Showing papers on "Circular polarization published in 1981"
TL;DR: In this paper, the nature of random coupling between normal modes of polarization is analyzed and discussed in connection with various applications, such as fibers with very small or very large birefringence for polarization dependent applications.
Abstract: Recent research on fibers with very small or very large birefringence for polarization-dependent applications is reviewed. The nature of random coupling between normal modes of polarization is analyzed and discussed in connection with various applications.
501 citations
TL;DR: In this paper, a method for designing backfeed-type one-point fed circularly polarized antennas is described, where antennas are fed at one point from the back side of the substrate and have degeneracy resolving segments.
Abstract: This paper describes a method for designing backfeed-type one-point fed circularly polarized antennas. These antennas are fed at one point from the back side of the substrate and have degeneracy-resolving segments. Characteristics of the rectangular microstrip antennas with degeneracy-resolving segments are obtained by means of a variational method. The equivalent circuit at and near the resonance with perturbations is obtained and the condition for circularly polarized antennas is found from both theoretical and experimental viewpoints. Configurations and radiation characteristics of these antennas are discussed and it is shown that these antennas can be used as array elements.
111 citations
TL;DR: In this article, the authors investigated the design criteria which produced the best circular polarization for a printed-circuit antenna with varying eccentricities. But their focus was on the design of the antenna.
Abstract: Elliptical-shaped printed-circuit antennas were fabricated with varying eccentricities, and their impedance and radiation patterns were measured. Special attention was devoted to investigating the design criteria which produced the best circular polarization.
69 citations
TL;DR: In this paper, the absorption coefficients for the ordinary and extraordinary modes for cyclotron radiation from hot plasmas with temperatures between 0.2 and 20 keV were calculated for AM Herculis binaries.
Abstract: Absorption coefficients for the ordinary and extraordinary modes are calculated for cyclotron radiation from hot plasmas with temperatures between 0.2 and 20 keV. The results are applied to the accretion columns of the AM Herculis binaries. The linear and circular polarization properties of the observed polarized light can be understood if the emission is at approximately the fifth harmonic of the cyclotron frequency. The magnetic fields in these systems is deduced to be roughly 4 x 10 to the 7th gauss.
68 citations
TL;DR: In this paper, a novel waveguide electro-optic device which is capable of performing general polarization transformations under electrical control is presented. But it is not yet suitable for the use with a single phase shifter.
Abstract: We propose and demonstrate a novel waveguide electro‐optic device which is capable of performing general polarization transformations under electrical control. The device, made with a Ti‐diffused lithium niobate waveguide, combines in a unique optical circuit an electro‐optic (e/o) TE⇄TM mode converter and two e/o phase shifters to provide general polarization transformations. This is the first report of a waveguide e/o device capable of performing arbitrary polarization transformations. As a linear rotator the device exhibits a rotation rate of 15°/V with better than 23‐dB fidelity. We also demonstrate transformation between circular and linear polarization.
67 citations
Abstract: Using the principles of quantum electrodynamics, the theory of two‐, three‐, and four‐photon absorption in polyatomic gases and liquids is developed. Expressions are derived for the rates of single‐frequency absorption from plane polarized, circularly polarized, and unpolarized light. It is shown that for n‐photon absorption with n?3, the rate for unpolarized radiation is in each case expressible as a linear combination of the rates for plane polarized and circularly polarized light; no such relationship exists for four‐photon absorption. For each multiphoton process, it is demonstrated how the fullest information about the symmetry properties of excited states can be derived by a simple linear processing of the results from experiments with different polarizations. A detailed examination of the selection rules is made, based on a reduction of the molecular transition tensor into irreducible components, and a new classification scheme is introduced to assist with the interpretation of experimental results...
58 citations
Patent•
02 Jun 1981TL;DR: In this paper, a plurality of layers of meandering electrical conductors are formed into a sandwich mounted one above the other, where at least some of the conductors on different sandwich layers are in phase with each other but in which at least one of the electrical conductor on at least 1 of the sandwich layers is formed so that adjacent or some of conductor are not in phase at all but are phase offset such that the composite structure produces improved circular polarization.
