skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Electromagnetic waves in uniaxial crystals with metallized boundaries: Mode conversion, pure reflections, and bulk polaritons

Abstract

A theory is constructed for the reflection of plane electromagnetic waves in uniaxial crystals with a positive definite permittivity tensor and an arbitrarily oriented metallized boundary. The problem is solved both for general-position orientations corresponding to three-partial reflection and for special conditions allowing two-partial reflections: mode conversions when the incident and reflected waves belong to different sheets of the refraction surface and 'pure' reflections when both waves belong to the same sheet. The space of pure reflections is shown to be formed by two types of optical-axis orientations: arbitrary directions in the plane of the crystal surface and in the plane of incidence. The configurations of the conversion surface for optically positive and negative crystals are investigated. A subspace of pure reflections that transform into one-partial bulk polaritons with the energy flux parallel to the surface at grazing incidence has been found. The domain of existence of such bulk eigenmodes is bounded by two 'lines' of solutions. These are any directions along the boundary containing the optical axis for ordinary polaritons and the direction along the projection of the optical axis onto the surface at an arbitrary orientation of the axis with respect to the boundary for extraordinary polaritons.

Authors:
;  [1];  [2]
  1. Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)
  2. Kielce University of Technology (Poland)
Publication Date:
OSTI Identifier:
21072557
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Experimental and Theoretical Physics; Journal Volume: 104; Journal Issue: 1; Other Information: DOI: 10.1134/S1063776107010025; Copyright (c) 2007 Nauka/Interperiodica; Article Copyright (c) 2007 Pleiades Publishing, Inc; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CONFIGURATION; CONVERSION; CRYSTALS; ELECTROMAGNETIC RADIATION; MODE CONVERSION; ORIENTATION; PERMITTIVITY; POLARONS; REFLECTION; REFRACTION; TENSORS

