Fig. 1. Schematic of (a) on-axis and (b) off-axis cascade metasurface OAM demultiplexing system

Fig. 2. (a) Polarization conversion efficiency of a unitary structure as a function of wavelength; (b) Polarization conversion efficiency of a unitary structure as a function of off-angle

Fig. 3. (a) Schematic of signal/noise in OAM demultiplexing system based on on-axis cascaded metasurface; (b) SNR of demultiplexing system as a function of polarization conversion efficiency

Fig. 4. (a) Schematic of signal/noise in OAM demultiplexing system based on off-axis cascaded metasurface; (b) SNR of demultiplexing system as a function of polarization conversion efficiency and off-angle

Fig. 5. (a) On-axis and (b) off-axis , intensity profiles corresponding to different OAM states (l = ±1, ±3); (c) Normalized noise intensities in the range of outgoing field for different OAM states (l = ±1, ±3) in on-axis and off-axis system