BEYOND EFFECTIVE-MEDIUM THEORY - PULSE STABILIZATION FOR MULTIMODE WAVE-PROPAGATION IN HIGH-CONTRAST LAYERED MEDIA

A multimode plane wave pulse propagates through a rapidly varying, sta tistically stationary, layered medium with high contrast between the m aterial parameters in consecutive layers. The wavelength of the pulse is long in comparison to a typical layer thickness. The pulse shape ch anges on a depth scale that is large in comparison to the wavelength. The pulse broadens and attenuates due to multiple scattering by the la yered structure. We find simple asymptotic formulas for the travel tim e and the pulse shape that account for fine layering effects. The limi ting pulse shape is given by a convolution of the incident pulse shape with a. Gaussian whose squared width is deterministic: i.e., it is in dependent of the particular realization of the random medium, and it d epends on the second-order statistics of the random medium only The ne w theory consolidates the localization phenomenon for waves with effec tive medium theory.