Figure 4: Statistical mixture of intensity increments and turbulent behaviour near the threshold in Er-RFL.

(a) Semi-log plot of the distribution P(x) of experimental intensity increments x (blue circles) near the threshold, at the excitation power (normalized by the threshold value) P/P_th=0.99 and the prediction from the hierarchical model (2) for the statistical mixture (11) (red line). The individual components of the mixture, given by two K-distributions with N=1, are shown by green lines. The inset shows the corresponding time series of intensity increments. A single time scale (N=1) in the dynamics of the background variable characterizes the turbulent behaviour of the intensity fluctuations dynamics in Er-RFL near the threshold. (b) Log–log plot of the density function f(ε) of the experimental variance series ε(t) (blue circles) and the hierarchical model prediction for the statistical mixture (12) (red line), with same parameters as in a. The individual components of the statistical mixture are shown by green lines. The inset displays the compounding of ε(t) with a Gaussian function (red line) and the experimental distribution (black circles).