Metasurface Based Optical Orbital Angular Momentum Multiplexing for 100 GHz Radio Over Fiber Communication

Optical vortex beams (VBs) carrying orbital angular momentum (OAM) have shown significant multiplexing ability in radio-over-fiber communication by virtue of their intrinsic mode orthogonality. However, the large bandwidth required by optical microwave and the narrow bandwidth of mode converters severely hinder its practical applications. By exploiting the Pancharatnam-Berry phase of metasurface, we experimentally demonstrate a mode conversion solution for OAM multiplexing based radio-over-fiber communication. Based on the dispersion-free Pancharatnam-Berry phase design, these metasurfaces show broadband working wavelengths (from 1540 nm to 1600 nm) and polarization-insensitive characteristic. These make them compatible with polarization division multiplexing (PDM) and wavelength division multiplexing (WDM). As a proof-on-concept, a three-dimensional multiplexing based radio-over-fiber communication are demonstrated with 2 OAM modes, 2 polarization states and 4 wavelengths, and these 16 channels are demultiplexed with crosstalk less than -13.29 dB. The communication sensitivity decreases about 2.5 dB after introducing PDM and WDM because of the increased crosstalk. The 96 Gbit/s QPSK-OFDM signals carried by 16 channels are demodulated with bit-error-rate lower than 3.2610^(-5) at 4.5 dBm.