Affecting weak light localization by strong magnetic fields

We report an experimental study of the magneto-optical Faraday effect in strongly multiple scattering media using magnetic fields up to 23 Tesla. Faraday rotation of the polarization of laser light, diffusing through samples consisting of colloidal particles embedded in a Faraday-active glass matrix, is found to destroy coherent backscattering. The angular shape of the coherent backscattering cone varies as a function of the applied field B in agreement with a simple model and with numerical simulations. In particular, the intensity at backscattering is found to decrease with B like the intensity with scattering angle at B = 0, as predicted. The multiple scattering Faraday effect provides a unique experimental way to destroy constructive interferences between time reversed optical scattering paths. It is thus expected to affect light localization and may be used to prove (or disprove) its existence.