Observations of non-Rayleigh statistics in the approach to photon localization

We measure the distribution of intensity of microwave radiation transmitted through absorbing random waveguides of lengths L up to localization length xi. For large intensity values the distribution is given by a negative str etched exponential to the 1/2 power, in agreement with predictions by Nieuw enhuizen and van Rossum [Phys. Rev. Lett. 74, 2674 (1995)] for diffusing wa ves in nonabsorbing samples, as opposed to a negative exponential given by Rayleigh statistics. The intensity distribution is well described by a tran sform derived by Kogan and Kaveh [Phys. Rev. B 52, R3813 (1995)] of the mea sured distribution of total transmission. (C) 1999 Optical Society of Ameri ca. OCIS codes: 290.0290, 290.4210, 030.6600.