Abstract: Apparatus for converting the polarization of electromagnetic waves from linear polarization to circular polarization wherein a plurality of layers of meandering electrical conductors are formed into a sandwich mounted one above the other wherein at least some of the conductors on different sandwich layers are in phase with each other but in which at least one of the electrical conductors on at least one of the sandwich layers are formed so that adjacent or some of the conductors are not in phase with each other but are phase offset such that the composite structure produces improved circular polarization as compared to polarization converters of the prior art. The sandwich structure according to the invention can be utilized as integrated into a radome of a tracking radar antenna for example.
53 citations
01 Oct 1981
52 citations
TL;DR: In this article, a Stokes polarimeter was built at the High Altitude Observatory to obtain line profiles in both linear and circular polarization in solar spectral lines, which were interpreted using the theory of radiative transfer in the presence of a magnetic field to obtain vector magnetic fields on the solar disk and using the theories of resonance scattering and the Hanle effect in prominences.
Abstract: A Stokes polarimeter has been built at the High Altitude Observatory to obtain line profiles in both linear and circular polarization in solar spectral lines. These measurements are interpreted using the theory of radiative transfer in the presence of a magnetic field to obtain vector magnetic fields on the solar disk and using the theory of resonance scattering and the Hanle effect to obtain vector magnetic fields in prominences. The polarimeter operates on the Sacramento Peak Observatory 40 cm coronagraph. It is an extensively modified and improved version of an earlier instrument.
42 citations
TL;DR: In this paper, a new whistler direction finder was developed and described and it has the following essential features; 1) the wave incidence situation is distinguished among the three cases, 1.1. vertical incidence with nearly circular polarization, 2.2. oblique incidence with elliptical polarization, or 1.3.
36 citations
TL;DR: In this paper, the feasibility of twisted circularly birefringent polarisation maintaining fibres was investigated and it was shown that the twist rate required to provide immunity from external effects is excessively large.
Abstract: The feasibility of twisted circularly birefringent polarisation maintaining fibres is investigated. It is shown that the twist rate required to provide immunity from external effects is excessively large.
TL;DR: In this article, four narrowband filters covering the 440-850 nm wavelengths were used to measure the polarization of the continuum of Comet West 1976 VI, and it was suggested by dirty silicates with radii approaching 5 microns may be responsible for the phenomena observed.
TL;DR: In this article, generalized selection rules for the production of spin-polarized electrons in cubic crystals by circularly polarized light are derived from general wave functions transforming irreducibly according to the double groups.
Abstract: From general wave functions transforming irreducibly according to the double groups, generalized selection rules for the production of spin-polarized electrons in cubic crystals by circularly polarized light are derived. Nonzero results are obtained for the $\ensuremath{\Delta}$ and $\ensuremath{\Lambda}$ direction, with equal strength for spin-up and spin-down electrons of a particular transition, if right-circular polarization is changed to left-circular polarization. The strength depends on a parameter proportional to the integral performed on the spatial parts of the wave functions. The results can be easily applied to hybridization effects and are confirmed by recent experimental data on tungsten.
TL;DR: In this paper, a simple but accurate method to determine the critical dimensions needed to produce circular polarisation for nearly square and nearly circular microstrip antennas is described. But the method is limited to the case of a single antenna.
Abstract: The letter describes a simple but accurate method to determine the critical dimensions needed to produce circular polarisation for nearly square and nearly circular microstrip antennas.
TL;DR: In this article, a method for producing a modulated circular polarization of high purity was presented, whose modulation frequency allows specific discrimination against linear polarization and unpolarized intensity, and it was applied to measure the circular dischroism and birefringence of high reflectivity multidielectric mirrors.
TL;DR: In this article, the minimum number of measurements needed to characterize bistatic radar data is determined based on the principle of electromagnetic reciprocity, and the symmetry relations are then combined with the principle to determine the maximum number of observations required to characterize target scattering.
