Cylindrical vector beam multiplexing for radio-over-fiber communication with dielectric metasurfaces.

Radio-over-fiber (ROF) technology, loading microwave signal on light beams, has attracted considerable attention in wireless access network for its superiority in processing high-frequency microwave signals. Multiplexing for achieving high-capacity density, however, remains elusive in ROF communication because the optical microwave occupies large bandwidth. Here, we introduce a cylindrical vector beam (CVB) multiplexing for ROF communication with dielectric Pancharatnam-Berry phase-based metasurfaces (PBMs). CVBs, a structured light beam possessing spatially nonuniform polarization distribution and carrying vector mode, provide an additional multiplexing dimension for optical communication with the advantages of weak scintillation in free-space and low mode injure in few-mode-fiber. Exploiting the spin-orbit interaction of the PB phase, we construct PBMs to manipulate CVBs, which show broadband working wavelengths ranging from C- to L-band. After 3 m free-space propagation, two multiplexed CVBs carrying 100 GHz microwave are successfully demultiplexed, and the 100 GHz ROF communication with 12 Gbit/s QPSK-OFDM signals is realized. The crosstalk of the multiplexed CVBs is less than -15.13 dB, and the bit-error-rates (BERs) are below 3.26 × 10-5. With 5 km few-mode-fiber transmission, the CVBs are also demultiplexed with the BERs of 6.51 × 10-5. These results indicate that CVB is not only capable of free-space transmission but also available for few-mode-fiber transmission, which might pave new avenues for the multiplexing of ROF communications.