Speckle experiments in random lasers

Abstract

We present measurements of speckle in a random laser. We analyze its first-order statistics and show that, contrary to what might be expected for passive systems, analyses of the intensity distribution [formula presented] and the speckle spot size do provide information about light transport inside the system. [formula presented] is used to determine the degree to which an incident probe is amplified by the random laser. The shrinking speckle spot size reflects the change in path length distribution [formula presented] we deduce that the average path length [formula presented] in the studied random laser is two times longer above threshold than in a passive diffusive system. © 2002 The American Physical Society.