Abstract: Circularly polarized bistatic scattering from plane-symmetric targets with otherwise arbitrary electrical properties exhibits reflection asymmetries, polarization reversal asymmetries, and polarization reversal reflection symmetries which are useful for bistatic radar data interpretation. Familiarity with these bistatic scattering polarization properties will also facilitate the interpretation of depolarization and beam displacement phenomena in off-set reflector antenna characteristics. In addition, the symmetries can he used to reduce the time and expense in obtaining data from bistatic scattering range measurements, offset reflector antenna measurements, and theoretical or computer calculations. The reflection asymmetry, polarization reversal asymmetry, and polarization reversal reflection symmetry relations are derived. The symmetry relations are then combined with the principle of electromagnetic reciprocity to determine the minimum number of measurements needed to characterize target scattering.
TL;DR: In this paper, a smooth modulation of the X-ray flux at the orbital period is obtained, along with an eclipse feature that is total for 0.1-0.8 keV photons.
Abstract: The X-ray light curve of the AM Herculis-type binary 2A 0311-227 is presented. A smooth modulation of the X-ray flux at the orbital period is obtained, along with an eclipse feature that is total for 0.1-0.8 keV photons yet not visible for photons above about 3 keV. This strong and smooth dependence on energy suggests an origin in the obscuration of the X-ray emitting region by a column of accreting gas. Furthermore, very strong quasi-periodic pulsations with a period of about 6 min are found in the soft X-ray light curve. This periodicity is also present in the optical and hard X-ray light curves, and in the circular polarization data. It seems likely that the periodicity arises from a modulation of the mass accretion rate onto the white dwarf, and possible that it originates in pulsations of a disk-magnetosphere boundary.
TL;DR: A statistical treatment gives the law of energy transfer to the undesired state of polarization and the tolerances required in both cases to obtain a given crosstalk.
Abstract: The influence of joins on the state of polarization in a polarization-maintaining single-mode fiber cable link is examined. The two practical cases of linear and circular polarization are studied. Assuming perfect fibers, two random variables are involved: the phase mismatch between eigenmodes in a fiber and the misalignment of linear birefringence axes at the joins. A statistical treatment, checked with a computer simulation, gives the law of energy transfer to the undesired state of polarization and the tolerances required in both cases to obtain a given crosstalk.
TL;DR: In this article, the effect of nonlinear electron distortion in a field B 0 described by an i-tensor of rank 4 and the reorientation mechanism represented by the product of two c-tensors, of ranks 3 and 1, were determined.
TL;DR: In this article, the effects of circular polarization of the incident light beams, in particular within a sample of randomly oriented optically active molecules, were studied and contributions to the induced third-order electric polarization were derived which are of first order in the magnetic dipole and electric quadrupole interactions.
TL;DR: Two-wave-coupling coefficients are presented in the high-J limit for all combinations of linearly and circularly polarized waves and all dipole-allowed transition branches to predict the optimum state of emission polarization and the anticipated output-power change under the influence of a circularly polarization pump in optically pumped lasers.
Abstract: Two-wave-coupling coefficients are presented in the high-J limit for all combinations of linearly and circularly polarized waves and all dipole-allowed transition branches. The results are used to predict the optimum state of emission polarization and the anticipated output-power change under the influence of a circularly polarized pump in optically pumped lasers.
TL;DR: In this article, an experiment to measure the circular polarization of γ-quanta, P γ, in the reaction of radiative capture of polarized thermal neutrons by protons is described.
TL;DR: In this paper, a one-point back-feed type circularly polarized microstrip disk antenna is investigated and the operating condition for circular polarization is studied and design formulas and data are presented.
Abstract: A one-point back-feed type circularly polarized microstrip disk antenna is investigated. To establish a design procedure, (1) the operating condition for circular polarization is studied and design formulas and data are presented and (2) the fabrication and radiation characteristics of arrays consisting of the present circularly polarized disk antenna element are discussed. It is demonstrated that this class of antennas can serve as a useful form of circularly polarized array element. Further, in order to analyze the mutual coupling of such antenna elements, the resonance and inter-element mutual admittance of an array consisting of two disk antennas located on the same plane are determined. The fundamental information on the mutual coupling thus obtained is presented for a design aid. Using these results, a circularly polarized array is realized with good axial ratio and boresight ratio less than 0.5 dB.
