LOCALIZATION OF LIGHT BY RANDOMLY ROUGH SURFACES - CONCEPT OF LOCALITON

We give an electromagnetic explanation of the phenomenon of localizati on of light by randomly rough surfaces, using the notion of a surface localiton, viz., a radiative field emitted by a finite part of the rou gh surface and having an exponential decrease in time. It is shown tha t these localitons are linked to the existence of poles of the scatter ing matrix in the complex plane of frequencies. Using the model of a r andom grating, we search for these poles for increasing values of the rms of the surface. The numerical calculations show that the localizat ion length decreases as the rms (mean height of the asperities) is inc reased. The structure of these localitons is described from numerical calculations. Finally, an electromagnetic explanation of enhanced back scattering of light by randomly rough surfaces in terms of localiton i nteraction is conjectured.