Fig. 2
From: Active sorting of orbital angular momentum states of light with a cascaded tunable resonator
Separation of co-propagating OAM states. a Intensity distribution of the incident beam with the superposition of two OAM states (|l = +1〉 and |l = +2〉). b, c Transmitted intensity distributions after the FP cavity is tuned on resonance. The topological charge of the transmitted OAM state is quantified via the fork-like interference patterns d, e. f. Transmission of the superposition OAM states as a function of the cavity length (blue line), accompanied by reference spectra of the two individual OAM states (green: |l = +1〉; red: |l = +2〉). The much smaller peaks in the data mainly originate from errors inherent in the iterative algorithm used to generate the superimposed states