TL;DR: In this article, a two-tier Gaussian model for raindrops, which assumes Gaussian distributions both for instantaneous canting angle and time-varying mean canting angles, together with gross features of ice particles, provide a theoretical framework to organize the experimental data and to yield functional dependence of cross-polarization on frequency, polarization and elevation angle.
Abstract: A two-tier Gaussian model for raindrops, which assumes Gaussian distributions both for instantaneous canting angle and time-varying mean canting angle, together with gross features of ice particles, provide a theoretical framework to organize the experimental data and to yield functional dependence of cross-polarization on frequency, polarization and elevation angle. Agreement has been obtained between measured depolarization data and theoretical results which are essentially independent of details of ice clouds. In particular, a linear relation has been found between cross-polarization amplitude and frequency throughout the centimeter wavelengths for a given earth-space path.
Patent•
18 Feb 1981
TL;DR: In this article, a laser may include within its optical cavity an element which produces stable linear polarization of the output beam of the laser, and then covers the polarization into circular polarization.
Abstract: Laser cutting apparatus comprises a laser (20), means (24,25) for directing the output beam of the laser on to a workpiece (26), and means such as a quarter-wave plate (27) for producing circular polarization of the laser output beam. The laser may include within its optical cavity an element which produces stable linear polarization of the output beam. The quarter-wave plate (27) then covers the polarization into circular polarization.
Patent•
08 Jul 1981TL;DR: In this paper, a means for re-polarizing and generating circularly polarized waves using a single or multi-layer lattice structure which is placed in front of a radiation aperture is presented.
Abstract: Means for re-polarizing and generating circularly polarized waves using a single or multi-layer lattice structure which is placed in front of a radiation aperture with the lattice structure consisting of a plurality of conductors extending in the form of lines which meander and might be rectangular combinations or the like. With a lattice, a polarization conversion into circular polarization and the suppression of orthogonal polarization components is simultaneously achieved by providing that the meandering lines 4 extend in a direction such that the meander lines have an angle of 45° at every location with respect to the respective E vectors of the linearly polarized E-vector fields at such locations. The re-polarization means can be used as a Radome of a target tracking radar antenna.
01 May 1981
TL;DR: In this paper, the penetration of a plane electromagnetic wave into a ferromagnetic conducting semispace is investigated in the cases of plane and circular polarizations of electromagnetic fields, and the approximate analytical solutions taking into account the nonlinear and hysteresis properties of the medium are given.
Abstract: The penetration of a plane electromagnetic wave into a ferromagnetic conducting semispace is investigated in the cases of plane and circular polarizations of electromagnetic fields. In the case of plane polarization of the electromagnetic field the approximate analytical solutions taking into account the nonlinear and hysteresis properties of the medium are given. The numerical results obtained according to this method are compared with the experimental data. In the case of circular polarization of the electromagnetic field the exact analytical solutions of the nonlinear differential equations of the skin effect are found. Comparison of the results obtained for the plane and circular polarizations allows us to estimate to what extent the main relationships of the nonlinear skin effect depend on the kind of polarization.
TL;DR: In this paper, the Mueller matrix of a medium exhibiting a complex Faraday effect is derived and a procedure is developed that permits computation of optical transmission, Faraday rotation, and magnetic circular dichroism (MCD) in planar layered structures when all internal reflections are taken into account.
Abstract: After the Mueller matrix of a medium exhibiting a complex Faraday effect is derived, a procedure is developed that permits computation of optical transmission, Faraday rotation, and magnetic circular dichroism (MCD) in planar layered structures when all internal reflections are taken into account. The structures are represented by Mueller matrices and have, therefore, a depolarizing effect on an incident wave of other than circular polarization. The formulas for some common experimental arrangements including ellipticity and azimuth modulation techniques are given and are then applied to three special cases, i.e., a single absorbing plate, a single absorbing layer on a nonabsorbing substrate, and two identical absorbing layers on either side of a nonabsorbing substrate. For magnetic garnet films on nonabsorbing garnet substrates in the region of low absorption, the formulas predict an increase of MCD because of multiple reflections of the order of a few percent. On thin sections of magnetic semiconductors the effect can approach 15%, provided that the absorption is low.