a solution in one of the GR branches does not, except in special cases, admit an alternative development in another branch. Finally, the path-integral quantization of the theory is discussed at a formal level and a heuristic argument is given suggesting that in the semiclassical limit the path integral is dominated by solutions in one of the non-GR sectors, which would mean that the theory quantized in this way is not a quantization of GR.

Diffraction of a spherical electromagnetic wave by a perfectly conducting strip in a biisotropic medium

The diffraction of an electromagnetic spherical wave (emanating from a point source) by a perfectly conducting strip in a biisotropic medium is investigated. This consideration is important because the point source is regarded as a fundamental radiating device. The vector diffraction problem is reduced to the scattering of a single scalar field, this scalar field being the normal component of either a left-handed or a right-handed Beltrami field. The diffraction problem of the left-handed field component is explicitly analyzed, that of the right-handed field component being analogously tractable. The problem is solved using the Wiener–Hopf technique and asymptotic methods. The diffracted field is shown to be sum of fields produced by the two edges of the strip and an interaction field. Finally, physical interpretation of the result is discussed.

Why auxiliary fields matter: the strange case of the 4D, N = 1 supersymmetric QCD effective action (II)

Within a four-dimensional N = 1 superspace, we present a new ansatz for the Skyrme term and for the gauged WZNW term embedded into a superaction. We use the new chiral-non-minimal multiplet (CNM) formulation for the effective low-energy action of 4D, N = 1 supersymmetric QCD constructed by assigning right-handed components of Dirac fields to chiral multiplets and left-handed components of Dirac fields to non-minimal multiplets. It is noted that such a construction likely allows for a new type of parity violation in low-energy 4D, N = 1 supersymmetric QCD.

Topological geometrodynamics and the solar neutrino problem

A solution of the solar neutrino problem based on certain differences between T(opological) G(eometro) D(ynamics) and the standard model of the electroweak interactions is proposed. First, TGD predicts the existence of a right-handed neutrino inert with respect to ordinary electroweak interactions. Second, the generalization of the massless Dirac equation contains terms mixing differentM 4 chiralities, unlike the ordinary massless Dirac equation. This and the observation of anticorrelations of the solar neutrino flux with sunspot number suggest that solar neutrinos are transformed to right-handed neutrinos on the convective zone of the Sun. Third, the compactness ofCP 2 implies topological field quantization: space-time decomposes into regions, topological field quanta, characterized by a handful of vacuum quantum numbers. In particular, there are topological obstructions for the smooth global imbeddings of magnetic fields and the decomposition of the solar magnetic field into flux tubes is predicted. Finally, every electromagnetically neutral mass distribution is accompanied by a long-rangeZ 0 vacuum field. If the vacuum quantum numbers inside the flux tubes of the solar magnetic field are considerably smaller than in the normal phase, theZ 0 electric force becomes strong and implies Thomas precession for the spin of the lefthanded component of the neutrino. As a consequence, left-handed neutrinos are transformed to right-handed ones and the process is irreversible, since righthanded neutrinos do not couple toZ 0.

Structural changes in positively and negatively supercoiled DNA.

The effect of superhelical constraint on the structure of covalently closed circular DNA (cccDNA; pBR322) with positive and negative writhe (superturn) has been investigated as a function of decreasing and increasing specific linking difference (mean superhelical density sigma). At low and moderate negative superhelical densities sigma, the overall average structure is maintained in an unwound B-form slightly modified. The overwound cccDNAs with positive writhe differ from those with negative writhe by an absence of cruciform structure. At high negative densities of supercoiling different changes involving the reversal of twist handedness are shown to lead to the formation of DNA segments in a conformation identical to the left-handed component of form V DNA.

Axial ratio of an antenna illuminated by an imperfectly circularly polarized source

A method for determining the axial ratio of an antenna illuminated by an imperfectly circularly polarized source is described. This method requires measurements of the right- and left-handed amplitude components and their relative phases for both the receiving and transmitting (or source) antennas. From these measured data and, of course, the theory of power transfer between the source and receiving antennas, an algorithm is derived for the actual axial ratio of the receiving antenna. Illustrative results showing the effects of the phase angle are presented.

