Conservation of energy in coherent backscattering of lightS. Fiebig1, C. M. Aegerter1, W. Bührer1, M. Störzer1, E. Akkermans2, G. Montambaux3 and G. Maret1
1 Fachbereich Physik, University of Konstanz - Box M621, 78457 Konstanz, Germany
2 Department of Physics, Technion Israel Institute of Technology - 32000 Haifa, Israel
3 Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris-Sud - 91405 Orsay, France
received 8 November 2007; accepted in final form 26 January 2008; published March 2008
published online 22 February 2008
Although conservation of energy is fundamental in physics, its principles seem to be violated in the field of wave propagation in turbid media by the energy enhancement of the coherent backscattering cone. In this letter we present experimental data which show that the energy enhancement of the cone is balanced by an energy cutback at all scattering angles. Moreover, we give a theoretical description which is in good agreement with these data. The additional terms needed to enforce energy conservation in this description result from an interference effect between incident and multiply scattered waves, which is reminiscent of the optical theorem in single scattering.
42.25.Dd - Wave propagation in random media.
73.20.Fz - Weak or Anderson localization.
42.25.Hz - Interference.
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