Bandwidth-efficient subcarrier multiplexing radio-over-fiber system based on independent-sideband modulation

We propose and experimentally demonstrate a broadband subcarrier multiplexing (SCM) radio-over-fiber (RoF) system using the optical independent-sideband (O-ISB) modulation, to improve bandwidth efficiency and to compensate for fiber dispersion induced power fading. The O-ISB modulation allows the upper and lower sidebands to carry individual data, thus doubling the spectral efficiency. A novel crosstalk mitigation scheme based on the judicious frequency plan of the low-frequency SCM channels is incorporated with advanced digital signal processing (DSP) algorithms, to effectively harvest the advantages of O-ISB modulation. In proof-of-concept experiments, the transmission of 45 500-MHz QPSK-OFDM SCM channels (corresponding to a data rate of 45 Gbit/s) over a 50-km fiber link is successfully demonstrated, while the required bandwidth is less than 16 GHz.