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We present a stochastic model for amplifying, diffusive media like, for instance, random lasers. Starting from a simple random-walk model, we derive a stochastic partial differential equation for the energy field with contains a multiplicative random-advection term yielding intermittency and power-law distributions of the field itself. Dimensional analysis indicate that such features are more likely to be observed for small enough samples and in lower spatial dimensions. The model prediction are compared with experimental data.
References S. Lepri Fluctuations in a diffusive medium with gain Phys. Rev. Lett. 110, 230603 (2013). E. Ignesti et al Experimental and theoretical investigation of statistical regimes in random laser emission to appear in Phys. Rev. A |