Citation Formats

Alshits, V. I., E-mail: alshits@ns.crys.ras.ru, Lyubimov, V. N., and Radowicz, A. Electromagnetic waves in uniaxial crystals with metallized boundaries: Mode conversion, pure reflections, and bulk polaritons. United States: N. p., 2007. Web. doi:10.1134/S1063776107010025.
Alshits, V. I., E-mail: alshits@ns.crys.ras.ru, Lyubimov, V. N., & Radowicz, A. Electromagnetic waves in uniaxial crystals with metallized boundaries: Mode conversion, pure reflections, and bulk polaritons. United States. doi:10.1134/S1063776107010025.
Alshits, V. I., E-mail: alshits@ns.crys.ras.ru, Lyubimov, V. N., and Radowicz, A. Thu . "Electromagnetic waves in uniaxial crystals with metallized boundaries: Mode conversion, pure reflections, and bulk polaritons". United States. doi:10.1134/S1063776107010025.
@article{osti_21072557,
title = {Electromagnetic waves in uniaxial crystals with metallized boundaries: Mode conversion, pure reflections, and bulk polaritons},
author = {Alshits, V. I., E-mail: alshits@ns.crys.ras.ru and Lyubimov, V. N. and Radowicz, A.},
abstractNote = {A theory is constructed for the reflection of plane electromagnetic waves in uniaxial crystals with a positive definite permittivity tensor and an arbitrarily oriented metallized boundary. The problem is solved both for general-position orientations corresponding to three-partial reflection and for special conditions allowing two-partial reflections: mode conversions when the incident and reflected waves belong to different sheets of the refraction surface and 'pure' reflections when both waves belong to the same sheet. The space of pure reflections is shown to be formed by two types of optical-axis orientations: arbitrary directions in the plane of the crystal surface and in the plane of incidence. The configurations of the conversion surface for optically positive and negative crystals are investigated. A subspace of pure reflections that transform into one-partial bulk polaritons with the energy flux parallel to the surface at grazing incidence has been found. The domain of existence of such bulk eigenmodes is bounded by two 'lines' of solutions. These are any directions along the boundary containing the optical axis for ordinary polaritons and the direction along the projection of the optical axis onto the surface at an arbitrary orientation of the axis with respect to the boundary for extraordinary polaritons.},
doi = {10.1134/S1063776107010025},
journal = {Journal of Experimental and Theoretical Physics},
number = 1,
volume = 104,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • The transverse bulk polariton dispersion curves in the region above 400 cm/sup -1/ in uniaxial Al/sub 2/O/sub 3/ were determined from the inflection points on the smooth edges of the high-reflectivity bands in infrared spectra measured at various angles of incidence for TM polarization.
  • One of the mechanisms for generating electromagnetic plasma waves (Z-mode and LO-mode) is mode conversion from electrostatic waves into electromagnetic waves in inhomogeneous plasma. Herein, we study a condition required for mode conversion of electrostatic waves propagating purely perpendicular to the ambient magnetic field, by numerically solving the full dispersion relation. An approximate model is derived describing the coupling between electrostatic waves (hot plasma Bernstein mode) and Z-mode waves at the upper hybrid frequency. The model is used to study conditions required for mode conversion from electrostatic waves (electrostatic electron cyclotron harmonic waves, including Bernstein mode) into electromagnetic plasma wavesmore » (LO-mode). It is shown that for mode conversion to occur in inhomogeneous plasma, the angle between the boundary surface and the magnetic field vector should be within a specific range. The range of the angle depends on the norm of the k vector of waves at the site of mode conversion in the inhomogeneous region. The present study reveals that inhomogeneity alone is not a sufficient condition for mode conversion from electrostatic waves to electromagnetic plasma waves and that the angle between the magnetic field and the density gradient plays an important role in the conversion process.« less
  • A coupled state of an electromagnetic field with an electric or magnetic dipole-carrying excitation is well known as a polariton. Such a state is the result of the mixing of a photon with the excitation of a material. The most discussed types of polaritons are phonon polaritons, exciton polaritons, and surface-plasmon polaritons. Recently, it was shown that, in microwaves, strong magnon-photon coupling can be achieved due to magnetic-dipolar-mode (MDM) vortices in small thin-film ferrite disks. These coupled states can be specified as MDM-vortex polaritons. In this paper, we study the properties of MDM-vortex polaritons. We numerically analyze a variety ofmore » topological structures of MDM-vortex polaritons. Based on analytical studies of the MDM spectra, we give theoretical insight into a possible origin for the observed topological properties of the fields. We show that the MDM-vortex polaritons are characterized by helical-mode resonances. We demonstrate the PT-invariance properties of MDM oscillations in a quasi-two-dimensional ferrite disk and show that such properties play an essential role in the physics of the observed topologically distinctive states with the localization or cloaking of electromagnetic fields. We may suppose that one of the useful implementations of the MDM-vortex polaritons could be microwave metamaterial structures and microwave near-field sensors.« less
  • We have derived analytic expressions, in terms of Airy functions, for thereflection and mode-conversion coefficients of Langmuir and electromagneticwaves in an inhomogeneous, unmagnetized plasma. The reflection coefficient forthe ''direct'' problem (incident electromagnetic wave) is equal in magnitude tothat for the ''inverse'' problem (incident electrostatic wave) and thecorresponding mode-conversion coefficients satisfy energy conservation. Ourresults, which are valid in the limit of nonrelativistic electron temperature,/ital T///ital mc//sup 2//much lt/1, agree with earlier numerical calculations.
  • A fourfold increase in the conversion of thermal electron Bernstein waves ~EBW! to the extraordinary mode (X mode! was measured when the density scale length (Ln) was progressively shortened by a local boron nitride limiter in the scrape-off of an Ohmically heated National Spherical Torus Experiment plasma @M. Ono, S. Kaye, M. Peng et al., Proceedings of the 17th IAEA Fusion Energy Conference ~IAEA, Vienna, 1999!, Vol. 3, p. 1135#. The maximum conversion efficiency approached 50% when Ln was reduced to 0.7 cm, in agreement with theoretical predictions that used locally measured Ln . Calculations indicate that it is possiblemore » to establish Ln ,0.3 cm with a local limiter, a value predicted to attain ;100% EBW conversion to the X mode in support of proposed EBW heating and current drive scenarios. 2003 American Institute of Physics. @DOI: 10.1063/1.1564081#« less