Bidirectional 60-GHz RoF System With Multi-Gb/s $M$-QAM OFDM Single-Sideband Modulation Based on Injection-Locked Lasers

We have experimentally demonstrated a 60-GHz bidirectional radio-over-fiber system with single-sideband (SSB) modulation of orthogonal frequency-division-multiplexing (OFDM) signals for the downlink and wavelength reuse for the uplink. A two-carrier-injected distributed-feedback laser is used to realize the OFDM signals' SSB modulation in the central office for the downlink. In the uplink, the weakly modulated one of the two downlink carriers is filtered out for wavelength reuse. Transmission of 4.3-Gb/s 16-quadrature-amplitude-modulation (QAM) or 3.2-Gb/s 64-QAM OFDM signals on the 60-GHz carrier for the downlink and the 2.5-Gb/s nonreturn-to-zero signal for the uplink are both successfully demonstrated over 56-km standard single-mode fiber without chromatic dispersion compensation.