Effects of Left-Right Scalar Quark Flavor Mixings on CP Violation in Supersymmetry

Studies of flavor mixings among left squarks (superpartners of left-handed components of quarks) and right squarks are made in the minimal low energy supergravity model, where all one-loop corrections are taken into account from renormalization group equations. So far, their effects on physics have been presumed to be negligible. Ii is found, contrary to that presumption, that they play major roles in two phenomena, the electric dipole moment of neutron and the asymmetry of muon polarization in K L .... fJ.+ fJ.decay.

The Gazli, USSR, 19 March 1984 earthquake: The mechanism and tectonic implications

The fault parameters of the Gazli, USSR, earthquake of 19 March 1984 Ms = 7.0 were determined from the inversion of the GDSN long-period P and SH and short-period P seismograms. The frequency of the short-period seismograms was broadened by partially deconvolving the effect of the recording instruments. The earthquake represents a thrust fault with a small amount of a left-handed strike-slip component on a NE-SW trending fault dipping northwest. The average depth is 9 km. The rupture propagated essentially continuously while breaking several high stress asperities. Directivity of the observed waveforms indicates principal rupture direction from SE to NW. The total duration of rupture is about 13 sec. The average scalar seismic moment found from the long-period wave-forms is 2.5 × 1019 N-m. In addition to the 1984 event, the Gazli region experienced two large ( Ms = 7.0) earthquakes in 1976 and one medium size earthquake ( Ms = 5.7) in 1978. The mechanisms of the 1976 events were studied by Hartzell (1980) and Kristy et al . (1980), and are thrust events striking in the general E-W direction. We determined the mechanism of the 1978 earthquake and find it similar to those of the 1976 earthquakes. An interesting feature of the Gazli earthquake sequence is the migration of activity from east to west along an arc shaped fault zone. Prior to 1976, the region was relatively aseismic, based on instrumental and historical seismicity data.

Reflectance, Transmittance and Color Gamut of superimposed Layers of Cholesteric Liquid Crystals

Abstract The spectral reflectance curves of superimposed layers of cholesteric liquid crystals (CLC) having the same handedness add as there is little absorption. The peak reflectance of the sum cannot exceed 0.5 and the transmittance cannot be less than 0.5, which is the theoretical limit. The shape of the reflection and transmission band resembles rectangles and thus can be compared with the spectral curves of optimum colors. The chromaticity loci of CLC colors and its luminous reflectance equals 0.5 of the value of the luminous reflectance attached to the optimum colors. The color gamut thus produced can be shown to be greater than that which has been obtained with pigments. A significant improvement can be obtained using superimposed layers of CLC having opposite handedness. Their spectral curves add and the peak reflectance is not limited by the value of 0.5 but approaches 1.0. Use of CLC's of opposite handedness is not always practical as they have different chemical and physical properties. A similar result can be obtained using two CLC layers of the same handedness and a half-wave retardation plate interposed between them. This plate converts the transmitted through the upper layer right-handed (left-handed) component into a left-handed (right-handed) one, which is then reflected from the lower layer and contributes to the reflected left-handed (right-handed) component from the upper layer. The chromaticity loci and color gamut of such superimposed CLC pairs of coatings now approaches that of optimum colors of the same luminous reflectance.

Reflectance, Transmittance and Color Gamut of Superimposed Layers of Cholesteric Liquid Crystals

Abstract The spectral reflectance curves of superimposed layers of cholesteric liquid crystals (CLC) having the same handedness add as there is little absorption. The peak reflectance of the sum cannot exceed 0.5 and the transmittance cannot be less than 0.5, which is the theoretical limit. The shape of the reflection and transmission band resembles rectangles and thus can be compared with the spectral curves of optimum colors. The chromaticity loci of CLC colors and its luminous reflectance equals 0.5 of the value of the luminous reflectance attached to the optimum colors. The color gamut thus produced can be shown to be greater than that which has been obtained with pigments. A significant improvement can be obtained using superimposed layers of CLC having opposite handedness. Their spectral curves add and the peak reflectance is not limited by the value of 0.5 but approaches 1.0. Use of CLC's of opposite handedness is not always practical as they have different chemical and physical properties. A similar result can be obtained using two CLC layers of the same handedness and a half-wave retardation plate interposed between them. This plate converts the transmitted through the upper layer right-handed (left-handed) component into a left-handed (right-handed) one, which is then reflected from the lower layer and contributes to the reflected left-handed (right-handed) component from the upper layer. The chromaticity loci and color gamut of such superimposed CLC pairs of coatings now approaches that of optimum colors of the same luminous reflectance.

