Fluctuation channeling and time delay of a pulse signal in a randomly stratified medium

The method of resonance expansion of one-dimensional fields is extended to the case of point-source-radiated narrow-band signals propagating in randomly layered low-dissipative media. Pulse ducting within a fluctuation waveguide and unification of the intensity spectrum far away from the source are predicted. It is an interference (Anderson) localization of multiply scattered constituent plane harmonics that causes the appearance of the low-decaying pulse tail in a 1D disordered system. Interference localization is known to appear in the case of elastic scattering only. As regards the classical waves, it was previously predicted for monochromatic point-source signals. In this paper, the problem is solved with regard to the propagation of non-stationary narrowband signals. In this case correlation of harmonics of different genuine frequencies is of decisive importance and should be properly taken into account.