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Raman Scattering by Polaritons in Polyatomic Crystals

  • E. Burstein
  • S. Ushioda
  • A. Pinczuk
  • J. F. Scott

Abstract

Polaritons participate in first order Raman scattering via atomic displacement and macroscopic electric field induced changes in the electric susceptibility, \[{\chi _\pi }^{\left( 1 \right)}\,\overrightarrow {\left( u \right)} \] and χ Π (1) (E), respectively. In polyatomic crystals, polaritons correspond to photons coupled to all of the q ≈ 0 IR active TO phonons. \[{\chi _\pi }^{\left( 1 \right)}\,\overleftarrow {\left( u \right)} \] is accordingly expressed in terms of the atomic displacement vector \[\overrightarrow {{u_j}} \left( {{\omega _\pi }} \right)\] and the atomic displacement susceptibility tensor a. of the q ≈ 0 TO phonons. χ Π (1) (E) is expressed in terms of the macroscopic electric field of the polariton mode \[\overrightarrow {{E_T}} \left( {{\omega _\pi }} \right)\], and the macroscopic electro-optic coefficient, b, of the crystal. \[\overrightarrow {{u_j}} \left( {{\omega _\pi }} \right)\] is expressed in terms of \[\overrightarrow {{E_T}} \left( {{\omega _\pi }} \right)\] by means of the coupled equations of motion and \[\overrightarrow {{E_T}} \left( {{\omega _\pi }} \right)\] is obtained from the expressions for the energy density of electromagnetic radiation in a dispersive medium and the frequency dependent dielectric constant ε (ω). The use of polariton scattering spectra to obtain ω vs q polariton dispersion curves and ε (ω) is illustrated for the A1 symmetry polaritons in tetragonal BaTiO3.

Keywords

Atomic Displacement Polariton Mode Order Band Scatter Wave Vector Macroscopic Electric Field 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 1969

Authors and Affiliations

  • E. Burstein
    • 1
  • S. Ushioda
    • 1
  • A. Pinczuk
    • 1
  • J. F. Scott
    • 2
  1. 1.Laboratory for Research on the Structure of Matter and Department of PhysicsUniversity of PennsylvaniaPhiladelphiaUSA
  2. 2.Bell Telephone LaboratoriesIncorporatedHolmdelUSA

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