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DF: Fachverband Dielektrische Festkörper

DF 14: Photonic Dielectrics III

DF 14.3: Vortrag

Donnerstag, 26. März 2009, 11:00–11:20, WIL A317

Space-charge wave excitation by static and moving interference patterns — •Burkhard Hilling, Kay-Michael Voit, and Mirco Imlau — Department of Physics, University of Osnabrück, Germany

We report on our first experimental results, where SCW excitation was succesfully realized by simultaneous exposure with a static and a running interference pattern having the same spatial frequency. The static and running interference patterns are generated independently from each other using a new designed four-beam interferometer with only one light source. For this study, a single crystal of BGO (Bi₁₂GeO₂₀) was applied as an example. The investigations were performed at a wavelength of 514 nm using a total light intensity of 30 mW/cm² and spatial frequencies of (0.5−12)· 10³ cm⁻¹, while static electric fields of up to 10 kV/cm were applied. For a better evaluation of this method SCW were also excited in the same sample under the same experimental conditions using the established method of an oscillating interference pattern. The comparison of both sets of data shows an improvement in the way of excitation of the new method, particularly the quality factor is increased. This method also enables us to determine the sign of the charge carriers participating in SCW formation. Further advantages and disadvantages are discussed. Financial support from the Deutsche Forschungsgemeinschaft within the Graduate College 695 is gratefully acknowledged.