Low Frequency Rf Heating with a Helical Coupler in a Hot Electron Plasma

A magnetic mirror (mirror ratio 2.38:1) containing ECRH generated hydrogen plasma, with a density of 5 x 1010 cm-3 with cold electron temperature of 11 eV, was used to study propagation of an artificially launched wave varying as ej(ωt + mθ - kz) at approximately the ion cyclotron frequency. The wave was transmitted between two similar internally placed helically wound antennas separated by 11 wavelengths. The coupling between them was enhanced by as much as 50 times in the presence of plasma. The m = 1 left-handed component was cut off when (ω > (ωci. Electron temperatures could be increased by more than 2 times with the m = 1 mode, presumably due to ion heating. Little pump-out was observed.

Structure, Stratigraphy, and Origin of Iron Formations, Michipicoten Area, Algoma District, Ontario, Canada

The Michipicoten group, of Precambrian age, comprises flows and pyroclastic rocks of the andesite-rhyolite association together with conformable zones of clastic sediments and banded iron formations. Volcanic rocks display great heterogeneity, typically exhibiting marked variation in lithology, structure, and thickness over short intervals. The typical volcanic cycle progressed from (1) widespread and prolonged outpouring of andesite-basalt flows and pyroclastic material, through (2) brief but violent expulsion of rhyolite-dacite pyroclastic rocks, to (3) large-scale hot-spring and fumarolic activity. Clastic sediments are interpreted as products of contemporaneous erosion of expanding volcanic piles. Development of the Michipicoten group is viewed as a continuous process which, once initiated, proceeded through explosive, erosional, and chemical phases to produce a complex volcanic-sedimentary family group in which the members, although each possessing unique characteristics, are related by common volcanic heritage. Volcanic divisions are described in terms of distribution, lithology, relationship to adjacent formations, and environment of deposition. Average chemical analyses of volcanic rocks are presented. In contrast to the typical andesite-rhyolite suite, Michipicoten volcanic rocks are deficient in CaO, Na 2 O, K 2 O, and SiO 2 , and enriched in Fe, MnO, and CO 2 . Banded iron formations contain two mutually gradational facies associated respectively with sedimentary and volcanic rocks. The latter type contains large bodies of siderite and pyrite. Banded iron formations are ascribed genetically to large-scale hot-spring and fumarolic activity. Iron carbonate and sulfur components appear to be of subvolcanic, presumably magnatic, derivation, whereas silica was largely derived by chemical leaching of the volcanic rocks. Average chemical compositions of banded chert, pyrite, and carbonate members of the iron formation are presented. The clastic sediments are like true volcanic sediments in that rock and mineral components have their counterparts in subjacent volcanic rocks in either extrusive or intrusive form and appear to have been derived from them by rapid, contemporaneous erosion. Granite detritus in coarse clastic sediments is inferred to reflect contemporaneous erosion of near-surface granite stocks and apophyses emplaced under conditions of high geothermal gradient. Michipicoten rocks have been folded about east-west-trending primary axes, themselves cross-folded about northwest-trending axes. As a result, fold axes describe undulating patterns in longitudinal and cross sections. Prominent, northerly striking vertical faults with left-hand horizontal components of displacement have sliced the area into large parallel blocks.

