Berlin 2014 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 19: Quantum effects: Light scattering and propagation

Q 19.6: Vortrag

Dienstag, 18. März 2014, 11:45–12:00, DO26 208

Frequency Correlations in Reflection from a Random Medium — •Angelika Knothe and Thomas Wellens — Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg

For the treatment of wave propagation in random media, a proper understanding of the interference effects that have impact on the average intensity is crucial. Well-known manifestations of such interference effects are coherent backscattering (enhancement of average backscattered intensity in backscattering direction) or weak localization (reduction of diffusion constant). In an earlier work [1], we studied the first order corrections to the average reflected intensity in an expansion in the disorder parameter 1/kℓ (k denotes the wave number, and ℓ stands for the scattering mean free path). In the present contribution, we focus on the properties of the frequency correlation function defined as the average product of two intensities reflected from a random scattering medium at different frequencies. As revealed by experiment [2], this correlation function proved to be much more sensitive to an increase of the disorder strength than the coherent backscattering cone, and undergoes a breakdown for larger values of 1/kℓ approaching the localization threshold. In order to obtain a better understanding of the experimental results, we include those scattering diagrams giving rise to the first order corrections in 1/kℓ in our theoretical treatment.

[1] A. Knothe and T. Wellens, J. Phys. A 46, 315101 (2013)

[2] O. L. Muskens, T. van der Beek and A. Lagendijk, Phys. Rev. B 84, 035106 (2011)