Figure 3: Gaussian distribution of intensity increments and non-turbulent prelasing behaviour in Er-RFL.

Semi-log plot of the distribution P(x) of experimental intensity increments x in the non-turbulent prelasing regime at the excitation power (normalized by the threshold value) P/P_th=0.72 (blue circles) and best fit to a Gaussian function (red line). The intensity increments are defined as the stochastic process given by , where δI(t) ≡ I(t+1)−I(t) denotes the fluctuations of maximum intensities in 150,000 successive optical spectra and var(δI(t)) is the variance of the time series of intensity increments. The inset displays the corresponding time series of x(t) as function of the dimensionless time index t=1, 2, …, 150,000.