Measurements of Intensity Distributions in the Approach to Localization

M. Stoytchev, A. Z. Genack

Published 1998-05-19Version 1

We report measurements of intensity distributions of transmitted microwave radiation in quasi-1D samples with lengths L as large as the localization length $\xi$. In contrast to negative exponential statistics found in the diffusive limit, the distribution falls as a stretched exponential of power 1/2 and becomes nearly log-normal as L approaches $\xi$. We confirm the relation between the moments and full distributions of the intensity and total transmission obtained by Kogan and Kaveh using random matrix theory. Good agreement is found when this relationship is used to compare measurements of intensity distribution in strongly absorbing samples with lengths as large as $\xi$ with calculations by Brouwer of the transmission distribution. The variances of the measured distributions increase superlinearly near the localization threshold confirming the coexistence of localization and absorption and the suitability of these variances as measures of the closeness to the localization threshold.