Figure 6
(a) Relative-Intensity-Noise RF spectrum of the vortex laser measured by integrating a fraction of the beam surface, for 
and fc = 12 MHz. (b) Measured and simulated beat frequencies between selected 
and 
vortex modes and residual contra-rotating modes, as a function of the modal phase perturbation amplitude |Δϕmodal|. The cavity frequency cutoff fc = 12 MHz (F = 625, 
) is represented by dashed horizontal line splitting the figure into two parts: upper and lower with strong and weak control of the OAM sign respectively.