Microwave Hall effect and the accompanying rotation of the plane of polarization

Faraday rotation of the plane of polarization of an electromagnetic wave, propagated through a medium in the direction of an independently applied steady magnetic field, has been interpreted in terms of gyromagnetic action and in certain circumstances as a consequence of Hall effect.The paper calls particular attention to the Hall-effect mechanism, which is shown to lead to different propagation coefficients for the right-handed and left-handed circularly-polarized components of a plane wave.The contention is advanced that a Hall effect can be expected to arise from a displacement current in the material medium and that, as a consequence, the Faraday rotation effect in dielectrics and semiconductors may, in some cases, be significantly modified at frequencies above the microwave part of the spectrum. Some elementary calculations are given in support of this argument.

Triple-splitting of the F-echoes

An account is given of the polarization studies made on the triple F-echoes, obtained by employing pulses of waves of frequency, 3 Mc/s, at vertical incidence. The polarization studies revealed that the first component after the ground-pulse was the normal extraordinary component having a right-handed sense of rotation, the second component was the normal ordinary component having a left-handed sense of rotation and the third component was the Z-component having a left-handed sense of rotation. In addition to the coupling process suggested by Eckersley and Rydbeck between the ordinary and extraordinary waves, and operative only in high geomagnetic latitudes, the partial reflection and transmission at the level of ionospheric reflection for the ordinary component have been considered as a plausible process for getting the Z-component. Since the coupling process is not likely to produce a detectable Z-component at low geomagnetic latitudes, the occasional presence of the Z-component at low latitudes has been attributed to the partial reflection and transmission process which may take place at all latitudes. The view that the Z-component really corresponds to the left-handed ordinary component suffering reflection at the level corresponding to p 0 2 = p 2 + p · p H has been supported.

Polarization of Solar Radio-frequency Emissions

THE recent experimental proof1 that the sun emits energy on radio frequencies was followed by evidence2 that the amount of such energy can increase markedly during the passage of important sunspots across the solar disk. Such sunspots are invariably associated with strong magnetic fields, the influence of which almost certainly extends into the upper chromosphere and inner corona. Considerations of optical depth indicate that the observed emissions cannot come from below these levels, so that they must arise in regions where the electron collision frequency is much less than the (radio) wave-frequency, and where the latter is probably of the same order of magnitude as the gyromagnetic frequency He/ m. Under these conditions we should expect to find evidence of the magnetic field in the production of gyratory effects at the source of the emissions, and/or in differential absorption of right-handed and left-handed components of polarization during transmission through the corona.

Unimolecular Elimination and the Significance of the Electrical Conduction, Racemization and Halogen Replacement of Organic Halides in Solution

THERE are a number of cases in which the development of electrical conductivity in sulphur dioxide solution has been held to indicate the electrolytic dissociation of an alkyl halide. One of the best known examples is that of tert. -butyl iodide1. We find, however, that tert.-butyl chloride absorbs bromine quantitatively in sulphur dioxide, the products being isobutylene dibromide and hydrogen chloride. This suggests a rather rapidly established equilibrium, Me3CClMe2C: CH2+HCl, in which, however, the left-hand components have the smaller free energy, -Phenylethyl chloride also is said to give a conducting solution in sulphur dioxide: we find that the pure chloride in the pure solvent does not conduct, but that when there is conduction, styrene and hydrogen chloride are present: CHPhMeClCHPh: CH2+HCl. Under conditions of purity in which the chloride does not conduct, hydrogen chloride itself has negligible conductivity in small concentration, but even in these circumstances the addition of bromine leads to a quantitative yield of styrene dibromide.

A New Test of the Magneto- Ionic Theory

ACCORDING to the magneto-ionic theory of Appleton1, we should expect a wireless wave incident on the ionosphere to be returned to the earth as two differently polarised components (the ordinary and the extraordinary) with a slight difference in the time of travel. For wave-lengths shorter than 214 metres (the critical wave-length of the theory, given by the expression ), the theory has been experimentally confirmed2,3 and the following points are well established: (a) The two magneto-ionic components are circularly polarised. (b) The left-handed (ordinary) component penetrates the F region and the E region more easily than the right-handed (extraordinary). (c) The intensity of the extraordinary wave decreases markedly as the magneto-ionic critical wave-length is approached. The theory predicts different results for waves of length greater than 214 metres, but so far as we know, experiments have not been made to test it for these wave-lengths.