Random lasing under diffusive light propogation

The physical model of random lasing (RL) based on the concept of feedback distributed laser (FDL) are developed. It based on similarity of RL formation from scattered waves in a random laser and from reflected waves in FDL. In contrast to FDL the RL spatial feedback distribution along the radiation trajectories is random. All radiation trajectories interrelated in the tangle by scattering can be represented as the imaginary one-dimensional chain including all enabled scatterers and keeping radiation under any scattering event. Output intensity of this chain is described by the expression being similar to one for the single-pass amplifier with length determined by concentration of scattering particles and gain. The expression adequately describes the main RL behaviors: narrowing of radiation spectrum under pump intensity and scatterer concentration increase.