Excitation of localized modes in active random media

Summary form only given. Lasing in strongly scattering media with resonant feedback has recently been reported. In this work, we discuss the interplay of Anderson localization and laser action in active random media. The system is a two-dimensional medium made of circular scatterers imbedded in an active matrix. We have used a numerical model, which solves simultaneously the Maxwell's equations and the rate equations of a four-level atomic system.