COHERENT BACKSCATTERING OF A LIGHT-PULSE BY A SLAB OF DISORDERED MEDIUM

We obtain an exact analytical solution to the problem of the enhanced backscattering of a short pulsed signal from a two- and three-dimensio nal medium with isotropically scattering centres. The angular spectrum is expressed in terms of the solution to the corresponding stationary problem. The intensity oscillations are shown to appear on the tails of the angular spectrum. The origin of these oscillations is associate d with the ballistic phase shift between the interfering waves arrivin g at the detector. It is shown that the finiteness of the slab thickne ss influences the magnitude of the backscattering intensity and does n ot change the shape of the angular spectrum. The range of validity for the diffusion approximation is pointed out. The results obtained in t he paper also contain a generalization of the well known solution to t he problem of incoherent transfer of a pulsed signal to the case of tw o-dimensional disordered media.