Optimization of Vector Signal Delivery Over Double-Sideband Carrier-Suppressed Optical Millimeter-Waves Through DC Coupling

A novel vector signal transmission scheme through double-sideband carrier-suppressed (DSB-CS) radio-over-flber system is proposed and experimentally demonstrated. Traditionally, the single-stage DSB-CS optical millimeter (mm)-wave generation scheme could not deliver a vector signal due to the loss of phase information at the receiver. However, we found that by simply adding dc offset to the transmitting vector signal, the desired signal after beating at the receiver can be preserved and enhanced without introducing any hardware complexity to existing systems. A feasibility demonstration of transmitting a 200-Mb/s quadrature phase-shift-keying orthogonal frequency-division-multiplexing (QPSK-OFDM) signal on 60-GHz optical mm-wave over 10-km standard single-mode fiber (SSMF) has been successfully completed with a demodulated error vector magnitude (EVM) less than 5.52% in our experiment. In addition, the value of the required dc offset and its impact to the system performance is also experimentally investigated.