Weak localization and enhanced backscattering of light in dilute suspensions

The differential scattering cross-section of light from a cluster of two small dielectric spheres is calculated exactly and it has been shown that after averaging over cluster orientations a backscattering peak emerges. The height and the width of this peak depend on the polarization state of the incoming and the outgoing waves and for a linearly polarized incident wave the peak is anisotropic, in agreement with existing experimental data. It is predicted that a giant backscattering peak will be observed for light in an appropriate frequency range if metal instead of dielectric spheres are used in the experiment. Fluctuations of the scattered intensity are also calculated.