Skip to Main Content
We experimentally studied the dependence of the threshold energy density Eth/S in Nd0.5La0.5Al3(BO3)4 random laser on the diameter of the pumped spot d and found that at d≥130μm, Eth/S is proportional to 1/d+const. This functional dependence is different from the one commonly expected in the case of diffusion, ∝1/d2+const. However, the obtained experimental dependence does not mean the failure of the diffusion model. Calculating the mean photon's residence time τresp (which photons, making their diffusion-like random walks, spend inside the gain volume) as the function of d and further assuming that Eth/S∝(τpres)-1, we predicted the experimentally obtained functional dependence, ∝1/d+const. The major difference between our model and that of and was in the boundary conditions.