Polarization-dependent phase-modulation metasurface for vortex beam (de)multiplexing

Vortex beams (VBs) carrying orbital angular momentum (OAM) have shown promising potential in enhancing communication capacity through the possession of multiple multiplexing dimensions involving the OAM mode, polarization, and wavelength. Although many research works on multidimensional multiplexing have been conducted, the (de)multiplexer compatible with these dimensions remains elusive. Following the expanded concept of the Pancharatnam-Berry (PB) phase, we designed a polarization-dependent phase-modulation metasurface to phase-modulate the two orthogonal linearly polarized components of light, and two Dammann vortex gratings with orthogonal polarization responses were loaded to simultaneously (de)multiplex OAM mode and polarization channels. As a proof of concept, we constructed a 16-channel multidimensional multiplexing communication system (including two OAM modes, two polarization states, and four wavelengths), and 400 Gbit/s quadrature-phase shift-keying (QPSK) signals were transmitted. The results demonstrate that the OAM mode and polarization channels are successfully (de)multiplexed, and the bit-error-rates (BERs) are below 1.67 × 10^-6 at the received power of -15 dBm.