Dresden 2006 – scientific programme
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DF: Dielektrische Festkörper
DF 10: Electric, Electromechanical and Optical Properties I
DF 10.7: Talk
Thursday, March 30, 2006, 16:50–17:10, M{\"U}L Elch
Ferroelectric domain gratings contributing to photo-induced polarization-anisotropic light scattering in LiNbO3:Fe — •A. Selinger, U. Voelker, and M. Imlau — Fachbereich Physik, Universität Osnabrück, Barbarastrasse 7, D-49069 Osnabrück
Only recently, the appearence of a bright polarization-anisotropic elliptical scattering pattern upon exposure to cw- and pulsed laser light has been discovered in thin Fe-doped LiNbO3 crystals, i.e. in samples with thicknesses below 900 µm [1]. Our further investigations reveal that this phenomenon can be explained by the interplay of photo-induced refractive-index and ferroelectric-domain gratings. For example, the kinetics of the scattering intensity of the ellipse is found to be identical to the kinetics of the so called e-line, which is a scattering pattern originating solely from the photo-induced formation of microdomains. At the same time, the polarization-flip observed in the ellipse, comparable to that in the well-known anisotropic ring, gives rise to a contribution of photorefractive gratings via the electrooptic tensor element r42. This approach is strongly supported by experimental studies of the influence of temperature towards appearence, stability and decay of the elliptical scattering pattern. An Ewald-construction, taking into account both photo-induced refractive-index and ferroelectric-domain gratings, is presented and allows to explain the specific shape of the ellipse.
Financial support by the Deutsche Forschungsgemeinschaft (DFG, project IM 37/2-1) is greatfully acknowledged.
[1] A. Selinger, U. Voelker, M. Imlau, OSA Trends in Optics and Photonics (TOPS), Vol. 99, pp. 61 -67