Fig. 4
From: Active sorting of orbital angular momentum states of light with a cascaded tunable resonator
Simultaneous sorting of OAM and wavelength. Simultaneous OAM and wavelength multiplexing/demultiplexing in an incident beam. The blue and green lines indicate the single OAM states generated from the same laser with three laser lines (the central wavelength is 632.816 nm in air, and the separation of each laser line is 0.000584 nm), while the red line represents an incident beam with both OAM states at the three laser lines. The peaks of the mixed OAM states match those of the individual OAM states. Insets: CCD images of each of the six resonant transmissions
