LOCALIZATION OF LIGHT BY RANDOMLY ROUGH SURFACES - CONCEPT OF LOCALITON

We give an electromagnetic explanation of the phenomenon of localization of light by randomly rough surfaces, using the notion of a surface localiton, viz., a radiative field emitted by a finite part of the rough surface and having an exponential decrease in time. It is shown that these localitons are linked to the existence of poles of the scattering matrix in the complex plane of frequencies. Using the model of a random grating, we search for these poles for increasing values of the rms of the surface. The numerical calculations show that the localization length decreases as the rms (mean height of the asperities) is increased. The structure of these localitons is described from numerical calculations. Finally, an electromagnetic explanation of enhanced backscattering of light by randomly rough surfaces in terms of localiton interaction is conjectured.