Localization-induced coherent backscattering effect in wave dynamics.

We investigate the statistics of single-mode delay times of waves reflected from a disordered waveguide in the presence of wave localization. The distribution of delay times is qualitatively different from the distribution in the diffusive regime, and sensitive to coherent backscattering: The probability of finding small delay times is enhanced by a factor close to sqrt[2] for reflection angles near the angle of incidence. This dynamic effect of coherent backscattering disappears in the diffusive regime.

High-frequency dynamics of wave localization.

We study the effect of localization on the propagation of a pulse through a multimode disordered waveguide. The correlator of the transmitted wave amplitude u at two frequencies differing by delta omega has for large delta omega the stretched exponential tail proportional to (- square root[tau(D)delta omega/2]). The time constant tau(D)=L(2)/D is given by the diffusion coefficient D, even if the length L of the waveguide is much greater than the localization length xi. Localization has the effect of multiplying the correlator by a frequency-independent factor exp(-L/2 xi), which disappears upon breaking time-reversal symmetry.