Dresden 2006 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 3: Poster Session

DF 3.15: Poster

Montag, 27. März 2006, 09:30–17:00, P1

Phonon modes of monoclinic BiB₃O₆ — •Th. Möller¹, A. Gößling¹, W.-D. Stein¹, P. Becker², L. Bohatý², and M. Grüninger³ — ¹2nd Physical Institute, University of Cologne, Zülpicher Str. 77, 50937 Cologne, Germany — ²Institute of Crystallography, University of Cologne, Zülpicher Str. 49b, 50674 Cologne, Germany — ³2nd Physical Institute, RWTH Aachen, Huyskensweg, 52056 Aachen, Germany

The large optical nonlinearities of BiB₃O₆, a polar, non-ferroelectric crystal, open up a rich field of applications for frequency conversion of laser light via χ⁽²⁾ and χ⁽³⁾ processes, e.g. phase-matched second harmonic generation (SHG) or optical parametric oscillation (OPO) and stimulated Raman scattering (SRS). The exceptional optical nonlinearities of BiB₃O₆ have been attributed to the hyperpolarisabilities of the [BO₃] structural units and the [BiO₆] units with a lone electron pair. Lattice dynamics studies are required for a quantitative description of the crystal structure and are the basis for an interpretation of the nonlinear optical interaction. We present a detailed study of the phonon modes of this monoclinic compound based on polarized reflectivity measurements on single crystals. The spectra are analysed by means of a generalized Drude-Lorentz model, which allows us to resolve the modes of A and B symmetry.