INTENSITY STATISTICS AND THE FINESSE OF ELECTROMAGNETIC-RADIATION IN RANDOM STRUCTURES

The correlation function of microwave intensity with frequency shift is measured in random mixtures of Teflon and aluminum spheres at a metallic filling fraction of 0.20. We observe the first three terms in an expansion of the correlation function in a parameter that is the ratio of the spacing to the width of modes of the random medium. The expansion also applies to optical and electron waves. The expansion parameter is equivalent to the finesse of optical resonators. The intensity distribution at all sample thicknesses is found to be a stretched exponential.