PROBABILITY OF REFLECTION BY A RANDOM LASER

A theory is presented (and supported by numerical simulations) for pha se-coherent reflection of light by a disordered medium which either ab sorbs or amplifies radiation. The distribution of reflection eigenvalu es is shown to be the Laguerre ensemble of random-matrix theory. The s tatistical fluctuations of the albedo (the ratio of reflected and inci dent power) are computed for arbitrary ratio of sample thickness, mean foe path, and absorption or amplification length. On approaching the laser threshold all moments of the distribution of the albedo diverge. Its modal value remains finite, however, and acquires an anomalous de pendence on the illuminated surface area.