Coherent light transport in randomly assembled, highly multiple scattering media

Éric Akkermans, Gilles Montambaux

Stephan Smolka, Alexander Huck, Ulrik L. Andersen +1 more

俊 三宮

Otto L. Muskens, Timmo van der Beek, Thomas Wellens

We experimentally demonstrate ultrafast control over reciprocal light paths in random media. The combination of multiple scattering and coherence of light gives rise to strong interference contributions in light transport. An important interference correction to diffusion theory is the coherent backscattering effect, the constructive interference of reciprocal light paths in the backscattering direction. Our experiments show that the phase coherence between these paths can be suppressed by introducing dynamics faster than the photon dwell time. This adiabatic dephasing is of interest for its potential for controlling weak and strong localization and adiabatic storage and release of photonic information.

Igor M. Sokolov, William Guerin

Collective effects in the atom–light interaction are of great importance for cold-atom-based quantum devices or fundamental studies on light transport in complex media. Here we discuss and compare three different approaches to light scattering by dilute cold atomic ensembles. The first approach is a coupled-dipole model, valid at low intensity, which includes cooperative effects, such as superradiance, and other coherent properties. The second one is a random-walk model, which includes classical multiple scattering and neglects coherence effects. The third approach is a crude approximation based only on the attenuation of the excitation beam inside the medium, the so-called shadow effect. We show that in the case of a low-density sample, the random-walk approach is an excellent approximation for steady-state light scattering and that the shadow effect surprisingly gives rather accurate results at least up to optical depths on the order of 15.

C.H. Wang