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Dispersion of the Exciton Polariton Branches in CuCl and Their k ‐Dependent Splitting in a Magnetic Field
Author(s) -
Fröhlich D.,
Köhler P.,
Nieswand W.,
Mohler E.
Publication year - 1991
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221670117
Subject(s) - polariton , laser linewidth , photon , excited state , exciton , physics , dispersion (optics) , magnetic field , condensed matter physics , wave vector , field (mathematics) , mixing (physics) , resonance (particle physics) , atomic physics , optics , quantum mechanics , laser , mathematics , pure mathematics
The method of three‐photon difference‐frequency generation is used to measure resonances on the lower polariton branch in CuCl. Due to the small linewidth of the resonances (smallest width 80 μeV) it is possible to determine the splitting of the lower branch in a magnetic field at different k ‐values for the first time. Resonances on the upper polariton branches and on the longitudinal exciton branches can also be excited with the use of two‐ and three‐photon sum‐frequency generation and two‐photon absorption. The rather peculiar wavevector‐dependent splitting of the lower polariton branch is explained quantitatively by taking into account the field induced mixing of the Z 3 ‐ and Z 1,2 ‐excitons.